yx^i^X^ ...iiiiiX^ " " ^^^ UMI "M ltlif " "'^^ FROM THE MEDICAL LIBRARY OF DR. CORYDON L. FORD. ] Bequeathed by Dr. Ford to the Medical Library of ^ 3 the University, June. 1894. t 3 „„^^,,.,,,,lltlTTfTTTIIIlllllli n lMTTTTTTTTTlT.Vf - -* - H mmm t^r IJ^ c$6^^r>^^ ^ ^ 2.2. mr-] \\ Digitized by the Internet Arciiive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/systemofhumanana1843wils WILSON'S ANATOMY. A SYSTEM HUMAN ANATOMY, GENERAL AND SPECIAL. BY ERASMUS WILSON, M.D., LECTURER OS ANATOMY, LONDON. AMERICAN EDITION EDITED BY PAUL B. GODDARD, A.M., M. D., DEMONSTRATOR, OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA ; MEMBER OF THE AMERICAN PHILOSOPHICAL SOCIETY; ACADEMY OF NATURAL SCIENCES ; PHILADELPHIA MEDICAL SOCIETY, ETC., ETC. '"'-BERr Sr WITH ONE HUNDRED AND SEVENTY ILLUSTRATIONS BY GILBERT, . FROM T H R S t: (J O N D LONDON EDITION. PHILADELPHIA: LEA AND B L A N C H A R D. 1843. 6iM /83 /rh Mi^f Entered, according to the Act of Congress, in the year 1842, by Lea and Bi-ANCHARD, in the Office of the Clerk of the District Court of the United States in and for the Eastern District of Pennsylvania. C. Sherman, Printer, 1!) St. James Street. ^ SIR ASTLEY PASTON COOPER, Bart., F.R.S., MEMBER OF THE INSTITUTE OF FRANCE, THIS WORK IS RESPECTFULLY INSCRIBED, IN ADMIRATION OP HIS GREAT AND ACKNOWLEDGED GENIUS; AND OF HIS SPLENDID AND UNWEARYING LABOURS IN THE CAUSE OF MEDICAL SCIENCE, BY THE AUTHOR. PREFACE TO THE FIRST ENGLISH EDITION. The favourable reception which my recent Work on Practical and Surgical Anatomy has received, both from the Profession and the press, commands my first attention and grateful remem- brance on again presenting myself to public notice as an aspirant for honours in the field of Medical Science. On the present occasion, I submit the Anatomist's Vade Mecum to the Members of the Profession, with the fullest assurance that they will find it to be a complete system of descriptive Anatomy, recording in its pages, in a clear, precise, and perspicuous style of expression, every important detail of human structure, and the most modern and valuable discoveries and researches in the Science of Anatomy. To the established practitioner it is a matter of great impor- tance that he should be possessed of the means, during the few spare hours which he can abstract from his anxious and respon- sible duties, of easily and agreeably refreshing his acquaintance with that science which is the acknowledged basis of all safe and skilful medical practice. Of this application of my pi'esent labours I have not been unmindful, in composing the Anatomist's Vade Mecum ; and I sincerely trust that the work will prove to be the instructive and interesting companion of his important practical avocations. The Student of Medicine, from the first moment of commen- cing his labours in the study of Anatomy, must be made aware of the absolute necessity that exists for clearness of thought, ex- actness of language, and a rigorous arrangement of ideas. He must feel confidence in the knowledge which he possesses, and he will then exhibit that confidence in the decision by which all 2 his actions will be characterized. As a text-book for illustrating in, a precise method the materials of instruction, this work is especially designed ; and the severity and inflexibility of order have not been departed from in treating of a single branch of the subject. Among the modern investigations of great interest of which I have availed myself, I may particularly enumerate those of Sir Astley Cooper, Kiernan, Henle, Good sir, and Searle, in addition to the important observations of other excellent anatomists. My thanks are especially due to Sir Astley Cooper, who, with his usual urbanity, has furnished me with much useful informa- tion, and has permitted me to emblazon my pages with the flat- tering patronage of his name. I have regarded this condescen- sion of so distinguished a surgeon and physiologist as a sacred trust reposed in my hands, and I have exerted myself to render my labours not unworthy of such gratifying confidence. I hope I may be permitted to say that the Engravings are beautiful examples of a most instructive and valuable art. The advantages of such illustrations in a demonstrative science cannot be too highly appreciated. The mode in which the Engravings have been printed, — a distinct branch of art in itself, — will not pass unnoticed by those who are acquainted with the complicated process and extreme care which are necessary to the production of the dehcacy and force of effect of such graphic illustrations. In conclusion, it giv^es me much pleasure to express the obliga- tions which are due from me to my friend and late pupil Mr. Oliver Thomas Miller, of Her Majesty's Navy, for the patient and industrious perseverance with which he devoted his time and ability during the summer months to assist me in the prosecution of my labours. 55 Upper Charlotte Street, Fitzroy Square, March 1840. PREFACE TO THE SECOND ENGLISH EDITION. Two years have not yet elapsed since the First Edition of the Anatomist's Vade Mecum was presented to the Public ; but that short period, brief though it is, has been most eventful as regards the history of this work. The most prominent of the events to which I allude is the departure from this earthly sphere of the distinguished patron of my undertaking. When he was pleased to crown my labours with his sanction, and lend to them the brightness of his name, he was in the enjoyment of perfect health ; he was still labouring in the field of Medical Science, an untiring labourer ; he was still looking forward to a long vista of usefulness and benevolent action. Now, Sir Astley Cooper is no more. It is not my in- tention, — and, indeed, if I were so inclined, I should lack the ability, — to write the eulogium of that universally esteemed and noble-hearted man. I shall content myself with remarking, that in him I have lost a kind and a warm friend, the Medical Pro- fession a distinguished ornament, and society a consolation and a resource under the torments of disease. Sir Astley Cooper was doubly eminent ; he was great as a scientific surgeon, but he was greater as a man : and though in his former capacity his name will be remembered as long as letters endure, his memory will survive until the human heart shall cease to vibrate to the note of sympathy and benevolence. But while I am thus humbly endeavouring to do justice to my own feelings in recording a feeble tribute towards a great debt of gratitude which I owe to the memory of Sir Astley Cooper, I do not forget that my warmest thanks are also due to my other patrons, the Medical Practitioners and Students of Great Britain, and to the conductors of the Medical Press. From the former 1 take this opportunity of acknowledging the receipt of numerous letters containing the most cheering and gratifying expressions ; and to the latter I am indebted for the independence of opinion, and liberality of sentiment, with which they have regarded my labours. It has been no slight source of gratification to me, that the work should have received so much attention from the profession in distant countries. The Anatomist's Vade Mecum is to be reprinted in the United States of America ; it is at this moment undergoing translation at Berlin ; while repeated overtures have been made to Mr. Churchill for its publication in France. I have endeavoured to render the present Edition more perfect than the preceding, by entering more fully into the description of such parts as were only scantily treated in the first. I regret that these additions have increased the size of the volume, — an effect that it has always been my foremost desire to avoid ; for if a large and a verbose book be at any time a great evil, it is so to its fullest extent in a volume which is intended to record only facts, as is the case with a work on Anatomy. In the present Edition, as in the former, I have availed myself of the labours of those who have been pursuing successfully separate branches of our science. Of them, I have recorded the investigations of Mr. Bowman, of King's College, on the minute anatomy of muscular fibre ; of Mr. Nasmyth, on the developement of the epithelium ; and of Mr. Curling, of the London Hospital, on the descent of the testis in the foetus. I have also contributed in this department some original researches, which I have myself made, on the minute structure of bone. The principal additions to the present Edition will be found in the chapters on the ligaments, muscles, nervous system, organs of sense, and viscera. I have appended to each muscle a separate paragraph, indicating its relations to surrounding parts ; and have augmented the number of wood-cut illustrations. January 1812. PREFACE TO THE AMERICAN EDITION. In republishing the present work, it was thought that its origi- nal title " Wilson's Anatomist's Vade Mecum," would lead to an incorrect appreciation of the nature and extent of the work ; the term " Vade Mecum" being in this country usually applied to small and concise manuals. The present work is, as its American title implies, a complete System of Human Anatomy, brought up to the present day, and although it is written in a curt and concise style, nothing is omitted which can be deemed important by the student or the general practitioner. In some points its author had not described parts and structures with sufficient accuracy, and had evidently neglected the contri- butions to the science from this side of the water ; these defi- ciencies I have endeavoured to supply by notes and additional illustrations. Some few alterations of names have been made in the body of the work, where the author's names were too English and not in common use in the United States. The illustrations are by far the most beautiful which have ever appeared in any anatomical work, and much praise is due Mr. R. S. Gilbert of this city for the masterly and spirited manner in which he has copied them. The originals were designed and executed expressly for this work, by Bagg, of London, whose reputation in this branch of art is deservedly high. I have long been convinced that the day would come in which it would be useless to present to the public a work on science. XIV PREFACE. unless it was accompanied with numerous and exact illustrations, as the road to the mind is so much shorter and easier through the eye, than any other avenue. This fact has been appreciated by the student of anatomy for some time, and although numerous splendid works have appeared, there has been none which gave so many and exact views at so low a cost, as the present. Paul B. Goddard. Philadelphia, October 1842. CONTENTS. CHAPTER I. OSTEOLOGY. Definition — Chemical composi- Regions of the skull . 55 tion of bone — Division in- Base of the skull . . 59 to classes - . - 17 Face - , 60 Structure of bone . - . 18 Orbits . 61 Developement of bone 21 Nasal fossae . 62 The skeleton - . . - 22 Teeth . 63 Vertebral column 23 ■ Structure , 64 Cervical vertebrae ... 24 Developement . 65 Atlas — Axis . - . -i 24-25 Growth . 68 Vertebra prominens 26 Eruption . 68 Dorsal vertebrae 26 Succession - . 69 Lumbar vertebrce ... 27 Os hyoides , 70 General considerations - 27 Thorax and upper extremity 70 Developement - . . 28 Sternum — Ribs - 71 Attachment of muscles - 28 Costal cartilages - . 72 Sacrum 29 Clavicle — Scapula - . 73 Coccyx 30 Humerus . 75 Bones of the cranium 30 Ulna . . 76 Occipital bone - . . 30 Radius ... . 77 Parietal bone ... 33 Carpal bones . 79 Frontal bone 34 Metacarpal bones . . 82 Temporal bone ... 36 Phalanges . 84 Sphenoid bone ... 40 Pelvis and lower extremity 84 Ethmoid bone ... 44 Os innominatum - . 85 Bones of tlie face ... 45 Ilium — Ischium - _ 85 Nasal 45 Os pubis . 85 Superior maxillary 45 Pelvis — Its Divisions — Axes Lachrymal bone - 48 — Diameters - . 88 Malar bone — Palate bone 48 Femur - . 89 Inferior turbinated bone 51 Patella— Tibia . 91 Inferior maxillary - - - 51 Fibula - . 93 Table of developements, articula- Tarsal bones - . 94 tions, &c. 53 Metatarsal bones . _ 95 Sutures - - . . 54 Phalanges Sesamoid bones - 98 99 CHAPTER II. THE LIGAMENTS. Forms of articulation - - 100 Synarthrosis — Amphi-arthro- sis — Diartbrosis - - 101 Movements of joints - - . 102 Gliding — Angular movement - 103 Circumduction — Rotation - 102 General anatomy of articular structures - . - 102 XVI Cartilage — Fibro-cartilage Ligament — Synovial mem- brane - - . - Ligaments of the trunk — Ar- rangement ... Articulation of the vertebral co- lumn . - . - Of the atlas with the occipital bone . . . - Of the axis with the occipital bone . . - - Of the atlas with the axis Of the lower jaw - . . Of the ribs witli tlie vertebrte Of the ribs witli the sternum, and with each other Of the vertebral column, with the pelvis ... Of tlie pelvis- ... Ligaments of the upper extre- MITY . - - - Sterno-clavicular articulation Scapulo-clavicular articulation - CONTENTS. 102 Ligaments of the scapula - 120 Shoulder-joint .... 120 103 Elbow-joint .... 121 Radio ulnar articulation - 123 104 Wrist-joint .... 124 Articulations of the carpal bones 125 104 Carpo-metacarpal articulation - Metacarpo-phalangeal articula- 126 107 tion .... 127 Articulation of the phalanges . 127 108 Ligaments of the lower extre- 108 mity .... 128 110 Hip-joint 128 112 Knee-joint .... Articulation between the tibia 12:j 113 and fibula ... 134 Ankle-joint .... 135 114 Articulation of the tarsal bones - 13(; 115 Tarso-mctatarsal articulation Metatarso-phalangeal articula- 138 117 tion .... 139 118 Articulation of the phalanges - 139 119 CHAPTER III. General anatomy of muscle Nomenclature — Structure Muscles of the head and face . Arrangement into groups - Epicranial region — Dissection Occipito-frontalis - Orbital group — Dissection Orbicularis palpebrarum Corrugator supcrcilii — Tensor tarsi Actions ... Ocular group — Dissection . Levator palpcbra3 — Rectus su. perior Rectus inferior — Rectus intcr- nus Rectus cxternus — Obliquus su- perior . . - Obliquus inferior — Actions Nasal group Pyramidalis nasi . Compressor nasi — Actions Superior labial group Orbicularis oris — Levator labii supcrioris aheque nasi Levator labii supcrioris pro- prius Levator anguli oris — Zygoma- tic! Depressor labii supcrioris ala)- quc nasi - Actions .... Inferior labial group . Dissection THE MUSCLES. - 140 Inferior labial group — continued. - 141 Depressor labii inferioris 153 . 144 . 144 Depressor anguli oris — Leva- tor labii inferioris - 153 - 145 Actions .... 153 . 145 - 146 - 146 Maxillary group Masseter — Temporal muscle - Buccinator — External ptery. 153 154 goid muscle - 155 - 147 - 147 Internal pterygoid muscle Actions 156 156 . 147 Auricular group ... 156 Dissection .... 156 - 148 Attollcns aurem — Attrahens aurem .... 156 - 149 Retrahens aurem — Actions - J 57 Muscles of the neck 157 . 149 Arrangement into groups . 157 - 150 Superficial group — Dissection - 158 - 150 Phitysma myoides - 158 - 150 Stcrno-cleido-mastoideus — Ac - 151 tions .... 158 - 151 Depressors of the os hyoides and . 151 larynx . - - . Dissection . . - - Stcrno-liyoideus — Stcrno-thy- 160 100 - 152 roideus . . - - 100 - 152 Thyro-Iiyoideus — Omo-hyoi- deus .... 161 Actions .... 101 . 152 Elevators of the os hyoides 161 . 152 Dissection .... 162 . 153 Diirasti'icus - - . . J (\2 - 153 Stylo- hyoideus — inylo-hyoidcus 162 CONTENTS. XVll Genio-hyoideus — Genio-hyo- glossus - - - - 163 Actions - - - - 163 Muscles of the tongue - - 163 Hyo-glossus — Lingualis - 1 64 Stylo-glossus - - -165 Palato-g-lossus — Actions - 165 Muscles of the pharynx - - 1 65 Dissection - - - - 165 Constrictor inferior - - 166 Constrictor medius — Constric- tor superior - - - 16G Stylo - pharyngeus — Palato- pharyngeus — Actions - 167 Muscles of the soft palate - - 168 Dissection - - - - 168 Levator palati — Tensor palati 168 Azygos uvulfE — Palato-glossus 169 Palato-pharyngeus — Actions 169 Prsevertebral muscles - - 170 Dissection - - - - 170 Rectus anticus major — Rectus anticus minor - - 170 Scalenus anticus — Scalenus posticus - - - 170 Longus colli - - - - 171 Actions .... 171 Muscles of the trunk - - 172 Muscles of the back — Arrange- ment .... 172 First layer — Dissection - - 173 Trapezius - - - - 173 Latissimus dorsi - - 174 Second layer — Dissection - 174 Levator anguli scapulae - 174 Rhomboideus minor et major - . - . 176 Third layer — Dissection . 176 Serratus posticus superior et inferior - - - - 176 Splcnius capitis et colli - 177 Fourth layer — Dissection - 177 Sacro-lumbalis — Longissi- mus dorsi - - - 177 Spinalis dorsi - . . 177 Cervicalis ascendens — Trans- versalis colli - - - 178 Trachelo-mastoideus — Com- plexus - - - - 179 Fifth layer — Dissection - - 179 Semispinalis dorsi et colli - 180 Rectus posticus, major et minor .... ISO Rectus lateralis — Obliquus inferior - - - - 180 Obliquus superior - - 130 Sixth layer — Dissection - - 180 Multifidus spinae — Levatores costarum - - - 181 Supra-gpinales — Inter-spi- nales .... 181 Intcr-transversales - - 181 Actions .... 182 Table of origins and insertions of the muscles of the back - 184 Muscles of the thorax 186 Intercostales externi et interni 186 Triangularis sterni 188 Actions . . , . 188 Muscles of the Abdomen . 188 Dissection . . . . 188 Obliquus externus 188 Obliquus internus — Cremaster 189 Transversalis — Rectus . 191 Pyramidalis — Quadratus lum- borum — Psoas parvus 193 Diaphragm . . . . 194 Actions . . . . 195 Muscles of the perineum - 196 Dissection . . . . 196 Acceleratores urinaj 197 Erector penis — Transversus perinei . . . . 197 Compressor urethrcB 198 Sphincter and externus et in. ternus . . . . 199 Levator ani — Coccygeus 199 Muscles of the female peri- neum .... 200 Muscles of the upper ex- tremity ... 201 Anterior thoracic region . 202 Dissection .... 202 Pectoralis major - 203 Pectoralis minor — Subelavius — Actions 203 Lateral thoracic region 204 Serratus magnus — Actions 204 Anterior scapular region . 204 Scapularis .... 204 Actions .... 205 Posterior scapular region - 205 Supra-spinatus — Infra-spina- tus ... 205 Teres minor — Teres major 205 Actions .... 206 Acromial region - - . 206 Deltoid — Actions ... 206 Anterior humeral region - 207 Dissection - . - . 207 Coraco-brachialis — Biceps 207 Brachialis anticus — Actions - 209 Posterior humeral region . 209 Triceps .... 209 Anterior brachial region . 210 Superficial layer — Dissection • 210 Pronator radii teres . 210 Flexor carpi radialis - 210 Palmaris longus 210 Flexor sublimis digitorum . 211 Flexor carpi ulnaris - 212 Deep layer — Dissection 212 Flexor profundus digitorum 212 Flexor longus pollicis 213 Pronator quadratus — Ac- tions .... 213 Posterior brachial region 213 Superficial layer — Dissec tion .... 213 Supinator longus 3 214 XVIU CUNTEKTS, Posterior brachial region — continue Extensor carpi radialis lon- gior - - - Extensor carpi radialis bre- vier . . . - Extensor communis digito- rum ... - Extensor minimi digiti Extensor carpi ulnaris — An- coneus - - - - Deep layer — Dissection - Supinator brevis Extensor ossis metacarpi pollicis - - - - Extensor primi internodii pollicis - - - . Extensor secundi internodii pollicis - - - - Extensor indicis Actions . - - - Muscles of the hand - Radial region — Dissection Ulnar region — Dissection Palmar region - - - Actions . - - - Muscles of the lower extre- mity . - - - Gluteal region — dissection Gluteus maximus - - - Gluteus medius et minimus • Pyriformis . . - - Gemellus superior — Obturator internus - . - - Gemellus inferior — Obturator externus ... Quadratus femoris Actions .... Anterior femoral region — Dissec- tion .... Tensor vaginse femoris — Sar- torius - - . - Rectus — Vastus externus Vastus internus — Crureus ed. Anterior femoral region — continued. Actions .... 229 214 Internal femoral region — Dissec- tion .... 229 214 Iliacus internus Psoas magnus — Pectineus — 229 214 Abductor Inngus 230 216 Abductor brevis — Abductor magnus — Gracilis - 231 216 Actions .... 232 216 Posterior femoral region — Dis- 216 section .... 232 Biceps flexor cruris 232 217 Semi-tendi n osus — Semi-mem- branosus 233 217 Actions . . . - 234 Anterior tibial region — Dissection 234 217 Tibialis anticus 234 217 Extensor longus digitorum - 234 218 Peroneus tertins — Extensor 218 proprius pollicis 235 218 Actions .... 236 219 Posterior tibial region 236 220 Superficial layer — Dissection 221 Gastrocnemius . 236 Plantaris — Soleus — Actions 237 222 Deep layer — Dissection - 237 223 Popliteus — Flexor longus 224 pollicis . - - . 238 224 Flexor longus digitorum 225 Tibialis posticus 238 Actions .... 240 225 Fibular region .... Peroneus longus — Peroneus 240 22G brevis .... 240 226 Actions .... 241 226 Foot — Dorsal region - 241 Plantar region -241 227 First layer — Dissection 241 Second layer — Dissection - 243 227 Third layer — Dissection 244 228 Fourth layer 245 229 Actions .... 245 CHAPTER IV. THE FASCI^>, General anatomy - - - 246 Fasciae of the hkad and neck - 247 Temporal fascia - - - 247 Cervical fascia - - - 247 Fascia of the trunk - - 249 Thoracic fascia - - - 249 Fascia transversalis - - 249 Oblique inguinal hernia - - 250 Congenital hernia - - - 251 Encysted hernia - - - 251 Direct inguinal hernia - - 251 Fascia iliaca . - - . 252 Fascia pelvica .... 252 Obturator fascia ... 252 Superficial perineal fascia - - 253 Deep perineal fascia ... 253 FASCIyEOF THE UPPER EXTREMITY 256 FaSCI.15 of the LOWER EXTRE. MITV .... 256 Fascia lata .... 257 Femoral hernia ... 259 Plantar fascia .... 260 CONTENTS. CHAPTER V. THE ARTERIES. General anatomy of arteries - 262 Inosculations — Structure - - 263 Aorta 264 Table of branches - - 268 Coronary arteries - - - 268 Arteria innominata ... 268 Common carotid arteries - . 269 External carotid artery - - 270 Table of branches . - 271 Superior thyroid artery - - 271 Lingual arlery ... 273 Facial artery ... 273 Mastoid artery - - . 275 Occipital artery ... 275 Posterior auricular artery . 275 Parotidean arteries - . 275 Ascending pharyngeal artery 275 Transverse facial artery - 276 Temporal artery - . . 276 Internal masiUary artery - 276 Internal carotid artery . . 278 Ophthalmic artery . . 279 Anterior cerebral artery . 281 Middle cerebral artery - . 281 Subclavian artery ... 281 Table of branches - . 283 Vertebral artery ... 283 Basilar artery . . . 284 Thyroid axis — Inferior thyroid artery .... 285 Supra-scapular artery — Poste- rior scapular ... 285 Circle of WiUis - . . 286 Subclavian artery — continued. Superficialis cervicis — Profun- da cervicis ... 287 Superior intercostal artery — In. ternal mammary - . 287 Axillary artery .... 288 Table of branches ... 289 Brachial artery .... 291 Radial artery - . . - 292 Ulnar artery - . . - 295 Thoracic aorta ; branches - . 297 Abdominal aorta; branches . 298 Phrenic arteries . - - 298 Cceliac axis — Gastric artery - 298 Hepatic artery . - - 299 Splenic artery ... 300 Superior mesenteric artery . 301 Spermatic arteries - . 303 Inferior mesenteric artery . 304 Renal arteries - - - 305 Common iliac arteries - - 306 Internal iliac artery - - . 306 Ischiatic .... 308 Internal pudic artery - . 309 External iliac artery . - . 312 Femoral artery - - - .313 Pophteal artery . . . 317 Anterior tibial artery - - 318 Dorsalis pedis artery - - 320 Posterior tibial artery • - 322 Peroneal artery - - - 322 Plantar arteries ... 323 Pulmonary artery ... 325 CHAPTER VI. THE VEINS. General anatomy . . .327 Veins of the head and neck - 329 Veins of the diplofi - . .330 Cerebral and cerebellar veins - 331 Sinuses of the dura mater - 331 Veins of the neck - - . 334 Veins of the upper extremity - 336 Veins of the lower extremity . 338 Veins of the trunk - - - 339 Venffi innominatcB ... 339 Veins of the trunk — continued. Superior vena cava - - 339 Iliac veins .... 340 Inferior vena cava ... 341 Azygos veins - . . 342 Vertebral and spinal veins - 343 Cardiac veins - - - 344 Portal vein . . . . 344 Pulmonary veins ... 346 CONTENTS. CHAPTER VII. THE LYMPHATICS. General anatomy - - - 347 Lymphatics of the head and neck 348 Lymphatics of the upper extre- mity - - - - 349 Lymphatics of the lower extre- mity .... 350 Lymphatics of the trunk - - 351 Lympliatics of the viscera - 352 Lacteals .... 354 Thoracic duct .... 354 Ductus lymphaticus dexter - 356 CHAPTER VIII. THE NERVOUS SYSTEM. General anatomy 357 Spinal cord The brain .... 362 Cranial nerves - Membranes of the encephalon - 362 Nerves of special sense Dmra mater . . . - 363 Nerves of motion - Arachnoid membrane - 365 Respiratory nerves Pia mater . . . - 366 Trifacial nerve Cerebrum .... 366 Spinal nerves - Lateral ventricle . . - 367 Cervical plexus Fifth ventricle ... 371 Brachial plexus Third ventricle 373 Dorsal nerves Fourth ventricle ... 374 Lumbar nerves Lining membrane of the ven- Sacral nerves tricles . - - - 375 Sympathetic system - Cerebellum . . . - 375 Cranial ganglia Base of the brain 376 Cervical ganglia Medulla oblongata - - - 378 Thoracic ganglia - Diverging fibres ... 380 Lumbar ganglia Converging fibres; commissures 382 Sacral ganglia 383 386 386 387 390 398 403 404 407 413 415 419 425 425 430 432 434 434 CHAPTER IX. ORGANS OF SENSE. Nose Nasal fossae .... Eyeball Sclerotic coat and cornea Choroid coat ; ciliary ligament; iris - - - - - Retina ; zonula ciliaris - Humours - - - . - Physiological observations Appendages of the eye Lachrymal apparatus Organ of hearing - . - External car ; pinna ; meatus 435 Organ of hearing — continued. 437 Tympanum . - - - 452 438 Ossicula auditCis - 452 439 Muscles of the tympanum 454 Internal ear — Vestibule - 456 440 Semicircular canals 459 443 Cochlea .... 459 444 Membranous labyrinth - 460 446 Organ of taste — Tongue - 462 447 Organ of touch — Skin 464 448 Appendages to the skin — Nails - 467 450 Hairs — Sebaceous glands 467 450 Perspiratory ducts — Pores 467 CONTENTS. CHAPTER X. THE VISCERA. Thorax . . . - 469 Abdomen — continued. Heart .... . 469 Anus - 506 Pericardium ... . 470 Liver ... - 511 Adult circulation . 471 Kiernan's researches - 515 Structure of the heart — Searle's Gall-bladder . - 522 researches . 476 Pancreas - 523 Organs of respiration and voice - 4S0 Spleen - - 524 Larynx — Cartilages . 480 Supra-renal capsules - 525 Ligaments — Muscles - . 481 Kidneys - 526 Trachea and Bronchi - . 485 Pelvis - 529 Thyroid gland . 486 Bladder . 529 Lungs . . . - . 486 Prostate gland . 532 Pleurae . - . - . 489 Vesiculse seminales . 533 Mediastinum - . 489 Male organs of generation 534 Abdomen — Regions . . 490 Penis ... . 534 Peritoneum - - . . 491 Urethra . 536 Alimentary canal - . 495 Testes . - 539 Lips— Cheeks — Gums- -Pa. Female pelvis - . 543 late . 496 Bladder — Urethra - . 543 Tonsils — Fauces - . 497 Vagina - . 544 Salivary glands . 497 Uterus - . 544 Pharynx ... . 499 Fallopian tubes - 547 Stomach ... . 500 Ovaries - . 547 Small intestine . 502 External organs of generation 548 Large intestine . 503 Mammary glands . 550 Structure of the intestinal canal 504 CHAPTER XL Osseous and ligamentous system Muscular system Vascular system Foetal circulation Nervous system Organs of sense — Eye- Nose Thyroid gland - Thymus gland - ANATOMY OF THE FCETUS. 3 system 552 Foetal lungs .... 558 . 552 Foetal heart .... 558 . 552 Viscera of the abdomen 559 - 552 Omphalo-mesenteric vessels - 559 . 555 Liver 560 — Ear— Kidneys and supra-renal cap- . 555 sules .... 560 . 555 Viscera of the pelvis . . - 560 . 556 Testes — Descent - 561 TABLE OF ILLUSTRATIONS. 1. Minute Structure of bone - 20 35. Femur ; posterior view 91 2. Cervical vertebra 24 36. Tibia and fibula 92 3. Atlas .... 25 37. Foot ; dorsal surface - 94 4. Axis 25 38. Foot ; plantar surface 97 5. Dorsal vertebra - 26 39. Ligaments of the vertebrae 6. Lumbar vertebra 27 and ribs ; anterior view - 105 7. Sacrum .... 29 40. Posterior common ligament 106 8. Occipital bone — External 41. Ligamenta subflava . 106 surface .... 30 42. Ligaments of the atlas, axis, 9. Occipital bone — Internal and occipital bone, ante- surface .... 32 rior view 107 10. Parietal bone — External 43. Id. ; posterior view - 107 surface .... 33 44. Id. ; internal view 108 11. Parietal bone — Internal 45. Id. ; internal view 109 surface - . . - 33 46. Ligaments of the lower jaw ; 12. Frontal bone — External external view ... 110 surface .... 35 47. Id ; internal view 111 13. Frontal bone — Internal sur- 48. Id. ; section 111 face .... 36 49. Ligaments of the vertebral 14. Temporal bone — External column and ribs ; poste. surface .... 36 rior view 113 15. Temporal bone — Internal 50. Ligaments of the pelvis and surface . - - . 38 hip-joint - 115 16. Sphenoid bone — Superior 51. Id. id. - - - 116 surface ..... 41 52. Ligaments ofthe sternal end 17. Sphenoid bone — Antero-in- of the clavicle and costal ferior surface - 42 cartilages 119 18. Ethmoid bone - 44 53. Ligaments of the scapula 19. Superior maxillary bone 46 and shoulder-joint - 120 20. Palate bone — Internal sur- 54. Ligaments of the elbow ; face .... 49 internal view - 122 21. Palate bone — External sur- 55. Id. external view 122 face . - . . 50 56. Ligaments of the wrist and 22. Inferior maxillary bone 52 hand .... 124 23. Skull, anterior view - 56 57. Synovial membranes of the 24. Base of the skull ; internal wrist .... 126 view . . . - 56 58. Knee-joint ; anterior view - 130 25. Base of the skull ; external 59. Id. ; posterior view . 131 view .... 59 60. Id. ; internal view 132 26. Os hyoides 70 61. Id.; reflections ofthe syno. 27. Thorax .... 71 vial membrane 132 28. Scapula .... 74 62. Ankle-joint ; internal view 135 29. Humerus .... 76 63. Id. external view - 135 30. Ulna and radius 78 64. Id. posterior view 137 31. Bones of the carpus ; poste- 65. Ligaments ofthe sole ofthe rior view 79 foot .... 138 32. Hand ; anterior view 83 66. Minute structure of muscle 141 33. Os innominatum 85 67. Minute structure of muscle 142 34. Femur ; anterior view 90 68. MuKcIes of the face - 145 TABLE OF ILLUSTRATIONS, 69. Muscles of the ovbit - 70, Pterygoid muscles 7J. Muscles of the neck; super- ficial and deep 72. Muscles of the tongue 73. Muscles of the pharynx 74. Muscles of the soft palate - 75. Muscles of the prEevertebral region . . . - 76. Muscles of the back; 1st, 2d, and 3d layer 77. Muscles of the back ; deep layer . . . - 78. Muscular of the anterior aspect of the trunk - 79. Muscles of the lateral aspect of the trunk - 80. Diaphragm . . - 81. Muscles of the perineum - 82. Muscles of the anterior hu- meral region - 83. Triceps extensor cubiti 84. Superficial layer of muscles of the anterior aspect of the fore-arm - 85. Deep layer of muscles of the anterior aspect of the fore-arm ... 86. Superficial layer of mus- cles ; posterior aspect of the fore-arm - - . 87. Deep layer ; posterior aspect of the fore-arm 88. Muscles of the hand, ante- rior aspect . - - 89. Muscles of the gluteal re- gion, deep layer 90. Muscles of the anterior and internal femoral region - 91. Muscles of the gluteal and posterior femoral region - 92. Muscles of the anterior tibial region . - - 93. Muscles of the posterior tibial region, superficial layer .... 94. Muscles of the posterior tibial region, deep layer . 95. Muscles of the sole of the foot: 1st layer 96. " " 2d layer 97. Section of the neck, show- ing the distribution of the deep cervical fascia 98. Transverse section of the pelvis, showing the distri- bution of the fasciae 99. Deep perineal fascia - 100. Distribution of the deep perineal fascia, side view 101. Distribution of the fasciaj ; at the femoral arch 102. The great vessels of the chest - . - - 103. Brandies of the external carotid artery 148 • 104. Branches of the subclavian 155 artery - - . . 283 105. The circle of AVillis . 286 159 106. Axillary and brachial arte- 164 ries .... 290 167 107. Arteries of the fore-arm — 168 Radial and ulnar - 294 108. Branches of the abdominal 170 aorta . . . - 299 109. Cceliac axis with its bran- 175 ches .... 301 110. The superior mesenteric 178 artery . - . . 302 111. The inferior mesenteric ar- 187 tery . - - . 304 112. The internal iliac artery 192 with its branches - 307 194 113. The arteries of the peri- 198 neum - - - . 308 114. The femoral artery with its 207 branches . - . 313 209 115. The anterior tibial artery - 321 116. Posterior tibial and peroneal artery .... 321 211 117. Arteries of the sole of the foot 324 118. Sinuses of the dura mater - 332 119. Sinuses of the base of the 211 skull .... 334 120. Veins and nerves of the bend of the elbow . 337 215 121. Veins of the trunk and neck 340 122. The portal vein 345 215 123. The thoracic duct 355 124. The lateral ventricles of the 219 cerebrum ... 368 125, Longitudinal section of the 225 brain .... 372 126. Base of the brain 379 228 127. Distribution of the fibres of the brain 380 233 128. Nerves of the tongue and neck .... 388 237 129. Facial nerve and superficial cervical nerves 392 130 Origin and distribution of 237 the eighth pair of nerves 396 131 Branches of the trifacial 239 nerve .... 400 132. Axillary plexus and nerves 242 of the upper extremity - 409 242 133. Lumbar and sacral plexus, with the nerves of the lower extremity 416 248 134 The cranial ganglia of the sympathetic nerve - 426 135 Fibro-cartilages of the nose 436 252 136. Longitudinal section of the 253 globe of the eye 439 137 A transverse section of the 254 globe of the eye 442 138. Another transverse section 257 of the globe of the eye 443 139 A diagram of the ear - 453 264 140 Anatomy of the cochlea 458 141 Osseous and membranous 271 labyrinth of the car 460 TABLE or ILLUSTRATIONS. 142. Tlie anatomy of tlie skin - 464 158 143 Anatomy of tlie skin - 465 159. 144. The heart - - . . 470 14.5. Muscles of the larynx 482 146. MuTscles of the larynx 482 160. 147. Anatomy of the lungs and 161. heart - . - - 487 148. The peritoneum 491 162. 149. The pharynx 499 163. 150. Anatomy of the stomach and duodenum 501 164. 151. Columns and pouches of the 165. rectum . . - - 506 166. 152. Muscular coat of the rectum 510 167. 153. The liver; its upper surface 511 154. The liver; its under surface 513 168. 155. Lobules of the liver - 514 156. Section of the kidney 527 169. 157. A side view of the viscera 170. of the male pelvis - 528 Neck of the bladder - A posterior view of the bladder and vesiculsB seminales ... Anatomy of the urethra Transverse section of the testicle . . - - Anatomy of the testis A side view of the viscera of the female pelvis Fcetal circulation Section of the thymus g-land Ducts of the thymus gland Descent of the testis in the fcetus .... Descent of the testis in the foetus .... Vignette, Faces title, Time and Death. 331 533 537 540 542 545 553 556 557 561 561 SYSTEM OF HUMAN ANATOMY. CHAPTER I. OSTEOLOGY. The bones are the organs of support to the animal frame ; they give firmness and strength to the entire fabric, afford points of con- nection to the numerous muscles, and bestow individual character upon the body. In the limbs they are hollow cylinders, admirably calculated by their conformation and structure to resist violence and support weight. In the trunk and head, they are flattened and arched, to protect cavities and provide an extensive surface for attachment. In some situations they present projections of variable length, which serve as levers ; and in others are grooved into smooth surfaces, which act as trochlece or pulleys for the passage of tendons. More- over, besides supplying strength and solidity, they are equally adapted, by their numerous divisions and mutual apposition, to fulfil every movement which may tend to the preservation of the creature, or be conducive to his welfare. According to the latest analysis by Berzelius, bone is composed of about one-third of animal substance, which is almost completely reducible to gelatine by boiling, and of earthy matters ; in the fol- lowing proportions : — Cartilage .... . 32-17 parts. Blood-vessels .... 113 Phosphate of lime . . 51-04 Carbonate of lime 11-30 Fluate of lime . 2- Phosphate of magnesia 1-16 Soda, chloride of sodium 1-20 100-00 Bones are divisible into four classes : Long, short, Jlat,anc\ irregular. The long bones are found principally in the limbs, and they con- sist of a shaft and two extremities. The shaft is cylindrical or prismoid in form, dense and hard in texture, and hollowed in the interior into a medullary canal. The extremities are broad and ex- panded, to articulate with adjoining bones ; and cellular or cancel- 3 18 STRUCTURE OF BONE. lous in their internal structure. Upon the exterior of the bone are processes and rough surfaces for the attachment of muscles, and fora.mina for the transmission of vessels and nerves, and the attach- ment of ligaments. The character of long bones is, therefore, their general type of structure and their divisibility into a central portion and extremities, and not so much their length ; for there are some long bones — as the second phalanges of the toes — which are less than a quarter of an inch in length, and are almost equal, and in some instances, exceed in breadth their longitudinal axis. The long bones are, the clavicle, humerus, radius and ulna, femur, tibia, and fibula, metacarpal bones, metatarsal, phalanges and ribs. S/io7't* bones are such as have no predominance of length or breadth, but are irregularly cuboid in form : they are spongy in in- ternal texture, and invested by a thin crust of condensed osseous tissue. The short bones are, the vertebrae, coccyx, carpal and tarsal bones, patellae, and sesamoid bones. Flat bones are composed of tv\ro layers of dense bone with an inter- mediate cellular structure, and are divisible into surfaces, borders, angles, and processes. They are adapted to enclose cavities ; have processes upon their surface for the attachment of muscles ; and are perforated by foramina, for the passage of nutrient vessels to their cells, and for the transmission of vessels and nerves. They articulate with long bones by means of smooth surfaces plated with cartilage, and with each other either by cartilaginous substance, as at the symphysis pubis ; or by suture, as in the bones of the skull. The two condensed layers of the bones of the skull are named tables ; and the intermediate cellular structure diploe. The flat bones are the occipital, parietal, frontal, nasal, lachrymal, vomer, sternum, scapulae, and ossa innominata. Irregular bones are those which are not distinctly referrible to either of the above heads ; but present a mixed character, being partly short and partly flat in their conformation. The bones of this class are, the temporal, sphenoid, ethmoid, superior maxillary, in- ferior maxillary, palate, inferior turbinated bones, os hyoides, and sacrum. Structure. — In structure, bone is composed of lamellae, which are concentric in long, and parallel in flat bones. Between the lamellee are situated numerous small longitudinal canals and minute oval corpuscules. The longitudinal canals (canals of Havers) contain me- dullary substance and vessels, and communicate with each other, and with the medullary canal or cells. Each longitudinal canal is surrounded by a scries of concentric lamellae, and between these lamellae, as well as between the lamellae which constitute the great medullary canal of the bone, the oval corpuscules are situated. In the extremities of long, in short, and in flat bones, the cells repre- sent the Haversian canals, and are each surrounded by concentric * Wilson's classep of short and irregular bones arc usually included in the title ossa r.raasa or thick bones. G. STRUCTURE OF BONE. 19 lamellae ; indeed, the medullary canal of long bones may be con- sidered as a single Haversian canal exceedingly dilated. The oval corpuscules* are minute cells, from which are given off a number of radiating and branching tubuli,t which anastomose with the cor- responding tubuli of neighbouring cells. The cells and tubuli are filled with calcareous substance: hence they have been named calcigerous cells and tubuli. Deutsch, in his excellent researchesj on the minute structure of bone, has described certain radiating lines which traverse the thick- ness of the concentric lamellae. They are thus referred to by Miiller.§ " It is very remarkable that the thickness of the lamellse is traversed by numerous lines which are separated by very small intervals, and which correspond in length to the thickness of the lamellas, namely, ^lo^h of a Une. Deutsch supposes these lines to be tubes in which the calcareous matter of the bones is deposited(?) ; if one lamella be separated from another the ends of the lines are seen, he says, of a triangular form. The existence of these fine tubes (?) was hitherto quite unknown ; but it is not probable that they serve for the reception of the calcareous matter, for the first appearance of ossification is in the form of a microscopic net- work !"|| Having been engaged during the past summer (1841), and being still occupied with the investigation of the minute struc- sture of bone, I have had the good fortune to discover the true nature of the lines thus alluded to by Deutsch and Miiller. I have found that the corpuscules of Purkinje are arranged very differently in different kinds of bones ; that in flat bones, and in the thin lamella of cellular bones, they exist in great numbers, are of considerable size, and are disposed with no regularity. Their tubuU are short, tapering, and tortuous, and proceed irregularly from every part of the surface of the corpuscules. In the long bones, the corpuscules are apparently smaller than the preceding, they are oval and flattened, and lie between the concentric lamellse. Their tubuli are long and only slightly undulating, and diminish very gradually towards their termination, where they communicate with the tubuli of other cor- * Discovered by Purkinje. They are about goth of a line tlirough their long diameter. + Discovered by Mttller. They are very distinct. Their larger trunks are about __! th of a line in diameter. ^0 00 t De penitiori ossium structura observationes. Dissert, inaug. Vratisl. § Physiology, Translation, p. 378. II In reference to this question, Dr. Bayly, the translator of Miiller, observes, " Miescher does not confirm Deulsch's statement as to the still more minute tubes traversing the concentric lamella;, although he perceived the radiated appearance around the larger canals, w^hich was produced by dots or short lines, which do not occupy the whole thickness of each lamella. Some of the lines appear to traverse more than one lamella, though the majority, as Miescher describes, are very short. They appear more like the separations between the granules of cartilage that form tJie lamella; than distinct tubes." Dr. Bayly has given the figure of a transverse section of an Haversian canal, in which Deutsch and Miescher's views are clearly illustrated. 20 STRUCTURE OF BONE. Fiff. 1.* pusciiles or with the corpiiscules themselves. Among the concen- tric lamellas of the Haversian canals, the tubuli are given off from the surfaces, lying in contact vs^ith the lamellae, and they proceed straight through the lamellae in two directions, inwards towards the area of the Haversian canal, or out- wards towards the outer- most lamellae. If in their course the tubuli meet with another corpuscule, they ter- minate in it or communicate with its branches ; but the direct course of the tubuli towards the centre is never interfered with. So evident is the tendency of all the tubuli to attain the centre, that in several corpuscules situated between the outer- most lamellae, I have ob- served the tubuli from the external surface to curve around the ex- tremities of the corpuscule, in order to proceed with those given off from the internal surface, to their central destination. From their general appearance in relation to the lamellae, these tubuli seem to me to deserve the title of converging tubuli; they all proceed towards the central canal, and those which reach that destination terminate upon its internal surface. The trunks of the tubuli not unfrequently give off one or two branches. As regards their form, the tubuli are undoubtedly cylindrical, and they probably contain calcareous substance, as do the calcigerous tubuli described by MuUer. The lines remarked by Deutsch are, therefore, according to my observations, cylindrical tubuli, traversing the concentric lamellae of bone, communicating with the corpuscules, and with the cavity of the Haversian canal, and identical with the calcigerous tubuU of Miiller. In the fresh state bones are invested by a dense fibrous mem- brane, the 'periosteum, covering every part of their surface with the exception of the articular extremities, which are coated by a * Minute structure of bono, drawn with the microscope from nature, by Bagg. M.'ifrnified 300 diameters. 1. One of the Haversian canals surrounded by its concentric lamelifc. The corpuscules are seen between the lamella) ; but the converging tubuli are omitted. 2. An Haversian canal with its concentric lamellfE, Purkinjean corpus- cules, and converging tubuli. 3. The area of one of the canals. 4, 4. Direction of the lamellfE of the great medullary canal. Between the lamella at the upper part of the figure, several very long corpuscules with their tubuli are seen. In the lower part of the figure, the outlines of three other canals are given, in order to show their form and mode of arrangement in the entire bone. DEVELOPEMENT OF BONE. 21 thin layer of cartilage. The periosteum of the bones of the skull is termed 'pericranium ; and the analogous membrane of external cartilages, perichondrium. Lining the interior of the medullary canal of long bones, the Haversian canals, the cells of the cancelli, and the cells of short, flat, and irregular bones, is the medullary membrane, which acts as an internal periosteum. It is through the medium of the vessels supplying these membranes that the changes required by nutrition occur in bones, and the secretion of medulla into the interior is effected. The medullary canal of long bones, and the cells of other bones, are filled with a yellowish oily substance — the medulla, which is contained in a loose cellular tissue formed by the medullary membrane. Developement of Bone. — The earliest trace of skeleton in the human embryo is observed in the presence of semi-opaque lines, which are seen through the transparent embryonic mass. This trace is composed of a consistent granular jelly, and constitutes the gelatinous state of osteo-genesis. In the second or cartilaginous state, the semi-opaque jelly becomes dense, transparent, and homogeneous, the change taking place from the surface towards the centre, and con- stituting cartilaginijication. In the third stage, the cartilage is tra- versed by vessels carrying red blood, which proceed from the fibrous investment and ramify in its interior. The cartilage immediately surrounding these vessels, becomes opaque and of a yellowish red colour. In the fourth stage,* the earthy constituents are attracted from the blood by the opaque cartilage, which becomes altered in character, and shoots into the transparent cartilage in the form of reddish gray fibres, which communicate with each other at acute angles and constitute an areolar osseous tissue. This is the state of ossification. The succeeding changes are those of condensation and the formation of cells, the Haversian and medullary canals. Cartilaginification is complete in the human embryo at about the sixth week ; and the first point of ossification is observed in the clavicle at about the seventh week. Ossification commences at the centre, and thence proceeds towards the surface ; in flat bones the osseous tissue radiates between two membranes from a central point towards the periphery, in short bones from a centre towards the circumference, and in long bones from a central portion, diaphysis, towards a secondary centre, epiphysis, situated at each extremity. Large processes, as the trochanters, are provided with a distinct centre, which is named apophysis. The growth of the bone in length takes place at the extremity of the diaphysis, and in bulk by fresh deposition on the surface ; while the medullary canal is formed and increased by absoi-ption from within. The period of ossification-\ is different in different bones ; the order of succession may be thus arranged : — * The spot at which this stage commences is called the piincttmi of^xi/icntioiiix. f». t Burdach, Physiologic. 22 DEVELOPEMENT OF BONE. From the sixth to the eightli week, ossification commences first in the clavicle, then in the lower jaw, upper jaw, and femur. From the eighth to the tenth week, in the frontal, occipital, humerus, radius and ulna, tibia and fibula, scapulae, ribs. From the tenth to the twelfth week, in the temporal, sphenoid, malar, parietal, palate, nasal, vertebras, metacarpus, metatarsus, last phalanges of the hands, and feet. From the third to the fourth month, in the vomer, first and second phalanges, ossa innominata. From the fourth to the fifth month, in the ethmoid, lachrymal and spongy bones. From the fifth to the sixth month, in the sternum, carpus, and tarsus. From the sixth to the tenth month in the os hyoides, coccyx, and cuboid bone. At one year, in the coracoid process of the scapula, os magnum, OS unciforme, and internal cuneiform bone. At three years, in the patella, and carpal cuneiform bone. At four years, in the external and middle cuneiform bone. At five years, in the tarsal scaphoid bone, trapezium, and semi- lunare. At eight years, in the carpal scaphoid. At nine, in the trapezoid, and at the twelfth year, in the pisiform bone. The ossicula auditus are the only bones completely ossified at birth. The entire osseous framework of the body constitutes the skeleton, which in the adult man is composed of two hundred and forty-six distinct bones. They may be thus arranged : — Cranium Ossicula auditus Face .... Teeth Vertebral column Os hyoides, sternum, and ribs Upper extremities Pelvis Lower extremities Sesamoid bones 246 The skeleton is divisible into 1st. The vertebral column or central axis. 2. The cranium and face or superior dcvclopemcnt of the central axis. 3. The hyoid arch. 4. The thoracic arch and upper extremities. .0. The ]r)clvic arch and lower extremities. * Wilson describes throe bones to tlic car viz : malleus, inr.us and stapes, making the orhicnlare of other anatomistw a part of the staprs. lie also countR thirty-two teeth in this enumeration, which is not common. G. . 8 6* . 14 32 . 24 s ... 26 . 64 4 . 60 8 VERTEBRAL COLUMN. 23 VERTEBRAL COLUMN. The Vertebral column is the first and only rudiment of internal skeleton in the lower Vertebrata, and constitutes the type of that great division of the animal kingdom. It is also the first developed portion of the skeleton in man, and the centre around which all the other parts are produced. In its earliest formation it is a simple cartilaginous cylinder, surrounding and protecting the primitive trace of the nervous system ; but, as it advances in growth and or- ganization, it becomes divided into distinct pieces, which constitute vei'tehrcr. The vertebrsB are divided into true and false. The true vertebrse are twenty-four in number, and are classified according to the three regions of the trunk which they occupy, into the cervical, dorsal, and lumbar. The false vertebrae consist of nine pieces united into two bones, — the sacrum and coccyx. The arrangement of the vertebrae may be better comprehended by means of the accompanying table : — C 7 Cervical, True vertebrse 24 ^ 12 Dorsal, ( 5 Lumbar. False vertebrse 9 ( 5 Sacrum, I 4 Coccyx. Characters of a Vertebra. — A vertebra consists of a body, two laminae, a spinous process, two transverse processes, and four ar- ticular processes. The body is the solid part of the vertebra ; and by its articulation with adjoining vertebrae, gives strength and sup- port to the trunk. It is flattened above and below, convex in front, and slightly concave behind. Its anterior surface is constricted around the middle, and pierced by a number of small openings which give passage to nutritious vessels. Upon its posterior surface is a singular irregular opening, or several, for the exit of the vence basis vertebrcB or vertebral sinuses. The lamincB commence upon the sides of the posterior part of the body of the vertebra by two pedicles ; they then expand, and arching backwards, enclose a foramen which serves for the protec- tion of the spinal cord. The upper and lower borders of the laminae are rough for the attachment of the ligamenta subflava. The con- cavities above and below the pedicles are the intervertebral notches. The spinous process stands backwards from the angle of union of the laminae of the vertebra. It is the succession of these projecting processes along the middle line of the back, that has given rise to the common designation of the vertebral column — the spine. The use of the spinous process is for the attachment of muscles. The transverse processes project one at each side from the laminae of the vertebra ; they are intended for the attachment of muscles. The articular processes, four in number, stand upwards and downwards from the lamina3 of the vertebras to articulate with the vertebra above and below. ^f Parietal Bone. — The pa- rietal bone is situated at the side and vertex of the skull ; it is quadrilateral in form, and di- visible into an external and in- ternal surface, four borders and four angles. The superior border is straight, to articulate wdth its fellow of the opposite side. The inferior border is arched and thin, to articulate with the tem- poral bone. The anterior border is concave, and the posterior somewhat convex. External Surface. — Crossing the bone in a longitudinal direction from the anterior to the posterior border, is an arched hne, the temporal ridge, to which the temporal fascia is attached. In the middle of this line, and nearly in the centre of the bone, is the pro- jection called the -parieial boss or eminence, which marks the centre of ossification. Above the temporal ridge the surface is rough, and covered by the aponeurosis of the occipito- frontahs ; below the ridge the bone is smooth for the attach- ment of the fleshy fibres of the temporal muscle. Near the superior border of the bone, and at about one-third from its posterior extremity, is the pa- rietal foramen, which transmits a vein to the superior longitu- dinal sinus. Internal Surface. — The internal table is smooth, and marked Fig. ll.t 6' r-^-mmk:^... * The external surface of the left parietal bone. 1. The superior or sagittal border. 2. The inferior or squamous border. 3. The anterior or coronal border. 4. The pos- terior or lambdoidal border. 5. The temporal ridge; the figure is situated immediately in front of the parietal eminence. 6. The parietal foramen, unusually large in tiic bone from which this figure was drawn. 7. The anterior inferior or elongated angle. 8. The posterior inferior or truncated angle. t The internal surface of the left parietal bone. 1. The superior, or sagittal border. 5 34 PARIETAL BONE. over every part of its surface by numerous furrows, which cor- respond with the ramifications of the arteria meningea magna. Along the upper border is part of a shallow groove, completed by the opposite parietal bone, which serves to contain the superior longitudinal sinus. Some slight pits are also observable near to this groove, wliich lodge the glandulse Pacchioni. The anterior inferior angle is thin and lengthened, and articu- lates with the greater wing of the sphenoid bone. Upon its inner surface it is deeply channelled by a groove for the trunk of the arteria meningea magna. This groove is frequently converted into a canal. The 'posterior inferior angle is thick, and presents a broad and shallow groove for the lateral sinus. Developement. — By a single centre. Articulations. — With_^ ye bones; with the opposite parietal bone, the occipital, frontal, temporal, and sphenoid. Attachment of Muscles. — To one only, — the temporal. The occi- pito-frontalis glides over its upper surface. Frontal Bone. — The frontal bone bears some resemblance in form to the under valve of a scallop shell. It is situated at the anterior part of the cranium, forming the forehead, and assists in the construction of the roof of the orbits and nose. Hence it is divisible into a superior or frontal portion, and an inferior or orbito- nasal portion. Each of these portions presents for examination an external and internal surface, borders and processes. External Surface. — At about the middle of each lateral half of the frontal portion is a projection, the frontal boss or eminence, which denotes the situation of the centre of ossification. Below these points are the superciliary ridges, large towards their inner termina- tion, and becoming gradually smaller as they arch outwards ; they support the eyebrows. Beneath the superciliary ridges are the sharp and prominent arches which form the upper margin of the orbits, the supra-orbital ridges. Externally the supra-orbital ridge terminates in the external angular process, and internally in the internal angular process ; at the inner third of this ridge is a notch, sometimes converted into a foramen, the supra-orbital notch, which gives passage to the supra-orbital or frontal artery, veins, and nerve. Between the two superciliary ridges is a rough projection, the nasal tuberosity : the whole of this portion of the bone is some- what prominent, and denotes the situation of the frontal sinuses. Extending upwards and backwards from the external angular pro- cess is a sharp ridge, the commencement of the temporal ridge, and beneath this a depressed surface that forms part of the temporal fossa. 2. The inferior, or squamous border. 3. Tlic anterior, or coronal border. 4. The posterior, or lambdoidal border. 5. Part of the jrroovc for the superior longitudinal Hinus. G. The internal termination of the parietal foramen. 7. The anterior inferior angle of the bone, on wliicli is seen the groove for the trunk of the arteria meningea magna. 8. The posterior inferior angle, upon which is seen a portion of the groove for the lateral sinus. FRONTAL BONE. 35 "''■M.irjp^ The orhito-nasal portion of the bone consists of two thin processes, the orbital plates, which form the roof of the orbits, and of an inter- vening notch which lodges the ethmoid bone, and is called the ethmoidal fissure. The edges of the ethmoidal fissure are hollowed into cavities, which, by their union with the ethmoid bone, Fiff- 12.* complete the ethmoidal cells ; and, crossing these edges trans- versely, are two small grooves, sometimes canals, which open into the orbit by the anterior and posterior ethmoidal fora- mina. At the anterior termi- nation of these edges, are the irregular openings which lead into the frontal sinuses ; and be- tween the two internal angular processes is a rough excavation which receives the nasal bones, and a projecting process, the nasal spine. Upon each orbital } plate, immediately beneath the external angular process, is a shallow depression which lodges the lachrymal gland ; and beneath the internal angular process a small pit, sometimes a tubercle, to which the cartilaginous pulley of the superior oblique muscle is attached. Internal Surface. — Along the middle hne of this surface is a grooved ridge, the edges of the ridge giving attachment to the falx cerebri and the groove lodging the superior longitudinal sinus. At the commencement of the ridge is an opening, sometimes completed by the ethmoid bone, the. foramen ccecum. This opening lodges a process of the dura mater, and occasionally gives passage to a small vein which communicates with the nasal veins. On each side of the vertical ridge are some slight depressions which lodge the glandulae Pacchioni, and on the orbital plates a number of irre- gular pits called digital fossa, which correspond with the convolu- tions of the anterior lobes of the cerebrum. The superior border is thick and strongly serrated, bevelled at the expense of the internal table in the middle, where it rests upon the junction of the two parietal, and at the expense of the external table, on each side, where it receives the lateral pressure of those bones. The infe- *The external surface of the frontal bone. 1. The situation of the frontal emi- nence of the right side. 2, The superciliary ridge. 3. The supra-orbital ridge. 4. Tlie external angular process. 5. The internal angular process. 6. The supra-orbital notch for the transmission of the supra-orbital nerve, and artery ; in the figure it is almost converted into a foramen by a small spiculum of bone. 7. The nasal tubero- sity ; tlie swelling around this point denotes llie situation of the frontal sinuses. 8. The temporal ridge commencing from the external angular process (4). The depres- sion in which tlie figure 8 is situated is a part of the temporal fcssa. 9. The nasal spine. 36 TEMPORAL BONE. visible The thin, tr Fig. 14.t rior border is thin, irregular, and squamous, and articulates with the sphenoid bone. Developement. — By two cen- tres, one for each lateral half. Articulations. — With tiuelve bones ; the two parietal, the sphenoid, ethmoid, two nasal, two superior maxillary, two lachrymal, and two malar. Jlttachment of Muscles. — To four pairs ; occipito-frontalis, orbicularis palpebrarum, cor- rugator supercilii, and tem- poral. Temporal Bone. — The tem- poral bone is situated at the side and base of the skull, and is di- into a squamous, mastoid, and petrous portion. Squamous portion, forming the anterior part of the bone, is anslucent, and contains no diploe. Upon its external surface it is smooth, to give attachment to the fleshy fibres of the tem- poral muscle, and has projecting from it an arched and lengthened process, the zygoma. Near the commencement of the zygoma upon its lower border, is a pro- jection called the tubercle, to which is attached the external lateral ligament of the lower jaw, and continued horizontally inwards from the tubercle a rounded eminence, the eminentia articularis. The process of bone which is continued from the tu- bercle of the zygoma into the * Tho internal surface of the frontal bone ; the bono is raised in such a manner as to show the orbito-nasal portion. 1. The grooved ridge for the lodgment of ihe superior longitudinal sinus and attachment of the falx. 2. The foramen caacum. 3. The su- perior or coronal border of the bono ; the figure is situated near that part which is bevelled at the expense of the internal table. 4. The inferior border of the bone. 5. The orbital plate of the left side. 6. Tlie cellular border of the ethmoidal fissure. Tlie foramen CiocMim (2) is seen tlirough the ethmoidal fissure. 7. The anterior and pos- tcrior ethmoidal foramina; the anterior seen leading into its canal. 8, The nasal spine. 9. The depression within the external angular i)rocess (12) for the lachrymal gland. 10. The depression for the pulley of the superior oblique muscle of the eye ; immediately to the loft of this number is the supra-orbital notch, and to its right the internal angular process. 11. The opening leading into the frontal sinuses. The same parts are seen upon the opposite side of the figure. 12. The external angular process. t The external surface of the temporal bone of the left side. 1. The squamous por- TEMPORAL BONE. 37 eminentia articularis is the inferior root of the zygoma. The swpe- rior root is continued, upwards from the upper border of the zygoma, and forms the posterior part of the temporal ridge, serving by its projection to mark the division of the squamous from the mastoid portion of the bone; and the middle root is continued directly backwards, and terminates abruptly at a narrow fissure— the fissura Glaseri or glenoid fissure. The internal surface of the squa- mous portion is marked by several shallow fossae, which correspond with the convolutions of the cerebrum, and by a furrow for the pos- terior branch of the arteria meningea magna. The superior or squamous border, is very thin and bevelled at the expense of the inner surface, so as to overlap the lower and arched border of the parietal bone. The inferior border is thick and dentated to articu- late with the spinous process of the sphenoid bone. The Mastoid 'portion forms the posterior part of the bone ; it is thick and hollowed between its tables into a loose and cellular diploe. Upon its external surf ace it is rough for the attachment of muscles, and contrasts strongly with the smooth and poHshed-hke surface of the squamous portion ; every part of this surface is pierced by small foramina, which give passage to minute arteries and veins ; one of these openings, obHque in its direction, of large size, and situated near the posterior border of the bone, the mastoid foramen, transmits a vein to the lateral sinus. This foramen is not unfre- quently situated in the occipital bone. The inferior part of this por- tion is round and expanded, — the m.astoid process, — and excavated in its interior into numerous cells, w^iich form a part of the organ of hearing. In front of the mastoid process and between the supe- rior and middle roots of the zygoma, is the large oval opening of the meatus auditorius externus, surrounded by a rough lip, the processus auditorius. Directly to the inner side, and partly concealed by the mastoid process, is a deep groove, the digastric fossa ; and a little more internally the occipital groove, which lodges the occipital artery. Upon its internal surface the mastoid portion presents a broad and shallow groove for the lateral sinus, and terminating in this groove the internal opening of the mastoid foramen. The superior border of the mastoid portion is dentated, and its posterior border thick and less serrated for articulation with the inferior border of the occipital bone. The Petrous portion of the temporal bone is named from its ex- treme hardness and density. It is a three-sided pyramid, projecting horizontally forwards into the base of the skull, the base being tion. 2. The mastoid portion. 3. The extremity of the petrous portion. 4. The zygoma. 5. Indicates the tubercle of the zygoma, and at the same time its anterior root turning inwards to form the eminentia articularis. 6. The superior root of the zygoma, forming the posterior part of the temporal ridge. 7. The middle root of the zygoma terminating abruptly at the glenoid fissure. 8. The mastoid foramen. 9. The meatus auditorius externus, surrounded by the processus auditorius. 10. The digastric fossa, situated immediately to the inner side of (2) the mastoid process. 11. The sty- loid process. 12. The vaginal process. 13. The glenoid or Glnserian fissure; the leading line from this number crosses the rough posterior portion of the glenoid fossa. 14. The opening and part of the groove for tlic Eustachian tube. 38 TEMPORAL BONE, ' applied against the internal surface of the squamous and mastoid portions, and the apex being received into the triangular interval be- tween the spinous process of the sphenoid and basilar process of the occipital bone. For convenience of description it is divisible into three surfaces — anterior, posterior, and basilar ; and three borders — superior, anterior, and posterior. Surfaces. — The anterior surface, forming the posterior boundary of the middle fossa of the interior rig. 15,* of the base of the skull, presents ^^^•^^f^ for examination from base to apex, first an eminence caused by the projection of the perpendicular se- micircular canal ; next, a groove leading to an irregular oblique opening — the hiatus Fallopii — for the transmission of the petrosal branch of the Vidian nerve ; thirdly, another and smaller ob- lique foramen, immediately be- neath the preceding, for the pas- sage of the nervus petrosus su- perficialis minor, — a branch of Jacobson's nerve ; and lastly a large foramen near the apex of the bone, the termination of the carotid canal. The posterior surface forms the front boundary of the posterior fossa of the base of the skull ; near its middle is the oblique entrance of the meatus auditorius internus. The meatus pursues a course directly outw^ards ; it is about one-third of an inch in length, and terminates in two deep depressions (nearly one-eighth of an inch in depth) separated by a sharp, horizontal ridge. The superior depres- sion, the smaller of the two, is divided at its extremity, by a vertical ridge, into an anterior portion, which is the commencement of the aqua^ductus Fallopii, for the transmission of the facial nerve ; and a posterior portion which corresponds with the upper part of the inner wall of the vestibule, and is pierced by numerous openings for * The left temporal bone, seen from within. 1. Tlie squamous portion. 2. The mastoid portion. The number is placed immediately above the inner opening- of the mastoid foramen. 3. The petrous portion. 4. Tiie groove for the posterior branch of the arteria meningca magna. 5. Tiie bevelled edge of tlie squamous border of the bone. 6. The zygoma. 7. The digastric fossa immediately internal to the mastoid process. 8. The occipital groove. !). The groove for the lateral sinus. 10. Tlie ele- vation upon the anterior surficc of the petrous bone marking the situation of the per- pendicular semicircular cunal. 11. The opening of termination of the carotid canal. 12. The meatus auditorius internus. 13. A dotted line leads upwards from tins number to the narrow fissure which lodges a process of the dura mater. Another line leads down- wards to tlic sharp edge which conceals the opening of the aquwductus coclileaj, while the number itself is situated on the bony lamina whieli overlies the opening of the aqutcductus vcstibuli. 14. 'J'he styloid process, l.'j. The sty lo-mnstoid foramen. 16, The carotid foramen. 17. The jugular process. The deep excavation to the left of this process forms part of the jugular fossa, and that to the right is the groove for the vein of the cochlea. 18, The notch for tlie fifth nerve upon the upper border of the petrous bone, near to its apex. 19. The extremity of the petrous bone wliich gives origin to the levator palati and tensor lympani muscles. TEMPORAL BONE. 39 the passage of filaments of the vestibular nerve. The inferior depression terminates in tv^o oval pits, w^hich correspond with the inferior part of the inner wall of the vestibule, and are also pierced with openings for the passage of filaments of the vestibular nerve. Upon the anterior wall of the infeiior depression, and near to its termination, is a spiral groove, perforated by minute openings for the passage of the filaments of the cochlear nerve; and in the centre of the spine is a foramen larger than the rest, which leads into the central canal of the modiolus, tuhulus centralis modioli. This groove corresponds with the base of the cochlea, and is termed the tractus spiralis foraminulenius. Upon the posterior wall of the depression, and opposite to the spiral groove, is a longitudinal groove leading to a foramen which transmits a considerable branch of the vestibular nerve. Above the meatus auditorius internus is a small oblique fissure, and a minute foramen ; the former lodges a process of the dura mater, and the foramen gives passage to a small vein. Further outwards, towards the mastoid portion of the bone, is a small slit, almost hidden by a thin plate of bone ; this is the aquceductus vestibuli, and transmits a small artery and vein of the vestibule and a process of dura mater. Below the meatus, and partly concealed by the margin of the posterior border of the bone, is the aqucBductus cochlece, through which passes a vein from the cochlea to the internal jugular vein and a process of dura mater. The basilar surface is rough and irregular, and enters into the formation of the under surface of the base of the skull. Projecting downwards, near its middle, is a long sharp spine, — the styloid pro- cess, — occasionally connected with the bone only by cartilage, and lost during maceration, particularly in the young subject. At the base of this process is a rough sheath-like ridge, into which the styloid process appears implanted, the vaginal process. In front of the vaginal process is a broad triangular depression, the glenoid fossa, bounded in front by the eminentia articularis, behind by the vaginal process, and externally by the rough lip of the processus auditorius. This fossa is divided transversely by the glenoid fissure (fissura Glaseri) which lodges the extremity of the processus gracilis of the malleus, and transmits the laxator tympani muscle, chorda tympani nerve, and anterior tympanic artery. The surface of the fossa in front of this fissure is smooth, to articulate with the condyle of the lower jaw ; and that behind the fissure is rough, for the reception of a part of the parotid gland. At the extremity of the inner angle of the glenoid fossa is the foramen for the Eustachian tube ; and separated from it by a thin lamella of bone, called processus cochlea- riformis, is a small canal for the transmission of the tensor tympani muscle. Directly behind, and at the root of the styloid process, is the stylo-mastoid foramen, the opening of exit to the facial nerve, and of entrance to the stylo-mastoid artery. Nearer to the apex of the bone is a large oval opening, the carotid foramen — the com- mencement of the carotid canal, which lodges the internal carotid artery and the carotid plexus. And between the stylo-mastoid and 40 SPHENOIDAL BONE. carotid foramen in the posterior border, is an irregular excavation forming part of the jugular fossa, and divided into two parts by a ridge and a sharp spine, the jugular process. Upon this ridge, at the posterior margin of the carotid foramen, is a small opening leading into the canal which transmits the tympanic branch of the glosso-pharyngeal nerve (Jacobson's nerve). Borders. — The superior border is sharp, and gives attachment to the tentorium cerebelli. It is grooved for the superior petrosal sinus, and near its extremity is marked by a smooth notch upon which reclines the fifth nerve. The anterior border is grooved for the Eustachian tube, and forms the posterior boundary of the foramen lacerum basis cranii ; by its sharp extremity it gives attachment to the tensor tympani and levator palati muscles. The posterior border is gi'ooved for the inferior petrosal sinus, and excavated for the jugular fossa ; it forms the anterior boundary of the foramen lacerum posterius. Developement. — By five centres ; one for the squamous portion, one for the mastoid, one for the petrous portion, one for the audi- tory process, and one for the styloid process. Articulations. — With Jive bones ; occipital, parietal, sphenoid, in- ferior maxillary, and malar. .Attachment of Muscles. — To fourteen ; by the squamous portion, to the temporal ; by the zygoma, to the masseter ; by the mastoid portion, to the occipito-frontaHs, splenius capitis, sterno-mastoid, trachelo-mastoid, digasticus and retrahens aurem ; by the styloid process, to the stylo-pharyngeus, stylo-hyoideus, stylo-glossus, and two ligaments — the stylo-hyoid and stylo-maxillary; and by the petrous portion, to the levator palati, tensor tympani, and stapedius. Sphenoidal Bone. — The sphenoid (rfcp^v, a wedge) is an irregular bone situated at the base of the skull, wedged between the other bones of the cranium, and entering into the formation both of the cranium and face. It bears some resemblance in form to a bat with its wings extended, and is divisible into body, wings, and pro- cesses. The body forms the central mass of the bone, from which the wings and processes are projected. From the upper and anterior part of the body extend on each side two small triangular plates, — the lesser wings ; from either side and expanding laterally are the greater wings ; proceeding backwards from the base of the greater wings, the spinous processes ; and downwards, the pterygoid pro- cesses. The body presents for examination a superior or cerebral sur- face, an antero-infcrior surface, and a posterior surface. Superior Surface. — At the anterior extremity of this surface is a small projecting plate, the ethmoidal spine, and spreading out on either side the lesser wings. Behind the ethmoidal spine in the middle line is a rounded elevation, the olivary process, which sup- ports the commissure of the optic nerves. Passing outwards and forwards from the olivary process, are the optic foramina, which transmit the optic nerves and ophthalmic; arteries. Behind the optic SPHENOID BONE. 41 foramina are two sharp tubercles, the anterior clinoid processes, which are the inner termination of the lesser wings. Beneath these processes, on the sides of the olivary process, are ' ^^S- 16* two depressions! fo^ ^he last turn of the internal /^^%-rSn "^"^f-^J^v carotid arteries. Behind '^''^^ ' ^- - . the olivary process, is the sella Turcica, the deep fossa which lodges the pituitary gland and cir- cular sinus ; behind and somewhat overhanging the sella Turcica, is a broad rough plate, bound- ed at each angle by a tubercle, the 'posterior clinoid processes ; and behind this plate an inclining surface, w^hich is continuous with the basilar process of the occipital bone. On either side of the sella Turcica is a broad groove {carotid) which lodges the internal carotid artery, the cavernous sinus, and its nerves. Immediately external to this groove, at the junction of the greater wings with the body, are four foramina : the first is a broad interval, the sphe- noidal fissure, which separates the greater and lesser wings, and transmits the third, fourth, the three branches of the ophthalmic division of the fifth and the sixth nerves, and the ophthalmic vein. Behind and beneath this fissure is the foramen rotundum for the superior maxillary nerve ; and still farther back, in the base of the spinous process, the foramen ovale for the inferior maxillary nerve, arteria meningea parva, and nervus petrosus superficialis minor. Behind the foramen ovale, near the apex of the spinous process, is the foramen spinosum for the arteria meningea magna. * The superior or cerebral surface of the sphenoid bone. 1. The processus olivaris. 2. The ethmoidal spine. 3. The lesser wing- of the left side. 4. The cerebral sur- face of the greater wing of the same side. 5. The spinous process. 6. The extremity of the pterygoid process of the same side, projecting downwards from the under sur- face of the body of the bone. 7. The foramen opticum. 8. The anterior clinoid pro- cess. 9. The groove by the side of the sella Turcica ; for lodging the internal carotid artery, cavernous plexus, cavernous sinus, and orbital nerves. 10. The sella Turcica. 11. The posterior boundary of the sella Turcica; its projecting angles are the pos terior clinoid processes. 12. The basilar portion of the bone. 13. Part of the sphe- noidal fissure. 14. The foramen rotundum. 15. The foramen ovale, 16. The fora- men spinosum. 17. The angular interval which receives the apex of the petrous portion of the temporal bone. The posterior extremity of the Vidian canal terminates at this angle. 18. The spine of tlie spinous process; it affords attachment to the internal lateral ligament of tlie lower jaw. 19. The border of the greater wing and spinous process which articulates with the anterior part of the squamous portion of the tem- poral bone. 20. The internal border of the spinous process, which assists in the formation of the foramen laeerum basis cranii. 21. That portion of tlie greater ala which articulates with the anterior inferior angle of the parietal bone. 22. The por- tion of the greater ala which articulates with the orbital process of the frontal bone. t These depressions are occasionally, as in a skull before me, converted into fora- mina by the extension of a short bony pillar from the anterior clinoid process to the body of tlie sphenoid. 6 42 SPHENOID BONE. Upon the aniero-inferior surface is a long flattened spine, the rostrum, which articulates with the vomer ; and on each side of the rostrum an irregular opening, Fig. 17* leading into the sphenoidal cells : these openings are par- tially closed by two thin plates of bone (frequently broken away), the sphenoidal spongy bones. On each side of the sphenoidal cells are the out- lets of the optic foramina, sphenoidal fissures, and fora- mina rotunda, the lesser and greater wings ; and below, the pterygoid processes. Upon the under surface of the body are two small fissures, con- verted into canals by the vomer, the pterygo-palaiine canals, which transmit the pterygo-palatine arteries ; and traversing the roots of the pterygoid at their union with the body, two pterygoid or Vidian canals, which give passage to the Vidian nerve and artery at each side. The posterior surface is flat and rough, and articulates with the basilar process of the occipital bone. In the adult this union is usually completed by bone; from which circumstance the sphenoid, in conjunction with the occipital, was described by Soemmering and Meckel as a single bone, under the name of spheno-occipilal or basilar bone. This surface is continuous on each side with the spinous process, and at the angle of union is the termination of the Vidian canal or foramen pterygoideum. The lesser wings (processes of Ingrassias) are thin and triangular, the base being attached to the upper and anterior part of the body of the sphenoid, and the apex extended outwards, and terminating in an acute point. The anterior border is irregularly serrated, the posterior being free and rounded, and received into the fissure of Sylvius of the cerebrum. The inner extremity of this border forms the anterior clinoid process, which is supported by a short pillar of bone, giving attachment to a part of the common tendon of the muscles of the orbit. The lesser wing forms the posterior part of the roof of the orbit, and its base is traversed by the optic foramen. The greater wings present three surfaces ; a superior or cerebral, which forms part of the middle fossa of the base of the skull, an * The antcro-inferior view of the sphenoid hone. 1. The ethmoid spine. 2. Tiie rostrum. 3. Tiic sphenoidal sponfry bone, partly closing the left opening of the sphe- noidal ccUs.t 4. The lesser wing. .'>. 'I'lie foramen opticum piereing the bnse of the lesser wing. 6. The sphenoidal fissure. 7. Tlic foramen rotundiun. 8. The orbital surface of the greater wing. 9. Its temporal surface. 10. The pterygoid ridge. 11. The pterygo-pahitine canal. 12. The foramen of entrance to the Vidian canal. 13. Tlie internal pterygoid plate. M. The hamnhir process. 1.5. The external pterygoid plate. Ifj. Tlie foramen spinosum. 17. The foramen ovale. 18. The extremity of the spinous process of the sphenoid. + This is a part of the pyramid of Wistar. See description of elhnioid. SPHENOID BONE, 43 anterior surface which assists in forming the outer wall of the orbit, and an external surface, divided into two parts by the pterygoid ridge. The superior part of the external surface enters into the formation of the temporal fossa, and the inferior portion forms part of the zygomatic fossa. The pterygoid ridge, dividing the two, gives attachment to the upper origin of the pterygoideus externus muscle. The spinous processes project backwards at each side from the base of the greater wings of the sphenoid, and are received into the angular intervals between the squamous and petrous portions of the temporal bones. Piercing the base of each process is a large oval opening, the foramen ovale ; nearer its apex a smaller opening, the foramen spinosum ; and extending downwards from the apex a short spine, which gives attachment to the internal lateral ligament of the lower jaw and to the laxator tympani muscle. The external border of the spinous process is rough, to articulate with the lower border of the squamous portion of the temporal bone ; the internal forms the anterior boundary of the foramen lacerum basis cranii, and is somewhat grooved for the reception of the Eustachian tube. The pterygoid processes descend perpendicularly from the base of the greater wings, and form in the articulated skull the lateral boun- daries of the posterior nares. Each process consists of an external and internal plate, and an anterior surface. The external plate is broad and thin, giving attachment, by its external surface, to the external pterygoid muscle, and by its internal surface to the internal pterygoid. This plate is sometimes pierced by a foramen, which is frequently formed by a process of communication passing between it and the spinous process. The internal pterygoid plate is long and narrow, and terminated at its extremity by a curved hook, the hamular process, around which plays the tendon of the tensor palati muscle. At the base of the internal pterygoid plate is a small oblong depression, the scaphoid fossa, from which arises the cir- cumflexus, or tensor palati muscle. The interval between the two pterygoid plates is the pterygoid fossa ; and the two plates are separated inferiorly by an angular notch {palatine), which receives the tuberosity, or pterygoid process, of the palate bone. The ante- rior surface of the pterygoid process is broad near its base, and supports Meckel's ganglion. The base of the process is pierced by the Vidian canal. Developement. — By twelve centres ; four for the body, viz, two for its anterior, and two for its posterior part ; four for the wings ; two for the external pterygoid plates, and two for the sphenoidal spongy bones. Articulations. — With twelve bones ; all the bones of the head and five of the face, viz. the two malar, two palate, and the vomer. Attachment of Muscles. — To twelve pairs; temporal, external ptery- goid, internal pterygoid, superior constrictor, tensor palati, laxator tympani, levator palpebras, obliquus superior, superior rectus, internal rectus, inferior rectus, and external rectus. 44 ETHMOID BOiVE. Ethmoid Bone. — The ethmoid (^i^i^oj, a sieve) is a square-shaped cellular bone, situated between the two orbits, at the root of the nose, and perforated upon its upper surface by a number of small open- ings, from which pecuHarity it has received its name. It consists of a perpendicular lamella and two lateral masses. The "perpendicular lamella is a thin central plate, which arti- culates with the vomer and cartilage of ^* ■ the septum, and assists in forming the sep- tum of the nose. It is surmounted supe- riorly by a thick and strong process, the crista galli, which projects into the cavity of the skull, and gives attachment to the falx cerebri. On each side of the crista galh, upon the upper surface of the bone, is a thin and grooved plate, perforated by a number of small openings, the cribriform lamella, which supports the bulb of the olfactory nerve, and gives passage to its filaments, and to the internal nasal nerve. The cribriform lamella serves to connect masses with the perpen- dicular plate. The lateral masses are divisible into an internal and external sur- face, and four borders — superior, inferior, anterior, and posterior. The internal surface is rough and slightly convex, and forms the external boundary of the upper part of the nasal fossae. Towards the posterior border of this surface is a narrow horizontal fissure, — the superior meatus of the nose, — the upper margin of which is thin, and somewhat curled inwards ; hence it is named the superior tur- binated bone. Below the meatus is the convex surface of another thin plate which is curled outwards, and forms the lower border of the mass, the middle turbinated bone. The external surface is quad- rilateral and smooth, hence it is named os planum ; it enters into the formation of the inner wall of the orbit. The superior border is irregular and cellular, the cells being com- pleted by the edges of the ethmoidal fissure of the frontal bone. This border is crossed by two grooves, sometimes complete canals, open- ing into the orbit by the anterior and posterior ethmoidal foramina. The inferior border is formed internally by the lower border of the middle turbinated bone, and externally by a concave irregular * The ethmoid bone seen from above and behind. 1. The central lamella. 2,2. The lateral masses ; the numbers are placed on the posterior border of the lateral mass at each side. .3. The crista galli process. 4. Tlic eribrifrom plate of tlie left side, pierced by the cribriform foramina. 5. The hollow space immediately above and to the left of this number is the superior meatus. G. The superior turbinated bono. 7. The middle turbinated bone ; the numbers 5, G, 7, are situated upon the internal sur- face of the loft lateral mass, near its posterior part. The interval between these parts is the superior meatus. 8. Tlic external surface of the lateral mass, or os planum. 9. The superior or frontal border of the lateral mass, jrrooved by the anterior and poste- rior ethmoidal canals. 10. Refers to tlie concavity of the middle turbinated bone, which is the upper boundary of the middle meatus. NASAL BONES. 45 fossa, the upper boundary of the middle meatus. The anterior border presents a number of incomplete cells, which are closed by the superior maxillary and lachrymal bones ; and the -posterior border is irregularly cellular, to articulate with the sphenoid and palate bones.* The lateral masses are composed of cells, which are divided by a thin partition into anterior and posterior ethmoidal cells. The ante- rior, the most numerous, communicate with the frontal sinuses, and open by means of an irregular and incomplete tubular canal, the infundibulum, into the middle meatus. The posterior cells, fewer in number, open into the superior meatus. Vevelopement — By three centres ; one for each lateral mass, and one for the perpendicular lamella. Articulations. — With thirteen bones ; two of the cranium, — the frontal and sphenoid; the rest of the face, viz. the nasal, superior maxillary, lachrymal, palate, the inferior turbinated, and the vomer. No muscles are attached to this bone. BONES OF THE FACE. The face is composed of fourteen bones ; viz. the Two nasal. Two palate. Two superior maxillary, Two inferior turbinated, Two lachrymal, Vomer, Two malar. Inferior maxillary. Nasal Bones. — The nasal (fig. 23) are two small quadrangular bones, forming by their union the bridge and base of the nose. Upon the upper surface they are convex, and pierced by a foramen, for a small artery ; on the under surface they are somewhat con- cave, and marked by a groove, which lodges the nasal branch of the ophthalmic nerve. The superior border is narrow and thick, the inferior broad, thin, and irregular. Developement. — By a single centre for each bone. Articulations. — With four bones ; frontal, ethmoidal, nasal, and superior maxillary. Attachment of Muscles. — It has in relation with it the pyramidalis nasi, and compressor nasi ; but neither of these muscles is inserted into it. Superior Maxillary Bones. — The superior maxillary arc the largest bones of the face, with the exception of the lower jaw ; they form, by their union, the whole of the upper jaw, and assist in the construction of the nose, the orbit, the cheek, and the palate. Each bone is divisible into a body and four processes. * Mr. Wilson has entirely omitted the description of the pyramids of Wrslnr, which in their early stage project as thin triangular laniinre from the posterior borders of the lateral masses. As they become developed the edges of the laminte fold over so as to form an imperfect triangular pyramid, encroacliing upon the body of the sphenoid bone on its under surface, and finally coalescing with it so as to perfect the sphenoidal cells. The remains of these pyramids mny be seen on the adult bone, and are called by Wilson the sphenoidal spongy bones. They were first studied by Professor Wistar, and are called after him. G. 46 SUPERIOR MAXILLARY BONES. The body is triangular in form, and hollowed in its interior into a large cavity, the antrum maxillare (antrum of Highmore). It presents for examination three sides ; an external or facial, internal or nasal, and a posterior or zygomatic, and a superior surface — the orbital. " The external or facial surface forms the anterior part of the bone ; it is irregularly concave, and pre- sents a deep depression towards its centre, — the canine fossa, which gives attachment to two muscles, the compressor nasi and levator anguli oris. Immediately above this fossa is the infra-orhital foramen, — the termination of the infra-orbital canal, — transmitting the superior maxillary nerve, and infra-orbital artery ; and above the infra-orbital foramen, the lower margin of the orbit, continuous externally with the rough articular surface of the malar process, and internally with a thick ascending plate, the nasal process. Towards the middle line of the face this surface is bounded by the concave border of the opening of the nose, which is projected forwards at its in- ferior termination into a sharp process, forming, with a similar pro- cess of the opposite bone, the nasal spine. Beneath the nasal spine, and above the two superior incisor teeth, is a slight depression, the incisive or myrtiformfossa, which gives origin to the depressor labii superioris alaeque nasi muscle. The myrtiform fossa is divided from the canine fossa by a perpendicular ridge, corresponding with the direction of the root of the canine tooth. The inferior boundary of the facial surface is the alveolar process which contains the teeth of the upper jaw, and it is separated from the zygomatic sur- face by a strong projecting eminence, the malar process. The in- ternal, or nasal surface, presents a large irregular opening, leading into the antrum maxillare ; this opening is nearly closed in the ar- ticulated skull by the ethmoid, palate, lachrymal, and inferior turbi- nated bones. The cavity of the antrum is somewhat triangular, corresponding in shape with the form of the body of the bone. Upon its internal surface are numerous grooves, lodging branches of the superior maxillary nerve, and projecting into its floor several conical processes, corresponding with the roots of the jEirst and second molar teeth. In front of the opening of the antrum is the * The superior maxillary bones of the right side, as seen from the lateral aspect. 1. The externa], or facial surface ; the depression in which the iigure is placed is tlie canine fossa. 2. The posterior, or zygomatic surface. 3. The superior, or orbital sur- face. 4. The infra-orbital foraraen ; it is situated immediately below the number. 5. The infra-orbital canal, leading to the infra-orbital foramen. G. The inferior border of the orbit. 7. The malar process. 8. The nasal process. 9. The concavity forming the lateral boundary of the anterior narcs. 10. The nasal spine. 11. The incisive, or myrtiform fossa. 12. The alveolar process. 1.3. The internal border of the orbital surface, which articulates with the ethmoid and jjalatc bone. 14. Tiie concavity which articulates with the lachrymal bone, and forms the commencement of the nasal duct. 1.5. The palute prof.c-:s. i. TIjc two incisor teeth, c. The canine. 6. The two bicus- pidati. m. The tJiree molares. SUPERIOE MAXILLARY BONES. 47 Strong ascending plate of the nasal process, marked inferiorly by a rough horizontal ridge, which gives attachment to the inferior tur- binated bone. The concave depression immediately above this ridge corresponds with the middle meatus of the nose, and that below the ridge with the inferior meatus. Between the nasal process and the opening of the antrum, is a deep groove, which is converted into a canal by the lachrymal bone, and constitutes the nasal duct or ductus ad nasum. The superior border of the nasal surface is irregularly cellular, and articulates with the lachrymal and ethmoid bone ; the posterior border is rough, and articulates with the palate bone ; the anterior border is sharp, and forms the free margin of the opening of the nose ; and from the inferior border projects inwards a strong horizontal plate, the palate process. The posterior surface may be called zygomatic, from forming part of the zygomatic fossa ; it is bounded externally by the malar process, and internally by a rough and rounded border, the tuberosity, which is pierced by a number of small foramina, giving passage to the posterior dental nerves and branches of the superior dental artery. The lower part of this tuberosity presents a rough oval surface, to articulate with the palate bone, and immediately above and to the inner side of this articular surface a smooth groove, which forms part of the posterior palatine canal. The superior border is smooth and rounded to form the lower boundary of the spheno-maxillary fissure, and is marked by a notch, the commence- ment of the infra-orbital canal. The inferior boundary is the alveolar process, containing the two last molar teeth. The orbital surface is triangular and thin, and constitutes the floor of the orbit. It is bounded internally by an irregular edge, which articulates with the palate, ethmoid, and lachrymal bone ; posteriorly, by the smooth border which enters into the formation of the spheno-maxillary fissure ; and anteriorly, by a convex margin, partly smooth and partly rough, the smooth portion forming part of the lower border of the orbit, and the rough articulating with the malar bone. The middle of this surface is channelled by a deep groove and canal, the infra-orbital, which terminates at the infra-orbital foramen. The four processes of this bone are, the nasal, malar, alveolar, and palate. The nasal process ascends by the side of the nose, to which it forms the lateral boundary, and articulates with the frontal and nasal bone. By its external surface it gives attachment to the levator labii superioris aleeque nasi, and to the orbicularis palpebrarum muscle ; its internal surface contributes to form the inner wall of the nares, and the posterior border is thick and hollowed into a groove for the nasal duct. The margin of the nasal process, which is continuous with the lower border of the orbit, is sharp and marked by a small tubercle which serves as a guide to the introduction of the knife in the operation for fistula lachrymalis. The malar process, large and irregular, is situated at the angle 48 LACHRYMAL BONES, of separation between the facial and zygomatic surfaces, and pre- sents a large triangular surface for articulation with the malar bone. The alveolar process forms the lower margin of the bone ; it is spongy and cellular in textm'e, and excavated into deep holes for the reception of the teeth. The palate process is thick and strong, and projects horizontally inwards from the inner surface of the body of the bone. Superiorly, it is concave, and forms the floor of the nares ; inferiorly, it is also concave, and assists in the formation of the roof of the palate. Its internal edge is raised into a ridge, which, with a corresponding ridge in the opposite bone, forms a groove for the reception of the vomer. At the anterior extremity of its nasal surface is a foramen, which leads into a canal formed conjointly by the two superior maxillary bones, — the naso-palatine canal. The termination of this canal is situated immediately behind the incisor teeth, hence it is also named the incisive foramen.* Developement — By six centres ; one for the body, one for each of the three processes, nasal, malar, and palate ; and two for the alveolar process. Articulations. — With nine bones, viz. with two of the cranium and with all the bones of the face, excepting the inferior maxillary. These are, the frontal and ethmoid, nasal, lachrymal, malar, inferior turbinated, palate, vomer, and with its fellow of the oppo- site side. Attachment of Muscles. — To nine; orbicularis palpebrarum, obli- quus inferior oculi, levator labii superioris alseque nasi, levator labii superioris proprius, levator anguli oris, compressor nasi, depressor labii superioris alajque nasi, buccinator, masseter. Lachrymal Bones — (os unguis, from an imagined resemblance to a finger nail). The lachrymal (fig. 23) is a thin oval-shaped plate of bone, situated at the anterior and inner angle of the orbit. It may bo divided into an external and internal surface and borders. The external surface is smooth and marked by a vertical ridge, — the lachrymal crest, — into two portions, one of which is flat and enters into the formation of the orbit, hence may be called the orbital portion; the other is concave, and lodges the lachrymal sac, hence the lachrymal portion. The internal surface is rough and completes the anterior ethmoid cells, it assists in forming the wall of the nasal fossa: and nasal duct. Developement. — By a single centre. Articulations. — Wiihfour bones; two of the cranium, frontal and ethmoid ; and two of the face, superior maxillary, and inferior turbinated bone. Attaclirnent of Muscles. — To one muscle, the tensor tarsi, and to an expansion of the tcndo oculi, the former arising from the orbital surface, the other being attached to the lachrymal crest. Malar Bones — (mala, the cheek). The malar (fig. 23) is the strong quadrangular bone which forms the pi-ominence of the * It contains a ganglion from the fifth pair. G. PALATE BONES. 49 cheek. It is divisible into an external and internal surface, and four processes, the frontal, orbital, maxillary, and zygomatic. The external surface is smooth and convex, and pierced by several small openings which give passage to filaments of the temporo- malar nerve and minute arteries. The internal surface is concave, partly smooth and partly rough; smooth where it forms part of - the temporal fossa, and rough where it articulates with the superior maxillary bone. The frontal process ascends perpendicularly to form^ the outer border of the orbit, and articulate with the external angular process of the frontal bone. The orbital process is a thick plate, which pro- jects inwards from the frontal process, and unites with the great ala of the sphenoid to constitute the outer wall of the orbit. It is pierced by several small foramina for the passage of temporo-malar filaments of the superior maxillary nerve. The maxillary process is broad, and articulates with the superior maxillary bone. The zygomatic process, narrower than the rest, projects backwards to unite with the zygoma of the temporal bone. Developement. — By a single centre. Articulations. — With four bones ; three of the cranium, frontal, temporal, and sphenoid ; and one of the face, the superior maxillary bone. Attachment of Muscles. — To six ; orbicularis palpebrarum, levator labii superioris proprius, zygomaticus minor and major, masseter, and temporal. Palate Bones. — The palate bones are situated at the posterior part of the nares, where they enter into the formation of the palate, the side of the nose, and the posterior part of the floor of the orbit ; hence they might with great propriety be named the palato-naso- orbital bones. Each bone resembles in general form the letter L, and is divisible into a horizontal plate, a perpendicular plate, and a pterygoid process or tuberosity. The horizontal plate is quadrilateral ; and presents two surfaces, one superior, which ^i?- 20.* enters into the formation of the floor of the nares, the other inferior, forming the posterior part of the hard palate. The superior surface is concave and rises towards the middle line, where it unites with its fellow of the opposite side and forms a crest, which articulates with the vomer. The inferior surface is marked by a slight transverse ridge, to which is attached the tendinous expansion of the tensor palati muscle, and near to the external border are two openings, the posterior palatine foramina, which transmit the posterior palatine nerves and artery. The posterior * A posterior view of the palate bone in its natural position ; it is slightly turned to one side to obtain a sight of the internal surface of the perpendicular plate (2.) 1. The horizontal plate of the bone ; its upper or nasal surface. 2. The perpendicular plate ; 7 50 PALATE BONES. border is concave, and presents at its inner extremity a sharp point, which with a corresponding point in the opposite bone constitutes the palate spine for the attachment of the azygos uvulse muscle. The perpendicular plate is also quadrilateral ; and presents two surfaces, one internal or nasal, forming a part of the wall of the nares ; the other external, bounding the spheno-maxillary fossa and antrum. The internal surface is marked near its middle by a horizontal ridge, to which is united the inferior turbinated bone. The slightly concave surface below this ridge enters into the formation of the inferior meatus of the nose, and that above the ridge of the middle and superior meatus. The external surface, extremely irregular, is rough on each side for articulation with the neighbouring bones, and smooth in the middle to constitute the inner boundary of the spheno-maxillary fossa. This smooth surface terminates inferiorly in a deep groove, which being completed by the tuberosity of the superior maxillary bone forms the posterior palatine canal. Near the upper part of the perpendicular plate is a large opening, the spheno-palatine foramen, which transmits the Fig. 21.* spheno-palatine nerves and artery, and serves to divide the upper extremity of the bone into two portions, an anterior or orbital, and a posterior or sphenoidal portion. The orbital portion pre- sents five surfaces ; three articular, and two free ; the three articular are the anterior, which looks forward and articulates with the superior maxillary bone, internal with the ethmoid, and posterior with the sphenoid. The free surfaces are the superior or orbital, which forms the pos- terior part of the floor of the orbit, and the exter- nal, which looks into the spheno-maxillary fossa. The sphenoidal portion,^ much smaller than the orbital, has three surfaces, two lateral and one superior. The external lateral surface enters into the formation of the spheno- its internal or nasal surface. 3. 10, 11. The pterygoid pi'occss or tuberosity. 4. The broad internal border of the horizontal plate which articulates with the similar border of the opposite bone. 5. The pointed process, which with a similar process of the opposite bono forms the palate spine. 6. The horizontal ridge which gives attach- ment to the inferior turbinated bone ; the concavity below this ridge enters into the formation of the inferior meatus, and the concavity (2) above the ridge into that of the middle and superior meatus. 7. The spheno-palatine foramen. 8. Tlie orbital portion. 10. Tlie middle facet of the tuberosity, which enters into the formation of the pterygoid fossa. Tlie ficets 11 and .3 articulate with the two pterygoid plates, — 11 with the internal, and 3 with the external. * 1'he perpendicular plate of the palate bone seen upon its external or spheno-maxil- lary surface. 1. The rough surface of this plate, which articulates with the superior maxillary bone. 2. The posterior palatine canal, completed by the tuberosity of the superior maxillary bone. The rough surface to the left of the canal (2) articulates with tiie internal pterygoid plate. 3. The splicno-palatine foramen. 4, 5, G. The orbital portion of the |)erpendicular plate. 4. The spheno-maxillary facet of this por- tion ; .0. its orbital facet ; G. its maxillary facet, to articulate with the superior maxil- lary bone. 7. The splienoidal portion of the perpendicular plate. 8. The pterygoid process or tuberosity of the bone. t Called by Horner, the pterygoid apophysis. — G. INFERIOR TURBINATED BONE. 51 mamillary fossa ; the internal lateral forms part of the lateral boun- dary of the nares ; and the superior surface articulates with the under part of the body of the sphenoid bone. The pterygoid process or tuberosity of the palate bone is the thick and rough process which stands backwards from the angle of union of the horizontal with the perpendicular portion of the bone. It is received into the angular fissure, which exists between the two plates of the pterygoid process at their inferior extremity, and pre- sents three surfaces : one concave and smooth, which forms part of the pterygoid fossa ; and one at each side to articulate with the pterygoid plates. The anterior face of this process articulates with the superior maxillary bone. Developement. — By a single centre. Articulations. — With six bones; two of the cranium, the sphenoid and ethmoid ; and four of the face, the superior maxillary, inferior turbinated bone, vomer, and with the palate bone of the opposite side. Attachment of Muscles. — Ho four ; the tensor palati, azygos uvulae, internal, and external pterygoid. Inferior Turbinated Bones. — The inferior turbinated or spongy bone is a thin layer of loose and spongy bone, slightly curled upon itself, and projecting inwards from the inner wall of the nares. It is developed from a single centre, and gives attachment to no muscles. Articulations. — 'With four bones; the ethmoid, superior maxillary, lachrymal, and palate. Vomer. — The vomer is a thin and quadrilateral plate, forming a part of the septum of the nares. Superiorly, it is broad and expanded, and forms a sheath for the rostrum of the sphenoid ; inferiorly, it is thin, and received into a groove, formed by the articulation between the palate processes of the superior maxillary and palate bone of opposite sides. The posterior border is free, and divides the poste- rior nares ; the anterior is rough, and often slit into two layers, to receive the sharp edge of the perpendicular lamella of the ethmoid bone, and of the cartilage of the septum. The vomer frequently presents a convexity to one or the other side; it is developed by a single centre, and has no muscles attached to it. Articulations. — With six bones ; the sphenoid, ethmoid, two supe- rior maxillary, and two palate bones, and with the cartilage of the septum. Inferior Maxillary Bone. — The lower jaw is the arch of bone which contains the inferior teeth ; it is divisible into a horizontal portion or body, and a pei'pendicular portion, the ramus, at each side. Upon the external surface of the body of the bone, at the middle line, and extending from between the two first incisor teeth to the chin, is a slight ridge, called the symphysis. Immediately external to this ridge is a depression which gives origin to the depressor labii 52 INFERIOR MAXILLARY BONE. inferioris muscle; and corresponding with the root of the lateral incisor tooth, another depression, the incisive fossa, for the levator labii inferioris. Further outwards is an oblique opening, the anterior ?nental foramen, for the exit of the inferior dental nerve and artery, and below this foramen, an obhque ridge which gives attachment to the depressor anguli oris, and platysma myoides. Near the posterior part of this surface is a rough impression made by the masseter muscle ; and immediately in front of this impres- sion, a groove may occasionally be seen lor the facial artery. The projecting tuberosity at the posterior extremity of the lower jaw, at the point where the body and ramus meet, is the angle. Upon the internal surface of the body of the bone at the symphysis, are two small pointed tubercles ; immediately beneath these, two other tubercles less marked and pointed, beneath them a ridge, and beneath the ridge a rough depression of some size. These four points give attachment from above downwards to the genio-hyo- glossi, genio-hyoidei, part of the mylo-hoidei and to the digastric muscles. Running outwards into the body of the bone from the above ridge, is a prominent line, the mylo-hyoidean ridge, which gives attachment to the mylo-hyoideus muscle, and by its extremity to the pterygo-maxillary ligament and superior constrictor muscle. Immediately above the ridge, and by the side of the symphysis, is a smooth concave surface, which corresponds with the sublingual gland; and below the ridge, and more externally, a deeper fossa for the submaxillary gland. The ramus is a strong square-shaped process, differing in direc- tion at various periods of life; thus, in the foetus and infant, it is almost parallel with the body ; in youth it is obhque, and gradually increases in the vertical direction imtil man- hood ; in old age, after the loss of the teeth, it again declines and assumes the oblique direction. Upon its external surface it is rough, for the. attachment of the masseter muscle ; and at the junc- tion of its posterior border with the body of the bone, is a rough tube- rosity, the angle of the lower jaw, which gives attachment by its inner margin to the stylo-maxillary ligament. The upper extremity of the ramus presents two processes, sepa- rated by a concave sweep, the sigmoid notch. The anterior is the * The lower jaw. 1. The body. 2. The ramus. .^. The symphysis. 4. The fossa for the depressor labii inferioris muscle. .5. The mental foramen. 6. The external oblique ridge. 7. The groove for the facial artery. 8. The angle. 9. The extremity of the mylo-hyoidcan ridge. 10. The coronoid process. 11. The condyle. 12. The sigmoid notcli. 13. The inferior dental foramen. 14. The mylo-hyoidean groove. 15. The alveolar process, i. The middle and lateral incisor tooth of one side. c. The canine tooth, b. The two bicuspides. in. The three molares. Fig. 22.* TABLE OF DEVELOPEMENTS, ARTICULATIONS, ETC. 53 coronoid process ; it is sharp and pointed, and gives attachment by- its inner surface to the temporal muscle. The anterior border of the coronoid process is grooved at its lower part for the buccinator muscle. The posterior process is the condyle of the low^er jaw, which is flattened from before backwards, and smooth upon its upper surface, to articulate with the inter-articular fibro-cartilage. The constriction around the base of the condyle is its neck, into which is inserted the external pterygoid muscle. The sigmoid notch is crossed by the masseteric artery and nerve. The internal surface of the ramus is marked near its centre by a large oblique foramen, the inferior dental,* for the inferior dental artery and nerve. Around this opening is a rough margin, to which is attached the internal lateral ligament, and passing downwards from the opening a narrow groove which lodges the mylo-hyoidean nerve. To the rough surface above, and in front of the inferior dental foramen, is attached the temporal muscle, and to that below it the internal pterygoid. The internal surface of the neck of the condyle gives attachment to the external pterygoid muscle ; and the angle to the stylo-maxillary ligament. Developement. — By two centres ; one for each lateral half, the two sides meeting at the symphysis, where they become united. Articulations. — With the glenoid fossas of the two temporal bones, through the medium of a fibro-cartilage. Attachment of Muscles. — To fourteen pairs; by the external sur- face commencing at the symphysis, and proceeding outwards, — levator labii inferioris, depressor labii inferioris, depressor anguli oris, platysma myoides, buccinator and masseter ; by the internal surface also commencing at the symphysis, the genio-hyo-glossus, genio-hyoideus, mylo-hyoideus, digastricus, superior constrictor, temporal, external pterygoid, and internal pterygoid. Table of tJie Points of Developement, Articulations, and Attachment of Muscles, of the Bojies of the Head. Occipital Parietal De velopement. 4 1 Articulatior 6 5 Attachment of Ls. muscles. 13 pairs. 1 muscle. Frontal . 2 12 4 pairs. Temporal Sphenoid Ethmoid • 5 . 12 3 5 12 13 . 14 muscles 12 pairs, none. Nasal . 1 4 . none. Superior maxillary Lachrymal . Malar . . . . 6 9 4 . 4 9 muscles. 1 ib. 6 ib. Palate . . 6 . 4 ib. Inferior turbinated 4 none. Vomer . . 6 none. Lower jaw . 2 2 14 pairs. * Called also posterior mental foramen. — G. 54 SUTURES OSSA TRiaUETRA. SUTURES. The bones of the cranium and face are connected with each other by means of sutures (sutura, a seam), of whicli there are four principal varieties, — serrated, squamous, harmonia, and schindylesis. The serrated suture is formed by the union of two borders pos- sessing serrated edges, as in the coronal, sagittal, and lambdoid sutures. In these sutures the serrations are formed almost wholly by the external table, the edges of the internal table lying nearly in apposition. The squamous suture (squama, a scale) is formed by the over- lapping of the bevelled edges of two contiguous bones, as in the articulation between the temporal and lower border of the parietal. In this suture the approximated surfaces are roughened, so as to adhere mechanically with each other. The harmonia suture (agw, to adapt) is the simple apposition of contiguous surfaces, the surfaces being more or less rough and re- tentive. This suture is seen in the connexion between the superior maxillary bones, or of the palate processes of the palate bones with each other. The schindylesis suture {d'xiv^xj'kridig, a fissure) is the reception of one bone into a sheath or fissure of another, as occurs in the articu- lation of the sphenoid with the vomer, or of the latter with the per- pendicular lamella of the ethmoid, and with the palate processes of the superior maxillary and palate bones. The serrated suture is formed by the interlocking of the radia- ting fibres along the edges of the flat bones of the cranium during growth. When this process' is retarded in the infant by over-dis- tention of the head, as in hydrocephalus, and sometimes without any such apparent cause, distinct ossific centres are developed in the interval between the edges; and, being surrounded by the suture, form independent pieces, which are called ossa triquetra, or ossa Wormiana. In the lambdoid suture there is generally one or more of these bones ; and, in a beautiful adult hydrocephalic skeleton in the possession of Mr. Liston, there are upwards of one hundred. The coronal suture (fig. 23) extends transversely across the vertex of the skull, from the upper part of the greater wing of the sphenoid to the same point on the opposite side ; it connects the frontal with the parietal bones. In the formation of this suture the edges of the articulating bones are bevelled, so that the parietal rest upon the frontal at each side, and in the middle the frontal rests upon the parietal bones, so as to afford each other mutual support in the consolidation of the skull. The sagittal suture (fig. 23) extends longitudinally backwards along the vertex of the skull, from the middle of the coronal to the apex of the lambdoid suture. It is very much serrated, and serves to unite the two parietal bones. Sometimes this suture is continued SUPERIOR REGIONS OF THE SKULL. 55 through the middle of the frontal bone to the root of the nose, under the name of the frontal suture. The lambdoid suture is named from some resemblance to the Greek letter A, consisting of two branches, which diverge at an acute angle from the extremity of the sagittal suture. This suture connects the occipital with the parietal bones. At the posterior and inferior angle of the parietal bones, the lambdoid suture is con- tinued onwards in a curved direction into the base of the skull, and serves to unite the occipital bone with the mastoid portion of the temporal, under the name of the additamentum sutures lamhdoidalis. It is in the lambdoid suture that the ossa triquetra occiu* most frequently. The squamous suture (fig. 23) unites the squamous portion of the temporal bone with the greater ala of the sphenoid and with the parietal, overlapping the lower border of the latter. The portion of the suture which is continued backwards from the squamous portion of the bone to the lambdoid suture, and connects the mas- toid portion with the posterior inferior angle of the parietal is the additamentum suturce squamoscB. Across the upper part of the face is an irregular suture, the trans- verse, which connects the frontal bone with the nasal, superior max- illary, lachrymal, ethmoid, sphenoid, and malar bones. The other sutures are too unimportant to deserve particular names or descrip- tion. REGIONS OP THE SKULL. The skull, considered as a whole, is divisible into four regions, — a superior region, or vertex ; a lateral region ; an inferior region, or base ; and an anterior region, the face. The superior region, or vertex of the skull, is bounded anteriorly by the frontal eminences ; on each side by the temporal ridge and parietal eminences ; and behind by the superior curved line of the occipital bone and occipital protuberance. It is crossed trans- versely by the coronal suture, and marked from before backwards by the sagittal, which terminates posteriorly in the lambdoid suture. Near the posterior extremity of the region, and on each side of the sagittal suture, is the parietal foramen. Upon the inner, or cerebral surface of this region, is a shallow groove, extending along the middle line from before backwards, for the superior longitudinal sinus ; on either side of this groove are several small fossse for the Pacchionian bodies, and still further outwards numerous ramified markings for lodging the branches of the arteria meningea media. The lateral region of the skull is divisible into three portions ; temporal, mastoid, and zygomatic. The temporal portion, or temporal fossa, is bounded above and behind by the temporal ridge, in front by the external angular pro- cess of the frontal bone and by the malar bone, and below by the zygoma. It is formed by part of the frontal, great wing of the 56 BASE OF THE SKULL. sphenoid, parietal, squamous portion of the temporal, and malar bone, and lodges the temporal muscle. Fio'. 23* Fiff. 24.t The mastoid portion is rough, for the attachment of muscles. Upon its posterior part is the mastoid foramen, and below> the mas- toid process. In front of the mastoid process is the external audi- tory foramen, surrounded by the external auditory process ; and * A front view of the skull. 1. The frontal portion of the frontal bone. The 2 im- mediately over the root of the nose, refers to the nasal tuberosity ; the 3 over the orbit, to the supra-orbital rido^e. 4. The optic foramen. 5. Tlie sphenoidal fissure. 6. The spheno-maxillary fissure. 7. The lachrymal fossa in the lachrymal bone, the com- mencement of the nasal duct. The fig-ures 4, 5, 6, 7, are within the orbit. 8. The opening of the anterior nares, divided into two parts by the vomer ; the number is placed upon the latter. 9. The infra-orbital foramen. ]0. The malar bone. 11. The symphysis of the lower jaw. 12. The mental foramen. 13. The ramus of the lower jaw. 14. The parietal bone. 15. The coronal suture. 16. The temporal bone. 17. The squamous suture. 18. The upper part of the great ala of the sphenoid bone. 19. The commencement of the temporal ridge. 20. The zygoma of the temporal bone, assisting to form the zygomatic arch. 21. The mastoid process. t The cerebral surface of the base of the skull. 1. One side of the anterior fossa ; the number is placed on the roof of the orbit, formed by the orbital plate of the frontal bone. 2. The lesser wing of the splienoid. 3. The crista galli. 4. The foramen csecum. 5. The cribriform lamella of the ethmoid. 6. The processus olivaris. 7. The foramen opticum. 8. The anterior clinoid process. 9. The carotid groove upon the side of the sella Turcica, for the internal carotid artery and cavernous sinus. 10, 11, 12. The middle fossa of the base of the skull. 10. Marks the great ala of the sphe- noid. 11. The sfjuarnous portion of the temporal bone. 12. The petrous portion of the tcmjjoral. 13. Tlic sella Turcica. 14. The basilar portion of the sphenoid bone surmounted by the posterior clinoid processes. 15. The foramen rotundum. 16. The foramen ovale. 17. The foramen spinosum ; the small irregular opening between 17, and 12 is the hiatus Fallopii. 18. The posterior fossa of the base of the skull. 19, 19. The groove for the lateral sinus. 20. The ridge upon the occipital bone, which gives attachment to the falx cerebelli. 21. The foramen magnum. 22. The meatus auditoriiis internus. 23. The jugular foramen. BASE OF THE SKULL. 57 in front of this foramen the glenoid cavity, bounded above by the middle root of the zygoma, and in front by its tubercle. The zygomatic 'portion, or fossa, is the irregular cavity below the zygoma, bounded in front by the superior maxillary bone, internally by the external pterygoid plate, above by part of the great wing of the sphenoid and squamous portion of the temporal bone, and by the temporal fossa, and externally by the zygomatic arch and ramus of the lower jaw. It contains the external pterygoid, with part of the temporal and internal pterygoid muscle, and the internal maxillary artery and inferior maxillary nerve, with their branches. At the bottom of the zygomatic fossa are two fissures, the spheno-maxillary and the pterygo-maxillary. The spheno-maxillary fissure is horizontal in direction, opens into the orbit and is situated between the great ala of the sphenoid and the superior maxillary bone. The pterygo-maxillary fissure is vertical, and descends at right angles from the extremity of the preceding. It is situated between the pterygoid process and tuberosity of the superior maxillary bone, and transmits the internal maxillary artery. At the angle of junc- tion of these two fissures is a small cavity, the spheno-maxillary fossa, bounded by the sphenoid, palate, and superior maxillary bones, in which are seen the openings of five foramina, — the foramen ro- tundum, spheno-palatine, ptery go-palatine, posterior palatine, and Vidian. It lodges Meckel's ganglion and the termination of the in- ternal maxillary artery. The base of the skull presents an internal or cerebral, and an ex- ternal or basilar surface. The cerebral surface is divisible into three parts, which are named the anterior, middle, and posterior fossa of the base of the cranium. The anterior fossa is somewhat convex on each side, where it cor- responds with the roofs of the orbits ; and concave in the middle, in the situation of the ethmoid bone, and the anterior part of the body and lesser wings of the sphenoid, which constitute its posterior boundary. It supports the anterior lobes of the cerebrum. In the middle fine of this fossa, at its anterior part, is the crista galli, im- mediately in front of this process, the foramen ccecum, and on each side the cribriform plate, with its foramina, for the transmission of the filaments of the olfactory and nasal branch of the ophthalmic nerve. Farther back in the middle line is the processus olivaris, and on the sides of this process the optic foramina, anterior clinoid pro- cesses, and vertical grooves for the internal carotid arteries. The middle fossa of the base, deeper than the preceding, is bounded in front by the lesser wing of the sphenoid ; behind, by the petrous portion of the temporal bone ; and is divided into two lateral parts by the sella Turcica. It is formed by the posterior part of the body, great ala, and spinous process of the sphenoid, and by the petrous and squamous portion of the temporal bones. In the centre of this fossa is the sella Turcica, which lodges the pituitary gland, bounded in front and behind bv the anterior and posterior clinoid 8* 58 BASE OF THE SKULL. processes. On each side of the sella Turcica is the carotid groove for the internal carotid artery, the cavernous plexus of nerves, the cavernous sinus, and the orbital nerves, and a little farther outwards the following foramina from before backwards, s-phenoidal fissure (foramen lacerum anterius) for the transmission of the third, fourth, three branches of the ophthalmic division of the fifth, and the sixth nerve, and ophthalmic yein; foramen rotundum, for the superior max- illary nerve ; foramen ovale, for the inferior maxillary nerve, arteria menincrea parva, and nervus petrosus superficialis minor ; — foraynen spinosum, for the arteria meningea magna ; foramen lacerum basis cranii, which gives passage to the internal carotid artery, carotid plexus, and petrosal branch of the Vidian nerve. On the anterior surface of the petrous portion of the temporal bone is a groove, leading to a fissured opening, the hiatus Fallopii, for the petrosal branch of the Vidian nerve ; and immediately beneath this a smaller foramen, for the nervus petrosus superficialis minor. Towards the apex of this portion of bone is the notch for the fifth nerve, and below it a slight depression for the Casserian ganglion. Farther outwards is the eminence which marks the position of the perpen- dicular semicircular canal. Proceeding from the foramen spinosum are two grooves which mark the course of the trunks of the arteria menino-ea media. The whole fossa lodges the middle lobes of the cerebrum. The posterior fossa, larger than the other two, is formed by the occipital bone, by the petrous and mastoid portion of the temporals, and by a small part of the sphenoid and parietals. It is bounded in front by the upper border of the petrous portion, and by the poste- rior clinoid processes, and along its posterior circumference by the groove for the lateral sinuses, and gives support to the pons Varolii, medulla oblongata, and cerebellum. In the centre of this fossa is the foramen magnum bounded on each side by a rough tubercle, which gives attachment to the odontoid ligament, and by the anterior condyloid foramen. In front of the foramen magnum is the con- cave surface which supports the medulla oblongata and pons Va- rolii, and on each side the following foramina from before back- wards. The internal auditory foramen, for the auditory and facial nerve and auditory artery ; behind, and external to this is a small foramen leading into the aquceductus vesiibuli ; and below it, partly concealed bv the edge of the petrous bone, the aquceductus cochlea ; next, a long fissure, the foramen lacerum poslerius, or jugular fora- men, giving passage to the commencement of the internal jugular vein and the eighth pair of nerves. Converging towards this fora- men from behind is the deep grove for the lateral sinus, and from the front the groove for the inferior petrosal sinus. Behind the foramen magnum is a longitudinal ridge, which gives attachment to the falx cerebelli, and divides the two inferior fossae of the occipital bone ; and above the ridge is the elevation correspond- ing with the tubercle of the occipital bone and the transverse groove lodging the lateral sinus. BASE OF THE SKULL. 59 Fig. 25.* The external surface of the base of the skull is extremely irregu- lar. From before backwards it is formed by the palate processes of the superior maxillary and pa- late bones ; the vomer ; the ptery- goid, spinous processes, and part of the body of the sphenoid ; under surface of the squamous portion, and mastoid portion of the tem- porals ; and by the occipital bone. The palate processes of the supe- rior maxillary and palate bones constitute the hard palate, which is raised above the level of the rest of the base, and is surrounded by the alveolar processes contain- ing the teeth of the upper jaw. At the anterior extremity of the hard palate, and directly behind the front incisor teeth, is the incisive foramen, the termination of the naso- palatine canal, which contains the naso-palatine ganglion, and trans- mits the anterior palatine nerves. At the posterior angles of the palate are the posterior 'palatine foramina, for the posterior palatine nerves and arteries. Passing inwards from these foramina are the transverse ridges to which are attached the ex- pansions of the tensor palati muscles, and at the middle hne of the posterior border the palate spine which gives origin to the azygos uvulae. The hard palate is marked by a crucial suture, which distin- guishes the four processes of which it is composed. Behind, and above the hard palate, are the posterior nares, separated by the vomer, and bounded on each side by the pterygoid processes. At the base of the vomer, and partly formed by its expansion, are the pterygo-palatine canals. The internal pterygoid plate is long and narrow, terminated at its apex by the hamular process, and at its base by the scaphoid fossa. The external plate is broad, and the space between the two is the pterygoid fossa, which contains part of the internal pterygoid muscle and the tensor palati. Externally to the external pterygoid * The external or basilar surface of the base of the skull. 1, 1. The hard palate. The figures are placed upon the palate processes of the superior maxillary bones. 2. The incisive, or anterior palatine foramen. 3. The palate process of the palate bone. The large opening near the figure is the posterior palatine foramen. 4. The palate spine; the curved line upon vs^hich the number rests, is the transverse ridge. 5. The vomer, dividing the openings of the posterior nares. 6. The internal pterygoid plate. 7. The scaphoid fossa. 8. The external pterygoid plate. The interval between 6 and 8, (left side of the figure,) is the pterygoid fossa. 9. The zygomatic fossa. 10. The basilar process of the occipital bone. 11. The foramen magnum. 12. The foramen ovale. 13. The foramen spinosum. 14. The glenoid fossa. 15. The meatus audi- torius externus. 16. The foramen lacerum basis cranii. 17. The carotid foramen of the left side. 18. The foramen lacerum posterius, or jugular foramen. 19. The styloid process. 20. The stylo-mastoid foramen. 21. The mastoid process. 22. One of the condyles of the occipital bone. 23. The posterior condyloid foramen. 60 BASE OF THE SKULL. is the zygomatic fossa. Behind the nasal fossse, in the middle line, is the under surface of the body of the sphenoid, and the basilar process of the occipital bone, and still further back, the foramen magnum. At the base of the external pterygoid plate, on each side, is the foramen ovale, and behind this the foramen spinosum, with the prominent spine which gives attachment to the internal lateral ligament of the lower jaw and the laxator tympani muscle. Running outwards from the apex of the spinous process of the sphenoid bone, is the fissura Glaseri, which crosses the glenoid fossa transversely, and divides it into an anterior smooth surface, bounded by the eminentia articularis, for the condyle of the lower jaw, and a posterior rough surface for a part of the parotid gland. Behind the foramen ovale and spinosum, is the irregular fissure between the spinous process of the sphenoid bone and the petrous portion of the temporal, the foramen lacerum basis cranii, which lodges the internal carotid artery and Eustachian tube, and in which the carotid branch of the Vidian nerve joins the carotid plexus. Following the direction of this fissure outwards is the foramen for the Eustachian tube, and that for the tensor tympani muscle, separated from each other by the processus cochleariformis. Behind the fissure is the pointed process of the petrous bone which gives origin to the levator palati muscle, and, externally to this pro- cess, the carotid foramen for the transmission of the internal carotid artery and the ascending branch of the superior cervical ganglion of the sympathetic ; and behind the carotid foramen, the foramen lacerum posterius and jugular fossa. Externally, and somewhat in front of the latter, is the styloid process, and at its base the vaginal process. Behind and at the root of the styloid process is the stylo- mastoid foramen, for the facial nerve and stylo-mastoid artery, and further outwards the mastoid process. Upon the inner side of the root of the mastoid process is the digastric fossa ; and a little far- ther internally, the occipital groove. On either side of the fora- men magnum, and near to its anterior circumference, are the con- dyles of the occipital bone. In front of each condyle, and piercing its base, is the anterior condyloid foramen, and directly behind the condyle the irregular fossa in which the posterior condyloid foramen is situated. Behind the foramen magnum are the two curved fines of the occipital bone, the spine, and protuberance, with the rough surfaces for the attachment of muscles. The Face is somewhat oval in contour, irregular in surface, and excavated for the reception of two principal organs of sense, — the eye and the nose. It is formed by part of the frontal bone and by the bones of the face. Superiorly it is bounded by the frontal eminences ; beneath these are the superciliary ridges, converging towards the nasal tuberosity ; beneath the superciliary ridges are the supra-orbital ridges, terminating externally in the external border of the orbit, and internally in the internal border, and pre- senting towards their inner third the supra-orbital notch, for the supra-orbital nerve and artery. Beneath the supra-orbital ridges are the openings of the orbits. Between the orbits is the bridge of THE FACE. 61 tlie nose, overarching the anterior nares ; and on each side of this opening the canine fossa of the superior maxillary bone and the infra-orbital foramen, and still farther outwards the prominence of the malar bone ; at the lower margin of the anterior nares is the nasal spine, and beneath this the superior alveolar arch containing the teeth of the upper jaw. Forming the lower boundary of the face is the lower jaw, containing in its alveolar process the lower teeth, and projecting inferiorly to form the chin ; on either side of the chin is the mental foramen. If a perpendicular line be drawn from the inner third of the supra-orbital ridge to the inner third of the body of the lower jaw, it will be found to intersect three open- ings ; — the supra-orbital, infra-orbital, and mental, each giving passage to one of the facial branches of the fifth nerve. ORBITS. The orbits are two quadrilateral hollow cones, situated in the upper part of the face, and intended for the reception of the eye- balls, with their muscles, vessels, and nerves, and the lachrymal glands. The central axis of each orbit is directed outwards, so that the axes of the two continued into the skull through the optic foramina, would intersect over the middle of the sella Turcica.* The superior boundary of the orbit is formed by the orbital plate of the frontal bone, and by part of the lesser wing of the sphenoid ; the inferior, by part of the malar bone and by the orbital processes of the superior maxillary and palate bone; the internal by the lachrymal bone, the os planum of the ethmoid and part of the body of the sphenoid ; and the external, by the orbital process of the malar bone and the great ala of the sphenoid ; these may be expressed more clearly in a tabular form : — Frontal. Sphenoid (lesser wing). Malar. Lachrymal. Sphenoid (greater wing). Orbit. Ethmoid (os planmn). Sphenoid (body). Malar. Superior maxillary. Palate. There are nine openings communicating with the orbit: — the optic, for the admission of the optic nerve and ophthalmic artery ; the sphenoidal fissure, for the transmission of the third, fourth, the three branches of the ophthalmic division of the fifth, and the sixth nerve, and the ophthalmic vein ; the spheno-maxillary fissure, for the passage of the superior maxillary nerve and artery to the openino- of entrance of the infra-orbital canal; temporo-malar fm^amina — two or three small openings in the orbital process of the malar * The axes of the orbits form an angle of 90° with each other. G. 62 NASAL POSS^, bone, for the passage of filaments of the orbital branch of the supe- rior maxillary nerve ; anterior and posteyior ethmoidal foramina in the suture between the os planum and frontal bone, the former transmitting the nasal nerve and anterior ethmoidal artery and the latter the posterior ethmoidal artery and vein ; the opening of the nasal duct; and the swpra-orhiial notch or foramen, for the supra-orbital nerve and artery. NASAL FOSS^. The nasal fossae are two irregular cavities, situated in the middle of the face, and extending from before backwards. They are bounded above by the nasal bones, ethmoid, and sphenoid ; below by the palate processes of the superior maxillary palate bones ; externally by the superior maxillary, lachrymal, inferior turbinated, ethmoid, palate, and internal pterygoid plate of the sphenoid ; and the two fossae are separated by the vomer and the perpendicular lamella of the ethmoid. These may be more clearly expressed in a tabular form : — Nasal bones. Ethmoid. Sphenoid. o-Ph (r> ^ 6 rt >> "B. (^ 13 h ^ IPh &. Palate processes of superior maxillary, Palate processes of palate bone. Each nasal fossa is divided into three irregular longitudinal pas- sages, or meatuses by three processes of bone, which project from its outer wall, — the superior, middle, and inferior turbinated bones ; the superior and middle turbinated bones being processes of the ethmoid, and the inferior a distinct bone of the face. The superior meatus occupies the superior and posterior part of each fossa ; it is situated between the superior and middle turbinated bones, and has opening into it three foramina, viz. the opening of the posterior ethmoid cells, the opening of the sphenoid cells, and the spheno- palatine foramen. The middle meatus is the space between the middle and inferior turbinated bones ; it also presents three foramina, — the opening of the frontal sinuses, of the anterior ethmoid cells, and of the antrum. The largest of the three passages is the in- ferior meatus, which is the space between the inferior turbinated bone and the floor of the fossa; in it there are two foramina, — the TEETH-*— DIVISIONS. 63 termination of the nasal duct, and the opening of the naso-palatine canal. The nasal fossae commence upon the face by a large irregu- lar opening, — the anterior nare§, — and terminate posteriorly in the two posterior nares. TEETH. Man is provided with two successions of teeth ; the first are the teeth of childhood, they are called temporary or deciduous ; the second continue until old age, and are named permanent. The permanent teeth are thirty-two in number, sixteen in each jaw ; they are divisible into four classes, — incisors, of which there are four in each jaw, two central and two lateral; canine, two above and two below ; bicuspid, four above and four below ; and molars, six above and six below. The temporary teeth, are twenty in number ; eight incisors, four canine, and eight molars. The temporary molars have four tubercles, and are succeeded by the permanent bicuspides, which have only two tubercles. Each tooth is divisible into a crown, which is the part apparent above the gum ; a constricted portion around the base of the crown, the neck ; and a root or fang, which is contained within the alveolus. The root is invested by periosteum, which lines the alveolus, and is then reflected upon the root of the tooth as far as its neck. The incisor teeth (cutting teeth) are named from presenting a sharp and cutting edge, formed at the expense of the posterior sur- face. The crown is flattened from before backwards, being some- what convex in front and concave behind ; the neck is considerably constricted, and the root compressed from side to side ; at its apex is a small opening for the passage of the nerve and artery of the tooth. The canine teeth (cuspidati) follow the incisors in order from before backwards ; two are situated in the upper jaw, one on each side, and two in the lower. The crown is larger than that of the incisors, convex before, and concave behind, and tapering to a blunted point. The root is longer than that of all the other teeth, compressed at each side, and marked by a slight groove. The bicuspid teeth (small molars), two on each side in each jaw, follow the canine, and are intermediate in size between them and the molars. The crown is compressed from before backwards, and surmounted by two tubercles, one internal, the other external ; the neck is oval ; the root compressed, and marked on each side by a deep groove, and bifid near its apex. The teeth of the upper jaw have a greater tendency to the division of their roots than those of the lower, and the posterior than the anterior pair. The molar teeth (grinders,) three on each side in each jaw, are the largest of the permanent set. The crown is quadrilateral, and surmounted by four tubercles, the neck large and round, and the 64 STRUCTURE OF TEETH. root divided into several fangs. In the upper jaw the first and second molar teeth have three roots, sometimes four, which are more or less widely separated from each other, two of the roots being external, the other internal. In the lower there are but two roots, which are anterior and posterior; they are flattened from behind forwards, and grooved so as to mark a tendency to division. The third molars, or dentes sapientise, are smaller than the other two ; they present three tubercles on the surface of the crown ; and the root is single and grooved, appearing to be made up of four or five fangs compressed together, or partially divided. In the lower jaw the fangs are frequently separated to some distance from each other, and much curved, so as to offer considerable resistance in the operation of extraction.* Structure.^ — The base of the crown of each tooth is hollowed into a small cavity, which is continuous with a canal passing through the middle of each fang. The cavity and canal, or canals, constitute cavitas pulpse, and contain a soft and secreting vascular organ, — the jiulp, which receives its supply of vessels and nerves through the small opening at the apex of each root. The tooth is composed of three distinct structures ; the ivory or tooth-bone, enamel, and a cortical substance or cementum. The ivory consists of microscopic undulating and branching tubuli, which open by their larger extremities upon the walls of the cavitas pulpse and radiate towards the surface of the ivory, where they ter-^ minate in ramifications of infinite minuteness. These tubuli have distinct walls, are separated from each other by intervals equal in breadth to the diameter of two or three tubes, and composed of dense dental substance, and they contain within their cylinders a calcareous substance disposed in irregular masses. J As the growth of the tooth takes place from the surface towards the centre, the most minute ramifications are first formed, and the trunks of the tubuli are the last deposited. The enamel forms a crust over the whole exposed surface of the crown of the tooth to the commencement of its root ; it is thickest over the upper part of the crown, and becomes gradually thinner as it approaches the neck. It is composed of minute hexagonal crys- talline fibres, resting by one extremity against the surface of the ivory, and constituting by the other the free surface of the crown. The enamel is separated from the ivory by a thin layer of mem- brane, continuous with a thin organic sheath which encloses each enamel fibre, and marks it by means of transverse lines into irre- gular divisions. Mr. Nasmyth is of opinion, that the enamel is in- * See a valuable little praetical work, " On the Structure, Economy, and Pathology of the Teeth," by Mr. Lintott. t The structure of the teeth was discovered by Purkinje and Retzius, and has been farther prosecuted in this country by Mr. Nasmyth, to whose beautiful work, " Re- searches on the Developcment, Structure and Diseases of the Teeth," I must refer those who may feel interested in this important subject. t The disintegrated condition of the calcareous substance is probably the effect of desiccation ; it is very remarkable in decayed teeth. DEVEL0PE3IENT OF TEETH. 65 vested by a thin layer of membrane, which is continued over the root, and is reflected through the opening in the apex of the fang into the cavitas pulpse, whicli it lines throughout. This membrane is considered by Mr. Nasmyth to be the ^'■persistent dental capsule." The cortical substance, or cementum, forms a thin coating over the root of the tooth, from the termination of the enamel to the opening of the apex of the fang. In structure it consists of true bone, characterized by the existence of numerous calcigerous cells and tubuli. The cementum increases in thickness with the advance of age, and gives rise to those exostosed appearances occasionally seen in the teeth of very old persons, or in those who have taken much mercury. In old age the cavitas pulpse is often found filled up and obliterated by osseous substance analogous to the cementum. Developement. — The developement of the teeth in the human sub- ject has been most successfully investigated by our countryman, Mr. Goodsir, to whose interesting researches I am indebted for the following narrative : — * The inquiries of Mr. Goodsir commenced as early as the sixth week after conception, in an embryo, which measured seven lines and a half in length and weighed fifteen grains. At this early period each jaw presents two semicircular folds around its circum- ference ; the most external is the true lip ; the internal, the rudiment of the palate ; and between these is a deep groove, Hned by the common mucous membrane of the mouth. A little later a ridge is developed from the floor of this groove in a direction from behind forwards, this is the rudiment of the external alveolus ; and the arrangement of the appearances from without inwards at this period is the following : — Most externally, and forming the boun- dary of the mouth, is the lip ; next we find a deep groove, which separates the lip from the future jaw ; then comes the external alveolar ridge ; fourthly, another groove, in which the germs of the teeth are developed, the primitive dental groove ; fifthly, a rudi- ment of the internal alveolar ridge ; and sixthly, the rudiment of the future palate bounding the whole internally. At the seventh week the germ of the first deciduous molar of the upper jaw has made its appearance, in the form of a " simple, free, granular papilla" of the mucous membrane, projecting from the floor of the primitive dental groove ; at the eighth week, the papilla of the canine tooth is developed ; at the ninth week the papillae of the four incisors (the middle preceding the lateral) appear ; and at the tenth week, the papilla of the second molar is seen behind the anterior molar in the primitive dental groove. So that at this early period, the tenth week, the papillas or germs of the whole of the ten deci- duous teeth of the upper jaw are quite distinct. Those of the lower jaw are a little more tardy ; the papilla of the first molar is merely * " On the Origin and Developement of the Pulps and Sacs of the Human Teetli," by John Goodsir, jun., in the Edinburgh Medical and Surgical Joyrnal, January 1839. 9 66 DEVELOPEMENT OF TEETH. a slight bulging at the seventh week, and the tenth papilla is not apparent until the eleventh week. From about the eighth week the primitive dental groove becomes contracted before and behind the first deciduous molar, and laminse of the mucous membrane are developed around the other papillae, which increase in growth and enclose the papilloe in follicles with open mouths. At the tenth week the follicle of the first molar is completed, then that of the canine ; during the eleventh and twelfth weeks the follicles of the incisors succeed, and at the thirteenth week the follicle of the posterior deciduous molar. During the thirteenth week the papillae undergo an alteration of form, and assume the shape of the teeth they are intended to repre- sent. And at the same time small membranous processes are de- veloped from the mouths of the follicles ; these processes are intended to serve the purpose of opercula to the follicles, and they correspond in shape with the form of the crowns of their appertaining teeth. To the follicles of the incisor teeth there are two opercula ; to the canine, three; and to the molars a number relative to the number of their tubercles, either four or five. During the fourteenth and fifteenth weeks the opercula have completely closed the folhcles, so as to convert them into dental sacs, and at the same time the papillse have become -pulfs. The deep portion of the primitive dental groove, viz. that which contains the dental sacs of the deciduous teeth, being thus closed in, the remaining portion, that which is nearer the surface of the gum, is still left open, and to this Mr. Goodsir has given the title of secondary dental groove ; as it serves for the developement of all the permanent teeth, with the exception of the anterior molars. During the fourteenth and fifteenth weeks small lunated inflections of the mucous membrane are formed, immediately to the inner side of the closing opercula of the deciduous dental follicles, commencing behind the incisors and proceeding onwards through the rest; these are the rudiments of the follicles or cavities of reserve of the four permanent incisors, two permanent canines, and the four bicuspides. As the secondary dental groove gradually closes, these folhcular inflections of the mucous membrane are converted into closed cavities of reserve, which recede from the surface of the gum and lie immediately to the inner side and in close contact with the dental sacs of the deciduous teeth, being enclosed in their submucous cel- lular tissue. At about the fifth month the anterior of these cavities of reserve dilate at their distal extremities, and a fold or papilla projects into their fundus, constituting the rudiment of the germ of the permanent tooth ; at the same time two small opercular folds *■ are produced at their proximal or small extremities, and convert them into true dental sacs. During the fifth month the posterior part of the primitive dental groove behind the sac of the last deciduous tooth has remained open, and in it has developed the papilla and follicle of the first per- manent molar. Upon the closure of this follicle by its opercula. DEVELOPEMENT OF TEETH. 67 the secondary dental groove upon the summit of its crown forms a large cavity of reserve, lying in contact with the dental sac upon the one side and with the gum upon the superficial side. At this period the deciduous teeth, and the sacs of the ten anterior perma- nent teeth, increase so much in size, without a corresponding lengthening of the jaws, that the first permanent molars are gra- dually pressed backwards and upwards into the maxillary tubero- sity in the upper jaw, and into the base of the coronoid process of the lower jaw; a position which they occupy at the eighth and ninth months of foetal fife. In the infant of seven or eight months the jaws have grown in length, and the first permanent molar returns to its proper position in the dental range. The cavity of reserve, which had been previously elongated by the upward move- ment of the first permanent molar, now dilates into the cavity which that tooth has just quitted ; a papilla is developed from its fundus, the cavity becomes constricted, and the dental sac of the second molar tooth is formed, still leaving a portion of the great cavity of reserve in connexion with the superficial side of the sac. As the jaws continue to grow in length, the second permanent dental sac descends from its elevated position and advances forwards into the dental range, following the same curve with the first permanent molar. The remainder of the cavity of reserve, already length- ened backwards by the previous position of the second molar, again dilates for the last time, developes a papilla and sac in the same manner with the preceding, and forms the third permanent molar or wisdom tooth, which, at the age of nineteen or twenty, upon the increased growth of the jaw, follows the course of the first and second molars into the dental range. From a consideration of the foregoing phenomena, Mr. Goodsir has divided the process of dentition into three natural stages : — 1, folhcular; 2, saccular; 3, eruptive. The first, or follicular stage, he makes to include all the changes which take place from the first appearance of the dental groove and papillos to the closure of their follicles ; occupying a period which extends from the sixth week to the fourth or fifth month of intra-uterine existence. The second, or saccular stage, comprises the period when the follicles S;re shut sacs, and the included papillae, pulps ; it commences at the fourth and fifth months of intra-uterine existence, and terminates for the median incisors, at the seventh or eighth month of infantile life, and for the wisdom teeth at about the twenty-first year. The third, or eruptive stage, includes the completion of the teeth, the eruption and shedding of the temporary set, the eruption of the per- manent, and the necessary changes in the alveolar processes. It extends from the seventh month till the twenty-first year. " The anterior -permanent molar," says Mr. Goodsir, "is the most remarkable tooth in man, as it forms a transition between the milk and the permanent set." If considered anatomically, i. e. in its developement from the primitive dental groove, by a papilla and follicle, " it is decidedly a milk tooth ;" if physiologically, " as the 68 GROWTH OF TEETH. most efficient grinder in the adult mouth, we must consider it a per- manent tooth." " It is a curious circumstance, and one which will readily suggest itself to the surgeon, that laying out of view the wisdom teeth, which sometimes decay at an early period from other causes, the anterior molars are the permanent teeth which most frequently give way first, and in the most symmetrical manner and at the same time, and frequently before the milk set." GroficLh of Teeth. — Immediately that the dental follicles have been closed by their opercula, the pulps become moulded into the form of the future teeth ; and the bases of the molars divided into two or three portions, representing the future fangs. The dental sac is composed of two layers, an internal or vascular layer, which was originally a part of the mucous surface of the mouth, and a cellulo- fibrous layer, analogous to the corium of the mucous membrane. Upon the formation of this sac by the closure of the follicle, the mucous membrane resembles a serous membrane in being a shut sac, and may be considered as consisting of a tunica propria, which invests the pulp ; and a timica reflexa, which is adherent by its outer surface with the structures in the jaM^ and by the inner surface is free, being separated from the pulp by an intervening cavity. As soon as the moulding of the pulp has commenced, this cavity increases and be- comes filled with a gelatinous granular substance, the enamel organ, which is adherent to the whole internal surface of the tunica reflexa, but not to the tunica propria and pulp. At the same period, viz. during the fourth or fifth month, a thin lamina of ivory is secreted by the pulp, and deposited upon its most prominent point : if the tooth be incisor or canine, the secreted layer has the form of a small hollow cone ; if molar, there will be four or five small cones corresponding with the number of tubercles on its crown. These cones are united by the secretion of additional layers, the pulp becomes gradually surrounded and diminishes in size, depositing fresh layers during its retreat into the jaws until the entire tooth with its fangs is completed, and the small cavitas pulpse of the per- fect tooth alone remains, communicating through the opening in the apex of each fang with the dental vessels and nerves. The number of roots appears to depend upon the number of nervous filaments sent to each pulp. When the secretion of the ivory has commenced, the enamel organ becomes transformed into a laminated tissue, corresponding with the direction of the fibres of the enamel, and the crystalline substance of the enamel is secreted into its meshes by the vascular lining of the sac. The cemenium appears to be formed at a later period of life, either by a deposition of osseous substance by that portion of the dental sac which continues to enclose the fang, and acts as its periosteum, or by the conversion of that membrane itself into bone; the former supposi- tion is the more probable. The secretion of ivory commences in the first permanent molar pre- viously to birth. Eruption. — Wlicn the crown of the toolh has been formed and coated with cnarnel, and the fan<:r has grown to liie bottom of its TEETH ERUPTION. 69 socket by the progressive lengthening of the pulp, the deposition of ivory, and the adhesion of the ivory to the contiguous portion of the sac, the pressure of the socket causes the reflected portion of the sac and the edge of the tooth to approach, and the latter to pass through the gum. The sac has thereby resumed* its original follicular con- dition, and has become continuous with the mucous membrane of the mouth. The opened sac nov^ begins to shorten more rapidly than the fang lengthens, and the tooth is quickly drawn upwards by the con- traction, leaving a space between the extremity of the unfinished root and the bottom of the socket, in which the growth and comple- tion of the fang is more speedily effected. During the changes which have here been described as taking place among the dental sacs contained within the jaws, the septa between the sacs, which at first were composed of spongy tissue, soon became fibrous, and were afterwards formed of bone, which was developed from the surface and proceeded by degrees more deeply into the jaws, to constitute the alveoli. The sacs of the ten anterior permanent teeth, at first enclosed in the submucous cellular tissue of the deciduous dental sacs, and received during their growth into crypts situated behind the deciduous teeth, advanced by degrees beneath the fangs of those teeth, and became separated from them by distinct osseous alveoli. The necks of the sacs of the permanent teeth, by which they originally communicated with the mucous lining of the secondary groove, still exist, in the form of minute ob- literated cords, separated from the deciduous teeth by their alveolus, but communicating through a minute osseous canal with the fibrous tissue of the palate, immediately behind the corresponding deciduous teeth. " These cords and foramina are not obhterated in the child," says Mr. Goodsir, "either because the cords are to become useful as ' gubernacula' and the canals as ^itinera dentium;' or, much more probably, in virtue of a law, which appears to be a general one in the developement of animal bodies, viz : that parts, or organs, lohick have once acted an important -part, however atrophied they may after- wards become, yet never altogether disappear, so long as they do not interfere with other parts or functions."" Succession. — The periods of appearance of the teeth are extremely irregular ; it is necessary, therefore to have recourse to an average, which, for the temporary teeth, may be stated as follows, the teeth of the lower jaw preceding those of the upper by a short interval : 7th month, two middle incisors. 18th month, canine. 9th month, two lateral incisors. 24th month, two last molares. 12th month, first molares. The periods for the permanent teeth are, 6| year, first molares. 10th year, second bicuspides. 7th year, two middle incisors. 11th to 12th year, canine. 8th year, two lateral incisors. 12th to 13th year, second molares. 9th year, first bicuspides. 17th to 21st year, last molares. * Mr. Nasmy til is of opinion that it is " by a process of absorption, and not of disrup- tion, that the tooth is emancipated." Medico-chirurgical Transactions. 1839. 70 OS HYOIDES. OS HYOIDES. The OS hyoides forms the second arch developed from the cranium, and gives support to the tongue, and attachment to numerous mus- cles in the neck. It is named from its resemblance to the Greek let- ter u, and consists of a central portion, or Fig. 26* body, of two larger cornua, which project backwards from the body, and two lesser cornua, which ascend from the angles of union between the body and the greater cornua. The body is somewhat quadrilateral, rough and convex on its anterior surface, where it gives attachment to muscles ; concave and smooth on the posterior surface, by which it lies in contact with the epiglottis. The greater cornua are flattened from above downwards, and terminated posteriorly in a tubercle ; and the lesser cornua, conical in form, give attachment to the stylo-hyoid ligaments. In early age and in the adult, the cornua are connected with the body by cartilaginous surfaces and ligamentous fibres ; but in old age they become united by bone. Deve/opement — By Jive centres, one for the body, and one for each cornu. Attachment of Muscles. — To eleven pairs ; sterno-hyoid, thyro- hyoid, omo-hyoid, pulley of the digastricus, stylo-hyoid, mylo-hyoid, genio-hyoid, genio-hyo-glossus, hyo-glossus, lingualis, and middle constrictor of the pharynx. It also gives attachment to the stylo- hyoid, thyro-hyoid, and hyo-epiglottic ligaments, and to the thyro- hyoidean membrane. THORAX AND UPPER EXTREMITY. The bones of the thorax are the sternum and ribs ; and, of the upper extremity, the clavicle, scapula, humerus, ulna, and radius, bones of the carpus, metacarpus, and phalanges. Sternum. — The sternum (fig. 27) is situated in the middle line of the front of the chest ; it is flat, or slightly concave in front, and convex behind ; broad and thick above, and flattened and pointed below. It consists of three pieces ; superior, middle, and inferior. The su-pcrior (1) is nearly quadrilateral ; broad and thick above, and somewhat narrowed at its junction with the middle piece. At each superior angle is a deep articular depression for the clavicle, and on either side two notches, for the articulation of the cartilage of the first rib, and one half of the second. The middle piece (2), considerably longer than the superior, is * The OS hyoides seen from before. 1. The anterior convex side of the body. 2. The great cornu of the loft side. 3. The lesser eornu of the same side. The cornua were ossified to tlic body of the bone in the specimen from which this figure was drawn. EIES TRUE AND FALSE. 71 broad in the middle, and somewhat narrower at each extremity. It presents on each side six articular notches, for the lower half of the second rib, the four next ribs, and the upper half of the seventh. The inferior 'piece, or ensiform cartilage (3), is the smallest of the three, often merely cartilaginous, and very various in appearance, being sometimes pointed, at other times broad and thin, and at other times again, perforated by a round hole, or bifid. It presents a notch at each side for the articulation of the lower half of the cartilage of the seventh rib. Developement. — By a number of centres, varying from six to fourteen. Articulations. — With sixteen bones ; viz. with the clavicle, and with seven true ribs at each side. Attachment of Muscles. — To nine pairs and one single muscle ; viz. to the pectoralis major, sterno-mastoid, sterno-hyoid, sterno- thyroid, triangularis sterni, aponeurosis of the obliquus externus, internus, and transversahs muscles, rectus, and diaphragm. Ribs. — The ribs are twelve in number at each side ; the seven first are connected with the sternum, and hence named t7'ue ; the remaining five are the false ribs ; and the two last shorter than the ^ig. 27.* rest, and free at their extremi- ties, are the floating ribs. The ribs increase in length from the first to the eighth, whence they again diminish to the twelfth; in breadth they diminish gra- dually from the first to the last. Each rib presents an external and internal surface, a superior and inferior border, and two extremities ; it is curved to cor- respond with the arch of the thorax, and twisted upon itself, so that when laid upon its side, one end is tilted up, while the other rests upon the surface. The external surface is con- vex, and marked by the attach- ment of muscles; the internal is flat, and corresponds with the pleura; the superior border is rounded ; and the inferior sharp and grooved upon its inner side, for the attachment of the intercostal muscles. Near its vertebral * An anterior view of the thorax. 1. The superior piece of the sternum. 2. The middle piece. 3. The inferior piece, or ensiform cartilage. 4. The first dorsal vertebra, o. The last dorsal vertebra. 6. The first rib. 7. Its head. 8. Its neck resting against the transverse process of the first dorsal vertebra. 9. Its tuberosity! 10. 1 he seventh or last true rib. 1 ]. The costal cartilages of the true ribs. 12 The two last false ribs-the floating ribs. 13. The groove along the lower border of the nb tor the lodgment of the intercostal vessels and nerve. 72 COSTAL CARTILAGES. extremity, the rib is suddenly bent upon itself; and opposite the bend, upon the external surface, is a rough oblique ridge, which gives attachment to a tendon of the sacro-lumbalis muscle, and is called the angle. The distance between the vertebral extremity and the angle increases gradually, from the second to the eleventh rib. Beyond the angle is a rough elevation, the tuberosity ; and immediately at the base and rather below the tuberosity a smooth surface for articulation with the extremity of the transverse pro- cess of the corresponding vertebra. Beyond the tuberosity is the neck ; and at the extremity of the neck an oval surface, the head, divided by a ridge into two facets for articulation with two con- tiguous vertebras. The posterior surface of the neck is rough, for the attachment of the middle costo-transverse ligament ; and upon its upper border is a crest, which gives attachment to the anterior costo-transverse ligament. The sternal extremity is flattened, and presents an oval depression, into which the costal cartilage is received. The ribs that demand especial consideration are the first, and the three last. The^rs^ is the shortest rib ; it is broad and flat, and placed hori- zontally at the upper part of the thorax, the surfaces looking up- wards and downwards, in place of forwards and backwards as in the other ribs. At about the anterior third of the upper surface of the bone, and near its internal border, is a tubercle which gives at- tachment to the scalenus anticus muscle, and immediately before and behind this tubercle, a shallow oblique groove, the former for the subclavian vein, and the latter for the subclavian artery. Near the posterior extremity of the bone is a thick and prominent tube- rosity, with a smooth articular surface for the transverse process of the first dorsal vertebra. There is no angle. Beyond the tube- rosity is a narrow constricted neck ; and quite at the extremity, a head, presenting a single articular surface. The second rib ap- proaches in some of its characters to the first. The tenth rib has a single articular surface on its head. The eleventh and twelfth have each a single articular surface on the head, no neck or tuberosity, and are pointed at the extremity. The eleventh has a slight ridge, representing the angle, and a shal- low groove on the lower border ; the twelfth has neither. Costal Cartilages. — The costal cartilages (fig. 27. 11, 11) serve to prolong the ribs forwards to the anterior part of, the chest, and contribute mainly to the elasticity of the thorax. They are broad at their attachment to the ribs, and taper slightly towards their oppo- site extremities ; they gradually diminish in breadth from the first to the last, and increase in length from the first to the seventh, and then diminish to the last. The seven first cartilages articulate with the sternum ; the three next with the lower border of the cartilage immediately preceding. All the cartilages of the false ribs terminate by pointed extremities. Developement. — The ribs are developed by three centres ; one for CLAVICLE SCAPULA. 73 the central part, one for the head, and one for the tuberosity. The two last have only one centre. Articulations. — Each rib articulates with two vertebra3, and one costal cartilage, with exception of the first, tenth, eleventh, and twelfth, which articulate each with a single vertebra only. Attachment of Muscles. — To the ribs and their cartilages are at- tached twenty-two pairs, and one single muscle. To the cartilages, the subclavius, sterno-thyroid, pectoralis major, internal oblique, rec- tus, transversalis, diaphragm, triangularis sterni, internal and exter- nal intercostals. To the rihs, the intercostal muscles, scalenus anticus, scalenus posticus, pectoralis minor, serratus magnus, obli- quus externus, obliquus internus, latissimus dorsi, quadratus lumbo- rum, serratus posticus superior, serratus posticus inferior, sacro- lumbalis, longissimus dorsi, cervicalis ascendens, levatores costarum, transversalis, and diaphragm. Clavicle. — The clavicle is a long bone shaped somewhat like the italic letter S, the convexity at one end being anterior and internal, at the other posterior and external. The inner half of the bone is rounded or irregularly quadrilateral, and terminates in a broad arti- cular surface. The outer half is flattened from above downwards, and broad at its extremity, the articular surface occupying only part of its extent. The upper surface is smooth and convex, and partly subcutaneous ; while the under surface is rough and depressed, for the insertion of the subclavius muscle. At the sternal extremity of the under surface is a very rough prominence, which gives attach- ment to the rhomboid hgament ; and at the other extremity a rough tubercle and ridge, for the coraco-clavicular ligament. The open- ing for the nutritious vessels is seen upon the under surface of the bone. Developement. — By two centres ; one for the shaft, and one for the anterior prominence of the sternal extremity. Articulations. — With the sternum and scapula. Attachment of Muscles. — To six; the sterno-mastoid, trapezius, pectoralis major, deltoid, subclavius, and sterno-hyoid. Scapula. — The scapula is a flat triangular bone, situated upon the posterior aspect and side of the thorax. It is divisible into an ante- rior and posterior surface, superior, inferior, and posterior border, anterior, superior, and inferior angle and processes. The anterior surface, or subscapular fossa, is concave and irregu- lar, and marked by several oblique ridges. The whole concavity is occupied by the subscapularis muscle, with the exception of a small triangular portion near the superior angle. The posterior surface or dorsum is convex, and unequally divided into two portions by the spine ; that portion above the spine is the supra-spinous fossa ; and that below, the infra-spinous fossa. The superior border is the shortest of the three ; it is thin and con- cave, and terminated at one extremity by the superior angle, and at the other by the coracoid process. At its inner termination, and 10 74 Fig. 28.^ formed partly by the base of the coracoid process, is tlie supra-sca- pular notch, for the transmission of the supra-scapular nerve. .The inferior or anterior border is thick, and marked by several grooves, and depressions ; it terminates superiorly at the glenoid cavity, and inferiorly at the inferior angle. Immediately below the glenoid cavity is a rough ridge, M^hich gives origin to the long head of the triceps muscle. Upon the posterior surface of the border is a depression for the teres minor; and upon its anterior surface a deeper groove for the teres major : near the inferior angle is a pro- jecting lip, which increases the surface of origin of the latter muscle. The posterior border, the longest of the three, is also named the base. It is intermediate in thickness between the superior and inferior, and convex, being considerably inflected forwards towards the superior angle. The anterior angle is the thickest part of the bone, and forms the head of the scapula ; it is immediately surrounded by a depressed surface, the neck. The head presents a shal- low pyriform articular surface, the glenoid cavity, having the pointed ex- tremity upwards ; and at its apex is a rough depression, which gives attach- ment to the long tendon of the biceps. The superior angle is thin and pointed. The inferior angle is thick and smooth upon the external surface for the ori- gin of the teres major, and for a large bursa over which the upper border of the latissimus dorsi muscle plays. The spine of the scapula crosses the upper part of its dorsum; it com- mences at the posterior border by a smooth triangular 'surface over which the trapezius glides upon a bursa, and terminates at the point of the shoulder in the acromion process. The upper border of the spine is rough and subcutaneous, and gives attachment by two projecting lips to the trapezius and deltoid muscles. The acromion is somewhat triangular and flattened from above downwards ; it overhangs the glenoid cavity, the upper surface being rough and subcutaneous, the lower smooth and correspond- ing with the shoulder-joint. Near its extremity is an oval articular * A posterior view of the scapula. 1. The supra-spinous fossa. 2. The infra- spinous fosHa. 3. The superior border. 4. The supra-scapular notch. 5. The anterior or inferior border. 6. The head of the scapula and glenoid cavity. 7. The inferior angle. 8. The neck of the scapul;i, the ridge opposite to the number gives origin to the long head of the triceps. 9. The posterior border or base of the scapula. 10. The spine. 11. The triangular smooth surface, over which the tendon of the trapezius glides. 12. The acromion process. 13. One of the nutritious foramina. 14. The coracoid process. HUMERUS. " 75 surface, for the end of the clavicle. The nutritious foramina of the scapula are situated in the base of the spine. The caracoid process is a thick, round, and curved process of bone, arising from the upper part of the neck of the scapula, and overarching the glenoid cavity. It is about two inches in length and very strong; it gives attachment to several ligaments and muscles. DevelopemenL — By six centres; one for the body, one for the coracoid process, two for the acromion, one for the posterior border, and one for the inferior angle. Articulations. — With the clavicle and humerus. Attachment of Muscles. — To sixteen ; by its anterior surface to the subscapularis ; posterior surface, supra-spinatus and infra-spi- natus; superior border, omo-hyoid; posterior border, levator an- guli scapulae, rhomboideus minor, rhomboideus major, and serratus magnus ; anterior border, long head of the triceps, teres minor, and teres major ; upper angle of the glenoid cavity, to the long tendon of the biceps ; spine and acromion, to the trapezius and deltoid ; coracoid process, to the pectoralis minor, short head of the biceps, and coraco-brachialis. The lig-aments attached to the coracoid process are, the coracoid, coraco-clavicular, and coraco-humeral, and the costo-coracoid membrane. Humerus. — The humerus is a long bone divisible into a shaft and two extremities. The swpenor ex^remz'/y presents a rounded head; a constriction immediately around the base of the head, the neck ; a greater and a lesser tuberosity. The greater tuberosity is situated most exter- nally, and is separated from the lesser by a vertical furrow — the bicipital groove, — which lodges the long tendon of the biceps. The edges of this groove below the head of the bone are raised and rough, and are called the anterior and posterior bicipital ridge; the former serves for the insertion of the pectoralis major muscle, and the latter for the teres major. The constriction of the bone below the tuberosities is the sur- gical neck, and is so named, in contradistinction to the true neck, from being the seat of the accident called by surgical writers frac- ture of the neck of the humerus. The shaft of the bone is prismoid at its upper part, and flattened from before backwards below. Upon its outer side, at about its middle, is a rough triangular eminence, which gives insertion to the deltoid ; and immediately on each side of this eminence is a smooth depression, corresponding with the two heads of the bra- chialis antic us. Upon the inner side of the middle of the shaft is a ridge, for the attachment of the coraco-brachiaUs muscle ; and behind, an oblique and shallow groove, which lodges the musculo- spiral nerve and superior profunda artery. The foramen for the medullary vessels is situated upon the inner surface of the shaft of the bone, a little below the coraco-brachial ridge ; it is directed downwards. 76 HUMERUS ULNA. The lower extremity is flattened from before backwards, and is terminated interiorly by a long articular surface, divided into two parts by an elevated ridge. The external portion of Fig. 29.* the articular surface is a rounded protuberance, which articulates with the cup-shaped depression on the head of the radius ; the internal portion is a '^>3 concave and pulley-like surface, which articulates ^' with the ulna. Projecting beyond the articular surface on each side are the external and internal condyle, the latter being considerably the longer ; and running upwards from the condyles upon the borders of the bone are the condyloid ridges, of which the external is the most prominent. Immedi- ately in front of the articular surface is a small de- pression, for receiving the coronoid process of the ulna during flexion of the fore-arm ; and immedi- ately behind it a large and deep fossa, for containing the olecranon process in extension. Developement. — By seven centres ; one for the shaft, one for the upper extremity, one for the greater tuberosity, one for the rounded protuberance, and one for the trochlear portion of the articular surface, and one for each condyle. Articulations. — With the glenoid cavity of the scapula, and with the ulna and radius. Attachment of Muscles. — To twenty-four ; by the greater tuberosity to the supra-spinatus,infra-spinatus, and teres minor; lesser tuberosity, subscapularis; anterior bicipital ridge, pectoralis major ; posterior bicipital ridge and groove, teres major and latissimus dorsi ; shaft, external and internal heads of the triceps, deltoid, coraco-brachialis, and brachialis anticus ; external condyloid ridge and condyle, extensors and supinators of the fore- arm, viz. supinator longus, extensor carpi radialis longior, extensor carpi radialis brevior, extensor communis digitorum, extensor minimi digiti, extensor carpi ulnaris, anconeus, and supinator brevis ; internal condyle, flexors and one pronator, viz. pronator radii teres, flexor carpi radialis, palmaris longus, flexor sublimis digitorum, and flexor carpi ulnaris. Ulna. — The ulna is a long bone, divisible into a shaft and two extremities. The upper extremity is large, and forms principally the articulation of the elbow ; while the lower extremity is small, * The humerus of the right side; its anterior surface. ]. The shaft of the bone. 2. The head. 3. The anatomical neck, 4. Tlie greater tuberosity. .5. Tlie lesser tuberosity. 6. The bicipital groove. 7. Tiie anterior bicipital ridge. 8. Tlie posterior bicipital ridge. 9. The rough surface into which the deltoid is inserted. 10. The nu- tritious foramen. 11. The rounded protuberance of tlie articular surface. 12. Tlie pulley-like surface. 13. The external condyle. 14. The internal condyle. 15. The external condyloid ridge. 16. The internal condyloid ridge. 17. The fossa for the coronoid proccBS of the ulna. ULNA. 77 and excluded from the wrist-joint by an inter-articular fibro- cartilage. The superior extremity presents a semilunar concavity of large size, the greater sigmoid notch, for articulation with the humerus ; and upon the outer side a lesser sigmoid notch, which articulates with the head of the radius. Bounding the greater sigmoid notch posteriorly is the olecranon process ; and overhanging it in front, a pointed eminence with a rough triangular base — the coronoid process. Behind the lesser sigmoid notch, and .extending downwards on the side of the olecranon, is a triangular rough surface, for the an- coneus muscle ; and upon the posterior surface of the olecranon another triangular surface, which is subcutaneous. The shaft is prismoid in form, and presents three surfaces, — an- terior, posterior, and internal ; and three borders. The anterior surface is occupied by the flexor profundus digitorum for the upper three-fourths of its extent ; and below by a depression, for the pro- nator quadratus muscle. A little above its middle is the nutritious foramen, which is directed upwards. Upon the posterior surface at the upper part of the bone is the triangular rough depression for the anconeus muscle, bounded inferiorly by an oblique ridge which runs downwards from the posterior extremity of the lesser sigmoid notch. Below the ridge the surface is marked into several grooves, for the attachment of the extensor ossis metacarpi, extensor secundi internodii, and extensor indicis muscle. The internal surface is covered in for its whole extent by the flexor carpi ulnaris. The anterior border is rounded, and gives origin by its lower fourth to the pronator quadratus ; the posterior is more prominent, and affords attachment to the flexor carpi ulnaris and extensor carpi ulnaris. At its upper extremity it expands into the triangular sub- cutaneous surface of the olecranon. The external or radial border is sharp and prominent, for the attachment of the interosseous membrane. The lower extremity terminates in a small rounded head, from the side of which projects the styloid process. Upon the posterior surface of the head is a groove, for the tendon of the flexor carpi ulnaris ; and upon the side opposite to the styloid process a smooth surface, for articulation with the side of the radius. Developement. — By four centres ; one for the shaft, one for each extremity, and one for the olecranon. Articulations. — With two bones ; the humerus and radius. Attachment of Muscles. — To twelve; by the olecranon, to the triceps extensor cubiti, one head of the flexor carpi ulnaris, and to the anconeus ; by the coronoid process, to the brachialis anticus, pronator radii teres, flexor sublimis digitorum, and flexor profundus digitorum ; by the shaft, to the flexor profundis digitorum, flexor carpi ulnaris, pronator quadratus, anconeus, extensor carpi ulnaris, extensor ossis metacarpi poUicis, extensor secundi internodii poUicis, and extensor indicis. Radius. — The radius is the rotatory bone of the fore-arm; it is di- 78 RADIUS. Fig. 30. visible into a shaft and two extremities : unlike the iiliia, its upper extremity is small, and merely accessoiy to the formation of the elbow-joint; while the lower extremity is large, and forms almost solely the joint of the wrist. The swperior extremity presents a rounded head, depressed upon its upper surface into a shallow cup. Around the margin of the head is a smooth articular siu'face, which is broad on the inner side, where it articulates with the lesser sigmoid notch of the ulna, and narrow in the rest of its circumference, to play in the orbicular licrament. Beneath the head is a romid constricted neck; and beneath the neck on its internal aspect a prominent process — the tuberosity. The surface of the tuberosity is partly smooth, and partly rough ; rough below, where it receives the at- tachment of the tendon of the biceps: and smooth above, where a bursa is inteiiDosed between the ten- don and the bone. The shaft of the bone is prismoid, and presents three surfaces. The anterior surface is somewhat concave superiorly, where it lodges the flexor longus poUicis; and flat below, where it supports the pro- nator quadratus. At about the upper third of this surface is the nuti'itious foramen, which is directed upwards. The posterior surface is round above, where it supports the supinator brevis muscle, and marked by several shal- low oblique grooves below, which afford attachment to the extensor muscles of the thumb. The external surface is roimded and con- vex, and marked by an oblique ridge, which extends from the tube- rosity to the styloid process at the lower extremity of the bone. Upon the inner margin of the bone is a sharp and prominent crest, which gives attachment to the interosseous membrane. The lower extremity of the radius is broad and triangular, and provided with two articular surfaces ; one at the side of the bone, which is con- cave to receive the rounded head of the ulna ; the other at the ex- tremity, and marked by a slight ridge into two facets, — one exter- nal and triangular, corresponding with the scaphoid; the other square, with tlie semilunar bone. Upon the outer side of the ex- tremity is a strong conical projection, tlie styloid process, which gives attachment by its base to the tendon of the supinator longus, by its apex to the external lateral ligament of the wrist joint, and by its inner side to the triangular interarticular cartilage. * The two bones of the fore-arm seen from the front. 1. The shaft of tlic ulna. 2, The greater sig-moid notch. 3. Tlie lesser sigmoid notch, with which the head of the radius is articulated. 4. The olecranon process. 5. The coronoid process. 6. The nutritious foramen. 7. The sliarp ridges upon the two bones to which the interosseous membrane is attached. 8. The rounded head at tlie lower extremity of the ulna. 9. The styloid process. 10. The shaft of the radius. 11. Its head surrounded by the smooth border for articulation with the orbicular ligament. 12. Tlie neck of the radius. 13, Its tuberosity. 14. The oblique line. 15. 'I'hc lower extremity oi" the bone. 1.6. Its styloid proees.s. CARPUS. 79 -With four bones ; humerus, uhia, scaphoid, and Fiff. 31* Immediately in front of the styloid process is a groove, -which lodges the tendons of the extensor ossis metacarpi poUicis, and ex- tensor primi internodii; and behind the process a broader groove, for the tendons of the extensor carpi radialis longior and brevior, and extensor secundi internodii ; behind this is a prominent ridge, and a deep and narrow groove, for the tendon of the extensor indicis ; and still farther back part of a broad groove, completed by the ulna, for the tendons of the extensor communis digitorum. Developement. — By t/iree centres ; one for the shaft, and one for each extremity. Articulation s.- semilunar. Attachment of Muscles. — To nine; by the tuberosity and obUque ridge, to the biceps, supinator brevis, pronator radii teres, flexor sub- limis digitorum, and pronator quadratus ; by the anterior surface, to the flexor longus pollicis and pronator quadratus; by the posterior surface, to the extensor ossis metacarpi pollicis, and extensor primi internodii ; and by the styloid process, to the supinator longus. Carpus. — The bones of the carpus are eight in number, they are arranged in two rows. In the first row, commencing from the radial side, are the os scaphoides, semilunare, cuneiforme, pisiforme ; and in the second row, in the same order, the os trapezium, trape- zoides, OS magnum and unciforme. The scaphoid bone is named from bear- ing some resemblance to the shape of a boat, being broad at one end, and nar- rowed like a prow at the opposite, con- cave on one side, and convex upon the other. It is, however, more similar in form to a cashew nut, flattened and con- cave upon one side. If carefully examined, it will be found to present a convex and a concave surface, a convex and a concave border, a broad end, and a narroio and pointed extremity — the tuberosity. To ascertain to which hand it belongs, let the student hold it horizontally, so that the convex surface may look backwards {i. e. towards himself,) and the convex bor- der upwards: the broad extremity will indicate its appropriate * A diagram showing the dorsal surface of the bones of the carpus, with their articu- lations. — Tlie right hand. R. The lower end of the radius. U. Tlie lower extremity of the ulna. F. Tlie inter-articular fibro-cartilage attached to the styloid process of the ulna, and to the margin of the articular surface of the radius. S. The scaphoid bone : the numeral (5) indicates the number of bones with which it articulates. L. The semilunare articulating with five bones. C. The cuneiforme, articulating with three bones. P. The pisiforme, articulating with the cuneiforme only. T. The first bone of the second row — the trapezium, articulating with fciu- bones. T. The second bone — the trapezoides, articulating also with four bones. M. The os magnum, articu- lating with seven. U. The unciforme articulating with five. The numerals, 1, 3, 1, 2, 1, on the metacarpal bones, refer to the number of their articulations with the car- pal bones. 80 SCAPHOID BONE SEMILUNARE CUNEIFORME. hand; if it be directed to the right, the bone belongs to the right; and if to the left, to the left carpus. Articulations. — With /lue bones; by its convex surface with the radius ;, by its concave surface, with the os magnum and semilunare ; and by the extremity of its upper or dorsal border, with the trapezium and trapezoides. Attachments. — By its tuberosity to the abductor pollicis, and amiular hgament. The semilunar bone may be known by having a crescentic con- cavity, and a somewhat crescentic outline. It presents for exami- nation four articular surfaces and two extremities; the articular surfaces are, one concave, one convex, and two lateral — one lateral surface being crescentic ; the other nearly'- circular, and divided o-enerally into two facets : and the extremities, one dorsal, which is quadrilateral, flat, and indented, for the attachment of ligaments ; the other palmar, which is convex, rounded, and of larger size. To determine to which hand it belongs, let the bone be held per- pendicularly, so that the dorsal or flat extremity look upwards, and the convex side backwards (towards the holder). The circular lateral surface will point to the side corresponding with the hand to which the bone belongs. Articulations. — With Jive bones, but occasionally with only four ; by its convex surface, with the radius; by its concave surface, with the OS magnum ; by its crescentic lateral facet, with the sca- phoid ; and by the circular surface, with the cuneiform bone and with the point of the unciform. This surface is divided into two parts by a ridge, when it articulates with the unciform as well as with the cuneiform bone. The cuneiform bone, although somewhat wedge-shaped in form, may be best distinguished by a circular and isolated facet, which articulates with the pisiform bone. It presents for examination three surfaces, a base, and an apex. One surface is very rough and irreo-ular ; the opposite forms a concave articular surface, while the third is partly rough and partly smooth, and presents that circular facet which is characteristic of the bone. The base is an articular surface, and the apex is rough and pointed. To distinguish its appropriate hand, let the base be directed backwards and the pisiform facet upwards ; the concave articular surface will point to the hand to which it belongs. Articulations. — With three bones, and with the triangular fibro- cartilagc. By the base, with the semilunare; by the concave sur- face, with the unci forme ; by flie circular facet, with the pisiforme ; and by the superior angle of the rough surface, with the fibro- cartilagc. Tho pisiform bone may be recognised by its small size, and by possessing a single articular facet. If it be examined carefully, it will be observed to present four sides and two extremities; one side is articiilar, the smooth facet approaching nearer to the superior than the inferior extremity. The side opposite to this is trapezitt:m — TRAPEzoror.s. 81 rounded, and the remaining sides are, one slightly concave, the other slightly convex. If the bone be held so that the articular facet shall look down- wards, and the extremity which overhangs the articular facet forwards, the concave side Avill point to the hand to which it belongs. Articulations. — With the cuneiform bone only. Attachments. — To two muscles — the flexor carpi ulnaris, and abductor minimi digiti ; and to the annular ligament. The trapezium is too irregular in form to be compared to any known object ; it may be distinguished by a deep groove for the tendon of the flexor carpi radialis muscle. It is somewhat com- pressed, and may be divided into two surfaces which are smooth and articular, and three rough borders. One of the articular sur- faces is ovial, concave in one direction, and convex in the other ; the other is marked into three facets. One of the borders presents the groove for the tendon of the flexor carpi radialis, which is sur- mounted by a prominent tubercle for the attachment of the annular ligament ; the other two borders are rough and form the outer side of the carpus. The grooved border is narrow at one extremity and broad at the other, where it presents the groove and tubercle. If the bone be held so that the grooved border look upwards while the apex of this border be directed forwards, and the base with the tubercle backwards, the concavo-convex surface will point to the hand to which the bone belongs. Articulations. — V^iih. four bones; by the concavo-convex surface, with the metacarpal bone of the thumb ; and by the three facets of the other articular surface, with the scaphoid, trapezoid, and second metacarpal bone. Attachments. — To tico muscles — flexor ossis metacarpi, and flexor brevis pollicis ; and by the tubercle, to the annular ligament. The trapezoides is a small, oblong, and quadrilateral bone, bent near its middle upon itself. It presents four articular surfaces and two extremities. One of the surfaces is concavo-convex, — i. e. con- cave in one direction and convex in the other ; another, contiguous to the preceding, is concave, so as to be almost angular in the middle, and is often marked by a small rough depression, for an interosseous ligament; the two remaining sides SiYejflat, and present nothing remarkable. One of the two extremities is broad and of large size, — the dorsal ; the other, or palmar, is small and rough. If the bone be held perpendicularly, so that the broad extremity be upwards, and the concavo-convex surface forwards, the angular concave surface will point to the hand to which the bone belongs. Articulations. — V^^'iXh. four bones ; by the concavo-convex surface, with tile second metacarpal bone ; by the angular concave surface, with the OS magnum ; and by the other two surfaces, with the trape- zium and scaphoid. Attachments. — To the flexor brevis pollicis muscle. The OS magnum is the largest bone of the carpus, and is divisible 11 82 OS 3IAGNU3I UNCIFORME, into a body and head. The head is round for the greater part of its extent, but is flattened on one side. The hodij is irregularly quadrilateral, and presents four sides and a smooth extremity. Two of the sides are rough, the one being square and flat — the dorsal, the other rounded and prominent — the palmar ; the other two sides are articular, the one being concave, the other convex. The extremity is a triangular articular sm'face, divided into three facets. If the bone be held pei-pendicularly, so that the articular extremity look upwards and the broad dorsal sui'face backwards (towards the holder), the concave articular surface will point to the hand to which the bone belongs. Articulations. — With seven bones; by the rounded head, with the cup formed by the scaphoid and semilunar bone ; by the side of the convex surface, with the trapezoides ; by the concave surface, with the unciforme ; and by the extremity, with the second, third, and fourth metacarpal bones. Attachments. — To the flexor brevis pollicis muscle. The unciforme is a triangular-shaped bone, remarkable for a long and curved process, which projects from its palmar aspect. It pre- sents five surfaces ; — three articular, and two free. One of the articular surfaces is divided by a slight ridge into two facets ; the other two converge, and meet at a flattened angle.* One of the free surfaces — the dorsal — is rough and triangular; the other — palmar, also triangular, but somewhat smaller, gives origin to the unciform process. If the bone be held perpendicularly, so that the articular surface with two facets look upwards, and the unciform process back- wards (towards the holder), the concavity of the imciform process will point to the hand to which the bone belongs. Articulations. — With five bones ; by the two facets on its base, with the fourth and fifth metacarpal bones ; by the two lateral arti- culating surfaces, with the magnum and cuneiforme ; and by the flattened angle of its apex, with the semilunare. Attachments. — To two muscles — the adductor minimi digiti, and flexor brevis minimi digiti ; and to the annular ligament. Developement. — The bones of the carpus are each developed by a single centre. The number of articulations which each bone of the carpus pre- sents with surrounding bones, may be expressed in figures, which will materially facilitate their recollection ; the number for the first row is 5531, and for the second 4475. Metacarpus. — The bones of the metacarpus are five in number. They arc long bones, divisible into a head, shaft, and base. The head is rounded at the extremity, and flattened at each side, for the insertion of strong ligaments ; the shaft is prismoid, and marked deeply on each side, for the attachment of the interossei muscles; and the base is irregularly quadrilateral and rough, for * When the uncilbrmc does not articulate with tlie sctnilunurc, tliis angle is siiarp. METACARPUS. 83 Fig. 32.* the insertion of tendons and ligaments. The base presents three articular surfaces, one at each side, for the adjoining metacarpal bones ; and one at the extremity for the carpus. The metacarpal bone of the thumb is one-third shorter than the rest, flattened and broad on its dorsal aspect, and convex on its palmar side; the articular surface of the head is not so round as that of the other metacarj^al bones ; and the base has a single concavo-convex surface, to arti- culate with the similar surface of the tra- pezium. The metacarpal bones of the different fingers may be distinguished by certain obvious characters. The base of the metacarpal bone of the index finger is the largest of the four, and presents four arti- cular surfaces. That of the middle finger may be distinguished by a rounded pro- jecting process upon the radial side of its base, and two small circular facets upon its ulnar lateral surface. The base of the metacarpal bone of the ring-finger is small and square, and has two small circular facets to correspond with those of the middle metacarpal. The metacarpal bone of the little finger has only one lateral articular surface. Developement. — By two centres ; one for the shaft, and one for the digital extremity. Articulations. — The first with the trapezium ; second, with the trapezium, trapezoides, and os magnum, and with the middle meta- carpal bone ; third, or middle, with the os magnum, and adjoining metacarpal bones ; fourth, with the os magnum and unciforme, and with the adjoining metacarpal bones ; and fifth, with the unciforme, and with the metacarpal bone of the ring-finger. The figures resulting from the nuinber of articulations which each metacarpal bone possesses, taken from the radial to the ulnar side, are 13121. Attachment of Muscles. — To the metacarpal bone of the thumb, three — the flexor ossis metacarpi, extensor ossis metacarpi and first dorsal interosseous ; of the index finger, fve — the extensor carpi radialis longior, flexor carpi radialis, first and second dorsal interos- seous, and first palmar interosseous ; of the middle finger, four — the extensor carpi radialis brevior, adductor pollicis, and second * The hand viewed upon its anterior or palmar aspect. ]. The scaphoid bone. 2. The semilunare. .3. The cuneiforme. 4. The pisiforme. 5. The trapezium. G. The groove in the trapezium tiiat lodges the tendon of the flexor carpi radialis. 7. The trapezoides. 8. The os magnum. 9. The unciforme. 10, 10. The five meta- carpal bones. 11, 11. The first row of phalanges. 12, 12. The second row. 13, 13. The third row, or ungual plialanges. 14. The first phalanx of the tlunnb. 1.5. The ■second and last phalanx of the thumb. 84 METACARPUS PHALANGES. and third dorsal interosseous ; of the ring-finger, three — the third and fourth dorsal interosseous, and second palmar ; and of the httle finger, /owr — extensor carpi ulnaris, adductor minimi digiti, fourth dorsal and third palmar interosseous. Phalanges. — The phalanges are the bones of the fingers ; they are named from their arrangement in rows, and are fourteen in number, — three to each finger, and two to the thumb. In confor- mation they are long bones, divisible into a shaft, and two extre- mities. The shaft is compressed from before backwards, convex on its •posterior surface, and flat with raised edges in front. The meta- carpal extremity of the first row is a simple concave articular surface — of the other two rows a double concavity, separated by a slight ridge. The digital extremities of the first and second row present a pulley-like surface, concave in the middle, and convex on each side. The ungual extremity of the last phalanx is broad, rough and expanded into a semilunar crest. Developement. — By two centres ; one for the shaft, and one for the metacarpal extremity. Articulations. — The first row, with the metacarpal bones and second row of phalanges ; the second row, with the first and third ; and the third, with the second row. Attachment of Muscles. — To the base of the j^r^^ phalanx of the thumb four muscles — abductor polhcis, flexor brevis poUicis, adductor poUicis, and extensor primi internodii ; and to the second phalanx, two — the flexor longus pollicis, and extensor, secandi in- ternodii. To the first -phalanx of the second, third, and fourth fingers, one dorsal and one palmar interosseous, and to the first phalanx of the little finger, the abductor minimi digiti, flexor brevis minimi digiti, and one palmar interosseous. To the second phalanges the flexor sublimis and extensor communis digitorum ; and to the last phalanges — the flexor profundus and extensor communis digi- torum. PELVLS AND LOWER EXTREMITY. The bones of the pelvis are the two ossa innominata, the sacrum, and the coccyx ; and of the lower extremity, the femur, patella, tibia and fibula, tarsus, metatarsus, and j)ha]angcs. Os Innominatum. — The os innorninatiiin is an irregular flat bone, consisting in the young subject of three parts, which meet at the acetabulum. Hence it is usually described in the adult as divisible into three portions, — ilium, ischium, and pubis. The ilium is the superior broad and expanded portion which forms the prominence of the hip, and articulates with the sacrum. The ischium is the inferior and strong part of the bone ctn which we sit. The pubis is that portion which forms the front of tlie pelvis, and gives support to the external organs of generation. The ilium, may bo described as divisible into an internal and ex- ternal surface, a crest, and an anterior and posterior border. 85 •'-kiS^' The internal surface is bounded above by the crest, below by a prominent hne — the Hnea ilio-pectinea, and before and behind by the anterior and posterior bor- ders ; it is concave and smooth ^i&- ^^•* for the anterior tw^o-thirds of its extent, and lodges the iliacus muscle. The posterior third is rough, for articulation with the sacrum, and is divided into two parts by a deep groove ; — an anterior or auricular -portion, which is shaped like the pinna, and coated by cartilage in the fresh bone; and a posterior portion, which is very rough, for the attachment of interos- seous ligaments. The external surface is rough, partly convex, and partly concave; it is bounded above by the crest; below, by a prominent arch, which forms the upper segment of the acetabulum; and before and behind by the anterior and posterior borders. Crossing this surface in an arched direction, from the anterior extremity of the crest to a notch upon the lower part of the posterior border, is a groove, which lodges the gluteal vessels and nerve — the superior curved line ; and below this, at a short distance, a rough ridge, — the inferior curved line. The surface included between the superior curved line and the crest, gives origin to the gluteus medius muscle ; that between the curved lines, to the gluteus minimus ; and the rough interval between the inferior curved line and the arch of the acetabulum, to one head of the rectus. The posterior sixth of this surface is rough and raised, and gives origin to part of the gluteus maximus. The crest of the ilium is arched and sigmoid in its direction, being bent inwards at its anterior termination, and outwards towards the posterior. It is broad for the attachment of three planes of muscles, which are connected with its external and internal borders or lips, and with the intermediate space. The anterior border is marked by two projections, — the anterior superior spinous process, which is the anterior termination of the * The OS innominatum of the right side. 1. Tlie ilium ; its external surface. 2. The ischium. 3. The os pubis. 4. The crest of the ilium. 5. The superior curved line. 6. The inferior curved line. 7. The surface for the gluteus maximus. 8. The anterior superior spinous process. 9. The anterior inferior spinous process. 10. The posterior superior spinous process. 11. The posterior inferior spinous process. 12. The spine of the ischium. ]3. The great sacro-ischiatic notch. 14. The lesser sacro- ischiatic notch. 1.5. The tuberosity of the ischium, showing its three facets. 16. The ramus of the ischium. 17. The body of the os pubis. 18. The ramus of the pubis. 86 ISCHIUM OS PUBIS. crest, and the anterior inferior spinous process; the two processes bemg separated by a notch for the attachment of the sartorius muscle. This border terminates inferiorly in the hp of the acetabu- him. The posterior border also presents two projections, — the poste- rior siipeiior and the posterior inferior spinous process, — separated by a notch. Inferiorly this border is broad and arched, and forms the upper part of the great sacro-ischiatic notch. The ischium is divisible into a thick and solid portion — the body, and into a thin and ascending part — the ramus; it may be consi- dered also, for convenience of description, as presenting an external and internal sm'face, and three borders, — posterior, inferior, and superior. The external surface is rough, for the attachment of muscles ; and broad and smooth above, where it enters into the formation of the acetabulum. Below the inferior lip of the acetabulum is a notch, which lodges the obturator externus muscle in its passage outwards to the trochanteric fossa of the femur. The internal surface is smooth, and somewhat encroached upon at its posterior border by the spine. The posterior border of the ischium presents towards its middle a remarkable projection, — the spine. Immediately above the spine is a notch of large size — the great sacro-ischiatic, and below the spine the lesser sacro-ischiatic notch; the former being converted into a foramen by the lesser sacro-ischiatic ligament, gives passage to the pyriformis muscle, and to the gluteal vessels and nerve, pudic vessels and nerve, and ischiatic vessels and nerves ; and the lesser com- pleted by the great sacro-ischiatic ligament, to the obturator internus muscle, and to the internal pudic vessels and nerve. The inferior border is thick and broad, and is called the tuberosity. The surface of the tuberosity is divided into three facets; one anterior, which is rough for the origin of the semi-membranosus ; and two posterior, which are smooth, and separated by a slight ridge for the semi-ten- dinosus and biceps muscle. The inner margin of the tuberosity is bounded by a sharp ridge, which gives attachment to a prolongation of the great sacro-ischiatic hgament. The superior border of the ischium is thin, and forms the lower circumference of the obturator foramen. The ramus of the ischium is continuous with the ramus of the pubis, and is slightly everted. The pubis is divided into a horizontal portion or body, and a de- scending portion or ramus; it presents for examination an external and internal surface, a superior and inferior border, and symphysis. The external surface is rough, for the attachment of muscles; and prominent at its outer extremity, where it forms part of the acetabu- lum. H\\e internal surf ace {'^ smooth.. The superior Wc?er is marked by a rough ridge — the crest ; the inner termination of the crest is the angle; and the outer end, the spine or tuberosity. Running out- M'ards from the spine is a sharp ridge, the pectineal line — or linea ilio-pec tinea, which marks the brim of the true pelvis. In front of ACETABULUM OBTURATOR FORAMEN. 87 the pectineal line is a smooth depression, which supports the femoral vein, and a little more externally an elevated prominence, the -pec- tineal eminence, which divides the surface for the vein from another depression which overhangs the acetabulum, and lodges the psoas and iliacus muscles. The inferior border is broad and deeply- grooved, for the passage of the obturator vessels and nerve ; and sharp upon the side of the ramus, to form part of the boundary of the obturator foramen. The symphysis is the inner extremity of the body of the bone ; it is oval and rough, for the attachment of a liga- mentous structure analogous to the intervertebral substance. The ramus of the pubis descends, and is continuous with the ramus of the ischium. Its inner border is considerably everted, to afford a strong attachment to the crus penis. The acetabulum is a deep cup-shaped cavity, situated at the point of union between the ilium, ischium, and pubis ; a little less than two-fifths being formed by the ilium, a little more than two-fifths by the ischium, and the remaining fifth by the pubis. It is bounded by a deep rim or lip, which is broad and strong above, where most resistance is required, and marked in front by a deep notch, which transmits the nutrient vessels into the joint. At the bottom of the cup, and communicating with the notch, is a deep and circular pit, which lodges a mass of fat, and gives attachment to the broad ex- tremity of the ligamentum teres. The obturator ox thyroid foramen is a large oval interval between the ischium and pubis, bounded by a narrow rough margin, to which a ligamentous membrane is attached. The upper part of the foramen is increased in depth by the groove in the under surface of the os pubis, which lodges the obturator vessels and nerve. Developernent. — By eight centres ; three principal — one for the ilium, one for the ischium, and one for the pubis ; and five secondary — one for the crest of the ilium, and one for its anterior inferior spinous process, one for the centre of the acetabulum, one for the tuberosity of the ischium, and one (not constant) for the angle of the pubis. Articulations. — With three bones ; sacrum, opposite innominatum, and femur. Attachment of Muscles and Ligaments. — Ho thirty-five muscles; to the ilium, thirteen ; by the outer lip of the crest, to the obliquus ex- ternus for two thirds, and to the latissimus dorsi for one-third its length, and to the tensor vaginse femoris by its anterior fourth ; by the middle of the crest, to the internal oblique for three-fourths its length, by the remaining fourth to the erector spinse ; by the inter- nal lip, to the transversalis for three-fourths, and to the quadratus lumborum by the posterior part of its middle third. By the external surface, to the gluteus medius, minimus and maximus, and to one head of the rectus ; by the internal surface, to the iliacus ; and by the anterior border, to the sartorius, and the other head of the rectus. To the ischium sixteen ; by its external surface, the adductor magnus and obturator externus'; by the internal surface, the obturator internus and levator ani ; by the spine, the gemellus superior, levator ani, 88 PELVIS. coccygeus, and lesser sacro-ischiatic ligament ; by the tuberosity, the biceps, semi-tendinosus, semi-membranosus, gemellus inferior, quad- ratus femoris, erector penis, transversus perinei, and great sacro- ischiatic ligament ; and by the ramus, the graciUs, accelerator urince, and compressor urethrse. To the Y>ubis ff teen ; by its upper border, the obliquus externus, .obliquus internus, transversalis, rectus, pyra- midalis, pectineus, and psoas parvus ; by its external surface, the adductor longus, adductor brevis and gracilis ; by its internal surface, the levator ani, compressor urethrse, and obturator internus ; and by the ramus, the adductor magnus, and accelerator urinse. PELVIS. The pelvis considered as a whole is divisible into a false and true pelvis ; the former is the expanded portion, bounded on each side by the ossa ilii, and separated from the true pelvis by the linea ilio- pectinea. The true pelvis is all that portion w^hich is situated be- neath the linea ilio-pectinea. This line forms the margin or bj^im of the true pelvis, while the included area is called the in/ct. The form of the inlet is heart-shaped, obtusely pointed in front at the symphysis pubis, expanded on each side, and encroached upon behind by a projection of the upper part of the sacrum, which is named the pro- montory. The cavity is somewhat encroached upon at each side by a smooth quadrangular plane of bone, corresponding with the internal surface of the acetabulum, and leading to the spine of the ischium. In front are two fossae around the obturator foramina, for lodging the obturator internus muscle, at each side. The inferior termination of the pelvis is very irregular, and is termed the outlet. It is bounded in front by the convergence of the rami of the ischium and pubis, which constitute the arch of the pubis ; on each side by the tuberosity of the ischium, and by two irregular fissures formed by the greater and lesser sacro-ischiatic notches ; and behind by the inferior borders of the sacrum, and by the coccyx. The pelvis is placed obliquely with regard to the trunk of the body, so that a line drawn through the central axis of the inlet, would touch by one extremity the lower part of the sacrum, and by the other would pass through the umbilicus. The axis of the inlet is thei^efore directed downwards and. hachoards, while that of the outlet points dovmvards and forivards, and corresponds with a line drawn from the upper part of the sacrum, through the centre of the outlet. The axis of the cavity represents a curve, the extremities of which will be indicated by the central points of the inlet and outlet. A know- ledge of the direction of these axes is most important to the surgeon, as indicating the line in which instruments should be used in opera- tions upon the viscera of the pelvis, and the direction of" force in the removal of calculi from the bladder; and to the accoucheur, as ex- plaining the course of the ftKtus during parturition. There arc certain striking differences between the male and female pelvis. In the male the bones are thicker, stronger, and PELVIS FEMUR. 89 more solid, and the cavity deeper and narrower. In the female the bones are lighter and more delicate, the iliac fossae are large and the ilia projecting ; the inlet, and the outlet, and the cavity are large, and the acetabula farther removed from each other ; the cavity is shallow, the tuberosities widely separated — the obturator foramina triangular, and the arch of the pubis wide. The precise diameter of the inlet and outlet, and the depth of the cavity, are very important considerations to the accoucheur. The diameters* of the inlet or brim are three; — 1, Antero-pos- terior, sacro-pubic or conjugate ; 2, transverse ; and 3, oblique. The antero-posterior extends from the symphysis pubis to the middle of the promontory of the sacrum, and measures four inches and a half. The transverse extends from the middle of the brim on one side to the same point on the opposite, and measures five inches and a quarter. The oblique extends from the sacro-iliac symphysis on one side, to the margin of the brim corresponding with the aceta- bulum on the opposite, and measures five inches and one-eighth. The diameters of the outlet are two, antero-posterior, and trans- verse. The antero-posterior diameter extends from the lower part of the symphysis pubis, to the apex of the coccyx ; and the trans- verse from the first part of one tuberosity to the same point on the opposite side ; they both measure four inches. The cavity of the pelvis measures in depth four inches and a half, posteriorly ; three inches and a half in the middle ; and one and a half at the sym- physis pubis. Femur. — The femur is a long bone, divisible, like other bones of the same class, into a shaft, a superior and an inferior extremity. At the superior extremity is a rounded head, directed upwards and inwards, and marked just below its centre by an oval depression for the ligamentum teres. The head is supported by a neck, which varies in length and obliquity at various periods of life, being long and oblique in the adult — short and almost horizontal in the aged. Externally to the neck is a large process, — the trochanter major, which presents upon its anterior surface an oval facet, for the attachment of the tendon of the gluteus minimus muscle ; and above, a double facet, for the insertion of the gluteus medius. On its poste- rior side is a vertical ridge — the linea quadrati, for the attachment of the quadratus femoris muscle. Upon the inner side of the tro- chanter major is a deep pit, trochanteric or digital fossa, in which are inserted the tendons of the pyriformis, gemellus superior and inferior, and obturator externus and internus muscles. Passing downwards from the trochanter major in front of the bone is an oblique ridge, which forms the inferior boundary of the neck, — the anterior intertrochanteric line ; and behind, another oblique ridge, the posterior intertrochanteric line, which terminates in a rounded * These diameters are quoted from an excellent " Manual of Practical Midwifery," by Dr. James Reid. 12 90 tubercle upon the posterior and inner side of the bone, the trochanter minor. The shaft of the femur is convex and rounded in front, and covered with muscles ; and somewhat concave and raised into a rough and prominent ridge behind, the linea aspera. The linea aspera near the upper extremity of the bone divides into three branches. The anterior branch is continued forwards in front of the lesser tro- chanter, and is continuous with the anterior intertrochanteric line ; the middle is continued directly upwards into the Hnea quadrati ; and the posterior, broad and strongly marked, Fig. 34* ascends to the base of the trochanter major. Towards the lower extremity of the bone the linea aspera divides into two ridges, which descend to the two condyles, and enclose a triangular space upon which rests the popliteal artery. The in- ternal condyloid ridge is less marked than the external, and presents a broad and shallow groove, for the passage of the femoral artery. The nutritious foramen is situated in or near the linea aspera, at about one-third from its upper extremity, and is directed obliquely from below upwards. The lower extremity of the femur is broad and porous, and divided by a smooth depression in front, and by a considerable notch behind, into two condyles. The external condyle is the broadest and most projecting, and the internal the narrowest and longest ; the difference in length depending upon the obliquity of the femur, in consequence of the separation of the two bones at their upper extre- mities by the breadth of the pelvis. The external condyle is marked upon its outer side by a promi- nent tuberosity, which gives attachment to the external lateral ligaments; and immediately beneath this is the groove which lodges the ten- dinous origin of the poplitcus. By the internal surface it gives attachment to the anterior crucial ligament of the knee-joint ; and by its upper and posterior part, to the external head of the gastrocnemius and to the plantaris. The internal condyle projects upon its inner side into a tuberosity, to which is attached the internal lateral ligament; above this tuberosity, at the extremity of the internal condyloid ridge, is a tubercle, for the insertion of the tendon * The riglit femur, Rccn upon the anterior aspect. 1. Tlic shaft. 2. The head. 3. The nock. 4. Tlie jrreat trochanter. 5. The anterior intertrochanteric Unc. C. The lesser trochanter. 7. The external condyle. 8. 'Die internal condyle. 9. The tuhe- rosity for the att.iohment of the external lateral ligaments. ] 0. The groove for the tendon of origin of the popliteus muscle. 11. The tuberosity for the attachment of the internal lateral ligament. m PATELLA TIBIA. 91 Fiff. 35 * Ui\ of the adductor magnus ; and beneath the tubercle, upon the upper surface of the condyle, a depression, from which the internal head of the gastrocnemius arises. The outer side of the internal condyle is rough and concave, for the attachment of the posterior crucial ligament. Developement. — By five centres; one for the shaft, one for each extremity, and one for each trochanter. Articulations. — With three bones ; with the os in- nominatum, tibia, and patella. Attachment of Muscles. — To iiventy-three ; by the greater trochanter, to the gluteus medius and mini- mus, pyriformis, gemellus superior, obturator in- ternus, gemellus inferior, obturator externus, and quadratus femoris ; by the lesser trochanter, to the common tendon of the psoas and ihacus. By the linea aspera, its outer lip, to the vastus externus, gluteus maximus, and short head of the biceps; by its inner lip, to the vastus internus, pectineus, ad- ductor brevis, and adductor longus; by its middle to the adductor magnus ; by the anterior part of the bone, to the crurseus and subcrurasus ; by its condyles, to the gastrocnemius, plantaris and popliteus. Patella. — The patella is a sesamoid bone, de- veloped in the tendon of the quadriceps extensor muscle, and usually described as a bone of the lower extremity. It is heart-shaped in figure, the broad side being directed upwards and the apex downwards, the external surface convex, and the internal divided by a ridge into two smooth surfaces, to articulate with the condyles of the femur. The external articular surface corresponding with the external condyle is the larger of the two, and serves to indicate the leg to which the bone belongs. Articulations. — With the two condyles of the femur. Attachment of Muscles. — To four; the rectus, crura3us, vastus internus, and vastus externus, and to the ligamentum patella. Tibia. — The tibia is the large bone of the leg ; it is prismoid in form, and divisible into a shaft, an upper and lower extremity. The upper extremittj, or head, is large, and expanded on each side into two tuberosities. Upon the upper surface the tuberosi- ties are smooth, to articulate with the condyles of the femur ; the internal articular surface being oval and oblong, to correspond with the internal condyle ; and the external broad and nearly cir- * A diagram of the posterior aspect of the riglit femur, showing the lines of attach- ment of the muscles. The muscles attached to the inner lip are, — p, tlie pectineus ; a b, the adductor brevis ; and a I, the adductor longus. The middle portion is occupied for its whole extent by a m, the adductor magnus ; and is continuous superiorly with qf, the linea quadrati, into which the quadratus femoris is inserted. The outer lip is occupied by g m, the glutens maximus ; and b, the short head of the biceps. 92 TIBIA. cular. Between the two articular surfaces is a spinous process; and in front and behind the spinous process a rough depression, giving attachment to the anterior and posterior ■ Fig. 36.* crucial ligaments. Between the two tuberosities on 4, the front aspect of the bone is a prominent eleva- tion, — the tubercle, — for the insertion of the ligamen- -2 tum patellae, and immediately above the tubercle, a smooth surface corresponding with a bursa. Upon the outer side of the external tuberosity is an articu- lar surface, for the head of the fibula ; and upon the posterior part of the internal tuberosity a depression, for the insertion of the tendon of the semi-membra- nosus muscle. The shaft of the tibia presents three surfaces; internal, which is subcutaneous and superficial; external, which is concave and marked by a sharp ridge, for the insertion of the interosseous membrane ; and posterior, grooved, for the attachment of muscles. Near the upper extremity of the posterior surface, is an oblique ridge, — the popliteal line, for the attach- ment of the fascia of the popliteus muscle ; and im- mediately below the oblique line, the nutritious canal, which is directed downwards. The inferior extremity of the bone is somewhat quadrilateral, and prolonged on its inner side into a large process, the internal malleolus. Behind the in- ternal malleolus, is a broad and shallow groove, for lodging the tendons of the tibialis posticus and flexor longus digito- rum ; and farther outwards another groove, for the tendon of the flexor longus poUicis. Upon the outer side the surface is concave and triangular, — rough above, for the attachment of the interosseous ligament ; and smooth below, to articulate with the fibula. Upon the extremity of the bone is a triangular smooth surface, for articu- lating with the astragalus. Developement. — By three centres ; one for the shaft, and one for each extremity. Jlrtlculatiovs. — With three bones ; femur, fibula, and astragalus. Attachment of Muscles. — To ten ; by the internal tuberosity, to the sartorius, graciUs, semitendinosus, and semimembranosus; by the external tuberosity, to the tibialis anticus and extensor longus digi- torum ; by the tubercle, to the ligamentum patellas ; by the external surface of the shaft, to the tibialis anticus ; and by the posterior surface, to the popliteus, soleus, flexor longus digitorum, and tibialis posticus. * The tibia and fibula of the right leg, articulated and seen from the firont. 1. The shaft of the tibia. 2. The inner tuberosity. 3. The outer tuberosity. 4. The spinous process. .O. 'I'lic tubercle. G. The internal subcutaneous surface of the shaft. 7. The lower extremity of the tibia. 8. The internal malleolus. 9. The shaft of the fibula. 10. Its upper extremity. 11. Its lower extremity, the external malleolue. FIBULA. 93 Fibula. — The fibula is a long and slender prismoid bone, divisible into a shaft and two extremities. The superior extremity or head is thick and large, and depressed upon the upper part by a concave surface, which articulates with the external tuberosity of the tibia. Externally to this surface is a thick and rough prominence, for the attachment of the external lateral Ugaments of the knee-joint, terminated behind by a styloid process, for the insertion of the tendon of the biceps. The lower extremity is flattened from without inwards, and pro- longed downwards beyond the articular surface of the tibia, form- ing the external malleolus. Its external side presents a rough and triangular surface, which is subcutaneous. Upon the internal surface is a smooth triangular facet, to articulate with the astragalus ; and a rough depression, for the attachment of the interosseous ligament. The anterior border is thin and sharp ; and the posterior, broad and grooved, for the tendons of the peronei muscles. To place the bone in its proper position, and ascertain to which leg it belongs, let the inferior or flattened extremity be directed downwards, and the narrow border of the malleolus forwards ; the triangular subcutaneous surface will then point to the side corre- sponding with the limb of which the bone forms a part. The shaft of the fibula is prismoid, and presents three surfaces ; external, internal, and posterior ; and three borders. The external surface is the broadest of the three ; it commences upon the anterior part of the bone above, and curves around it so as to terminate upon its posterior side below. The surface is completely occupied by the two peronei muscles. The internal surface commences on the side of the superior articular surface, and terminates below, by narrowing to a ridge, which is continuous with the anterior border of the malleolus. It is marked along its middle by the interosseous ridge, which is lost above and below in the inner border of the bone. The posterior surface is twisted like the external, it commences above on the posterior side of the bone, and terminates below on its internal side ; at about its middle is the nutritious foramen, which is directed downwards. The internal border commences superiorly in common with the interosseous ridge, and bifurcates interiorly into two lines, which bound the triangular subcutaneous space of the external malleolus. The external border begins at the base of the styloid process upon the head of the fibula, and winds around the bone, following the direc- tion of the corresponding surface. The posterior border is sharp and prominent, and is lost inferiorly in the interosseous ridge. Developement. — By three centres ; one for the shaft, and one for each extremity. Articulations. — With the tibia and astragalus. Attachment of Muscles. — To nine; by the head, to the tendon of the biceps and soleus ; by the shaft, — its external surface, — to the peroneous longus and brevis ; internal surface, to the extensor longus digitorum, extensor proprius poUicis, peroneus tertius, and tibialis 94 TARSUS ASTRAGALUS OS CALCIS. Fiff, 37* posticus ; by the posterior surface, to the popUteus and flexor longus poUicis. Tarsus. — The bones of the tarsus are seven in number ; viz. the astragalus, os calcis, scaphoid, internal, middle, and external cuneiform and cuboid. The Astragalus may be recognised by a rounded head, a broad articular facet upon its convex surface, and two articular facets, separated by a deep groove, upon its concave surface. The bone is divisible into a superior and inferior surface, an ex- ternal and internal border, and an anterior and posterior extremity. The superior surface is convex, and presents a large quadrilateral and smooth facet, somewhat broader in front than behind, to articu- late with the tibia. The inferior surface is concave, and divided by a deep and rough groove, which lodges a strong interosseous ligament, into two facets — the posterior large and quadrangular, and the anterior smaller and elliptic, — which articulate with the os calcis. The internal border is flat and irregular, and marked by a pyriform articular surface, for the inner mal- leolus. The external presents a large triangular articular facet, for the external malleolus, and is rough and concave in front. The anterior ex- tremity presents a rounded head, surrounded by a constriction somewhat resembling a neck ; and the posterior extremity is narrow, and marked by a deep groove, for the tendon of the flexor longus poUicis. Hold the astragalus with the broad articular surface upwards, and the rounded head for- wards; the triangular lateral articular surface will point to the side to which the bone belongs. Articulations.-— With, four bones; tibia, fibula, calcis, and scaphoid. The Os Calcis may be known by its large size and oblong figure, by the large and irregular portion which forms the heel, and by two articu- lar surfaces, separated by a deep groove upon its upper side. The OS calcis is divisible into four surfaces, — superior, inferior, external, and internal ; and two extremities, — anterior and posterior. The superior surface is convex behind and irregularly concave in front, where it presents two and sometimes three articular facets, divided by a broad and shallow groove, for the interosseous ligament. The inferior surface * Tlic dorsal surface of the left foot. 1. The astragalus; its superior quadrilateral and articular surface. 2. The anterior extremity of the astrajralus, which articulates with (4) the seaplioid bone. .3. 'J'he os calcis. 4. 'I'lic scaphoid hone. 5. The in- ternal cuneiform bone. G. The middle cuneiform bone. 7. "^I'lie external cuneiform bone. 8. The culjoid bone. 9. The metatarsal bones of the first and second toes. 10. The first phalanx of the jrreat toe. II. The second plialanx of the great toe. 12. The first phalanx of the second toe. 1.3. Its second phalanx. H. Its third phalanx. SCAPHOID INTERNAL CUNEIFORM, 95 is convex and rough, and bounded posteriorly by the two inferior tuberosities, of which the internal is broad and large, and the external smaller and prominent. The external surface is convex and subcutaneous, and mai'ked towards its anterior third by two grooves, often separated by a tubercle, for the tendons of the peroneus longus and brevis. The internal surface is concave and grooved, for the tendons and vessels which pass into the sole of the foot. At the anterior extremity of this surface is a projecting process, which supports the anterior articulating surface for the as- tragalus, and serves as a pulley to the tendon of the flexor longus digitorum. Upon the anterior extremity \s aflat articular surface, surmounted by a rough projection, which affords one of the guides to the surgeon in the performance of Chopart's operation. The posterior extremity is prominent and convex, and constitutes the posterior tuberosity ; it is smooth for the upper half of its extent, where it corresponds with a bursa ; and rough below, for the inser- tion of the tendo Achillis ; the lower part of this surface is bounded by the two inferior tuberosities. Articulations. — With two bones ; the astragalus and cuboid. Attachment of Muscles. — To nine ; by the posterior tuberosity, to the tendo AchiUis and plantaris ; by the inferior tuberosities and under surface, to the abductor poUicis, abductor minimi digiti, flexor brevis digitorum, flexor accessorius, and flexor brevis pollicis, and to the plantar fascia ; and by the external surface, to the extensor brevis digitorum. The Scaphoid bone may be distinguished by its boat-like figure, concave on one side, and convex with three facets upon the other. It presents for examination an anterior and posterior surface, a supe- rior and inferior border, and two extremities — one broad, the other pointed and thick. The anterior surface is convex, and divided into three facets, to articulate with the three cuneiform bones ; and the posterior concave, to articulate with the rounded head of the astra- galus. The superior border is convex and rough, and the inferior somewhat concave and irregular. The external extremity is broad and rough, and the internal pointed and projecting, so as to form a tuberosity. If the bone be held so that the convex surface with three facets look forwards, and the convex border upwards, the broad extremity will point to the side corresponding with the foot to which the bone belongs. Articulations. — ^With four bones ; astragalus and three cuneiform bones. Attachment of Muscles. — To the tendon of the tibialis posticus. The Internal Cuneiform may be known by its irregular wedge- shape, and by being larger than the two other bones bearing the same name. It presents for examination a convex and a concave surface, a long and a short articular border, and a small and a large extremity. Place the bone so that the small extremity may look upwards and 96 CUNEIFORM BONES, the long articular border forwards, the concave surface will point to the side corresponding with the foot to which it belongs. The convex surface is internal and free, and assists in forming the inner border of the foot, and the concave is external, and in apposition "with the middle cuneiform and second metatarsal bone; the long border articulates with the metatarsal bone of the great toe, and the short border with the scaphoid bone. The small extre- mity is sharp, and the larger extremity rounded into a broad tuberosity. Articulations. — With four bones ; a scaphoid, middle cuneiform, and the two first metatarsal bones. Attachment of Muscles. — To the tibialis anticus, and posticus. The Middle Cuneiform is the smallest of the three; it is wedge- shaped, the broad extremity being placed upwards, and the sharp end downwards in the foot. It presents for examination four arti- cular surfaces and two extremities. The anterior and ^posterior sur- faces have nothing worthy of remark. One of the lateral surfaces has a long articular facet, extending its whole length, for the inter- nal cuneiform ; the other has only a partial articular facet for the external cuneiform bone. If the bone be held so that the square extremity look upwards, the broadest side of the square being towards the holder, the small and partial articular surface will point to the side to which the bone belongs. Articulations. — With four bones ; scaphoid, internal and external cuneiform, and second metatarsal bone. Attachment of Muscles. — To the flexor brevis pollicis. The External Cuneiform is intermediate in size between the two preceding, and placed, like the middle, with the broad end upwards and the sharp extremity downwards. It presents for examination five surfaces, and a superior and an inferior extremity. The upper extremity is flat, of an oblong square form, and bevelled posteriorly at the expense of the outer surface, into a sharp edge. If the bone be held so that the square extremity look upwards and the sharp border backwards, the bevelled surface will point to the side corresponding with the foot to which the bone belongs. Articulations. — With six bones ; scaphoid, middle cuneiform, cu- boid, and second, third, and fourth metatarsal bones. Attachment of Muscles. — To its inferior extremity, the flexor brevis pollicis. The Cuboid Bone is irregularly cuboid in form, and marked upon its under surface by a deep groove, for the tendon of the peroneus longus muscle. It presents for examination six surfaces, three articular and three non-articular. The non-articular surfaces are the superior, which is slightly convex, and assists in forming the dorsum of the foot ; the inferior, marked by a prominent ridge and a deep groove, for the tendon of the peroneus longus ; and an external, the smallest of the whole, and deeply notched by the com- mencement of the peroneal groove. The articular surfaces are the posterior, which is of large size, and concavo-convex, to articulate METATARSAL BONES. 97 Fig. 38/ with the OS calcis ; anterior, of smaller size, divided by a ridge into two facets, for the fourth and fifth metatarsal bones ; and internal, a small oval articular facet, upon a large and quadran- gular surface, for the external cuneiform bone. If the bone be held so that the plantar surface, with the peroneal groove, look downwards, and the largest articular surface back- wards, the small non-articular surface, marked by the deep notch, will point to the side corresponding with the foot to which the bone belongs. Articulations. — ^With four bones ; os calcis, external cuneiform, and fourth and fifth metatarsal bones. Attachment of Muscles. — To three; the flexor brevis pollicis, adductor pollicis, and flexor brevis minimi digiti. Upon a consideration of the tarsus it will be observed, that each bone articulates with four adjoining bones, with the exception of the OS calcis, which articulates with two, and the external cunei- form with six. Developement. — By a single centre for each bone, with the ex- ception of the OS calcis, which has two centres of ossification ; the second centre makes its appearance at about the ninth year, and is not united with the preceding until the fifteenth. The Metatarsal Bones, five in number, are long bones, and divisible therefore into a shaft and two extremities. The shaft is pris- moid, and compressed from side to side ; the posterior extremity, or base, is square-shaped, to articulate with the tarsal boijes and with each other; and the anterior extremity pre- sents a rounded head, circumscribed by a neck, to articulate with the first row of pha- langes. Peculiar Metatarsal Bones. — The first is shorter and larger than the rest, forming the inner border of the foot; its posterior extre- mity presents only one articular surface on the side, and an oval rough surface upon a prominent process beneath, for the insertion of the tendon of the peroneus longus. The an- terior extremity has, upon its plantar surface, two grooved facets, for sesamoid bones. The second is the longest and larg-est of the remaining metatarsal bones ; it presents at its base three articular facets, for the three cunei- * The sole of the left foot. 1. The inner tuberosity of the os calcis. 2. The outer tuberosity. 3. The groove for the tendon of the flexor longus digitorum. 4. The rounded head of the astragalus. 5. The scaphoid bone. 6. Its tuberosity. 7. The internal cuneiform bone ; its broad extremity. 8. The middle cuneiform bone. 9. The external cuneiform bone. 10, 11. The cuboid bone. II. Refers to the groove for the tendon of the peroneus longus. 12, 12. The metatarsal bones. 13, 13. The first phalanges. 14,14. The second phalanges of the four lesser toes. 15,15. The third, or ungual phalanges of the four lesser toes. 16. The last phalanx of the great toe. 13 98 PHALANGES. form bones ; a large oval facet, but often no articular surface, on its inner side, to articulate with the metatarsal bone of the great toe, and two externally for the metatarsal bone. The third may be known by two facets upon the outer side of its base, corresponding with the second, and may be distinguished by its smaller size. The fourth may be distinguished by its smaller size, and by having a single articular surface on each side of the base. The fifth is recognised by its broad base, and by the absence of articular surface upon its outer side. Developement. — Each bone by two centres ; one for the body and one for the digital extremity in the four outer metatarsal bones ; and one for the body, the other for the base in the metatarsal bone of the great toe. Jlrticulations. — With the tarsal bones by one extremity, and with the first row of phalanges by the other. The number of tarsal bones with which each metatarsal articulates from within outwards, is the same as between the metacarpus and carpus, — one for the first, three for the second, one for the third, two for the fourth, and one for the fifth ; forming the cipher 13121. Attachment of Muscles. — To fourteen; to the first, the peroneus longus and first dorsal interosseous muscle ; to the second, two dor- sal interossei and transversus pedis ; to the third, two dorsal and one plantar interosseous, adductor pollicis and transversus pedis ; to the fourth, two dorsal and one plantar interosseous and adductor poUicis; to the fifth, one dorsal and one plantar interosseous, pero- neus brevis, peroneus tertius, abdjactor minimi digiti, flexor brevis minimi digiti, and transversus pedis. Phalanges. — There are two phalanges in the great toe, and three in the other toes, as in the hand. They are long bones, divisible into a central portion and extremities. The phalanges of the first row are convex above, concave upon the under surface, and compressed from side to side. The posterior extremity has a single concave articular surface, for the head of the metatarsal bone; and the anterior extremity, a pulley-like surface, for the second phalanx. The second 'phalanges are short and diminutive, but somewhat broader than the first row. The third, or ungual phalanges, including the second phalanx of the great toe, are flattened from above downwards, and spread out laterally at the base, to articulate with the second row, and, at the opposite extremity, to support the nail and the rounded extremity of the toe. Developement. — By tivo centres; one for the body and one for the metacarpal extremity. Jlrticulations. — The first row with the metatarsal bones and second phalanges ; the second, of the great toe with the first phalanx, and of the other toes with the first and third phalanges ; and the third, with the second row. SESAMOID BONES. 99 Attachment of Muscles. — To ticenty-tliree ; to the first p/ialanges ; great toe, the innei-most tendon of the extensor brevis digitorum, ab- ductor poUicis, adductor polUcis, flexor brevis polhcis, and transver- sus pedis ; second toe, first dorsal and first palmar interosseous and lumbricalis ; third toe, second dorsal and second palmar interosseous and lumbricalis; fourth toe, third dorsal and third palmar interos- seous and lumbricahs ; ffth toe, fourth dorsal interosseous, abductor minimi digiti, flexor brevis minimi digiti, and lumbricahs. Second phalanges ; great toe, extensor longus pollicis, and flexor longus pol- licis ; other toes, one shp of the common tendon of the extensor lon- gus digitorum, and extensor brevis digitorum, and flexor brevis digi- torum. Third phalanges ; two slips of the common tendon of the extensor longus and extensor brevis digitorum, and the flexor longus digitorum. Sesamoid Bones. — These are small osseous masses, developed in those tendons which exert a certain degree of force upon the sur- face over which they glide, or where, by continued pressure and friction, the tendon would become a source of irritation to neigh- bouring parts, as to joints. The best example of a sesamoid bone is the patella, developed in the common tendon of the quadriceps ex- tensor, and resting upon the front of the knee-joint. Besides the pa- tella, there are four pairs of sesamoid bones included in the number of pieces which compose the skeleton, two upon the metacarpo- phalangeal articulation of each thumb, and existing in the tendons of insertion of the flexor brevis pollicis, and two upon the correspond- ing joint in the foot, in the tendons of the muscles inserted into the base of the first phalanx. In addition to these there is often a sesa- moid bone upon the metacai^o-phalangeal joint of the little finger, and upon the corresponding joint in the foot, in the tendons inserted into the base of the first phalanx ; there is one also in the tendon of the peroneus longus muscle, where it glides through the groove in the cuboid bone ; sometimes in the tendons, as they wind around the inner and outer malleolus ; in the psoas and iliacus, where they glide over the body of the os pubis ; and in the external head of the gas- trocnemius. The bones of the tympanum, belonging to the apparatus of hear- ing, will be described with the anatomy of the ear. CHAPTER II ON THE LIGAMENTS. The bones are variously connected with each other in the con- struction of the skeleton, and the connexion between any two bones constitutes a joint or articulation. If the joint be immovable, the surfaces of the bones are applied in direct contact ; but if motion be intended, the opposing surfaces are expanded, and coated by an elastic substance, named cartilage ; a fluid secreted by a membrane closed on all sides lubricates their surface, and they are firmly held together by means of short bands of glistening fibres, which are called ligaments (ligare, to bind). The study of hgaments is named syndesmology (tfOv together, Ssdiiog, bond), which, with the anatomy of the articulations, forms the subject of the present chapter. The forms of articulation met with in the human frame may be considered under three classes : — Synarthrosis, Amphi-arthrosis and Diarthrosis. Synarthrosis (tfuv, a^6^u(fig articulation) is expressive of the fixed form of joint in which the bones are immovably connected with each other." The kinds of synarthrosis are four in number. 1. Sutura. 2. Harmonia. 3. Schindylesis. 4. Gomphosis. The cha- racters of the three first have been sufficiently explained in the pre- ceding chapter, p. 54. It is here only necessary to state that in the construction of sutures, the substance of the bones is not in imme- diate contact, but it is separated by a layer of membrane which is continuous externally with the pericranium and internally with the dura mater. It is the latter connexion which gives rise to the great difficulty sometimes experienced in tearing the calvarium from the dura mater. Cruveilhier describes this interposed membrane as the sutural cartilage : I never saw any structure in the sutures, which could be regarded as cartilage, and the history of the formation of the cranial bones would seem to point to a diflferent explanation. The fourth, Gomphosis (70^905, a nail) is expressive of the insertion of one bone into another, in the same manner that a nail is fixed into a board ; this is illustrated in the articulation of the teeth with the alveoli of the maxillary bones. Amphi-arthrosis (a|X(pi' both, a^^^uidig) is a joint intermediate in aptitude for motion between the immovable synarthrosis and the movable diarthrosis. It is constituted by the approximation of sur- faces partly coated with cartilage lined by synovial membrane, and partly connected by the interosseous ligaments, or by the interven- ARTICULATIONS MOVEMENTS. 101 tion of an elastic fibro-cartilage which adheres to the ends of both bones. Examples of this articulation are seen in the union between the bodies of the vertebrae, of the sacrum with the coccyx, of the two first pieces of the sternum, the sacro-iliac and pubic sym- physes (tfuv, cpusiv to grow together), and according to some, of the necks of the ribs, with the transverse processes. DiARTHROsis {5m through, a^^gwCij) is the movable articulation, which constitutes by far the greater number of the joints of the body. The degree of motion in this class has given rise to a sub- division into three genera, Arthrodia, Ginglymus, and Enarthrosis. Arthrodia is the movable joint in which the extent of motion is slight and limited, as in the articulation of the clavicle, of the ribs, articular processes of the vertebrse, axis with the atlas, radius with the ulna, fibula with the tibia, carpal and metacarpal, tarsal and metatarsal bones. Ginglymus (yiyyXufxoff, a hinge) or hinge-joint, is the movement of bones upon each other in two directions only, viz. forwards and backwards ; but the degree of motion may be very considerable. The instances of this form of joint are numerous ; they comprehend the elbow, wrist, metacarpo-phalangeal and phalangeal joints in the upper extremity ; and the knee, ankle, metatarso-phalangeal and phalangeal joints in the lower extremity. The lower jaw may also be admitted into this category, as partaking more of the character of the hinge-joint than of the less movable arthrodia. The form of the ginglymoid joint is somewhat quadrilateral and each of its four sides is provided with a ligament, which is named from its position, anterior, 'posterior, internal or external lateral. The lateral ligaments are thick and strong, and are the chief bond of union between the bones. The anterior and posterior are thin and loose in order to permit the required extent of movement. Enarthrosis (sv in, a^^^wtfi?) is the most extensive in its range of motion of all movable joints. From the manner of connexion and form of the bones in this articulation, it is called the ball and socket joint. There are three instances in the body, viz. the hip, the shoulder, and the articulation of the metacarpal bone of the thumb with the trapezium. The ball and socket joint has a circular form ; and, in place of the four distinct Hgaments of the ginglymus, is enclosed in a bag of ligamentous membrane, called a capsular ligament. The kinds of articulation may probably be conveyed in a more satisfactory manner in the tabular form, thus, Examples. f Sutura .... bones of the skull. o tu • 1 Harmonia . . . superior maxillary bones, synarthrosis. < o u- j i • -^i ^ •^ } fechmdylesis . . vomer with rostrum. l^Gomphosis . . . teeth with alveoli. Amphi-arthrosis . Bodies of the vertebrse . Symphyses. C Arthrodia . . . carpal and tarsal bones. Diarthrosis. \ Ginglymus . . . elbow, wrist, knee, ankle. ( Enarthrosis . . hip, shoulder. 102 STEUCTURE OF JOINTS. The motions permitted in joints may be referred to four heads, viz.: 1. Gliding. 2. Angular movement. 3. Circumduction. 4. Rotation. r. Gliding is the simple movement of one articular surface upon another, and exists to a greater or less extent in all the joints. In the least movable joints, as in the carpus and tarsus, this is the only motion which is permitted. 2. Angular movement may be performed in four different direc- tions, either forwards and backwards, as in flexion and extension ; or inwards and outwards, constituting adduction and abduction. Flexion and extension are illustrated in the ginglymoid joint, and exist in a large proportion of the joints of the body. Adduction and abduction conjoined with flexion and extension, are met with complete only in the most movable joints, as in the shoulder, the hip, and the thumb. In the wrist and in the ankle adduction and abduction are only partial. 3. Circumduction can be performed only in the shoulder and hip joints ; it consists in the slight degree of motion which takes place in the head of a bone against its articular cavity, while the extremity of the limb is made to describe a large circle upon a plane surface. 4. Rotation is the movement of a bone upon its own axis, and is illustrated in the hip and shoulder, or better in the rotation of the cup of the radius, against the rounded articular protuberance of the humerus. Rotation is also observed in the movements of the atlas upon the axis, in which the odontoid process serves as a pivot around which the atlas turns. The structures entering into the composition of a joint are bone, cartilage, fibro-cartilage, ligament, and synovial membrane. Cartilage is an elastic and apparently homogeneous substance of a pearly whiteness, which forms the thin incrustation upon the articular surfaces of bones. Upon convex surfaces it is thickest in the centre, and thin towards the circumference, and presents upon concave surfaces an opposite arrangement. It is composed of a number of minute fibres placed perpendicularly to the surface, attached by one extremity to the bone, and forming by the other a smooth plane, covered by synovial membrane. Fibro-cartilage, as expressed in its name, is a compound struc- ture, consisting in the combination of fibrous and cartilaginous tis- sues in variable proportions. It is found in joints under three forms : — 1. Of interarticular fibro-cartilages. 2. Of fibro-cartilages of cir- cumference. 3. Of intervertebral substance. The interarticular fibro-cartilages (menisci,) composed chiefly of cartilage, are found in the articulations of the lower jaw, sternal and acromial end of the clavicle, knee and wrist-joint. The trian- gular cartilage of the wrist is not admitted by Dr. Todd* among the fibro-cartilages, but is considered by him to be merely an exten- * Cyclopaedia of Anatomy and PJiysiolog-y : article, Articulation. STRUCTURE OF JOINTS. 103 sion of the cartilaginous incrustation of the inferior extremity of the radius. The Jibro-cartilages of circumference contain a large proportion of fibrous tissue ; they are situated upon the margins of the glenoid and cotyloid cavities, and serve to deepen those articulations, and at the same time to protect the edges from injurious pressure. The intervertebral substance is composed of concentric lamellae of fibrous structure, surrounding, tov^ards the centre, a soft cartilagi- nous and almost pulpy mass. The fibres of which the lamellae are formed, interlace with each other obliquely; the intervening meshes being filled with a soft cartilaginous substance, and becoming larger towards the central pulp. Ligament is composed of numerous straight fibres collected together, and arranged into short bands (fasciculi) of various breadth, or interwoven so as to form a broad layer w^hich com- pletely surrounds the articular extremities of the bones, and consti- tutes a capsular hgament. All the ligaments of the joints consist of fibres of this kind, which are white, glistening and inelastic. But besides these there are other ligaments, which are composed of yellow elastic tissue, and serve to connect parts which are subject to frequent and conside- rable separation, as the arches of the vertebrae, where they form the ligamenta subflava. The synovial membrane is a thin membranous layer, which invests the articular cartilages of the bones, and is thence reflected upon the surfaces of the ligaments which surround and enter into the composition of a joint. It resembles the serous membranes in being a shut sac, and secretes a transparent and viscous fluid, which is named synovia. Synovia is an alkaline secretion, containing album„en, which is coagulable at a boiling temperature. The con- tinuation of this membrane over the surface of the articular carti- lage, a much agitated question, has lately been decided by the inte- resting discoveries of Henle, who has ascertained the existence of an epithelium upon cartilage identical with that secreted by the reflected portion of the membrane. In some of the joints the synovial mem- brane is pressed into the articular cavity by a cushion of fat, which serves the purpose of facilitating the movements of the surfaces. This mass was called by Havers the synovial gland, from an incorrect supposition that it was the source of the synovia. It is found in the hip and in the knee-joint. In the knee-joint, moreover, the synovial membrane forms folds, which are most improperly named ligaments, — as the mucous and alar ligaments, — the two latter being an appendage to the cushion of fat. Besides the synovial membranes entering into the composition of joints, there are numerous smaller sacs of a similar kind interposed between surfaces which move upon each other so as to cause friction ; they are often associated with the articulations. These are the hurscp, mucosce ; they are shut sacs, analogous in structure to synovial membranes, and secreting a similar synovial fluid. 104 LIGAMENTS OF THE TRUNK. ARTICULATIONS. The joints may be arranged, according to a natural division, into those of the trunk, those of the upper extremity, and those of the lower extremity. LiGAME\TS OF THE Trunk. — The articulatious of the trunk are divisible into nine groups, viz. — 1 . Of the vertebral column. 2. Of the atlas with the occipital bone. 3. Of the axis, with the occipital bone. 4. Of the atlas, with the axis. 5. Of the lower jaw. 6. Of the ribs, with the vertebras. 7. Of the ribs, with the sternum, and with each other. 8. Of the vertebral column, with the pelvis. 9. Of the pelvis. 1. Articulation of the Vertebral Column. — The ligaments connect- ing together the different pieces of the vertebral column, admit of the same arrangement with that of the vertebras themselves. Thus the ligaments Of the bodies are the — Anterior common ligament. Posterior common ligament. Intervertebral substance. Of the arches, — Ligamenta subflava. Of the articular processes, — Capsular ligaments. Synovial membranes. Of the spinous processes, — Inter-spinous. Supra-spinous. Of the transverse processes, — Inter-transverse. Bodies. — The anterior common ligament is a broad and riband- like band of ligamentous fibres, extending along the front surface of the vertebral column, from the axis to the sacrum. It is intimately connected with the intervertebral substances, and less closely with the bodies of the vertebras. The anterior common ligament is thicker in the dorsal than in the cervical and lumbar regions, and consists of a median and two lateral portions separated from each other by a series of openings for the passage of vessels. The ligament is composed of fibres of various length closely interwoven with each other ; the deeper and shorter crossing the intervertebral substances from one vertebra to the next; and the superficial and longer fibres crossing three or four vertebra:. Relations. — The anterior common ligament is in relation by its posterior or vertebral surface, with the intervertebral substances, the LIGAMENTS OF THE VERTEBRAL COLUMN. 105 '-^1^ bodies of the vertebrae and with the vessels, principally veins, which separate its central from its lateral portions. By its ante- rior or visceral surface it is in relation in the neck, with the longus colli muscles, the pharynx and the cEsophagus ; in the thoracic re- gion, with the aorta, the venae azygos, and thoracic duct ; and in the lumbar region, with the aorta, right renal artery, right lumbar arteries, arteria sacra media, vena cava inferior, left lumbar veins, receptaculum chyli, the com- mencement of the thoracic duct, and the tendons of the lesser mus- cle of the diaphragm with the fibres of which the ligamentous fibres interlace. The posterior common ligament lies upon the posterior surface of the bodies of the vertebrae, and extends from the axis to the sacrum. It is broad opposite the intervertebral substances, to which it is closely adherent ; and narrow and thick over the bodies of the ver- tebra, from which it is separated by the veins of the base of the vertebrae. It is composed like the anterior ligament of shorter and longer fibres which are disposed in a similar manner. Relations. — The posterior common ligament is in relation by its anterior surface with the intervertebral substances, the bodies of the vertebrae, and with the venae basis vertebrae ; and by its poste- rior surface with the dura mater of the spinal cord, some loose cellular tissue and numerous small veins being interposed. The intervertebral substance is a lenticular disc of fibro-cartilage, interposed between each of the vertebrae from the axis to the sacrum, and retaining them firmly in connexion with each other. It differs in thickness in different parts of the column, and varies in depth at different points of its extent ; thus, it is thickest in the lum- bar region, deepest in front in the cervical and lumbar regions, and behind in the dorsal region; and contributes, in a great measure, to the formation of the natiu'al curves of the vertebral column. Arches. — The ligamenta suhflava are composed of yellow elastic tissue, and are situated between the arches of the vertebrae, from the axis to the sacrum. From the imbricated position of the laminae they are attached to the posterior surface of the vertebra below, and to the anterior surface of the arch of the vertebra above, and are separated from each other at the middle line by a slight fissure. They counteract, by their elasticity, the eflbrts of the flexor muscles * The anterior ligaments of the vertebrse, and ligaments of the ribs. 1. The ante- rior common ligament. 2. The anterior costo-vertebral or stellate ligament. 3. The anterior costo-transverse ligament. 4. The interarticular ligament connecting the head of the rib to the intervertebral substance, and separating the two synovial mem- branes of this articulation. 14 106 LIGAMENTS OF THE VERTEBRAL COLUMN. of the trunk ; and by preserving the upright position of the spine, Umit the expenditure of muscular force. They are longer in the cer- vical than in the other regions of the spine, and are thickest in the lumbar region. Fig. 40* Relations. — The ligamenta subflava are in relation by both sur- faces with the meningo-rachidian veins, and internally they are separated from the dura mater of the spinal cord by those veins and some loose cellular tissue. Articular Processes.' — The ligaments of the articular processes of the vertebrae, are loose synovial capsules which surround the articulating surfaces. They are protected on their external side by a thin layer of ligamentous fibres. Spinous Processes. — The inter-spinous hgaments are thin and membranous, and are extended between the spinous processes in the dorsal and lumbar regions. They are thickest in the latter region; and are in j^elation with the multifidus spinae muscle at each side. The supraspinous ligament (fig. 49) is a strong and inelastic fibrous cord, which extends from the apex of the spinous process of the last cervical vertebra to the sacrum, being attached to each spinous process in its course ; it is thickest in the lumbar region. The continuation of this ligament upwards to the tuberosity of the occipital bone, constitutes the rudimentary ligamentum nuchse of man. It is strengthened, as in animals, by a thin slip from the spinous process of each of the cervical vertebra). Transverse Processes. — The inter-transverse ligaments are thin * A ])osl.nrior view of the bodies of three dorsal vcrtobrro, connected by their inter- vertcbr;il substance 1,1. The lamina) (2) have been sawn away near to the bodies of the vertebra-, and tlic arches and processes removed, in order to show (3) the posterior common lijrament. A part of one of the opening's in tlie posterior surface of the verte- bra, for the transmission of the vena basis vertebra;, is seen at 4, by the side of the narrow and unattached portion of the lig-ament. t An internal view of the arches of the vcrtebrfc. To obtain this view the laminse have been divided tliroii;rh their pedicles. 1. One of tlic ligamenta subflava. 2. The capsular ligament of one side. LIGAMENTS OF THE VERTEBRAL COLUMN. 107 and membranous ; they are found only between the transverse pro- cesses of the lower dorsal vertebrse. 2. Articulation of the Atlas loith the Occipital bone. — The ligaments of this articulation are seven in number. Two anterior occipito-atloid. Posterior occipito-atloid. Lateral occipito-atloid. Two capsular. Of the two anterior ligaments one is a rounded cord, situated in the middle line, and superficially to the other. It is attached above, to the basilar process of the occipital bone ; and below, to the an- terior tubercle of the atlas. The deeper ligament is a broad mem- branous layer, attached above, to the margin of the occipital fora- men; and below, to the whole length of the anterior arch of the atlas. It is in relation in front with the recti antici minores and be- hind with the dura mater. Fig. 42.* Fig. 43.t The posterior ligament is extremely thin and membranous; it is attached above, to the margin of the occipital foramen ; and below, to the posterior arch of the atlas. It is closely adherent to the dura mater, by its inner surface ; and forms a ligamentous arch at each side, for the passage of the vertebral arteries and first cervical nerves. It is in relation posteriorly with the recti postici minores. The lateral ligaments are strong fasciculi of liijamentous fibres. * An anterior view of the ligaments connecting the atlas, the axis, and the occipital bone. A transverse section has been carried through the base of the skull, dividing the basilar process of the occipital bone and the petrous portions of the temporal bones. 1. The anterior round occipito-atloid ligament. 2, 2. The anterior broad occipito- atloid ligament. 3. The commencement of the anterior common ligament. 4. The an- terior atlo-axoid ligament, which is continuous inferiorly with the commencement of the anterior common ligament. 5. One of the atlo-axoid capsular ligaments ; the one on the opposite side (6) has been removed, to show the approximated surfices of the ar- ticular process. 7. One of the occipito-atloid capsular ligaments. The most external of these fibres constitute the lateral occipito-atloid ligament. t The posterior ligaments of the occipito-atloid, and atlo-axoid articulations. 1. Tlie atlas. 2, The axis. 3. The posterior ligament of the occipito-atloid articulation. 4,4. The c.ipsular and lateral ligaments of this articulation. 5. The posterior ligaments of the atlo-axoid articulation. 6,6. Its capsular ligaments. 7. The first of the ligamenta subflava passing between the axis and the third cervical vertebra. 8, 8. Their capsular ligaments. 108 LIGAMENTS OF THE VERTEBRAL COLUMN. attached below, to the base of the transverse process of the atlas at each side, and above to the transverse process of the occipital bone. With a ligamentous expansion derived from the vaginal process of the temporal bone, these ligaments form a strong sheath around the vessels and nerves which pass through the carotid and jugular fora- men. The capsular ligaments are the thin and loose ligamentous cap- sules, which surround the synovial membranes of the articulations, between the condyles of the occipital bone and the superior articular processes of the atlas. The ligamentous fibres are most numerous upon the anterior and external part of the articulation. The movements taking place between the cranium and atlas, are those of flexion and extension, giving rise to the forward nodding of the head. When this motion is increased to any extent the whole of the cervical region concurs in its production. 3. Articulation of the Axis ivit/i the Occipital bone. — The ligaments of this articulation are three in number, — Occipito-axoid, Two odontoid. The occipito-axoid ligament (appa- ratus ligamentosus colh) is a broad band, which covers in the odontoid process and its ligaments. It is at- tached below to the body of the axis, and is continuous with the posterior common ligament; superiorly it is inserted by a broad expansion, into the basilar groove of the occipital bone. It is firmly connected oppo- site the body of the axis, with the dura mater. It is sometimes de- scribed as consisting of a central and two lateral portions ; this how- ever is an unnecessary refinement. The odontoid ligaments (alar) are two short and thick fasciculi of fibres, which pass outwards from the apex of the odontoid process, to the sides of the occipital foramen and condyles. A third and smaller fasciculus also proceeds from the apex of the odontoid pro- cess, to the anterior margin of the foramen magnum.f These ligaments serve to limit the extent to which rotation of the head maybe carried, hence they are termed check ligaments. 4. Articulation of the Atlas ivith the Axis. — The ligaments of this articulation dire five in number: — Fig. 44.* *The upper part of the vertebral canal, opened from behind in order to show the occipito-axoid lifjaincnt. 1. The basilar portion of the sphenoid bone. 2. Section of the occipital bone. 3. The atlas, its posterior arch removed. 4. The axis, the posterior arch also removed. 5. The occipito-axoid ligament, rendered prominent at its middle by the projection of the odontoid process. 6. Lateral and capsular ligament of the oc- cipito-atloid articulation. 7. Capsular ligament between tlie articulating process of the atlas and axis. + Called middle straight ligament, — G. LIGAMENTS OF THE VERTEBRAL COLUMN. 109 Anterior atlo-axoid. Posterior atlo-axoid. Two capsular. Transverse. Fig. 45.+ The anterior ligament consists of ligamentous fibres, which pass from the anterior tubercle and arch of the atlas to the base of the odontoid process and body of the axis, where they are continuous with the commencement of the anterior common ligament.* The -posterior ligament is a thin and membranous layer, passing between the posterior arch of the atlas and the lamiuce of the axis. The capsular ligaments surround the articular processes of the atlas and axis ; they are loose, to permit of the freedom of movement which subsists between the atlas and axis. The hgamentous fibres are most numerous on the outer and anterior part of the articulation, and the synovial membrane usually commu- nicates with the synovial cavity be- tween the transverse ligament and the odontoid process. The transverse ligament is a strong Hgamentous band, which arches across the area of the ring of the atlas from a rough tubercle upon the inner surface of one articular process to a similar tubercle on the other. It serves to retain the odontoid process of the axis in connexion with the anterior arch of the atlas. As it crosses the odontoid process, some fibres are sent downwards to be attached to the body of the axis, and others pass upwards to be inserted into the basilar process of the occipital bone ;J hence the hgament has a cross-like appearance, and has been denominated cruciform. A synovial membrane is situated between the transverse ligament and the odontoid process ; and another between that process and the inner surface of the anterior arch of the atlas. Actions. — It is the peculiar disposition of this ligament in relation to the odontoid process, that enables the atlas, and with it the entire cranium, to rotate upon the axis ; the perfect freedom of movement between these bones being ensured by the two synovial membranes. The lower part of the ring, formed by the transverse ligament with the atlas, is smaller than the upper, while the summit of the odontoid process is larger than its base ; so that the process is still retained in * Usually considered a part of the anterior vertebral ligament. — G. + A posterior view of the ligaments connecting the atlas, the axis, and the occipital bone. The posterior part of the occipital bone has been sawn away, and the arches of the atlas and axis removed. 1. The superior part of the occipito-axoid ligament, which has been cut away in order to show the ligaments beneath. 2. The transverse ligament of the atlas. 3, 4. The ascending and descending slips of the transverse liga- ment, which have obtained for it the title of cruciform ligament. 5. One of the odon- toid ligaments. 6. One of the occipito-atloid capsular ligaments. 7. One of the atlo- axoid capsular ligaments. t These bands are called the appendices of the transverse ligament. — G. 110 LIGAMENTS OF THE LOWER JAW. its position by the transverse ligament, when the other Hgaments are cut throuD-h. The extent to which the rotation of the head upon the axis can be carried is determined by the odontoid hgaments. The odontoid process with its hgaments is covered in by the occipito- axoid hgament. 5. Articulation of the Lower Jaw. — The lower jaw has properly but one ligament, the external lateral; the ligaments usually described are three in number; to which may be added, as appertaining to the mechanism of the joint, an interarticular fibro-cartilage, and two synovial membranes : — External lateral, Internal lateral, Capsular. Interarticular fibro-cartilage, Two synovial membranes. The external lateral ligament is a short and thick band of fibres, passing obhquely forwards from the tubercle of the zygoma, to the external surface of the neck of the Fig, 46.* lower jaw. It is in relation, exter- nally with the integument of the face, and internally with the syno- vial membranes of the articulation, and with the interarticular fibro-car- tilage. The external lateral ligament acts conjointly with its fellow of the opposite side of the head in the move- ments of the jaw. The internal lateral ligament has no connexion with the articulation of the lower jaw, and is incorrectly named in relation to the joint ; it is a thin aponeurotic expansion extending from the extremity of the spinous process of the sphenoid bone to the margin of the dental foramen. It is pierced at its inser- tion, by the mylo-hyoidean nerve. A triano-ular space is left between the internal lateral ligament and the neck of the jaw, in which are situated the internal maxillary artery and auricular nerve, the inferior dental artery and nerve, and a part of the external pterygoid muscle ; internally it is in relation with the internal pterygoid. The capsular ligament consists of a few irregular ligamentous fibres, which pass from the edge of the glenoid cavity to the neck of the lower jaw, upon the inner and posterior side of the articula- » An external view of Uie articulation of the lower jaw, 1. The zygomatic arch. 2. The tubercle of the zygoma. 3. The ramus of the lower jaw. 4. The mastoid portion of the teitiijoral bone. 5. The external lateral ligament. 6, The stylo-maxil- lary ligament. LIGAMENTS OP THE LOWER JAW. Ill ^m^ Fig. 48.+ tion. These fibres scarcely deserve consideration as a distinct ligament. The interarticular fihro- cartilage is a thin oval plate, thicker at the edges than in the centre, and placed horizontally between the head of the condyle of the lower jaw and the glenoid ca- Fig- 47.* vity. It is connected by its outer border with the external lateral ligament, and in front receives some fibres of inser- tion of the external pterygoid muscle. Occasionally it is in- complete in the centre. It divides the joint into two dis- tinct cavities, the one being above and the other below the cartilage. The synovial membranes are situated the one above, the other below the fibro-cartilage, the former being the larger of the two. When the fibro-cartilage is perforate, the synovial membranes com- municate with each other. Besides the lower jaw, there are several other joints provided with a complete interarticular fibro-cartilage, and consequently, with two synovial membranes ; they are, the sterno-clavi- cular articulation, the acromio-clavi- cular, and the articulation of the ulna with the cuneiform hone. The interarticular fibro-cartilages of the knee-joint are partial, and there is but one synovial membrane. The articulations of the heads of the ribs with the vertebra have two syno- vial membranes, separated by an interarticular ligament without fibro-cartilage. Actions. — The movements of the lower jaw are depression by * An internal view of the articulation of the lower jaw. 1. A section through the petrous portion of the temporal bone and spinous process of the sphenoid. 2. An internal view of the ramus, and part of the body of the lower jaw. 3. The internal portion of the capsular ligament. 4. The internal lateral ligament. 5. A small interval at its insertion through which the mylo-hyoidean nerve passes, 6. The stylo-maxillary ligament, a process of the deep cervical fascia. + In this sketch a section has been carried through the joint, in order to show the natural position of the interarticular fibro-cartilage, and the manner in which it is adapted to the difference of form of the articulating surfaces. 1. The glenoid fossa. 2. The emincntia articularis. 3. The interarticular fibro-cartilage. 4. The superior synovial cavity. 5. The inferior synovial cavity. 6. An interarticular fibro-cartilage, removed from the joint, in order to show its oval and concave form; it is seen from below. 112 LIGAMENTS OF THE RIBS. which the mouth is opened ; elevation, by which it is closed; a. for- ward and hachrard movement, and a movement from side to side. In the movement of depressioJi the interarticular cartilage glides forwar dson the eminentia articularis, carrying with it the condyle. If this movement be carried too far, the superior synovial membrane is ruptured, and dislocation of the fibro-cartilage with its condyle into the zygomatic fossa occurs. In elevation the fibro-cartilage and condyle are returned to their original position. The forward and hachoard movement is a gliding of the fibro-cartilage upon the glenoid articular surface, in the antero-posterior direction ; and the movement from side to side, in the lateral direction. 6. Articulation of the Ribs with the Vertehrce. — The ligaments of these articulations are so strong as to render dislocation impossible, the neck of the rib would break before displacement could occur ; they are divisible into two groups : — 1. Those connecting the head of the rib with the vertebrcs ; and 2. Those connecting the neck and tubercle of the rib with the transverse processes. They are 1st Group. Anterior costo-vertebral or stellate, Capsular, Interarticular ligament, Two synovial membranes. 2c? Group. Anterior costo-transverse. Middle costo-transverse. Posterior costo-transverse. The anterior costo-vertebral or stellate ligament (fig. 39) consists of three short bands of ligamentous fibres that radiate from the anterior part of the head of the rib. The superior band passes upwards, and is attached to the vertebra above ; the middle fasci- culus is attached to the intervertebral substance ; and the inferior, to the vertebra below. In the first, eleventh, and twelfth ribs, the three fasciculi are attached to the body of the corresponding vertebra. The capsular ligament is a thin layer of ligamentous fibres sur- rounding the joint in the interval left by the anterior hgament; it is thickest a})ove and below the articulation, and protects the synovial memjjrancs. The interarticular ligament passes between the sharp crest on the head of the rib and the intervertebral substance. It divides the joint into two cavities, which are each furnished with a separate synovial membrane. The first, eleventh, and twelfth ribs have no interarticular ligament, anrl consequently but one synovial membrane. The anterior costo-transverse ligament is a broad band composed LIGAMENTS OF THE RIBS. 113 Fig. 49 * of several fasciculi, which ascend from the crest upon the neck of the rib, to the transverse process immediately above. This liga- ment separates the anterior from the posterior branch of the inter- costal nerves. The middle costo-transverse ligament is a very strong interosseous ligament, passing directly betw^een the posterior surface of the neck of the rib, and the transverse process against which it rests. The posterior costo-transverse ligament is a small but strong fasci- culus, passing obliquely from the tubercle of the rib, to the apex of the transverse process. The articulation between the tubercle of the rib and the transverse process is provided with a small synovial membrane. There is no anterior costo-transverse ligament to the first rib ; and only rudi- mentary posterior costo-transverse to the eleventh and twelfth ribs. Actions. — The movements permitted by the articulations of the ribs, are wptoards and dowmvards, and slightly forwards and bachvards ; the movement increasing in extent from the head to the extremity of the rib. The forward and backward movement is very trifling in the seven superior, but greater in the inferior ribs ; the eleventh and twelfth are very mo- vable. 7. Articulation of the Ribs with the Sternum, and loith each other. — The ligaments of the costo-sternal articulations are, Anterior costo sternal. Posterior costo-sternal, Superior costo-sternal, Inferior costo-sternal. Synovial membranes. The anterior costo-sternal ligament is a thin band of ligamentous fibres, that passes in a radiated direction from the extremity of the costal cartilage to the anterior surface of the sternum, and inter- mingles its fibres with those of the ligament of the opposite side, and with the tendinous fibres of origin of the pectoralis major muscle. The -posterior costo-sternal ligament is much smaller than the an- terior, and consists of only a thin fasciculus of fibres situated on the posterior surface of the articulation. * A posterior view of a part of the thoracic portion of the vertebral column, showing the ligaments connecting the vertebrte with each other and the ribs with the vertebrae. 1. The supra-spinous ligament. 2, 2. The ligamenta subflava, connecting the laminffi. 3. The anterior costo-transverse ligament. 4. The posterior costo-transverse liga- ments. 15 114 LIGAMENTS OF THE PELVIS. The superior and inferior costo-sternal ligaments are narrow fas- ciculi corresponding with the breadth of the cartilage, and connect- ing its superior and inferior border "svith the side of the sternum. The synovial membrane is absent in the articulation of the first rib, its cartilage being usually continuous with the sternum ; that of the second rib has an inter- articular Hgament, with two synovial membranes. The sixth and seventh ribs have several fasciculi of strong liga- mentous fibres, passing from the extremity of their cartilages to the anterior surface of the ensiform cartilage, which they are intended to support. They may be named the coslo-xypJwid ligaments. The sixth, seventh, and eighth, and sometimes the fifth and the ninth costal cartilages, have articulations with each other, and a perfect synovial membrane. They are connected by ligamentous fibres which pass from one cartilage to the other, external and internal ligaments. The ninth and tenth are connected at their extremities by liga- mentous fibres, but have no synovial membranes. Actions. — The movements of the costo-sternal articulations are very trifling; they are limited to a slight sliding motion. The first rib is the least, and the second the most movable. 8. Articulation of the Vertebral Column with the Pelvis. — The last lumbar vertebra is connected with the sacrum by the same liga- ments with which the various vertebrae are connected to each other ; viz. the anterior and posterior common ligaments, intervertebral sub- stance, ligamenta subflava, capsular ligaments, and inter and supra- spinous ligaments. There are only tim proper ligaments connecting the vertebral column with the pelvis; these are, the Lumbo-sacral, Lumbo-iUac. The lumbo-sacral ligament is a thick triangular fasciculus of liga- mentous fibres, connected above, with the transverse process of the last lumbar vertebra ; and below, with the posterior part of the upper border of the sacrum. The lumbo-iliac ligament passes from the apex of the transverse process of the last lumbar vertebra to that part of tlie crest of the ilium which surmounts the sacro-iliac articulation. It is triangu- lar in form. 9. The Articulations of the Pelvis. — The ligaments belonging to the articulations of the pelvis are divisible into four groups: — 1. Those connecting the sacrum and ilium; 2, those passing between the sacrum and ischium; 3, between the sacrum and coccyx; and 4, between the two pubic bones. 1st, Between the sacrum and ilium. Sacro-iliac anterior, Sacro-iliac posterior. LIGAMENTS OF THE PELVIS. 115 Fig. 50* 2nd, Between the sacrum and ischium. Sacro-ischiatic anterior (short), Sacro-ischiatic posterior (long). 3rd, Between the sacrum and coccyx. Sacro-coccygean anterior, Sacro-coccygean posterior. 4th, Between the ossa pubis. Anterior pubic, Posterior pubic, Superior pubic, Sub-pubic, Interosseous fibro-cartilage. 1. Between the Sacrum and Ilium. — The anterior sacro-iliac liga- ment consists of numerous short Hgamentous fibres, passing from bone to bone on the anterior surface of the joint. The posterior sacro-iliac or interos- seous ligament] is composed of nume- rous strong fasciculi of Hgamentous fibres, which pass horizontally be- tween the rough surfaces, in the pos- terior half of the sacro-iliac articula- tion, and constitute the principal I.. bond of connexion between the sa- crum and the ilium. One fasciculus of this ligament, longer and larger than the rest, is distinguished, from its direction, by the name of the ob- lique sacro-iliac ligament. It is at tached by one extremity, to the pos- terior superior spine of the ilium ; and by the other, to the third trans- verse tubercle on the posterior sur- face of the sacrum. The surfaces of the two bones forming the sacro-iliac articulation, are partly covered with carti- lage, and partly rough and connected by the interosseous ligament. The anterior or auricular half is coated with cartilage, which is thicker on the sacrum than on the ilium. The surface of the car- tilage is irregular, and provided with a very delicate synovial mem- *The lig^aments of the pelvis and hip-joint. 1. The lower part of the anterior com- mon ligament of the vertebrae, extending downwards over the front of tlie sacrum. 2. The himbo-sacral ligament. 3. The lumbo-iliac ligament. 4. The anterior sacro-iliac ligaments. 5. The obturator membrane. 6. Poupart's ligament. 7. Gimbernat's ligament. 8. The capsular ligament of the hip-joint. 9. Tlie ilio-fcmoral or acces- sory ligament. t This includes Horner's sacro-spinous ligament. — G. 116 LIGAMENTS OF THE PELVIS. brane, which cannot be demonstrated in the adult ; but is apparent in the young subject, and in the female during pregnancy. 2. Between the Sacrum and Ischium. — The anterior or lesser sacro- ischiatic ligament is thin, and triangular in form; it is attached by its apex to the spine of the Fig. 51 * • ischium ; and by its broad ex- tremity to the side of the sa- crum and coccyx, interlacing its fibres with the succeeding. The anterior sacro-ischiatic ligament is in relation in front, with the coccygeus muscle, and behind with the posterior ligament, with which its fibres are intermingled. By its up- per border it forms a part of the lower boundary of the great sacro-ischiatic foramen, and by the lower a part of the lesser sacro-ischiatic foramen. The posterior or greater sa- cro-ischiatic ligament, consi- derably larger, thicker, and more posterior than the pre- ceding, is narrower in the middle than at each extremity. It is attached by its smaller end, to the inner margin of the tuberosity and ramus of the ischium, where it forms a falciform process, which protects the internal pudic artery, and is continuous with the ob- turator fascia. By its larger extremity it is inserted into the side of the coccyx, sacrum, and posterior inferior spine of the ilium. The posterior sacro-ischiatic ligament is in relation in front with the anterior ligament, and behind with the gluteus maximus, to some of the fibres of which it gives origin. By its superior border it forms part of the lesser ischiatic foramen, and by its lower border, a part of the boundary of the perineum. It is pierced by the coc- cygeal branch of the ischiatic artery. The two ligaments convert the sacro-ischiatic notches into foramina. 3. Between the Sacrum and Coccyx. — The anterior sacro-coccy- geal ligament is a thin fasciculus passing from the anterior surface of the sacrum to the front of the coccyx. The posterior sacro-coccygean ligament is a thick ligamentous layer, * Ligaments of the pelvis and hip-joint. The view is taken from the side. 1. The oblique sacro-iliac ligament. The other fasciculi of the posterior sacro-iliae ligaments arc not seen in this view of the pelvis. 2. Tlic posterior sacro-ischiatic ligament. 3. The anterior sacro-ischiatic ligament. 4. The great sacro-iscliiatie foramen. 5. The lesser sacro-ischiatie foramen. 6. The cotyloid ligament of the acetabulum. 7. The ligamcntum teres. 8. The cut edge of the capsular ligament, showing its extent pos- teriorly as compared with its anterior attachment. 9. The obturator membrane only partly seen. LIGAMENTS OF THE PELVIS, 117 which completes the lower part of the sacral canal, and connects the sacrum with the coccyx posteriorly, extending as far as the apex of the latter bone. Between the two bones is a thin disc of a soft intervertebral sub- stance. In females there is frequently a small synovial membrane. This articulation admits of a certain degree of movement backwards during parturition. The ligaments connecting the different pieces of the coccyx con- sist of a few scattered anterior and 'posterior fibres, and a thin disc of intervertebral substance ; they exist only in the young subject, in the adult the pieces become ossified. 4. Between the Ossa Pubis. — The anterior pubic ligament is com- posed of ligamentous fibres, which pass obUquely across the union of the two bones from side to side, and form an interlacement in front of the symphysis. The posterior pubic ligament consists of a few irregular fibres uniting the pubic bones posteriorly. The superior pubic ligament is a thick band of fibres connecting the angles of the pubic bones superiorly, and filling the inequalities upon the surface of the bones. The sub-pubic ligament is a thick arch of fibres connecting the two bones inferiorly, and forming the upper boundary of the pubic arch. The interosseous fibro-cartilage unites the two surfaces of the pubic bones, in the same manner that the intervertebral substance con- nects the bodies of the vertebra. It resembles the intervertebral substance also in being composed of oblique fibres disposed in con- centric layers, which are more dense towards the surface than near the centre. It is broad in front, and narrow behind. A thin syno- vial membrane is sometimes found in the posterior half of the articu- lation. This articulation becomes movable towards the latter term of preg- nancy, and admits of a slight degree of separation of its surfaces. The obturator ligament or membrane is not a ligament of articula- tion, but simply a tendino-fibrous membrane stretched across the obturator foramen. It gives attachment by its surfaces, to the two obturator muscles ; and leaves a space in the upper part of the fora- men, for the passage of the obturator vessels and nerve. The numerous vacuities in the walls of the pelvis, and their clo- sure by ligamentous structures, as in the case of the sacro-ischiatic fissures and obturator foramina, serve to diminish very materially the pressure of the soft parts during the passage of the head of the foetus through the pelvis in parturition. LIGAMENTS OF THE UPPER EXTREMITY. The Ligaments of the upper extremity may be arranged in the order of the articulation between the different hones ; they are, tlie 118 STERNO-CLAVICULAR LIGAMENTS. 1. Sterno-clavicular articulation. 2. Scapulo-cla\'icular articulation. 3. Ligaments of the scapula. 4. Shoulder joint. 5. Elbow joint. 6. Radio-ulnar articulation. 7. Wrist joint. 8. Articulation between the carpal bones. 9. Carpo-metacarpal articulation. 10. Metacarpo-phalangeal articulation. 11. Articulation of the phalanges. I. Sterno-clavicular Articulation. — The sterno-clavicular is an arthrodial articulation ; its ligaments are, Anterior sterno-clavicular, Posterior sterno-clavicular, Inter-clavicular, Costo-clavicular {rhomboid), Interarticular fibro-cartilage, Two synovial membranes. The anterior sterno-clavicular ligament is a broad ligamentous layer, extending obliquely downwards and forwards, and covering the anterior aspect of the articulation. This ligament is in relation by its anterior surface with the integument and with the sternal origin of the sterno-mastoid muscle ; and behind with the interarti- cular fibro-cartilage and synovial membranes. The -posterior sterno-clavicular ligament is a broad fasciculus, covering the posterior surface of the articulation. It is in relation by its anterior surface with the interarticular fibro-cartilage and synovial membranes, and behind with the sterno-hyoid muscle. The two ligaments are continuous at the upper and lower part of the articulation, so as to form a complete capsule around the joint. The inter-clavicular ligament is a cord-like band which crosses from the extremity of one clavicle to the other, and is closely con- nected with the upper border of the sternum. It is separated by cellular tissue from the sterno-thyi'oid muscles. The costo-clavicular ligament {rhomboid) is a thick fasciculus of fibres, connecting the sternal extremity of the clavicle with the cartilage of the first rib. It is situated obliquely between the rib and the under surface of the clavicle. It is in relation in front with the tendon of origin of the subclavius muscle, and behind with the subclavian vein. Actions. — The movements of the sterno-clavicular articulation, arc a gliding movement of the fibro-cartilage with the clavicle, upon the articular surface of the sternum in the directions forwards, backwards, upwards, and downwards; and circumduction. This articulation is the centre of the movements of the shoulder. SCAPULO-CLAVICULAR LIGAMENTS, 119 ligament in dislocation of the Fig. 52.* The rupture of the rhomboid sternal end of the clavicle, gives rise to the deformity peculiar to this accident. The interarticular fibro-cartilage is nearly circular in form, and thicker at the edges than in the centre. It is attached above, to the clavicle ; below to the cartilage of the first rib ; and throughout the rest of its circumference to the anterior and posterior sterno-clavicular liga- ment ; it divides the joint into two cavities, which are hned by distinct synovial membranes. This cartilage is sometimes pierced through its centre, and not unfrequently absorbed to a greater or less extent, particularly at its lower part. 2. Scapulo-claviculai' Articulation. — The ligaments of the scapular end of the clavicle are, the Superior acromio-clavicular. Inferior acromio-clavicular, Coraco-clavicular (trapezoid and conoid), Interarticular fibro-cartilage, Two synovial membranes. The superior acromio-clavicular ligament is a moderately thick plane of superimposed fibres passing between the extremity of the clavicle and the acromion, upon the upper surface of the joint. The inferior acromio-clavicular ligament is a thin plane situated upon the under surface. These two hgaments are continuous with each other in front and behind, and form a complete capsule around the joint. The coraco-clavicular ligament (trapezoid, conoid) is a thick fasci- culus of ligamentous fibres, passing obhquely between the base of the coracoid process and the under surface of the clavicle, and holding the end of the clavicle in firm connexion with the scapula. When seen from before, it has a quadrilateral form : hence it is name trapezoid: and, examined from behind, it has a triangular form, the base being upwards ; hence another name, conoid. The interarticular fibro-cartilage is often indistinct, from having partial connexions with the fibro-cartilaginous surfaces of the two bones between which it is placed, and not unfrequently absent. When partial, it occupies the upper part of the articulation. The *The ligaments of the sterno-clavicular and costo-sternal articulations. 1. The anterior sterno-clavicular ligament. 2. The inter-clavicular ligament. 3. The costo- clavicular or rhomboid ligament, seen on both sides. 4. The inter-articular fibro- cartilage, brought into view by the removal of the anterior and posterior ligaments. 5. The anterior costo-sternal ligaments of the first and second ribs. 120 SHOULDER JOINT. Fiff. 53* synovial me?nbranes are very delicate. There is only one, when the fibro-cartilage is incomplete. Actions. — The acromio-clavicular articulation admits of two move- ments, the gliding of the surfaces upon each other ; and the rotation of the scapula, upon the extremity of the clavicle. 3. The Proper ligaments of the Scapula are the Coraco-acromial, Transverse. The coraco-acromial ligament is a broad and thick triangular band, which forms a protecting arch over the shoulder joint. It is attached by its apex to the point of the acromion process, and by its base to the external border of the coracoid process its whole length. This ligament is in relation above with the under surface of the deltoid muscle ; and below with the tendon of the supra-spi- natus muscle, a bursa mucosa being usually interposed. The transverse or coracoid ligament is a narrow but strong fasciculus which crosses the notch in the upper border of the scapula, from the base of the cora- coid process, and converts it into a fora- men. The supra-scapular nerve passes through this foramen. 4. Shoulder Joint. — The scapulo-hume- ral articulation is an enarthrosis, or ball and socket joint — its ligaments are, the Capsular, Coraco-humeral, Glenoid. The capsular ligament completely en- circles the articulating head of the sca- pula and the head of the humerus, and is attached to the neck of each bone. It is thick above, where resistance is most required, and is strengthened by the tendons of the supra-spinatus, infra-spinatus, teres minor, and subscapularis muscles : below it is thin and loose. The capsule is incomplete at the point of contact with the tendons, so that they obtain upon their inner surface a covering of synovial membrane The _ obliquely outwards from the border of the coracoid process to the greater tuberosity of the humerus, and serves to strengthen the superior and anterior part of the capsular ligament. The glenoid ligament is the prismoid band of fibro-cartilage, * The lifrnmonts of tlie scapula and shoulder joint. 1. The superior acromio-clavicu- lar ligament. 2. The coraco-clavicular ligament; this aspect of the ligament is named trapezoid. 3. The coraco-acromial ligament. 4. The transverse ligament. 5. The capsular ligament. 6. The coraco-humeral ligament. 7. The long tendon of the biceps issuing from the capsular ligament, and entering the bicipital groove. coraco-humeral ligament is a broad band which descends ELKOW JOINT. 121 which is attached around the margin of the glenoid cavity for the purpose of protecting its edges, and deepening its cavity. It divides superiorly into two slips which are continuous with the long tendon of the biceps ; hence the ligament is frequently described as being formed by the spHtting of that tendon. The cavity of the articu- lation is traversed by the long tendon of the biceps which is enclosed in a sheath of synovial membrane in its passage through the joint. The synovial membrane of the shoulder joint is very extensive ; it communicates anteriorly through an opening in the capsular liga- ment with a large bursal sac, which lines the under surface of the tendon of the subscapularis muscle. Superiorly, it frequently com- municates through another opening in the capsular ligament with a bursal sac belonging to the infra-spinatus muscle ; and it more- over forms a sheath around that portion of the tendon of the biceps, which is included within the joint. The muscles immediately surrounding the shoulder joint are the subscapularis, supra-spinatus, infra-spinatus, teres minor, long head of the triceps, and deltoid ; the long tendon of the biceps is within the capsular ligament. Actions. — The shoulder joint is capable of every variety of motion, viz. of movement forwards and backwards, of abduction, and adduc- tion, of circumduction and rotation. 5. Elbow Joint. — The elbow is a ginglymoid articulation; its Ugaments Sirefour in number : — Anterior, Posterior, Internal lateral. External lateral. The anterior ligament is a broad and thin membranous layer, descending from the anterior surface of the humerus, immediately above the joint, to the coronoid process of the ulna and orbicular ligament. On each side it is connected with the lateral Ugaments. It is composed of fibres which pass in three different directions, vertical, transverse, and oblique, the latter being extended from within outwards to the orbicular ligament, into which they are attached inferiorly. This ligament is covered in by the brachialis anticus muscle. The posterior ligament is a broad and loose fold passing between the posterior surface of the humerus and the anterior surface of the base of the olecranon, and connected at each side with the lateral ligaments. It is covered in by the tendon of the triceps. The internal lateral ligament is a thick triangular layer, attached above, by its apex, to the internal condyle of the humerus ; and below, by its expanded border, to the margin of the greater sig- moid cavity of the ulna, extending from the coronoid process to the olecranon. At its insertion it is intermingled with some trans- 16 122 ELBOW JOINT. verse fibres. The internal lateral ligament is in relation posteriorly with the ulnar nerve. The external lateral ligament is a strong and narrow band, which descends from the external condyle of the humerus, to be inserted into the orbicular ligament, and into the ridge on the ulna, with which the posterior part of the lateral ligament is connected. This ligament is closely united with the tendon of origin of the supinator brevis muscle. The synovial membrane is extensive, and is reflected from the cartilaginous surfaces of the bones upon the inner surface of the ligaments. It surrounds inferiorly the head of the radius, and forms an articulating sac between it and the lesser sigmoid notch. The muscles immediately surrounding, and in contact with, the elbow joint, are in front, the brachiahs anticus ; to the inner side, the pronator radii teres, flexor sublimis digitorum, and flexor carpi ulnaris; externally, the extensor carpi radiaUs brevier, extensor * An internal view of the ligaments of the elbow joint. 1. The anterior ligament. 2. The internal lateral ligament. 3. The orbicular ligament. 4. The oblique liga- ment. 5. The interosseous ligament. G. The internal condyle of the humerus, which conceals the posterior ligament. t An external view of the elbow joint. 1. The humerus. 2. The ulna. 3. The radius. 4. The external lateral ligament inserted inferiorly into (5) the orbicular liga- ment. 6. The posterior extremity of the orbicular ligiiment spreading out at its inser- tion into the ulna. 7. The anterior ligament, scarcely ap|)arcnt in this view of the articulation. 8. The posterior ligament, thrown into folds by the extension of the joint. ELBOW JOINT. 123 communis digitorum, extensor carpi ulnaris, anconeus, and supi- nator brevis ; and behind, the triceps. Actions. — The movements of the elbow joint are jlexion and extension, which are performed with remarkable precision. The extent to which these movements are capable of being effected, is limited, in front by the coronoid process, and behmd by the ole- cranon. 6. The Radio-ulnar Articulation. — The radius and ulna are firmly held together by ligaments which are connected with both extre- mities of the bones, and with the shaft ; they are, the Orbicular, • Anterior inferior, Oblique, Posterior inferior, Interosseous, Interarticular fibro-cartilage. The orbicular ligament {annular, coronary) is a firm band several lines in breadth, which surrounds the head of the radius, and is attached by each end to the extremities of the lesser sigmoid cavity. It is strongest behind where it receives the external lateral ligament, and is lined on its inner surface by a reflection of the synovial membrane of the elbow joint. The rupture of this ligament permits of the dislocation of the head of the radius. The oblique ligament is a narrow slip of ligamentous fibres, descending obliquely from the base of the coronoid process of the ulna to the lower part of the tuberosity of the radius. The interosseous ligament is a broad and thin plane of aponeurotic fibres passing obliquely downwards from the sharp ridge on the radius to that on the ulna. It is deficient superiorly, is broader in the middle than at each extremity, and is perforated at its lower part for the passage of the anterior interosseous artery. The pos- terior interosseous artery passes backwards between the oblique ligament and the upper border of the interosseous ligament. This ligament affords an extensive surface for the attachment of muscles. The interosseous ligament is in relation, in front, with the flexor profundus digitorum, the flexor longus pollicis, and pronator quad- ratus muscle, and with the anterior interosseous artery and nerve ; and behind with the supinator brevis, extensor ossis metacarpi pollicis, extensor primi internodii pollicis, extensor secundi inter- nodii pollicis, and extensor indicis muscle, and near the wrist "udth the anterior interosseous artery and posterior interosseous nerve. The anterior inferior ligament is a thin fasciculus of fibres, passing transversely between the radius and ulna. The posterior inferior ligament is also thin and loose, and has the same disposition on the posterior surface of the articulation. The interarticular, or triangular fibro-cartilage, acts the part of a ligament between the lower extremities of the radius and ulna. It is attached by its apex to a depression on the inner surface of the styloid process of the ulna, and by its base to the edge of the radius. This fibro-cartilage is lined upon its upper surface by a synovial 124 CARPAL ARTICULATIONS. membrane, which forms a diiplicature between the radius and ulna, and is called the memhrana sacciformis. By its lower surface it enters into the articulation of the wrist-joint. Actions. — The movements taking place between the radius and the ulna, are the rotation of the former upon the latter ; rotation forwards being termed pronation, and rotation backwards supina- tion. In these movements the head of the radius turns upon its own axis, within the orbicular ligament and the lesser sigmoid notch of the ulna ; while inferiorly the radius presents a con- cavity which moves upon the rounded head of the ulna. The "^^ movements of , the radius are chiefly limited by the anterior and posterior in- ferior ligaments, hence these are not un- frequently ruptured in great muscular efforts. 7. Wrist Joint — The wrist is a gingly- moid articulation ; the articular surfaces entering into its formation being the ra- dius and under surface of the triangular fibro-cartilage above, and the rounded surfaces of the scaphoid, semilunar, and cuneiform bone below ; its ligaments are four in number. Fiff. 56 * Anterior, Posterior, Internal lateral. External lateral. The anterior ligament is a broad and membranous layer consisting of three fas- ciculi, which pass between the lower part of the radius, and the scaphoid, semilu- nar, and cuneiform bones. The posterior ligament, also thin and loose, passes between the posterior surface of the radius, and the posterior surface of the semilunar and cuneiform bones. * The ligaments of the anterior aspect of the wrist and hand. 1. The lower part of the interosseous membrane. 2. The anterior inferior radio-ulnar ligament. 3. The anterior ligament of the wrist joint. 4. Its external lateral ligament. 5. Its internal lateral ligament. 6. The palmar ligaments of the carpus. 7. The pisiform bone, with its ligaments. 8. The ligaments connecting the second range of carpal bones with the metacarpal, and the metacarpal witli each other. !3. Tlie capsular ligament of the carpo-metacarpal articulation of the thumb. 10. Anterior ligament of the meta- carpo-phalangeal articulation of the thumb. 11. One of the lateral ligaments of that articulation. 12. Anterior ligament of the metacarpo-phalangcal articulation of the index finger; these hgaments have been removed in the other fingers. 13. Lateral ligaments of the same articulation ; the corresponding ligaments are seen in the other articulations. 14. Transverse ligament connecting the heads of the metacarpal bones of the index and middle fingers ; the same ligament is seen between the other fingers. 15. Anterior and one lateral ligament of the phalangeal articulation of the thumb. 16. Anterior and lateral ligaments of the phalangeal articulations of the index finger ; the anterior ligaments arc removed in the other fingers. WRIST JOINT. 125 The internal lateral ligament extends from the styloid process of the ulna to the cuneiform and pisiform bone. The external lateral ligament is attached by one extremity to the styloid process of the radius, and by the other to the side of the scaphoid bone. The radial artery rests on this ligament as it passes backwards to the first metacarpal space. The synovial membrane of the wrist joint lines the under surface of the radius and interarticular fibro-cartilage above, and the first row of bones of the carpus below. The relations of the wrist joint are the flexor and extensor ten- dons by which it is surrounded, and the radial and ulnar artery. Actions. — The movements of the wrist joint ^xe flexion, extension, adduction, abduction, and circumduction. In these motions the arti- cular surfaces glide upon each other. Articulations between the Carpal Bones. — These are amphi-arthro- dial joints, with the exception of the conjoined head of the os mag- num and unciforme, which is received into a cup formed by the scaphoid, semilunar, and cuneiform bones, and constitutes an enar- throsis. The ligaments are, Dorsal, Palmar, Interosseous, Anterior annular. The dorsal ligaments, are ligamentous bands, that pass from bone to bone in every direction, upon the dorsal surface of the carpus. The palmar ligaments are fasciculi of the same kind, but stronger than the dorsal, having the like disposition upon the palmar surface. The interosseous ligaments are situated between the adjoining bones in each range : in the upper range they close the upper part of the spaces between the scaphoid, semilunar, and cuneiform bones ; in the lower range they are stronger than in the upper, and connect the os magnum on the one side to the unciforme, on the other to the trapezoides, and leave intervals through which the synovial membrane is continued to the bases of the metacarpal bones. The anterior annular ligament is a firm ligamentous band, which connects the bones of the two sides of the carpus. It is attached by one extremity to the trapezium and scaphoid, and by the other to the unciform process of the unciforme and the base of the pisi- form bone, and forms an arch over the anterior surface of the carpus, beneath which the tendons of the long flexors and the median nerve pass into the palm of the hand. The articulation of the pisifm^m bone with the cuneiform, is pro- vided with a distinct synovial membrane, which is protected by fasciculi of ligamentous fibres, forming a kind of capsule around the joint ; they are inserted into the cuneiforme, unciforme, and base of the metacarpal bone of the little finger. 126 CARPO-METACARPAL ARTICULATION. Fig. 57. Synovial membranes. — There are five synovial membranes enter- ing into the composition of the articulations of the carpus : — The -first is situated between the lower end of the ulna and the interarticular fibro-cartilage ; it is called sacciform, from forming a sacculus between the lateral articulation of the ulna with the radius. The second is situated between the lower surface of the radius and interarticular fibro-cartilage above, and the first range of bones of the carpus below. The third is the most extensive of the synovial membranes of the wrist ; it is situated between the two rows of carpal bones, and passes between the bones of the second range, to invest the carpal extremities of the four metacarpal bones of the fingers. The fourth is the synovial membrane of the articulation of the metacarpal bone of the thumb with the trapezium. The fifth is situated between the pisiform and cuneiform bone. Actions. — Very little movement exists between the bones in each range, but more is permitted between the two ranges. The motions in the latter situation are those of flexion and extension. 9. The Carpo-metacarpal Articulation. — The second row of bones of the carpus articulates with the metacarpal bones of the four fin- gers by dorsal and palmar ligaments ; and the metacarpal bone of the thumb with the trapezium by a true capsular ligament. The dai^sal ligaments are strong fas- cicuh which pass from the second range of carpal to the metacarpal bones. The palmar ligaments are thin fasci- culi arranged upon the same plan on the palmar surface. The synovial membrane is a con- tinuation of the great synovial mem- brane of the two rows of carpal bones. The capsular ligament of the thumb is one of the three true capsular liga- ments of the skeleton ; the other two being the shoulder-joint and hip-joint. The articulation has a proper synovial membrane. * A diagram showing the disposition of the five synovial membranes of the wrist joint. 1. Tiie sacciform membrane. 2. The second synovial membrane. 3, 3, The third, or large synovial membrane. 4. The synovial mcml)rane between the pisiform bono and the cunoiformc. 5. The synovial membrane of tlie metacarpal articulation of the thumb. 6. Tlie lower extremity of the radius. 7. The lower extremity of the ulna. 8. The interarticular fibro-cartilage. S. The scaphoid bone. L. The semi- lunarc. C The cimeiibrme; the interosseous ligaments arc seen passing between these three bones and separating the articulation of the wrist (2) from the articulation of the carpal bones (3). V. The pisiformc. T. Tlic tra|)czium. T=. The trapc- zoides. M. The os magnum. U. The unciforme ; interosseous ligaments are seen connecting the os magnum with the trapezoides and unciforme. 9. The base of the metacarpal bone of the thumb. 10, 10. The bases of the other metacarpal bones. METACARPO-PHALANGEAL ARTICULATION. 127 The metacarpal hones of the four fingers are firmly connected at their bases by means of dorsal and palmar ligaments, which extend transversely from one bone to the other, and by interosseous Uga- ments which pass between their contiguous surfaces. Their lateral articular facets are lined by a reflection of the great synovial mem- brane of the two rows of carpal bones. Actions. — The movements of the metacarpal on the carpal bones are restricted to a slight degree of sliding motion, with the excep- tion of the articulation of the metacarpal bone of the thumb with the trapezium. In the latter articulation, the movements are, Jiexion, extension, adduction, abduction, and circumduction. 10. Metacarpo-phalangeal Articulation. — The metacarpo-phalan- geal articulation is a ginglymoid joint: its ligaments are four in number. Anterior, Two lateral, Transverse. The anterior ligaments are thick and fibro-cartilaginous, and form part of the articulating surface of the joints. They are grooved externally for the lodgment of the flexor tendons, and by their internal aspect form part of the articular surface for the head of the metacarpal bone. The lateral ligaments are strong narrow fasciculi, holding the bones together at each side. The transverse ligaments are strong ligamentous bands passing between the anterior Ugaments, and connecting together the heads of the metacarpal bones of the four fingers. The expansion of the extensor tendon over the back of the fingers takes the place of a posterior ligament. Actions. — This articulation admits of movement in four different directions, viz. oi Jiexion, extension, adduction, and abduction, the two latter being hmited to a small extent. It is also capable of cir- cumduction. 11. Articulation of the Phalanges. — These articulations are gingly- moid joints : they are formed by three Ugaments. Anterior, Two lateral. The anterior ligament is firm and fibro-cartilaginous, and forms part of the articular surface for the head of the phalanges. Exter- nally it is grooved for the reception of the flexor tendons. The lateral ligaments are very strong; they are the principal bond of connexion between the bones. The extensor tendon takes the place and performs the office of a posterior ligament. Actions. — The movements of the phalangeal joints are Jiexion and extension, these movements being more extensive between the first and second phalanges than between the second and third. 128 HIP JOINT. LIGAMENTS OF THE LOWER EXTREMITV. The ligaments of the lower extremity, like those of the upper, may be arranged m the order of the joints to which they belong ; these are, the 1. Hip joint. 2. Knee joint. 3. Articulation between the tibia and fibula. 4. Ankle joint. 5. Articulation of the tarsal bones. 6. Tarso-metatarsal articulation. 7. Metatarso-phalangeal articulation. 8. Articulation of the phalanges. 1. Hij) Joint. — The articulation of the head of the femur with the acetabulum constitutes an enarthrosis, or ball and socket joint. The articular surfaces are the cup-shaped cavity of the acetabulum and the rounded head of the femur; the ligaments are jive in number, viz. : Capsular, Ilio-femoral, Teres, Cotyloid, Transverse. The capsular ligament (fig. 50, 8) is a strong ligamentous cap- sule, embracing the acetabulum superiorly, and inferiorly the neck of the femur, and connecting the two bones firmly together. It is much thicker upon the upper part of the joint, where more resist- ance is required, than upon the under part, and extends farther upon the neck of the femur on the anterior and superior than on the pos- terior and inferior side, being attached to the intertrochanteric line in front, to the base of the great trochanter above, and to the middle of the neck of the femur behind. The ilio-femoral ligament* (fig. 50, 9) is an accessory and radiating band, which descends obliquely from the anterior inferior spinous process of the ilium to the anterior intertrochanteric line, and strengthens the anterior portion of the capsular ligament. The ligamentum teres (fig. 51, 7), triangular in shape, is attached by a rounded apex to the depression just below the middle of the head of the femur, and by its base, which divides into two fasciculi, into the borders of the notch of the acetabulum. It is. formed by a fasciculus of fibres of variable size, surrounded by synovial mem- brane ; sometimes the synovial membrane alone exists, or the liga- ment is wholly absent. The cotyloid ligament (fig. 51, 6) is a prismoid cord of fibro-car- * Called also ligamenlum adsciiiliuin. KA'EE JOINT. 129 tilage, attached around the margin of the acetabulum, and serving to deepen the cavity and protect its edges. It is much thicker upon the upper and outer border of the acetabukim than in front, and consists of fibres which arise from the whole circumference of the brim, and interlace with each other at acute angles. The transverse ligament is a strong fasciculus of ligamentous fibres, continuous with the cotyloid ligament, and extended across the notch in the acetabulum. It converts the notch into a foramen, through which the articular branches of the internal circumflex and obturator arteries enter the joint. The fossa at the bottom of the acetabulum is filled by a mass of fat, covered with synovial membrane, which serves as an elastic cushion to the head of the bone during its movements. This was considered by Havers as the synovial gland. The synovial membrane is extensive ; it invests the head of the femur, and is continued around the ligamentum teres into the ace- tabulum ; it is thence reflected upon the inner surface of the cap- sular hgament. The muscles immediately surrounding and in contact with the hip joint are, in front, the psoas and iliacus, which are separated from the capsular ligament by a large synovial bursa ; above, the short head of the rectus, and the gluteus minimus ; behind, the pyriformis, gemellus superior, obturator internus, gemellus inferior, and quadratus femoris ; and to the inner side, the obturator externus and pectineus. Actions. — The movements of the hip joint are very extensive ; they a.re Jlexion, extension, adduction, abduction, circumduction, and rotation. 2. Knee Joint. — The knee is a ginglymoid articulation of a large size, and is provided with numerous ligaments ; they are thirteen in number. Anterior or ligamentum patellae, Posterior or ligamentum posticum Winslowi, Internal lateral. Two external lateral, Anterior or external crucial, Posterior or internal crucial, Transverse, Two coronary, Ligamentum mucosum, ) ^ , Ligamenta alaria, \ /^'^^* Two semilunar fibro-cartilages, Synovial membrane. The five first are external to the articulation; the ^we next are internal to the articulation ; the three remaining are mere folds of synovial membrane, and have no title to the name of ligaments. In addition to the ligaments, there are two fibro-cartilages, wliich are sometimes very erroneously considered among the ligaments ; and 17 130 . KNEE JOINT, a synovial membrane, which is still more improperly named the capsular ligament. The anterior ligament or ligamentum fatellce, is the prolongation of the tendon of the extensor muscles of the thigh downwards to the tubercle of the tibia. It is, therefore, no ligament ; and, as we have before stated, that the patella is simply a sesamoid bone, developed in the tendon of the extensor muscles for the defence of the front of the knee joint, it has no title to consideration, either as a ligament of the knee joint or as a ligament of the patella. A small bursa mucosa is situated between the Fig. 58.* ligamentum patellae, near to its insertion, and the front of the tibia, and another of larger size is placed between the patella and the fascia lata, which extends over its anterior surface. The posterior ligament — ligamentum posticum Winslowi,^ — is a broad expansion of ligamentous fibres which covers the whole of the posterior part of the joint. It is divisible into two lateral portions which invest the condyles of the femur, and a central portion which is depressed and formed by the interlacement of fasciculi passing in different directions. The strongest of these fasci- culi is that which is derived from the tendon of the semimembranosus and passes obliquely upwards and outwards, from the posterior part of the inner tuberosity of the tibia to the external condyle. Other accessory fasciculi are given off by the tendon of the popUteus and by the heads of the gastrocnemius. The middle portion of the ligament supports the popliteal artery and vein, and is perforated by several openings for the passage of branches of the azygos articular artery, and for the nerves of the joint. The internal lateral ligament is a broad and trapezoid layer of ligamentous fibres, attached above to the tubercle on the internal condyle of the femur, and below to the side of the inner tuberosity of the tibia. It is crossed at its lower part by the tendons of the inner hamstring from which it is separated by a synovial bursa, and it covers in the anterior slip of the semi-membranosus tendon and the inferior internal articular artery. External lateral ligaments. — The long external lateral ligament is a strong rounded cord, which descends from the posterior part of the tubercle upon the external condyle of the femur to the outer * The anterior view of the lignments of the knee-joint. 1. The tendon of the quadriceps extensor muscle of the leg. 2. Tlie patella. 3. The anterior ligament, or ligamentum patellse, near its insertion. 4, 4. The synovial memhrane. 5. Tlie internal lateral ligament. 6. The long external lateral ligament, 7. The anterior superior tibio-fihular ligament. t In a recent dissection in Sydenham College, Mr. Joseph Chapman observed a small fleshy muscle, connected by one extremity with the external condyle of tlie femur, and inserted by the otlier into that portion of this ligament which is derived from the tendon of the semimembranosus. KNEE JOIXT. 131 Fig. 59. part of the head of the fibula. The shm^t external lateral ligament is an irregular fasciculus situated behind the pre- ceding, arising from the external condyle near the origin of the head of the gastrocnemius muscle, and inserted into the posterior part of the head of the fibula. It is firmly connected with the external semilunar fibro-cartilage, and appears principally intended to connect that cartilage with the fibula. The lono; external lateral ligament is covered in by the tendon of the biceps, and has passing beneath it the tendon of the origin of the popliteas muscle, and the in- ferior external articular artery. The true ligaments ivit/iin the joint are the crucial, transverse and coronary. The anterior or external crucial ligament, arises from the depression upon the head of the tibia in front of the spinous process, and passes upwards and back- wards to be inserted into the inner surface of the outer condyle of the femur, as far as its posterior border. It is smaller than the posterior. The posterior, or internal crucial ligament, arises from the depres- sion upon the head of the tibia, behind the spinous process, and passes upwards and forwards to be inserted into the inner condyle of the femur. This ligament is less obhque and larger than the anterior. The transverse ligament is a small slip of fibres which extends transversely from the external semilunar fibro-cartilage, near its anterior extremity, to the anterior convexity of the internal car- tilage. The coronary ligaments are the short fibres by which the convex borders of the semilunar cartilages are connected to the head of the tibia, and to the ligaments surrounding the joint. The semilunar fibro-cartilagss, are two falciform plates of fibro- cartilage, situated around the margin of the head of the tibia, and serving to deepen the surface of articulation for the condyles of the femur. They are thick along their convex border, and thin and sharp along the concave edge. The internal semilunar fibro-cartilage forms an oval cup for the reception of the internal condyle ; it is connected by its convex border to the head of the tibia, and to the internal and posterior * A posterior view of the ligaments of the knee-joint. 1. Tlie fasciculus of the liga- mentum posticum Winslowi, which is derived from, 2. Tiie tendon of the semi-mera- branosus muscle ; the latter is cut short. 3. The process of the tendon which spreads out in the fascia of the popliteus muscle. 4. The process which is sent inwards beneath the internal lateral ligament. 5. The posterior part of the internal lateral ligament. 6. The long external lateral ligament. 7. The short external lateral ligament. 8. The tendon of the popliteus muscle cut short. 9. The posterior superior tibio-fibular ligament. 132 KNEE JOINT. ligaments, by means of its coronary^ligament ; and by its two extremities is firmly implanted into the depression in front and behind the spinous process. The external semilunar fihro-cartilage Fiff. 60* Fig. 61.t bounds a circular fossa for the external condyle ; it is connected by its convex border with the head of the tibia, and to the external and posterior hgaments, by means of its coronary hgament ; by its two extremities it is inserted into the depression between the two pro- jections which constitute the spinous process of the tibia. The two * The right knee joint laid open from the front, in order to show the internal liga- ments. 1. The cartilaginous surface of the lower extremity of the femur with its two condyles ; the figure 5 rests upon the external ; the figure 3 upon the internal condyle. 2. The anterior crucial ligament. 3. The posterior crucial ligament. 4, The transverse ligament. 5. The attachment of the ligamentum mucosum, the rest has been removed. 6. T)ie internal semilunar fibro-cartilage. 7. The external fibro- cartilage. 8. A part of the ligamentum patellae turned down. 9. The bursa, situated between the ligamentum patelte and the head of the tibia ; it has been laid open. 10. The anterior superior tibio-fibular ligament. 11. The upper part of the interosseous membrane, the opening above this membrane is for the passage of the anterior tibial artery. t A longitudinal section of the left knee joint, showing the reflections of its synovial membrane. 1. The cancellous structure of the lower part of the femur. 2. The tendon of the extensor muscles of the leg. 3. Tlie patella. 4. The ligamentum patellse. 5. The cancellous structure of tlie head of the tibia. 6. A bursa situated between the ligamentum patcllce and the head of the tibia. 7. The mass of fat pro- jecting into the cavity of the joint below the patella. * * The synovial membrane. y. The pouch of synovial membrane which ascends between tlic tendon of the extensor muscles of the leg, and the front of the lower extremity of the femur. 9. One of the alar ligaments ; the other has been removed with tlie opposite section. 10. I'jie ligamentum mucosum left entire ; the section being made to its inner side. 11. TJie anterior or external crucial ligament. 12. The posterior ligament. The scheme of the synovial membrane which is here presented to the student, is divested of all unnecessary com- plications. It may be traced from the sacculus (at 8), along the inner surface of the patella ; then over the adipose mass (7) from whidi it throws off tlie mucous ligament (10) ; then over the head of the tibia, forming a sheath to the crucial ligaments ; then upwards along the posterior ligament and condyles of the femur, to the sacculus whence its examination commenced. KNEE JOINT, 133 extremities of the external cartilage being inserted into the same fossa, form almost a complete circle, and the cartilage being some- what broader than the internal, nearly covers the articular surface of the tibia. The external semilunar fibro-cartilage besides giving off a fasciculus from its anterior border to constitute the transverse liga- ment, is continuous by some of its fibres with the extremity of the anterior crucial ligament ; posteriorly it divides into three slips, one, a strong cord, ascends obhquely forwards and is inserted into the anterior part of the inner condyle in front of the posterior crucial ligament ; another is the fasciculus of insertion into the fossa of the spinous process ; and the third, of small size, is continuous with the posterior part of the anterior crucial ligament. The ligamenium mucosum is a slender conical process of syno- vial membrane enclosing a few ligamentous fibres which proceed from the transverse ligament. It is connected by its apex, with the anterior part of the condyloid notch, and by its base is lost in the mass of fat which projects into the joint beneath the patella. The alar ligaments are two fringed folds of synovial membrane, extending from the ligamentum mucosum, along the edges of the mass of fat to the sides of the patella. The synovial membrane of the knee joint is by far the most exten- sive in the skeleton. It invests the cartilaginous surface of the condyles of the femur, of the head of the tibia, and of the inner surface of the patella ; it covers both surfaces of the semilunar fibro-cartilages, and is reflected upon the crucial ligaments, and upon the inner surface of the ligaments which form the circum- ference of the joint. On each side of the patella, it lines the tendi- nous aponeuroses of the vastus internus and vastus externus muscles, and forms a pouch of considerable size between the extensor tendon and the front of the femur. It also forms the folds in the interior of the joint, called " ligamentum mucosum," and " hgamenta alaria." The superior pouch of the synovial membrane is supported and raised during the movements of the limb by a small muscle, the subcrureus which is inserted into it. Beneath the ligamentum patelljs and the synovial membrane is a considerable mass of fat, which presses the membrane towards the interior of the joint, and occupies the fossa between the two condyles. Besides the proper Ugaments of the articulation, the joint is pro- tected on its anterior part by the fascia lata, which is thicker upon the outer than upon the inner side, by a tendinous expansion from the vastus internus, and by some scattered ligamentous fibres w^hich are inserted into the sides of the patella. Actions. — The Imee joint is one of the strongest of the articulia- tions of the body, while at the same time it admits of the most per- fect degree of movement in the directions o^ flexion and extension. During flexion the articular surface of the tibia glides forward on the condyles of the femur, the lateral ligaments, the posterior, and crucial ligaments are relaxed, while the ligamentum patellce being 134 TIBIO-FIBULAR ARTICULATION. put upon the stretch, serves to press the adipose mass into the vacuity formed in the front of the joint. In extension all the ligaments are put upon the stretch with the exception of the ligamentum patellas. When the knee is semi-flexed, a partial degree of rotation is permitted. 3. Articulation between the Tibia and Fibula. — The tibia and fibula are held firmly connected by means of seven hgaments, viz. Anterior, ) i -n t ■ ? above. rostenor, ) Interosseous membrane, Interosseous inferior, Anterior, ) i i -r, , • M below, rostenor, ) Transverse. The anterior superior ligament is a strong fasciculus of parallel fibres passing obliquely downwards and outwards from the inner tuberosity of the tibia, to the anterior surface of the head of the fibula. The 'posterior superior ligament is disposed in a similar manner upon the posterior surface of the articulation. There is a distinct synovial membrane in this articulation. The interosseous membrane or superior interosseous ligament is a broad layer of aponeurotic fibres passing obliquely downwards and outwards, from the sharp ridge on the tibia, to the inner edge of the fibula and crossed at an acute angle by a few fibres passing in the opposite direction. The ligament is deficient above, leaving a con- siderable interval between the bones, through which the anterior tibial artery takes its course forwards to the anterior aspect of the leg, and near its lower third there is an opening for the anterior peroneal artery and vein. The interosseous membrane is in relation^ in front, with the tibiahs anticus, extensor longus digitorum, and extensor proprius pollicis muscle, with the anterior tibial vessels and nerve, and with the anterior peroneal artery ; and behind with the tibialis posticus, and flexor longus digitorum muscle, and with the posterior peroneal artery. The inferior interosseous ligament consists of short and strong fibres, which hold the bones firmly together, inferior ly, where they are nearly in contact. This articulation is so firm that the fibula is likely to be broken in the attempt to rupture the ligament. The anterior inferior ligament is a broad band, consisting of two fasciculi of parallel fibres that pass obliquely across the anterior as- pect of the articulation of the two bones at their inferior extremity, from the tibia to the fibula. The posterior inferior ligament (fig. G4. 2) is a similar band upon the posterior surface of the articulation. Both ligaments project ANKLE JOINT. 135 somewhat below the margin of the bones, and serve to deepen the cavity of articulation for the astragalus. The transverse ligament (fig. 64. 3) is a narrow band of ligamen- tous fibres, continuous with the preceding, and passing transversely across the back of the ankle joint between the two malleoli. The synovial membrane of the inferior tibio-fibular articulation, is a duplicature reflected upwards for a short distance between the two bones. Actions. — An obscure movement exists betM^een the tibia and fibula, which is principally calculated to enable the latter to resist injury by yielding for a trifling extent to the pressure exerted. 4. Ankle joint. — The ankle is a ginglymoid articulation, the sur- faces entering into the formation of the joint are the under surface of the tibia with its malleolus and the malleolus of the fibula, above ; and the surface of the astragalus with its two lateral facets, below. The ligaments are three in number : — Anterior, Internal lateral, External lateral. The anterior ligament is a thin membranous layer, passing from the margin of the tibia to the astragalus in front of the articular sur- face. It is in relation, in front, with the extensor tendons of the Fig. 62.* Fig. 63.t great and lesser toes, with the tendon of the tibialis anticus and pero- neus tertius, and with the anterior tibial vessels and nerve. Pos- teriorly it hes in contact with the extra- synovial adipose tissue and with the synovial membrane. The internal lateral ligament or deltoid, is a triangular layer of * An internal view of the ankle joint. 1. The internal malleolus of the tibia, 2, 2. Part of the astragalus; the rest is concealed by the ligaments. 3. The os calcis. 4. The scaphoid bone. 5. The internal cuneiform bone. 6. The internal lateral or del- toid ligament. 7, The anterior ligament. 8. The tendo Achillis ; a small bursa is seen interposed between this tendon and the tuberosity of the os calcis. t An external view of the ankle joint. 1. Tlie tibia. 2. The external malleolus of the fibula. 3, 3. The astragalus. 4. The os calcis. 5. The cuboid bone. 6. The an- terior fasciculus of the external lateral ligament attached to the astragalus. 7. Its middle fasciculus, attached to the os calcis. 8. Its posterior fasciculus, attached to the astragalus. 9. The anterior ligament of the ankle. 136 TARSAX AKTICULATION. fibres attached superiorly by its apex to the internal malleolus, and inferiorly by an expanded base to the astragalus, os calcis, and sca- phoid bone. Beneath the superficial layer of this ligament is a much stronger and thicker fasciculus of fibres, which connects the apex of the internal malleolus with the side of the astragalus. This internal lateral ligament is covered in and partly concealed by the tendon of the tibialis posticus, and at its posterior part is in relation with the tendon of the flexor longus digitorum, and of the flexor longus pollicis. The external lateral ligament consists of three strong fasciculi, which proceed from the inner side of the external malleolus, and diverge in three different directions. The anterior fasciculus passes forwards, and is attached to the astragalus ; the posterior, back- w^ards, and is connected with the astragalus posteriorly; and the middle, longer than the other two, descends to be inserted into the outer side of the os calcis. " It is the strong union of this bone," says Sir Astley Cooper, with the tarsal bones by means of the external lateral ligaments, " which leads to its being more frequently fractured than dislocated." The transverse ligament of the tibia and fibula occupies the place of a posterior ligament. It is in relation, behind, with the posterior tibial vessels and nerve, and with the tendon of the tibialis posticus muscle ; and in front, with the extra-synovial adipose tissue, and synovial membrane. The Synovial membrane invests the cartilaginous surfaces of the tibia and fibula, sending a duplicature upwards between their lower ends ; and the upper surface and two sides of the astragalus. It is then reflected upon the anterior and lateral ligaments, and upon the transverse ligament posteriorly. Actions. — The movements of the ankle joint are flexion and ex- tension only, without lateral motion. 5. Articulation of the Tarsal Bones. — The ligaments which con- nect the seven bones of the tarsus to each other are of three kinds, — Dorsal, Plantar, Interosseous. The dorsal ligaments are small fasciculi of parallel fibres, which pass from each bone to all the neighbouring bones with which it articulates. The only dorsal ligaments deserving of particular mention are, the external and posterior calcaneo-astragaloid, which, with the interosseous ligament, complete the articulations of the astragalus with the os calcis ; the superior and internal calcaneo-cuboid ligaments ; and the superior astragalo-scaphoid ligament. The internal calcaneo-cuboid and the superior calcaneo- scaphoid ligament, which are closely united posteriorly in the deep groove which intervenes between the astragalus and os calcis, separate anteriorly to reach their respective bones, and form the principal bond <)[ connexion between the first and second range of TARSAL ARTICULATIONS. 137 Fig. 64.* bones of the foot. It is the division of this portion of these hga- ments that demands the especial attention of the surgeon in per- forming Chopart's operation. The plantar ligaments have the same disposition on the plantar surface of the foot ; three of them, however, are of large size and have especial names, viz. the Calcaneo-scaphoid, Long calcaneo-cuboid, Short calcaneo-cuboid. The inferior calcaneo-scaphoid ligament is a broad and fibro- cartilaginous band of hgament, which passes for- wards from the anterior and inner border of the os calcis to the edge of the scaphoid bone. In addition to connecting the os calcis and scaphoid, it sup- ports the astragalus, and forms part of the cavity in which its rounded head is received. It is Hned upon its upper surface by the synovial membrane of the astragalo-scaphoid articulation. The firm connexion of the os calcis with the scaphoid bone, and the feebleness of the astragalo- scaphoid articulation are conditions favourable to the occasional dislocation of the head of the astra- galus. The long calcaneo-cuboid, or ligamentum longum plantcB, is a long band of ligamentous fibres, which proceeds from the under surface of the os calcis to the rough sur- face on the under pai't of the cuboid bone, its fibres being continued onwards to the bases of the third and fourth metatarsal bones. This ligament forms the inferior boundary of a canal in the cuboid bone, through which the tendon of the peroneus longus passes to its insertion into the base of the metatarsal bone of the great toe. The short calcaneo-cuboid, or ligamentum breve plantcs, is situated nearer to the bones than the long plantar ligament, from which it is separated by adipose tissue ; it is broad and extensive, and ties the under surface of the os calcis and cuboid bone firmly together. The interosseous ligaments are five in number; they are short and strong ligamentous fibres situated between adjoining bones, and firmly attached to their rough surfaces. One of these, the calcaneo-astragaloid, is lodged in the groove between the upper surface of the os calcis, and the lower of the astragalus. It is large and very strong, consists of vertical and oblique fibres, and serves to unite the os calcis and astragalus solidly together. The * A posterior view of the ankle ioint. 1. Tlie lower part of the interosseous mem- brane. 2. The posterior inferior ligament connecting the tibia and fibula. 3. The transverse ligament. 4. The internal lateral ligament. 5. The posterior fasciculus of the external lateral ligament. G. The middle fasciculus of the external ligament. 7. The synovial membrane of the ankle joint. 8. The os calcis. 18 138 TARSO-METATARSAL ARTICULATION. Fig. 65/ second interosseous ligament, also very strong, is situated between the sides of the scaphoid and cuboid bone ; while the three remain- ing ligaments connect strongly together the three cuneiform bones and the cuboid. The synovial membranes of the tarsus are four in number ; one, for the posterior calcaneo-astragaloid articulation; a second, for the anterior calcaneo-astragaloid and astragalo-scaphoid articulation. Occasionally an additional small synovial membrane is found in the anterior calcaneo-astragaloid joint ; a third, for the calcaneo- cuboid articulation ; and a fourth, the large tarsal synovial mem- brane for the articulations between the scaphoid and three cunei- form bones, the cuneiform bones with each other, the external cuneiform bone with the cuboid, and the two external cuneiform bones with the bases of the second and third metatarsal bones. The prolongation which reaches the metatarsal bones passes for- wards between the internal and middle cuneiform bones. A small synovial membrane is sometimes met with between the contiguous surfaces of the scaphoid and cuboid bone. Actions. — The movements permitted by the ar- ticulation between the astragalus and os calcis, are a shght degree of gliding, in the directions /onoarrfs and backwards and laterally from side to side. The movements of the second range of tarsal bones are very trifling, being greater between the scaphoid and three cuneiform bones than in the other articulations. The movements occurring between the first and second range are the most considerable ; they are adduction and abduction, and, in a minor degree, Jlexion, which increases the arch of the foot, and extension, which flattens the arch. 6. Tarso-metatarsal Articulations. — The liga- ments of this articulation are, Dorsal, Plantar, Interosseous. The dorsal ligaments connect the metatarsal to the tarsal bones, and the metatarsal bones with each other. The plantar ligaments have the same disposition on the plantar surface. * The ligaments of the sole of the foot. 1. Tlic os calcis. 2. The astragalus. 3. The tuberosity of the scaphoid bone. 4. Tlic long calcanco-cuboid ligament. 5 Part of the short calcaneo-cuboid ligament. G. 'J'hc calcaneo-scaphoid ligament. 7. The plantar tarsal ligiimcnts. 8,8. The tendon of the peroneus longus muscle. 9,9. Plantar tarso-motatarsa] ligaments. 10. Plantar ligament of the metatarso-phalangeal articula- tion of the great toe; the same ligament is seen upon the other toes. 11. Lateral ligaments of tiie metiilarso-jjhalangeal articulation. 12. Transverse ligament. 13. The lateral ligaments of the phalanges of the great toe ; the same ligaments are seen upon the other toes. METATARSO-PHALANGEAL ARTICULATION. 139 The interosseous ligaments are situated between the bases of the metatarsal bones of the four lesser toes, and also between the base of the second metatarsal bone, and the internal and external cunei- form bone. The metatarsal bone of the second toe is implanted by its base between the internal and external cuneiform bones, and is the most strongly articulated of all the metatarsal bones. This disposition must be recollected in amputation at the tarso-metatarsal articula- tion. The synovial membranes of this articulation are three in number : one for the metatarsal bone of the great toe ; one for the second and third metatarsal bones, which is continuous with the great tarsal synovial membrane ; and one for the fourth and fifth metatarsal bones. Actions. — The movements of the metatarsal bones upon the tarsal, and upon each other are very slight; they are such only as contri- bute to the strength of the foot by permitting a certain degree of yielding to opposing forces. 7. Metatarso-phalangeal Articulation. — The ligaments of this ar- ticulation, like those of the articulation between the first phalanges and metacarpal bones of the hand, are. Anterior or plantar. Two lateral, Transverse. The anterior or plantar ligaments are thick and fibro-cartilagi- nous, and form part of the articulating surface of the joint. The lateral ligaments are short and very strong, and situated on each side of the joints. The transverse ligaments are strong bands, which pass trans- versely between the anterior ligaments. The expansion of the extensor tendon supplies the place of a dor- sal ligament. Actions. — The movements of the first phalanges upon the rounded heads of the metatarsal bones, are Jlexion, extension, adduction and abduction. 8. Articulation of the Phalanges. — The ligaments of the phalanges are the same as those of the fingers, and have the same disposition; their actions are also similar. They are, Anterior or plantar, Two lateral. CHAPTER III. ON THE MUSCLES. Muscles are the moving organs of the animal frame : they con- stitute by their size and number the great bulk of the body, upon which they bestow form and symmetry. In the limbs they are situated around the bones, which they invest and defend, while they form to some of the joints a principal protection. In the trunk they are spread outto enclose cavities, and constitute a defensive wall capable of yield- ing to internal pressure, and again returning to its original form. Their colour presents the deep red which is characteristic of flesh, and their form is variously modified, to execute the varied range of movements which they are required to effect. Muscle is composed of a number of parallel fibres placed side by side, and supported and held together by a delicate web of cellular tissue ; so, that if it were possible to remove the muscular substance, we should have remaining a beautiful cellular frame- work, possessing the exact form and size of the muscle without its colour and soUdity. Towards the extremity of the organ the mus- cular fibre ceases, and the cellular structure becomes aggregated and modified, so as to constitute those glistening fibres and cords by which the muscle is tied to the surface of bone, and which are called tendons. Almost every muscle in the body is connected with bone, either by tendinous fibres, or by an aggregation of those fibres constituting a tendon ; and the union is so firm, that, under extreme violence, the bone itself rather breaks than permits of the separation #f the tendon from its attachment. In the broad muscles the tendon is spread so as to form an expansion, called aponeurosis (atfo, long ; vsugov* nervus — a nerve widely spread out). Muscles present various modifications in the arrangement of their fibres in relation to their tendinous structure. Sometimes they are completely longitudinal, and terminate at each extremity in tendon, the entire muscle being fusiform in its shape ; in other situations they are disposed like the rays of a fan, converging to a tendinous point, as the temporal, pectoral, glutei, &c., and constitute a radiate muscle. Again, they are penniform, converging like the plumes of a pen to one side of a tendon which runs the whole length of the muscle, as in the peronei ; or bipenniform, converging to both sides of the tendon. In other muscles the fibres pass obliquely from the surface of a tendinous expansion spread out on one side, to that of another extended on the opposite side, as in the semi-membranosus ; or they arc composed of penniform or bipenniform fasciculi as in the deltoid, and constitute a compound muscle. The nomenclature of the muscles is defective and confused, and is generally derived from some prominent character which each * The ancients named all the white fibres of the body v««ga ; the term has since been limited to the nervoB. STRUCTURE OP MUSCLE. 141 muscle presents : thus, some are named from their situation, as the tibialis, pei'oneus ; others from their uses, as the flexors, extensors, adductors, abductors, levators, tensors, &c. Some again from their form, as the trapezius, triangularis, deltoid, &c.; and others from their direction, as the rectus, obliquus, transversalis, &c. Some muscles have received names expressive of their attachments, as the sterno-mastoid, sterno-hyoid, &c. ; and others, of their divisions, as the biceps, triceps, digastricus, complexus, &c. In the description of a muscle we express its attachment by Fig. 66.* the vv^ords " origin" and " inser- tion;" the term or?^m being gene- rally applied to the more fixed or central attachment, or to the point towards which the motion is directed, while insertion is as- signed to the more movable point, or to that, most distant from the centre ; but there are many ex- ceptions to this principle, and as many muscles pull equally by both extremities, the use of such terms must be regarded as purely arbitrary. In structure, muscle is composed of bundles of fibres of variable size called fasciculi, which are enclosed in a cellular membranous investment or sheath, and the latter is continuous with the cellular framework of the fibres. Each fasciculus is composed of a number of smaller bundles, and these of single fibres, which, from their minute size and independent appearance, have been distinguished by the name of ultimate fibres. The ultimate fibre is found by microsco- pic investigation, to be itself made up of a number of ultimate fibrils enclosed in a delicate sheath or myolemma.f Two kinds of ulti- mate muscular fibre exist in the animal economy ; viz., that of voluntary or animal life, and that of involuntary or organic life. * A. A muscular fibre of animal life enclosed in its myolemma ; the transverse and longitudinal striae are seen. B, An ultimate fibril of muscular fibre of animal life. c. A muscular fibre of animal life, similar to a but more highly magnified. Its myolemma is so thin and transparent as to permit the ultimate fibrils to be seen through. The true nature of the longitudinal striae is seen in this fibre as well as the mode of for- mation of the transverse striae. D. A muscular fibre of organic life from the urinary bladder, magnified 600 times, linear measure. Two of the nuclei are seen. E, A muscular fibre of organic life, from the stomach, magnified 600 times. The diameter of this and of the preceding fibre, midway between the nuclei, was 1 -4750th of an inch. t In the summer of 1836, while engaged with Dr. Jones Quain in the examination of the animal tissues with a simple dissecting microscope, constructed by Powell, I first saw that the ultimate fibre of muscle was invested by a proper slieatli, for which I proposed the term " Myolemma ;" a term which was adopted by Dr. Quain in the fourth edition of his " Elements of Anatomy." We at that time believed that the trans- verse folding of that sheath gave rise to the appearance of transverse striae, an opinion which subsequent examinations proved to be incorrect, Mr. Bowman employs the term " Sarcolemma" as synonymous with Myolemma. 142 STRUCTURE OF MUSCLE. The -fibre of animal life is recognised from being marked by transverse and slightly waving striae. The fibre of organic life has no transverse stride, and is much smaller than the fibre of animal life. It is polygonal in form or nearly cylindrical, and appears to consist of a number of minute parallel filaments enclosed in a myo- lemma. The most remarkable character of the organic fibre is the existence from point to point of swellings somewhat larger than the diameter of the fibre, and produced by the nuclei of the original nucleated cells from which the fibre was developed. The ultimate fibrils are minute beaded filaments in the fibre of animal life, and cylindrical and uniform in the organic fibre. According to the researches of Mr. Bowman* the ultimate fibres (primitive fasciculi) are polygonal, a form which is well suited to admit of their being collected into bundles. In size they are very variable, not only in the different classes and genera of animals, but also in the same animal and even in the same muscle. He has observed, moreover, that they are somewhat smaller in the female than in the male ; thus the average diameter of the ultimate fibre in the female, is ^-i^; in the male ^i^; the average of both being -^i-j. In the different classes of animals examined by Mr. Bowman, the largest ultimate fibre was met with in fishes, in which the average diameter is 2 1 2- ' ^6^t in man ; and then in other classes in the following order : insects, ■^\-g', reptiles, ^^; mammalia, ^i-^ ; birds, ^iy. The ultimate fibrils (primitive fibrillse) consist of segments separated from each other by constrictions, which give to the entire fibril the appearance of a string of beads. The constric- tions are narrower than the segments, and their component substance is pro- bably less dense than that which forms the segments. An ultimate fibre con- sists of a bundle of fibrils, which are so disposed that all the segments and all the constrictions correspond, and these give rise to the alternate light and dark lines of the transverse strise.f The fibrils are connected together with very different degrees of closeness in different * On the Minute Structure and Movements of Voluntary Muscle, By Wm. Bow- man, Esq. From the Philosophical Transactions for 1840. F. Transverse section of ultimate fibres of the biceps, copied from the illustrations to Mr. Bowman's paper. In this figure the polygonal form of the fibres is seen, and their composition of ultimate fibrils. G. An ultimate fibre, in which ihc transverse splitting into discs, in the direction of the constrictions of the ultimate fibrils is seen. From Mr. Bowman's paper. t According to (Jerhr.r the transverse strise on the ultimate fibres are produced by a delicate thread of cellular tissue wound spirally around the ultimate fibrils so as to hold tlicrn in a bundle, and my own observations corroborate his, G, STRUCTURE OF MUSCLE, 143 animals ; in man they are but slightly adherent, and distinct lon- gitudinal lines of junction may be observed between them, — they also separate very easily when macerated for some time. Besides the more usual separation of the ultimate fibre into fibrils, it breaks, when stretched, into transverse sections, corresponding with the dark line of the strias, and consequently with the constrictions of the fibrillae. When this division occurs with the greatest facility, the longitudinal lines are indistinct or scarcely perceptible. " In fact," says Mr. Bowman, " the primitive fasciculus seems to consist of primitive component segments or particles, arranged so as to form, in one sense, fibrillae, and in another sense, discs ; and which of these two may happen to present themselves to the observer, will depend on the amount of adhesion, endways or sideways, existing between the segments. Generally, in a recent fasciculus, there are transverse striae, showing divisions into discs, and longitudinal striae, marking its composition by fibrillae." Mr. Bowman has observed that in the substance of the ultimate fibre there exist minute " oval or circular discs, frequently concave on one or both surfaces, and containing, somewhere ^ near the centre, one, two or three minute ^^=^ _g i^^-Z^^^" dots or granules." Occasionally they ~=3;;;;z^^ ^^^'^^ ^^ are seen to present irregularities of form, i^^^g-^^^^^=-^ which Mr. Bowman is inclined to regard J^^ ^^^^^^^T^]^^ as accidental. They are situated be- - '^jg= r:-"^^_~I!^"^=- tween, and are connected with the ^^^ -,= - \^^^s fibrils, and are distributed in pretty -^^^ ^^^ ^^^J' equal numbers through the fibre. These corpuscles are the nuclei of the nucle- ated cells from which the muscular fibre was originally developed. From observing, however, that their "absolute number is far greater in the adult than in the foetus, while their number, rela- tively to the bulk of the fasciculi, at these two epochs, remains nearly the same," Mr. Bowman regards it as certain, that " during developement, and subsequently, a further and successive deposit of corpuscles" takes place. The corpuscles are only brought into view when the muscular fibre is acted upon by a solution of " one of the milder acids, as the citric." Muscles are divided into two great classes, voluntary and involuntary, to which may be added as an intermediate and con- necting link, the muscle of the vascular system, the heart. The voluntary, or system of animal life, is developed from the external or serous layer of Ihe germinal membrane, and compre- hends the whole of the muscles of the limbs and of the trunk. The involuntary or organic system is developed from the internal or mucous layer, and constitutes the thin muscular structure of the H. Mass of ultimate fibres from tlie pectoralis major of the human foetus, at nine months, Tliese fibres have been immersed in a solution of tartaric acid, and their " numerous corpuscules, turned in various directions, some presenting nucleoli," are shewn. From Mr. Bowman's paper. 144 HUSCLES OF THE HEAD AND NECK. intestinal canal, bladder, and internal organs of generation. At the commencement of the aUmentary canal in the oesophagus, and near its termination in the rectum, the muscular coat is formed by a blending of the fibres of both classes. The heart is developed from the middle, or vascular layer of the germinal membrane ; and although involuntary in its action, is composed of ultimate fibres havdng the transverse striae of the muscle of animal life. The muscles may be arranged in conformity with the general division of the body into, — 1. Those of the head and neck. 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity. 1. MUSCLES OF THE HEAD AND NECK. The muscles of the head and neck admit of a subdivision into those of the head and face, and those of the neck. Muscles of the Head and Face. — These muscles may be divided into groups corresponding with the natural regions of the head and face ; the groups are eight in number, viz. — 1 . Cranial group. 5. Superior labial group. 2. Orbital group. 6. Inferior labial group. 3. Ocular group. 7. Maxillary group. 4. Nasal group. 8. Auricular group. The muscles of each of these groups may be thus arranged — 1. Cranial growp. Levator labii superioris pro- Occipito-frontalis. prius, _. ^ , . , Levator anguli oris, 2. Orbital group. Zygomaticus major, Orbicularis palpebrarum, Zygomaticus minor, Corrugator supercilii. Depressor labii superioris alse- Tensor tarsi. que nasi. 3. Ocular growp. 6. Inferior labial group. Levator palpebral, (Orbicularis oris),* Rectus superior. Depressor labii inferioris, Rectus inferior. Depressor anguli oris, Rectus internus. Levator labii inferioris. Rectus externus, „ n/r -n Obliquus superior, ^' ^^^^^^^ry group. Obiiquus inferior. Masseter, . ,, , Temporalis, 4. Nasal group. Buccinator, Pyramidalis nasi, Pterygoideus externus, Compressor nasi. Pterygoideus internus. 5. Superior labial group. 8. Auricular group. (Orbicularis oris), Attolens aurem. Levator labii superioris alsequc Attrahcns aurem, nasi, Rctrahcns aurem. * The orbicularis oris, from encircling llic mouth, belongs necessarily to both the superior and inferior labial regions ; it is therefore enclosed within brackets in both. OCCIPITO-FRONTALIS. 145 Fig. 68* Dissection. — The occipito-frontalis is to be dissected by making a longitudinal incision along the vertex of the head, from the tubercle on the occipital bone to the root of the nose ; and a second incision along the forehead and around the side of the head, to join the two extremities of the preceding. Dissect the integument and superficial fascia carefully outwards, beginning at the anterior angle of the flap, where the muscular fibres are thickest, and remove it alto- gether. This dissection requires care ; for the muscle is very thin, and without attention would be raised with the integument. There is no deep fascia on the face and head, nor is it required ; for here the muscles are closely applied against the bones upon which they depend for support, whilst in the extremities the support is derived from the dense layer of fascia by which they are invested, and which forms for each a distinct sheath. The occipito frontalis is a broad musculo-tendinous layer, which covers the whole of one side of the vertex of the skull, from the occiput to the eyebrow. It arises by tendinous fibres from the outer two-thirds of the superior curved line of the occipital bone, and from the mastoid portion of the temporal; it is inserted into the orbicularis palpebrarum muscle and the internal angular process of the frontal bone. The muscle is fleshy in front over the frontal bone and behind over the occipi- tal, the portions being connected by a broad aponeurosis. The two muscles cover the whole of the vertex of the skull, hence their designation galea capitis ; they are loosely adherent to the pericranium, but very closely to the in- tegument, particularly over the forehead. * The muscles of the head and face. 1. The frontal portion of the occipito-frontalis. 2. Its occipital portion. 3. Its aponeurosis. 4. The orbicularis palpebrarum, which conceals the corrugator supercilii and tensor tarsi. 5. The pyramidalis nasi. 6. The compressor nasi. 7. The orbicularis oris. 8. The levator labii superioris alajque nasi. The figure is placed on the nasal portion. 9. The levator labii superioris proprius ; the lower part of the levator anguli oris is seen between the muscles 10 and 11. 10. The zygomaticus minor. 11. The zygomaticus major. 12. The depressor labii infe- rioris. 13. The depressor anguli oris. 14. The levator labii inferioris. 15. The su- perficial portion of the masseter. 16. Its deep portion. 17. The attrahens aurem. 18. The buccinator. 19. The attolens aurem. 20. The temporal fascia which covers in the temporal muscle. 21. The retrahens aurem. 22. The anterior belly of the digas- tricus muscle ; tlie tendon is seen passing tln-ough its aponeurotic pulley. 23. The stylo-hyoid muscle pierced by the posterior belly of the digastricus. 24. The mylo- hyoideus muscle. 25. The upper part of the sterno-mastoid. 26. The upper part of the trapezius. The muscle between 25 and 26 is the splenius. 19 146 ORBITAL GROUP. Relations. — This muscle is in relation by its external surface from before backwards, with the frontal and supra-orbital vessels, the supra-orbital and facial nerve, the temporal vessels and nerve, the occipital vessels and nerves, and with the integument, to which it is very closely adherent. Its under surface is attached to the peri- cranium by a loose cellular tissue which admits of considerable movement. Action. — To raise the eyebrows, thereby throwing the integument of the forehead into transverse wrinkles. Some persons have the power of moving the entire scalp upon the pericranium by means of these muscles. Dissection. — The dissection of the face is to be effected by con- tinuing the longitudinal incision of the vertex of the previous dis- section onwards to the tip of the nose, and thence downwards to the margin of the upper lip ; then carry an incision along the margin of the lip to the angle of the mouth, and transversely across the face to the angle of the lower jaw. Lastly, divide the integument in front of the external ear upwards to the transverse incision which was made for exposing the occipito-frontalis. Dissect the integument and superficial fascia carefully from the whole of the region included by these incisions, and the three next groups of muscles will be brought into view. 2. Orbital growp. — Orbicularis palpebrarum, Corrugator supercilii, Tensor tarsi. The orbicularis palpebrarum is a sphincter muscle, surrounding the orbit and eyelids. It arises from the internal angular process of the frontal bone, from the nasal process of the superior maxillary, and from a short tendon {tendo oculi) which extends between the nasal process of the superior maxillary bone, and the inner ex- tremities of the tarsal cartilages of the eyelids. The fibres encircle the orbit and eyelids, forming a broad and thin muscular plane, which is inserted into the lower border of the tendo oculi and into the nasal process of the superior maxillary bone. Upon the eyelids the fibres are very thin and pale, and possess an involuntary action. The tendo oculi, in addition to its insertion into the nasal process of the superior maxillary bone, sends a process inwards which expands over the lachrymal sac, and is attached to the ridge of the lachry- mal bone ; this is the reflected aponeurosis of the tendo oculi. Relations. — By its superficial surface it is closely adherent to the integument, from which it is separated over the eyelids by a loose serous cellular tissue. By its deep surface it lies in contact above with the upper border of the orbit, with the corrugator supercilii muscle, and with the frontal and supra-orbital vessels and supra- orbital nerve ; below, with the lachrymal sac, with the origins of the labii supcrioris ateque nasi, levator labii supcrioris proprius, OCULAR GROUP. 147 zygomaticus major and minor muscles, and malar bone ; and exter- nally with the temporal fascia. Upon the eyelid it is in relation with the broad tarsal ligament and tarsal cartilages, and by its upper border gives attachment to the occipito-frontalis muscle. The corrugator sicpsrcilii is a small narrow and pointed muscle, situated immediately above the orbit and beneath the upper segment of the orbicularis palpebrarum muscle. It caises from the inner ex- tremity of the superciliary ridge and is inserted into the under ^ surface of the orbicularis palpebrarum. Relations. — By its supefficial surface, with the pyramidalis nasi, occipito-frontahs and orbicularis palpebrarum muscle ; and by its deej) surface with the supra-orbital vessels and nerve. The tensor tarsi (Horner's* muscle) is a thin plane of muscular fibres, about three lines in breadth and six in length. It is best dis- sected by separating the eyelids of the eye, and turning them over the nose without disturbing the tendo oculi ; then dissect away the small fold of mucous membrane called plica semilunaris, and some loose cellular tissue under which the muscle is concealed. It arises from the orbital surface of the lachrymal bone, and passing across the lachrymal sac divides into two slips, which are inserted into the lachrymal canals as far as the puncta. Actions. — The palpebral portion of the orbicularis acts involun- tarily in closing the lids, and from the greater curve of the upper lid, upon that principally. The entire muscle acts as a sphincter, drawing at the same time, by means of its osseous attachment, the integument and Uds inwards towards the nose. The corrugatores superciliorum draw the eyebrows downwards and inwards, and produce the vertical wrinkles of the forehead. The tensor tarsi, or lachrymal muscle, draws the extremities of the lachrymal canals inwards, so as to place the puncta in the best position for receiving the tears. It serves also to keep the lids in relation with the surface of the eye, and compresses the lachrymal sac. Dr. Horner is ac- quainted with two persons who have the voluntary power of draw- ing the lids inwards by these muscles so as to bury the puncta in the angle of the eye. 3. Ocular group. — Levator palpebrge. Rectus superior. Rectus inferior. Rectus internus, Rectus externus. Obliquus superior, Obliquus inferior. Dissection. — To open the orbit (the calvarium and brain havino- been removed) the frontal bone must be sawn through at the inner extremity of the orbital ridge ; and, externally, at its outer extremity. J* W. E. Horner, M.D., Professor of Anatomy in the University of Pennsylvania. *rhe notice of this discovery is contained in a work published in Philadelphia in 1827, entitled " Lessons in Practical Anatomy." 148 OCULAR GROUP. The roof of the orbit may then be comminuted by a few hght blows with the hammer ; a process easily accomplished, on account of the thinness of the orbital plate of the frontal bone and lesser wing of the sphenoid. The superciliary portion of the orbit may now be driven forwards by a smart blow, and the broken fragments of the roof of the orbit removed. The periosteum will then be exposed unbroken and undisturbed. Remove the periosteum from the whole of the upper surface of the exposed orbit, and the muscles may then be examined. The levator palpebrcB is a long, thin, and triangular muscle ; it arises from the upper margin of Fig. 69.* the optic foramen, and from the ^^^^.^^ fibrous sheath of the optic nerve, ^^;:::;^^^' and is inserted into the upper ^^^^^^i^c, border of the superior tarsal - ^^^^^^^^^ ^^^j\ Relations. — By its upper surface ''^''\-'^^^^^^^^m^ % m with the fourth nerve the supra- •■<2;^?"^s^^^^^^O^ 7 orbital nerve and artery, the peri- ^^^^^^^^^ osteum of the orbit, and in front with the broad tarsal ligament. By its under surface it rests upon the superior rectus muscle, and the globe of the eye ; it receives its nerve and artery by this aspect, and in front is lined for a short distance by the conjunctiva. The rectus superior (attollens) arises from the upper margin of the optic foramen, and from the fibrous sheath of the optic nerve, and is inserted into the upper surface of the globe of the eye at a point somewhat more than three lines from the margin of the cornea. Relations. — By its upper surface^Nii\i the levator palpebrse muscle; and by the iinder surface with the optic nerve, the ophthalmic artery and nasal nerve, from which it is separated by a layer of fascia and by the adipose tissue of the orbit, and in front with the globe of the eye, the tendon of the superior oblique muscle being interposed. The rectus inferior (depressor) arises from the inferior margin of the optic foramen by a tendon (ligament of Zinn) which is common to it, the internal and the external rectus, and from the fibrous sheath of the optic nerve ; it is inserted into the inferior sur- face of the globe of the eye at a little more than two lines from the margin of the cornea. Relations. — By its upper surface with the optic nerve, the infe- * The muscles of the eyeball ; the view is taken from the outer side of the right orbit. 1. A small fragment of the sphenoid hone around the entrance of the optic nerve into the orbit, y. The optic nerve. .3. The glol)e of the eye. 4. The levator palpebrtc muscle. .'5. The superior oblique muscle. 6. Its cartilaginous pulley. 7. Its reflected tendon. 8. The inferior oblifiuo muscle, the small square knob at its com- mencement is a piece of its bony origin broken off. 9. The superior rectus. 10. The internal rectus ahnost concealed by the optic nerve. 11. Part of the external rectus, shovfing its two heads of origin. 19. The extremity of the external rectus at its in- sertion ; the intermediate portion of tlie muscle having been removed. 13. The inferior rectus, H. The tunica albuginca, formed l)y the expansion of the tendons of the fbu^ recti. RECTI OBLIQUI. 149 rior oblique branch of the third nerve, the adipose tissue of the orbit, and the under surface of the globe of the eye. By its under surface with the periosteum of the floor of the orbit, and with the inferior oblique muscle. The rectus internus (adductor), the thickest and shortest of the straight muscles, arises from the common tendon, and from the fibrous sheath of the optic nerve ; and is inserted into the inner surface of the globe of the eye at two lines from the margin of the cornea. Relations. — By its internal surface with the optic nerve, the adi- pose tissue of the orbit and the eyeball. By its outer surface with the periosteum of the orbit ; and by its upper border with the ante- rior and posterior ethmoidal vessels, the nasal and supra-trochlear nerve. The rectus externus (abductor), the longest of the straight mus- cles, arises by two distinct heads, one from the common tendon, the other with the origin of the superior rectus from the margin of the optic foramen ; the nasal, third and sixth nerves passing between its heads. It is inserted into the outer surface of the globe of the eye at a little more than two hnes from the margin of the cornea. Relations. — By its internal surface with the third, the nasal, the sixth, and the optic nerve, the ciliary ganglion and nerves, the oph- thalmic artery and vein, the adipose tissue of the orbit, the inferior oblique muscle, and the eyeball. By its external surface with the periosteum of the orbit ; and by the wpper border with the lach- rymal vessels and nerve and the lachrymal gland. The recti muscles present several characters which are common to all : thus, they are thin, have the form of an isosceles triangle, bear the same relation to the globe of the eye, and are inserted in a similar manner into the sclerotica, at about two lines from the circumference of the cornea. The points of difference relate to thickness and length ; the internal rectus is the thickest and most short, the external rectus the longest of the four, and the superior rectus the most thin. The insertion of the four recti muscles into the globe of the eye forms a tendinous expansion, which is continued as far as the margin of the cornea, and is called the tunica albuginea. The obliquus superior (trochlearis) is a fusiform muscle arising from the margin of the optic foramen, and from the fibrous sheath of the optic nerve ; it passes forwards to the pulley beneath the internal angular process of the frontal bone ; its tendon is then reflected beneath the superior rectus muscle, to the outer and poste- rior part of the globe of the eye, where it is inserted into the sclerotic coat, near the entrance of the optic nerve. The tendon is surrounded by a synovial membrane, while passing through the cartilaginous pulley. Relations. — By its superior surface with the fourth nerve, the supra-trochlear nerve, and with the periosteum of the orbit. By the inferior surface with the adipose tissue of the orbit, the upper 150 OCULAR GROUP. border of the internal rectus, and the vessels and nerves in rela- tion with that border. The obliquus inferior, a thin and narrow muscle, arises from the inner margin of the superior maxillary bone, immediately external to the lachrymal groove, and passes beneath the inferior rectus, to be inserted into the outer and posterior part of the eyeball, at about two lines from the entrance of the optic nerve. Relations. — By its superior surface with the inferior rectus muscle and with the eyeball ; and by the inferior surface with the perios- teum of the floor of the orbit and the external rectus muscle. According to Mr. Ferrall* the muscles of the orbit are separated from the globe of the eyeball and from the structures immediately surrounding the optic nerve, by a distinct fascia, which is continuous with the broad tarsal ligament and with the tarsal cartilages. This fascia the author terms, the tunica vaginalis oculi;\ it is pierced anteriorly for the passage of the six orbital muscles, by six openings through which the tendons of the muscles play as tlirough pulleys. The use assigned to it by Mr. Ferrall is to protect the eyeball from the pressure of its muscles during their action. By means of this structure the recti muscles are enabled to impress a rotatory move- ment upon the eyeball ; and in animals provided with a retractor muscle, they also act as antagonists to its action. Actions. — The levator palpebrse raises the upper eyelid. The four recti, acting singly, pull the eyeball in the four directions of upwards, downwards, inwards, and outwards. Acting by pairs, they carry the eyeball in the diagonal of these directions, viz. upwards and inwards, upwards and outwards, downwards and inwards, or downwards and outwards. Acting altogether, they directly retract the globe within the orbit. The superior oblique muscle, acting alone, rolls the globe inv/ards and forwards, and carries the pupil outwards and downwards to the lower and outer angle of the orbit. The inferior oblique, acting alone, rolls the globe outwards and backwards, and carries the pupil outwards and upwards to the upper and outer angle of the eye. Both muscles acting together, draw the eyeball forwards, and give the pupil that slight degree of aversion which enables it to admit the largest field of vision. &^ 4. JVasal Group. — -Pyramidalis nasi,J Compressor nasi. The pyramidalis nasi is a small pyramidal slip of muscular fibres sent downwards upon the nose by the occipito-frontalis. It is inserted into the tendinous expansion of the compressores nasi. Relations. — By its upper surface with the integument; by its under surface with the periosteum of the nasal bone. Its outer * In a paper read before the Royal Society, on the 10th of June, 1841, t This faso-ia was first described by Mr. Dalrymple in his work on the "Anatomy of the Human Eye." 1834. t This is described by Horner as one of the insertions of the occipito-frontalis. G. SUPERIOR LABIAL GROUP. 151 border corresponds with the edge of the orbicularis palpebrarum, and its inner border with its fellow, from which it is separated by a slight interval. The compressor nasi is a thin and triangular muscle; it arises by- its apex from the canine fossa of the superior maxillary bone, and spreads out upon the side of the nose into a thin tendinous expan- sion, which is continuous across its ridge with the muscle of the opposite side. Relations. — By its superficial surface with the levator labii supe- rioris proprius, the levator labii superioris aleeque nasi, and the inte- gument ; by its deep surface with the superior maxillary and nasal bone, and with the alar and lateral cartilages of the nose. Actions. — The pyramidalis nasi, as a point of attachment of the occipito-frontalis, assists that muscle in its action: it also draws down the inner angle of the eyebrow, and by its insertion fixes the aponeurosis of the compressores nasi. The compressores nasi appear to act in expanding rather than in compressing the nares ; hence probably the compressed state of the nares from paralysis of these muscles in the last moments of life, or in compression of the brain. 5. Superior Labial Group. — Orbicularis oris. Levator labii superioris alseque nasi, Levator labii superioris proprius,* Levator anguli oris, Zygomaticus major, Zygomaticus minor, Depressor labii superioris alsequenasi. The orbicularis oris is a sphincter muscle, completely surrounding the mouth, and possessing consequently neither origin nor insertion. It is composed of two thick semicircular planes of fibres, which em- brace the rima of the mouth, and interlace at their extremities, where they are continuous with the fibres of the buccinator, and of the other muscles connected with the angle of the mouth. The upper segment is attached by means of a small muscular fasciculus (naso-labiahs) to the columna of the nose. Relations. — By its superficial surface with the integument of the lips with which it is closely connected. By its deep surface with the mucous membrane of the mouth, the labial glands and coronary arteries being interposed. By its circumference with the numerous muscles which move the lips, and by the inner border with the mucous membrane of the rima of the mouth. The levator labii superioris alceque nasi is a thin triangular muscle; it arises from the nasal process of the superior maxillary bone; and, becoming broader as it descends, is inserted by two distinct por- tions into the integument of the ala of the nose and upper lip. Relations. — By its superficial surface with a part of the orbicularis * These two levators are described as one by Horner. — G. 152 SUPERIOR LABIAL GROUP. palpebrarum muscle, the facial artery, and the integument. By its deep surface with the compressor nasi and alar cartilage. The levator lahii swperioris proprius is a thin quadrilateral muscle; it nrises from the lower border of the orbit, and is inserted into the integument of the upper lip. Relations. — By its superficial surface with the lower segment of the orbicularis palpebrarum, with the facial artery, and Avith the integument. By its deep surface with the origins of the compressor nasi and levator anguli oris muscle, and with the infra-orbital artery and nerve. The levator anguli oris arises from the canine fossa of the supe- rior maxillary bone, and passes outwards to be inserted into the angle of the mouth, intermingling its fibres with those of the orbicu- laris, zygomatici and depressor anguli oris. Relations. — By its superficial surface with the levator labii supe- rioris proprius, the branches of the infra-orbital artery and nerve, and inferiorly with the integument. By its deep surface with the superior maxillary bone and buccinator muscle. The zygomatic muscles are two slender fasciculi of fibres which arise from the malar bone, and are inserted into the angle of the mouth, where they are continuous with the other muscles attached to this part. The zygomaticus minor is situated in front of the major, and is continuous at its insertion with the levator labii supe- rioris proprius ; it is not unfrequently wanting. Relations. — The zygomaticus tnajor muscle is in relation by its superficial surface with the lower segment of the orbicularis palpe- brarum above, and the fat of the cheek and integument for the rest of its extent. By its deep surface with the malar bone, the masseter, and buccinator muscle, and the facial vessels. The zygomaticus minor being in front of the major, has no relation with the masseter muscle, while inferiorly it rests upon the levator anguli oris. The depressor labii superioris alaeque nasi (myrtiformis) is seen by drawing upwards the upper lip, and raising the mucous mem- brane. It is a small oval slip of muscle, situated at each side of the frsenum, arising from the incisive fossa, and passing upwards to be inserted into the upper lip and ala of the nose. This muscle is con- tinuous by its outer border with the edge of the compressor nasi. Relations. — By its superficial surface with the mucous membrane of the mouth, the orbicularis oris and levator labii superioris alaeque nasi muscle ; and by its deep surface with the superior maxillary bone. Actions. — The orbicularis oris produces the direct closure of the lips by means of its continuity at the angles of the mouth, with the fibres of the buccinator. When acting singly in the forcible closure of the mouth, the integument is thrown into wrinkles in consequence of its firm connexion with the surface of the muscle. The levator labii superioris alseque nasi lifts the upper lip with the ala of the nose, and expands the opening of the nares. The depressor labii superioris ala?que nasi is the antagonist to this muscle, drawing the upper lip INFERIOR LABIAL GROUP. 153 and ala of the nose downwards, and diminishing the opening of the nares. The levator labii superioris proprius is the proper elevator of the upper Up ; acting singly, it draws the lip a little to one side. The levator anguli oris lifts the angle of the mouth and draws it inwards, while the zygomatici pull it upwards and outwards, as in laughing. 6. hiferior Labial Group. — Depressor labii inferioris. Depressor anguli oris, Levator labii inferioris. Dissection. — To dissect the inferior labial region, continue the ver- tical section from the margin of the lower lip to the point of the chin. Then carry an incision along the margin of the lower jaw to its angle. Dissect off the integument and superficial fascia from the whole of this surface, and the muscles of the inferior labial region will be exposed. The depressor labii inferioris (quadratus menti) arises from the oblique line by the side of the symphysis of the lower jaw, and pass- ing upwards and inwards \s inserted into the orbicularis muscle and integument of the lower lip. Relations. — By its superficial surface with a part of the depressor anguli oris, and with the integument of the chin with which it is closely connected. By the deep surface with the levator labii in- ferioris, the labial glands and mucous membrane of the lower lip, and with the mental nerve and artery. The depressor anguli oris (triangularis oris) is a triangular plane of muscle arising by a broad base from the external oblique ridge of the lower jaw, and inserted by its apex into the angle of the mouth, where it is continuous with the levator anguli oris and zygomaticus major. Relations. — By its superficial surface with the integument, and by its deep surface with the depressor labii inferioris, the platysma my- oides, the buccinator and the branches of the mental nerve and artery. The levator labii inferioris (levator menti) is a small conical slip of muscle arising from the incisive fossa of the lower jaw, and inserted into the integument of the chin. It is in relation with the mucous membrane of the mouth, with its fellow, and with the depressor labii inferioris. Jlciions. — The depressor labii inferioris draws the lower lip di- rectly downwards, and at the same time a little outwards. The depressor anguli oris, from the radiate direction of its fibres, will pull the angle of the mouth either downwards and inwards, or down- wards and outwards, and be expressive of grief; or acting with the levator anguli oris and zygomaticus major, it will draw the angle of the mouth directly backwards. The levator labii inferioris raises and protrudes the integument of the chin. 7. Maxillary Group. — Masseter, TemporaUs, Buccinator, Pterygoideus externus, Pterygoideus internus. 20 154 MAXILLARY GROUr. Dissection. — The masseter has been ah'eady exposed by the pre- ceding dissection. The masseter ((ji^atfCaofxai, to chew,) is a short and thick and some- what quadrilateral muscle, composed of two planes of fibres, super- ficial and deep. The superficial layer aiises by a strong aponeuro- sis from the tuberosity of the superior maxillary bone, and from the lower border of the malar bone and zygoma, and passes backwards to be inserted into the ramus and angle of the inferior maxilla. The deep layer arises from the posterior part of the zygoma, and passes forwards, to be inserted into the upper half of the ramus. This muscle is tendinous and muscular in its structure. Relations. — By its external surface with the zygomaticus major and risorius Santorini muscle, the parotid gland and Stenon's duct, the transverse facial artery, the pes anserinus and the integument. By its internal surface with the temporal muscle, the buccinator, from which it is separated by a large mass of fat, and with the ramus of the lower jaw. By its posterior harder with the parotid gland ; and by the anterior border with the facial artery and vein. Dissection. — Make an incision along the upper border of the zygoma, for the purpose of separating the temporal fascia from its attachment. Then saw through the zygomatic process of the malar bone, and through the root of the zygoma, near to the meatus audi- torius. Draw down the zygoma, and with it the origin of the mas- seter, and dissect the latter muscle away from the ramus and angle of the inferior maxilla. Now remove the temporal fascia from the rest of its attachment, and the whole of the temporal muscle will be exposed. The temporal is a broad and radiating muscle occupying a consi- derable extent of the side of the head and filling the temporal fossa. It is covered in by a very dense fascia (temporal fascia) which is attached along the temporal ridge on the side of the skull, extending from the external angular process of the frontal bone to the mastoid portion of the temporal ; inferiorly, it is connected to the upper border of the zygoma. The muscle arises by tendinous fibres from the whole length of the temporal ridge and by muscular fibres from the temporal fascia, and from the entire surface of the temporal fossa. Its fibres converge to a strong and narrow tendon, which is inserted into the apex of the coronoid process, and for some way down upon its inner surface. Relations. — By its external surface with the temporal fascia, which separates it from the attollens and attrahcns aurem muscle, the temporal vessels and nerves ; and with the zygoma and masseter. By its internal surface with the bones forming the temporal fossa, the external pterygoid muscle, a part of the buccinator, and the in- ternal maxillary artery, with its deep temporal branches. By sawing through the coronoid process near to its base, and pull- ing it upwards, together with the tein])oral muscle, which may be dissected from the fossa, we obtain a view of the entire extent of the buccinator and of the external pterygoid muscle. BUCCINATOR PTERYGOIDEI. 155 The buccinator {huccina, a trumpet), the trumpeter's muscle, arises from the alveolar process of the superior maxillary and from the external oblique line of the inferior maxillary bone, as far for- ward as the second bicuspid tooth, and from the pterygo-m axillary ligament. This ligament is the raphe of union between the bucci- nator and superior constrictor muscle, and is attached by one extre- mity to the hamular process of the internal pterygoid plate, and by the other to the extremity of the molar ridge. The fibres of the muscle converge towards the angle of the mouth where they cross each other, the superior being continuous with the inferior segment of the orbicularis oris, and the inferior with the superior segment. The muscle is invested externally by a thin fascia. Relations. — By its external surface, posteriorly with a large and rounded mass of fat, which separates the muscle from the ramus of the lower jaw, the temporal, and the masseter ; anteriorly with the risorius Santorini, the zygomatici, the levator anguli oris, and the depressor anguh oris. It is also in relation with a part of Stenon's duct which pierces it opposite to the second molar tooth of the upper jaw, with the transverse facial artery, the branches of the facial and buccal nerve, and the facial artery and vein. By its internal surface with the buccal glands and mucous membrane of the mouth. The external pterygoid is a short and thick muscle, broader at its origin than at its insertion. It arises by two heads, one from the pterygoidr idge on the great ala of the sphenoid ; the other from the external pterygoid plate and tuberosity of the palate bone. The fibres pass backwards to be inserted into the neck of the lower jaw and the interarticular fibro-cartilage. The internal maxillary artery frequently passes between the two heads of this muscle. Relations. — By its external surface with the ramus of the lower jaw, the temporal muscle, and the internal maxillary artery ; by its internal surface with the internal pterygoid muscle, and the inferior Fig. 70.* maxillary nerve ; and by its upper border with the muscular branches of the inferior maxillary nerve ; the in- ternal maxillary artery passes between the two heads of this muscle, and its lower origin is pierced by the buccal nerve. The external pterygoid muscle must now be removed, the ramus of the lower jaw sawn through its lower third, and the head of the bone dislo- cated from its socket and withdrawn, for the purpose of seeing the pterygoideus internus. * The two pterygoid muscles. The zygomatic arch and greater part of tlie ramus of the lower jaw have been removed in order to bring these muscles into view. 1. Tlic sphenoid origin of the external pterygoid muscle. 2. Its pterygoid origin. 3. The internal pterygoid muscle. 156 AURICULAE GROUP, The inlerjial pterygoid is a thick quadrangular muscle. It arises from the pterygoid fossa, and descends obliquely backwards, to be inserted into the ramus and angle of the lower jaw : it resembles the masseter in appearance and direction, and was named by Winslow the internal masseter. Relations. — By its external surface with the internal pterygoid, the inferior maxillary nerve and its branches, the internal maxillary artery and branches, the internal lateral ligament, and the ramus of the lower jaw. By its internal surface with the tensor palati and superior constrictor of the pharynx with its fascia ; and by its pos- terior border with the parotid gland. Actions. — The maxillary muscles are the active agents in masti- cation, and form an apparatus beautifully fitted for that office. The buccinator circumscribes the cavity of the mouth, and with the aid of the tongue keeps the food under the immediate pressure of the teeth. By means of its connexion with the superior constrictor, it shortens the cavity of the pharynx, from before backwards, and becomes an important auxiliary in deglutition. The temporal, the masseter, and the internal pterygoid are the bruising muscles, draw- ing the lower jaw against the upper with great force. The two latter, by the obliquity of their direction, assist the external ptery- goid in grinding the food by carrying the lower jaw forward upon the upper ; the jaw being brought back again by the deep portion of the masseter and posterior fibres of the temporal. The whole of these muscles, acting in succession, produce a rotatory movement of the teeth upon each other, which, with the direct action of the lower jaw against the upper, effects the proper mastication of the food. 8. Auricular Group. — Attollens aurem, Attrahens aurem, Retrahens aurem. Dissection. — The three small muscles of the ear may be exposed by removing a square of integument from around the auricula. This operation must be performed with care, otherwise the muscles, which are extremely thin, will be raised with the superficial fascia. The attollens aurem (superior auris), the largest of the three, is a thin triangular plane of muscular fibres arising from the edge of the aponeurosis of the occipito-frontalis, and inserted into the upper part of the concha. It is in relation by its external surface with the integument, and by the internal with the temporal aponeurosis. The attrahens aurem (anterior auris,) also triangular, arises from the edge of the aponeurosis of the occipito-frontalis ; and is inserted into the anterior part of the concha, covering in the anterior and posterior temyjoral arteries. It is in relation by its external surface with the integument; and by the internal with the temporal aponeurosis and with tiie temporal artery and veins. MUSCLES OF THE NECK. 157 The retrahens aurem (posterior auris,) arises by three or four muscular shps from the mastoid process. They are inserted into the posterior surface of the concha. It is in relation by its external surface with the integument, and by its internal surface with the mastoid portion of the temporal bone. Actions. — The muscles of the auricular region possess but little action in man ; they are ■ the analogues of important muscles in brutes. Their use is sufficiently explained by their names. Muscles of the JVeck. — The muscles of the neck may be arranged into eight groups corresponding with the natural divisions of the region; they are the — 1. Superficial group. 2. Depressors of the os hyoides and larynx. 3. Elevators of the os hyoides and larynx. 4. Lingual group. 5. Pharyngeal group. 6. Soft palate group. 7. Prevertebral group. 8. Proper muscles of the larynx. And each of these groups consists of the following muscles : — viz. 1. Superficial Group. Platysma myoides, Sterno-cleido-mastoideus. 2. Depressors of the os hyoides and larynx. Sterno-hyoideus, Sterno-thyroideus, Thyro-hyoideus, Omo-hyoideus. 3. Elevators of the os hyoides and larynx. Digastricus, Stylo-hyoideus, Mylo-hyoideus, Genio-hyoideus, Genio-hyo-glossus. 4. Muscles of the tongue. Genio-hyo-glossus, Hyo-glossus, Lingualis, Stylo-glossus, Palato-glossus.* 5. Muscles of the Pharynx. Constrictor inferior, Constrictor medius, Constrictor superior, Stylo-pharyngeus, Palato-pharyngeus. 6. Muscles of the soft Palate. Levator palati, Tensor palati, Azygos uvulae, Palato-glossus,* Palato-pharyngeus, 7. Prcxvertehral Group. Rectus anticus major. Rectus anticus minor, Scalenus anticus. Scalenus posticus, Longus colli. 8. Muscles of the Larynx. Crico-thyroideus, Crico-aryttenoideus, posticus, Crico-aryt£enoideus, lateralis, Thyro-arytasnoideus, Aryteenoideus. Described by Horner as the Constrictor isthmii faucium. — G. 158 STERNO-CLEIDO-MASTOIDEUS. Dissection. — The dissection of the neck should be commenced by making an incision along the middle line of the neck from the chin to the sternum, and bounding it superiorly and inferiorly by two transverse incisions ; the superior one being carried along the margin of the lower jaw, and across the mastoid process to the tubercle on the occipital bone, the inferior one along the clavicle to the acromion process. The square flap of integument thus included should be turned back from the entire side of the neck, which brings into view the superficial fascia, and on the removal of a thin layer of superficial fascia the platysma myoides will be exposed. The platysma myoides ("rrXarvs, (xuj, slSog, broad muscle-like lamella,) is a thin plane of muscular fibres, situated between the two layers of the superficial cervical fascia ; it arises from the integument over the pectoralis major and deltoid muscles, and passes obliquely up- wards and inwards along the side of the neck to be inserted into the side of the chin, oblique line of the lower jaw, the angle of the mouth, and into the cellular tissue of the face. The most anterior fibres are continuous beneath the chin, with the muscle of the op- posite side ; the next interlace with the depressor anguh oris, and depressor labii inferioris, and the most posterior fibres are disposed in a transverse direction across the side of the face, arising in the cellular tissue covering the parotid gland, and inserted into the angle of the mouth, constituting the risorius Santorini. The entire muscle is analogous to the cutaneous muscle of brutes, the pannicu- lus carnosus. Relations. — By its external surface with the integument, with which it is closely adherent below, but loosely above. By its internal surface, below the clavicle, with the pectoralis major and deltoid ; in the neck, with the external jugular vein and deep cervical fascia ; on the face, with the parotid gland, the masseter, the facial artery and vein, the buccinator, the depressor anguli oris, and the depres- sor labii inferioris. On raising the platysma throughout its whole extent, the sterno- mastoid is brought into view. The sterno-cleido mastoid is the largest oblique muscle of the ■neck, and is situated between two layers of the deep cervical fascia. It arises as implied in its name from the sternum and clavicle (3cXsi(5iov), and passes obliquely upwards and backwards to be inserted into the mastoid process and into the superior curved line of the occipital bone. The sternal portion arises by a rounded tendon, increases in breadth as it ascends, and spreads out to a considerable extent at its insertion. The clavicular portion is broad and fleshy, and separate from the sternal portion below, but becomes gradually blended with its posterior surface as it ascends. Relations. — By its superficial surface with the integument, the platysma myoides, the external jugular vein, superficial branches of the anterior cervical plexus of nerves, and the anterior layer of the deep cervical fascia. By its deep surface with the deep layer of the cervical fascia ; with the sterno-clavicular articulation, the sterno-hyoid, stcrno-thyroid, omo-hyoid, scaleni, levator anguli STEKNO-CLEIDO-MASTOIDEUS. 159 scapulae, splenii, and posterior belly of the digastric muscle ; with the phrenic nerve, and the posterior, and supra-scapular artery ; with the deep lymphatic glands, the sheath of the common carotid arteiy and internal jugular vein, the descendens noni nerve, the external carotid artery and its posterior branches, the commencement of the internal carotid artery ; with the cervical plexus of nerves, the pneumogastric, the spinal accessory, the hypoglossal, the sympa- thetic and the facial nerve, and with the parotid gland. It is pierced on this aspect by the spinal accessory nerve and by the Fig. 71 * branches of the mastoid artery. The anterior border of the muscle is the posterior boundary of the great anterior triangle, the other two boundaries being the middle line of the neck in front, and the lower border of the jaw above. It is the guide to the operations for the ligature of the common carotid artery and arteria innomi- nata, and for ojsophagotomy. The posterior border is the anterior boundary of the great posterior triangle ; the other two boundaries being the anterior border of the trapezius behind, and the clavicle below. Actions. — The platysma produces a muscular traction on the integument of the neck, which prevents it from falling so flaccid in * The muscles of the anterior aspect of the neck ; on the left side the superficial muscles are seen, and on the right the deep. 1. The posterior belly of the digastricus muscle. 2. Its anterior belly. The aponeurotic pulley, through which its tendon is seen passing, is attached to the body of the os hyoides 3. 4. The stylo-hyoidcus mus- cle, transfixed by the posterior belly of the digastricus. 5, The mylo-liyoideus. 6. The genio-hyoideus. 7. The tongue. 8. The hyo-glossus. 9. The stylo-glossus. 10. The stylo-pharyngeus. 11. The sterno-mastoid muscle. 12. Its sternal origin. 13. Its clavicular origin, 14. The sterno-hyoid. 15. The stcrno-thyroid of the right side. 16. The thyro-hyoid. 17. The hyoid portion of the omo-hyoid. 18, 18. Its scapular portion ; on the left side, the tendon of the muscle is seen to be bound down by a portion of the deep cervical fascia. 19. The clavicular portion of the trapezius. 20. The scalenus anticus, of the right side. 21. The scalenus posticus. 160 DEPRESSORS OF THE OS HYOIDES AND LAKYMX. old persons as would be the case if the extension of the skin were the mere result of elasticity. It draws also upon the angle of the mouth, and is one of the depressors of the lower jaw. The trans- verse fibres draw the angle of the mouth outwards and slightly upwards'. The sterno-mastoid muscles are the great anterior mus- cles of connexion between the thorax and the head. Both mus- cles acting together will bow the head directly forwards, The clavicular portions, acting more forcibly than the sternal, give stability and steadiness to the head in supporting great weights. Either muscle acting single would draw the head towards the shoulder of the same side, and carry the face towards the opposite side. Second Group. — Depressors of the Os Hyoides and Larynx. Sterno-hyoid, Sterno-thyroid, Thyro-hyoid, Omo-hyoid. Dissection. — These muscles are brought into view by removing the deep fascia from off the front of the neck between the two sterno-mastoid muscles. The omo-hyoid to be seen in its whole extent requires that the sterno-mastoid muscle be divided from its origin and turned aside. The sterno-hyoideus is a narrow riband-like muscle, arising from the posterior surface of the jRrst bone of the sternum and inner ex- tremity of the clavicle. It is inserted into the lower border of the body of the os hyoides. The sterno-hyoidei are separated by a con- siderable interval at the root of the neck, but approach each other as they ascend ; they are frequently traversed by a tendinous inter- section. Relations. — By its external surface with the deep cervical fascia, the platysma myoides and sterno-mastoid muscle; by its internal surface with the sterno-thyroid and thyro-hyoid muscle, the thyroid gland, and the superior thyroid artery. The sterno-thyroideus, broader than the preceding beneath which it lies, arises from the posterior surface of the upper bone of the sternum, and from the cartilage of the first rib ; and is inserted into the oblique line, on the great ala of the thyroid cartilage. The inner borders of these muscles lie in contact along the middle line, and they are generally marked by a tendinous intersection at their lower part. Relations. — By its external surface, with the sterno-hyoid, omo- hyoid, and sterno-mastoid muscle ; by its internal surface, with the trachea and inferior thyroid veins, with the thyroid gland, the lower part of the larynx, the sheath of the common carotid artery and internal jugular vein, with the subclavian vein and vena innominata, and on the right side with the arteria innominata. The middle thy- roid vein lies along its inner border. The Ihyro-hyoideus is tlic continuation upwards of the sterno-thy- roid muscle. It arises from the oblique line on the thyroid cartilage. OMO-HYOIDEUS ELEVATORS OF THE OS HYOIDES. 161 and is inserted into the lower border of the body and great cornu of the OS hyoides. Relations. — By its external surface with the sterno-hyoid and omo- hyoid muscle; by its internal surf ace with the great ala of the thy- roid cartilage, thethyro-hyoidean membrane and the superior laryn- geal artery and nerve.^ The omo-hyoideus (uf^og, shoulder) is a double-bellied muscle pass- ing obliquely across the neck from the scapula to the os hyoides; it forms an obtuse angle behind the sterno-mastoid muscle, by means of a process of the deep cervical fascia which is connected to the inner border of its tendon. It arises from the upper border of the scapula, and from the transverse ligament of the supra-scapular notch, and is inserted into the lower border of the body of the os hyoides. Relations. — By its superficial surface with the trapezius, the sub- clavius and clavicle, the deep cervical fascia and platysma myoides, the sterno-mastoid, and the integument. By its dee-p surface with the brachial plexus, the scaleni muscles, the phrenic nerve, the sheath of the common carotid artery and jugular vein, the descendens noni nerve, and the sterno-thyroid, and thyro-hyoid muscle. The scapu- lar portion of the muscle divides the great posterior triangle into a superior or occipital triangle ; and an inferior or subclavian triangle, which contains the subclavian artery and brachial plexus of nerves ; the other two boundaries of the latter being the sterno-mastoid in front and the clavicle below. The hyoid portion of the muscle, divides the great anterior triangle into an inferior carotid triangle situated below the muscle, and into a superior triangle which lies above the muscle and is again subdivided by the digastricus muscle into the submaxillary triangle and the superior carotid triangle. The other two boundaries of the inferior carotid triangle, are the middle line of the neck in front and the anterior border of the sterno-mas- toid behind. The other boundaries of the superior carotid triangle are the posterior belly of the digastricus muscle above and the an- terior border of the sterno-mastoid behind. Actions. — The four muscles of this group are the depressors of the OS hyoides and larynx. The three former drawing these parts downwards in the middle line, and the two omo-hyoidei regulating their traction to the one or other side of the neck, according to the position of the head. The omo-hyoid muscles by means of their connexion with the cervical fascia are rendered tensors of that por- tion of the deep cervical fascia which covers in the lower part of the neck, between the two sterno-mastoid muscles. Third Group. — Elevators of the Os Hyoides. Digastricus. Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus. 21 162 ^ DIGASTEICUS STYLO-HYOIDEUS. Dissection. — These are best dissected by placing a high block be- neath the neck, and throwing the head backwards. The integument has been already dissected away, and the removal of the cellular tissue and fat brings them clearly into view. The digastricus {Slg, twice, yadrrj^ belly) is a small muscle situated immediately beneath the side of the body of the lower jaw ; it is fleshy at each extremity, and tendinous in the middle. It arises from the digastric fossa, upon the inner side of the mastoid process of the temporal bone, and is inserted into a depression on the inner side of the lower jaw, close to the symphysis. The middle tendon is held in connexion with the body of the os hyoides by an aponeu- rotic loop, through which it plays as through a pulley; the loop being lubricated by a synovial membrane. A thin layer of aponeu- rosis is given off from the tendon of the digastricus at each side, which is connected with the body of the os hyoides and forms a strong plane of fascia between the anterior portions of the two mus- cles. This fascia is named the supra-hyoidean. Relations. — By its superficial surface with the platysma myoides, the sterno-mastoid, the anterior fasciculus of the stylo-hyoid muscle, the parotid gland, and submaxillary gland. By its deep surface with the styloid muscles, the hyo-glossus, the mylo-hyoid muscle, the external carotid artery, the lingual and the facial arteries, the internal carotid artery, the jugular vein, and the hypoglossal nerve. The digastric muscle forms the two inferior boundaries of the sub- maxillary triangle, the superior boundary being the side of the body of the lower jaw. In the posterior half of the submaxillary triangle is situated the submaxillary gland and the facial artery. The stylo-hyoideus is a small and slender muscle situated in immediate relation with the posterior belly of the digastricus muscle, being pierced by its tendon. It arises from the middle of the styloid process, and is inserted into the body of the os hyoides near to the middle hne. Relations. — By its superficial surface with the posterior belly of the digastricus, the parotid gland and submaxillary gland ; its deep relations are similar to those of the posterior belly of the digastricus. The digastricus and stylo-hyoideus must be removed from their connexion with the lower jaw and os hyoides, and turned aside in order to see the next muscle. The myh-hyoideus (i^^vXyj, mola, i. e. attached to the molar ridge of the lower jaw) is a broad triangular plane of muscular fibres, forming, with its fellow of the opposite side, the inferior wall or floor of the mouth. It arises from the molar ridge on the lower jaw, and proceeds obliquely inwards to be inserted into the raphe of the two muscles and into the body of the os hyoides ; the raph^ is sometimes deficient at its anterior part. Relations. — By its superficial or inferior surface, with the pla- tysma myoides, the digastricus, the supra-hyoidean fascia, the sub- maxillary gland and the submental artery. By its deep or superior MUSCLES OF THE TONGUE. 163 surface, with the genio-hyoideus, the genio-hyo-glossus, the hyo- glossus, the stylo-glossus, the gustatory nerve, the hypo-glossal nerve, Wharton's duct, the subUngual gland, and the mucous mem- brane of the floor of the mouth. After the mylo-hyoideus has been examined, it should be cut away from its origin and insertion, and completely removed. The view of the next muscles would also be greatly improved by dividing the lower jaw a little to one side of the symphysis, and drawing it outwards, or by removing it altogether if the ramus have been already cut across in dissecting the internal pterygoid muscle. The tongue may then be drawn out of the mouth by means of a hook. The genio-hyoideus (jivzm, the chin) arises from a small tubercle upon the inner side of the symphysis of the lower jaw, and is inserted into the upper part of the body of the os hyoides. It is a short and slender muscle, very closely connected with the border of the fol- lowing. Relations. — By its superficial or inferior surface, with the mylo- hyoideus ; by the deep or superior surface with the lower border of the genio-hyo-glossus. The genio-hyo-glossus (yXutftfa, the tongue) is a triangular muscle, narrow and pointed at its origin from the lower jaw, broad and fan-shaped at its attachment to the tongue. It arises from a tubercle immediately above that of the genio-hyoideus, and spreads out to be inserted into the whole length of the tongue, from its base to the apex, and into the body of the os hyoides. Relations. — By its inner surface with its fellow of the opposite side. By its outer surface with the mylo-hyoideus, the hyo-glossus, the stylo-glossus, lingualis, the subhngual gland, the lingual artery and the hypo-glossal nerve. By its upper border with the mucous membrane of the floor of the mouth, by the side of the frsenum linguae ; and by the lower border with the genio-hyoideus. Actions. — The whole of this group of muscles acts upon the os hyoides, when the lower jaw is closed, and upon the lower jaw when the os hyoides is drawn dowaiwards, and fixed by the depressors of the os hyoides and larynx. The genio-hyo-glossus is, moreover, a muscle of the tongue ; its action upon that organ shall be considered with the next group. Fourth Group. — Muscles of the Tongue. Genio-hyo-glossus, Hyo-glossus, Lingualis, Stylo-glossus, Palato-o;lossus. These are already exposed by the preparation we have just made; there remains, therefore, only to dissect and examine them. 164 HYO-GLOSSUS LINGUALIS. i^,/ The genio-hyo-glossus, the first of these muscles, has been described with the last group. The hijo-glossris is a square-shaped plane of muscle, arising from the whole length of the great cornu and from the body of the os hyoides,and inserted between the stylo-glossus and lingualis into the side of the tongue. The ^ig- ■^'2* direction of the fibres of that portion of the muscle which arises from the body is obliquely backwards ; and that from the great cornu obliquely forwards ; hence they are described by Al- binus as two distinct muscles, under the names of the basio- glossus, and cerato-glossus, to which he added a third fasci- culus, arising from the lesser cornu, and spreading along the side of the tongue, the chon- dro-glossus. The basio-glossus slightly overlaps the cerato- glossus at its upper part, and is separated from it by the trans- verse portion of the stylo-glossus. Relations. — By its external surface with the digastric mus- cle, the stylo-hyoideus, stylo-glossus and mylo-hyoideus ; with the gustatory nerve, the hypoglossal nerve, Wharton's duct and the sublingual gland. By its internal surface with die middle con- strictor of the pharynx, and Hngualis, the genio-hyo-glossus, the lingual artery, and the glosso-pharyngeal nerve. The lingualis. — The fibres of this muscle may be seen towards the apex of the tongne, issuing from the interval between the hyo- glossus and genio-hyo-glossus ; it is best examined by removing the preceding muscle. It consists of a small fasciculus of fibres, running longitudinally from the base, where it is attached to the os hyoides, to the apex of the tongue. It is in relation by its under surface with the ranine artery. * The styloid muscles and the muscles of the tongue. 1. A portion of the temporal bone of the left side of the skull, including the styloid and mastoid processes, and the meatus auditorius cxternus. 2, 2. The right side of the lower jaw, divided at its sym- physis ; the left side having been removed. 3. The tongue. 4. The genio-hyoideus muscle. .5. The genio-hyo-glossus. 6. The hyo-glossus muscle ; its basio-glossus por- tion. 7. Its cerato-glossus portion. 8. The anterior fibres of the lingualis issuing from between the hyo-glossus and genio-hyo-glossus. 9. The stylo-glossus muscle, with a small portion of the stylo-maxillary ligament. 10. The stylo-hyoid. 11. The stylo-pharyngeus muscle. 12. The os hyoides. 13. The thyro-hyoidean membrane. 14. The thyroid cartilage. 1.5. The thyro-hyoideus muscle arising from the oblique line on the thyroid cartilage. 16. The cricoid cartilage. 17. The crico-lhyroidean rncmbranp, through which the operation of laryngotomy is performed. 18. The trachea. If). The commencement of the oesophagus. MUSCLES OF THE PHARYNX. 165 The stylo-glossus arises from the apex of the styloid process, and from the stylo-maxillary ligament ; and divides upon the side of the tongue into two portions, one transverse, vv^hich passes transversely invs^ards between the two portions of the hyo-glossus, and is lost among the transverse fibres of the substance of the tongue, and another longitudinal, which spreads out upon the side of the tongue as far as its tip. Relations. — By its external surface with the internal pterygoid muscle, the gustatory nerve, the parotid gland, sublingual gland, and the mucous membrane of the floor of the tongue. By its internal surface with the tonsil, the superior constrictor muscle of the pharynx, and the hyo-glossus muscle. The palaio-glossus* passes between the soft palate, and the side of the base of the tongue, forming a projection of the mucous mem- brane, which is called the anterior pillar of the soft palate. Its fibres are lost superiorly among the muscular fibres of the palato- pharyngeus, and inferiorly among the fibres of the stylo-glossus upon the side of the tongue. This muscle with its fellow constitutes the constrictor isthmii faucium. Actions, — The genio-hyo-glossus muscle effects several movements of the tongue, as might be expected from its extent. When the tongue is steadied and pointed by the other muscles, the posterior fibres of the genio-hyo-glossus would dart it from the mouth, while its anterior fibres would restore it to its original position. The whole length of the muscle acting upon the tongue, would render it concave along the middle line, and form a channel for the current of fluid towards the pharynx, as in sucking. The apex of the tongue is directed to the roof of the mouth, and rendered convex from before backwards by the linguales. The hyo-glossi, by drawing down the sides of the tongue, render it convex along the middle line. It is drawn upwards at its base by the palato-glossi, and backwards or to either side by the stylo-glossi. Thus the whole of the complicated movements of the tongue may be explained, by reasoning upon the direction of the fibres of the muscles, and their probable actions. Fifth Group. — Muscles of the Pharynx. Constrictor inferior. Constrictor medius, Constrictor superior, Stylo-pharyngeus, Palato-pharyngeus. Dissection. — To dissect the pharynx, the trachea and oesophagus are to be cut through at the lower part of the neck, and drawn upwards by dividing the loose cellular tissue which connects the * Called also constrictor isthmii faucium. — G. 166 CONSTRICTORS OF THE PHARYNX. pharynx to the vertebral column. The saw is then to be applied behind the styloid processes, and the base of the skull sawn through. The vessels and loose structures should be removed from the prepa- ration, and the pharynx stuffed with tow or wool for the purpose of distending it, and rendering the muscles more easy of dissection. The pharynx is invested by a proper pharyngeal fascia. The constrictor inferior, the thickest of the three muscles of this class, arises from the upper rings of the trachea, from the cricoid and the side of the thyroid cartilage. Its fibres spread out and are inserted into the fibrous raphe of the middle of the pharynx, the inferior fibres being almost horizontal, and the superior oblique, and overlapping the middle constrictor. Relations. — By its external surface Avith the anterior surface of the vertebral column, the longus colli, the sheath of the common carotid artery, the sterno-thyroid muscle, the thyroid gland, and some lymphatic glands. By its internal surface with the middle constrictor, the stylo-pharyngeus, the palato-pharyngeus, and the mucous membrane of the pharynx. By its lower border, near to the cricoid cartilage, it is in relation with the recurrent nerve ; and by the upper border with the superior laryngeal nerve. This muscle must be removed before the next can be examined. The constrictor medius arises from the great cornu of the os hy- oides, from the lesser cornu, and from the stylo-hyoidean ligament. It radiates from its origin upon the side of the pharynx, the lower fibres descending and being overlapped by the constrictor inferior, and the upper fibres ascending so as to cover in the constrictor superior. It is inserted into the raphe and by a fibrous aponeurosis into the basilar process of the occipital bone. Relations. — By its external surf ace -with, the vertebral column, the longus colli, rectus anticus major, the carotid vessels, infeiior con- strictor, hyo-glossus muscle, lingual artery, pharyngeal plexus of nerves, and some lymphatic glands. By its internal surface, with the superior constrictor, stylo-pharyngeus, palato-pharyngeus, and mucous membrane of the pharynx. The upper portion of this muscle must be turned down, to bring the whole of the superior constrictor into view ; in so doing, the stylo-pharyngeus muscle will be seen passing beneath its upper border. The constrictor superior is a thin and quadrilateral plane of muscu- lar fibres arising from the extremity of the molar ridge of the lower jaw, from the ptery go-maxillary ligament, and from the lower half of the internal pterygoid plate, and inserted into the raphe and basilar process of the occipital bone. Its superior fibres are arched and leave an interval between its upper border and the basilar pro- cess which is deficient in muscular fibres, and it is overlapped in- feriorly by the middle constrictor. Between the side of the pharynx and the ramus of the lower jaw is a triangular interval, the maxillo- pharyngeal space, which is bounded on the inner side by the supe- STYLO-PHARYNGETJS. 167 Fig-. 73* rior constrictor muscle ; on the outer side by the internal pterygoid muscle; and behind by the rectus anticus major and vertebral column. In this space are situated the internal carotid artery, the internal jugular vein, and the glosso-pharyngeal, pneumogastric, spinal accessory, and hypoglossal nerve. Relations. — By its external surface with, the vertebral column and its muscles, behind; with the vessels and nerves contained in the maxil/o-pharyngeal space laterally, the middle constrictor, stylo- pharyngeus, and tensor palati muscle. By its internal surface with the levator palati, palato-pharyngeus, tonsil, and mucous membrane of the pharynx, the pharyngeal fascia being interposed. The stylo-pharyngeus is a long and slender muscle arising from the inner side of the base of the styloid process : it descends between the superior and middle constrictor muscles, and spreads out beneath the mucous membrane of the pharynx, its inferior fibres being inserted into the posterior border of the thyroid cartilage. Relations. — By its external surface with the stylo-glossus muscle, external carotid artery, parotid gland, and the middle constrictor. By its internal surface with the internal carotid artery, internal jugular vein, superior constric- tor, palato-pharyngeus, and mucous membrane. Along its lower border is seen the glosso-pharyngeal'nerve which crosses it, opposite the root of the tongue. The palato-pharyngeus is described with the muscles of the soft palate. It arises from the soft palate, and is inserted into the inner surface of the pharynx, and posterior border of the thyroid -carti- lage. Actions. — The three constrictor muscles contract upon the morsel of food as soon as it is received by the pharynx, and convey it gradually downwards into the oesophagus. The stylo-pharyngei draw the pharynx upwards and widen it laterally. The palato- pharyngei also draw it upwards, and narrow the opening of the fauces. * A side view of the muscles of the pharynx. 1. The trachea. 2, Tlie cricoid car- tilag^e. 3. The crico-thyroid membrane. 4. The thyroid cartilage. 5. The thyro- hyoidean membrane. 6. The os hyoides. 7. The stylo-hyoidean ligament. 8. The (Esophagus. 9. The inferior constrictor. 10. The middle constrictor. 11. The supe- rior constrictor. 12. The stylo-pharyngeus muscle passing down between the superior and middle constrictor. 13. The upper concave border oftlie superior constrictor; at this point the muscular fibres of the pharynx are deficient. 14. The ptery go-maxillary ligament. 15. The buccinator muscle. 16. The orbicularis oris. ]7. The mylo- hyoideus. 168 MUSCLES OF THE SOFT PALATE. Fig. 74.* Sixth, Group. — Muscles of the soft Palate. Levator palati, Tensor palati, Azygos uvulae, Palato-glossus, Palato-pharyngeus. Dissection. — To examine these muscles, the pharnyx must be opened from behind, and the mucous membrane carefully removed from off the posterior surface of the soft palate. The levator palati, a moderately thick muscle, arises from the extremity of the petrous bone and from the posterior and inferior aspect of the Eustachian tube, and passing down by the side of the posterior nares spreads out in the structure of the soft palate as far as the middle line. Relations. — Externally with the tensor palati and superior con- strictor muscle ; internally and posteriorly with the mucous mem- brane of the pharynx and soft palate ; and by its lower border with the palato-pharyngeus. This muscle must be turned down from its origin on one side, and removed, and the superior con- strictor dissected away from its pterygoid origin, to bring the next muscle into view. The tensor palati (circumflexus) is a slender and flattened muscle ; it arises from the scaphoid fossa at the base of the internal pterygoid plate and from the anterior aspect of the Eustachian tube. It descends to the hamular process around which it turns, and expands into a tendinous aponeurosis, which is inserted into the transverse ridge on the horizontal portion of the palate bone, and into the raphe. Relations. — By its external surface with the internal pterygoid *The muscles of the soft palate. 1. A transverse section through the middle of the base of the skull, dividing the basilar process of the occipital bone in the middle line, and the petrous portion of the temporal bone at each side. 2. The vomer covered by mucous membrane and separating the two posterior nares. 3, 3. Eustachian tubes. 4. The levator palati muscle of the left side ; the right has been removed. 5. The ha- mular process of the internal pterygoid plate of the left side, around which the apo- ncuorosis of the tensor palati is seen turning. G. The pterygo-maxillary ligament. 7. The superior constrictor muscle of the left side, turned aside. 8. The ar.ygos uvulas muscle, fj. The internal pterygoid plate. 10. The external pterygoid plate. 11. The tensor palati muscle. 12. Its aponeurosis expanding in the structure of the soft palate. 13. The external pteiygoid muscle. 14. The attachments of two pairs of muscles cut short ; the superior pair belong to the genio-hyo-glossi muscles ; the inferior pair, to the genio-hyoidei. 1.5. The attachment of the mylo-hyoideus of one side and part of the opposite. 16. The anterior attachments of the digastric muscles. 17. The de- pression on the lower jaw corresponding with the submaxillary gland. The depression above the mylo-hyoideus, on which the number 15 rests, corresponds with the sub- lingual gland. PALATO-GLOSSUS PAL ATO- PHAR YNGEUS . 169 muscle ; by its internal surface with the levator palati, internal pterygoid plate and superior constrictor. In the soft palate, its ten- dinous expansion is placed in front of the other muscles and in con- tact with the mucous membrane. The azygos uvula, is not a single muscle, as might be inferred from its name, but a pair of small muscles placed side by side in the middle line of the soft palate. They arise from the spine of the palate bone, and are inserted into the uvula. By their anterior surface they are in contact with the tendinous expansion of the levatores palati, and by the posterior with the mucous membrane. The two next muscles are brought into view throughout the whole of their extent, by raising the mucous membrane from off the pillars of the soft palate at each side. The palaio-glossus (constrictor isthmii faucium) is a small fasci- culus of fibres that arises in the soft palate, and descends to be inserted into the side of the tongue. It is the projection of this small muscle covered by mucous membrane, that forms the anterior pillar of the soft palate. It has been named constrictor isthmii fau- cium from a function it performs in common with the palato- pharyngeus, viz. of constricting the opening of the fauces. Tiie palato-pharyngeus forms the posterior pillar of the fauces ; it arises by an e:^panded fasciculus from the lower part of' the soft palate where its fibres are continuous with those of the muscle of the opposite side ; and is inserted into the posterior border of the thyroid cartilage. This muscle is broad above where it forms the whole thickness of the lower half of the soft palate, narrow in the posterior pillar, and again broad and thin in the pharynx where it spreads out previously to its insertion. ' Relations. — In the soft palate it is in relation with the mucous membrane both by its anterior and posterior surface ; above, with the muscular layer formed by the levator palati, and below with the mu- cous glands situated along the margin of the arch of the palate. In the posterior pillar of the palate, it is surrounded for two-thirds of its extent by mucous membrane. In the pharynx, it is in relation by its outer surface with the superior and middle constrictor muscles, and by its inner surface with the mucous membrane of the pharynx, the pharyngeal fascia being interposed. Actions. — The azygos uvulce shortens the uvula. The levator palati raises the soft palate, while the tensor spreads it out laterally so as to form a septum between the pharynx and posterior nares during deglutition. Taking its fixed point from below, the tensor palati will dilate the Eustachian tube. The palato-glossus and pharyngeus constrict the opening of the fauces, and by drawing down the soft palate they serve to press the mass of food from the dorsum of the tongue into the pharynx. 22 170 PR^VEKTEBRAL MUSCLES. Seventh Group. — PrcBvertebral Muscles. Rectus anticus majoi", Rectus anticus minor, Scalenus anticus, Scalenus posticus, Longus colli. Dissection. — These muscles have already been exposed, by the removal of the face from the anterior aspect of the vertebral column ; all that is further needed is the removal of the fascia by which they are invested. The rectus anticus major, broad and thick above, and narrow and pointed below, arises from the anterior tubercles of the trans- verse processes of the third, fourth, fifth, and sixth cervical verte- brae, and is inserted into the basilar process of the occipital bone. Relations. — By its anterior surface with the pharynx, the internal carotid artery, internal jugular vein, superior cervical ganglion, sympathetic nerve, pneumogastric, and spinal accessory nerve. By its posterior surface wi^h the longus colli, rectus anticus minor, and superior cervical vertebree. The rectus anticus minor arises from the anterior border of the lateral mass of the atlas, and is in- ^^' '^^* serted into the basilar process ; its fibres being directed obliquely up- wards and inwards. Relations. — By its anterior surface with the rectus anticus major, and externally with the superior cervical ganglion of the sympathetic. By its posterior surface with the articulation of the condyle of the occipital bone with the atlas, and with the anterior occipito-atloid ligament. The scalenus anticus] is a trian- gular muscle, as its name implies, situated at the root of the neck and appearing like a continuation of the rectus anticus major; it arises from the anterior tubercles of the tej transverse processes of the third, fourth, fifth, and sixth cervical verte- broe, and is inserted into the tubercle upon the inner border of the first rib. * The projvcTtebral group of muscles of the neck. 1. The rectus anticus major muscle. 2. The scalenus anticus. .3. The lower part of the longus colli of the i-ig-ht side ; it is concealed superiorly by the rectus anticus major. 4. The rectus anticus minor. 5. The upper portion of the long-ns colli muf^cle. 6. Its lower portion; the figure rests upon the seventh cervical vertebra. 7. The scalenus posticus. 8. The rectus lateralis of the left side. 9. One of the intertransversales muscles. + Horner describes three scaleni, viz. : anticus, medius, and posticus ; the anticus LONGUS COLLI. 171 Relations. — By its anterior surf ace with the sterno-mastoid and omo-hyoid muscle, with the cervicaHs ascendens, and posterior sca- pular artery, with the phrenic nerve, and with the subclavian vein, by which it is separated from the subclavius muscle and clavicle. By its jjosterior surface with the nerves which go to form the brachial plexus, and below with the subclavian artery. By its inner side it is separated from the longus colli by the vertebral artery. Its relations with the subclavian artery and vein are very impor- tant, the vein being before and the artery behind the muscle.* The scalenus 'posticus arises from the posterior tubercles of all the cervical vertebrte excepting the first. It is inserted by two fleshy slips into the first and second ribs. The anterior of the two slips is very large, and occupies all the surface of the rib between the groove for the subclavian artery and the tuberosity. The pos- terior is small. Hence the scalenus medius and posticus of some anatomists. Relations. — By its anterior surface with the brachial plexus and subclavian artery ; posteriorly with the levator anguli scapula, cer- vicalis ascendens, transversalis colli and sacro-lumbahs ; internally with the first intercostal muscle, the first rib, the inter-transverse muscles, and cervical vertebra; and externally with the sterno- mastoid, omo-hyoid, supra-scapular, and posterior scapular arteries. The longus colli is a long and flat muscle, consisting of two portions. The upper arises from the anterior tubercle of the atlas, and is inserted into the transverse processes of the third, fourth, and fifth cervical vertebra. The loicer portion arises from the bodies of the second and third, and transverse processes of the fourth and fifth, and passes down the neck, to be inserted into the bodies of the three lower cervical and three upper dorsal vertebrse. We should thus arrange these attachments in a tabular form : Origin. Insertion. Upper ? Af] \ -^d, 4th, and 5th transverse portion. 3 ' ' ' \ processes. T ') 2d and 3d bodies C 3 lower cervical vertebree Lower f ^,, „„ , ^,. ,„„„_ _ > 4th and 5th transverse < bodies 3 upper dorsal bodies. > 4m ana om transverse < portion. V / ^ ) processes . . ( In general terms, the muscle is attached to the bodies and trans- verse processes of the five superior cervical vertebrse above, and to the bodies of the three last cervical and three first dorsal below. Relations. — By its anterior surface with the pharynx, oesophagus, the sheath of the common carotid internal jugular vein and pneumo- gastric nerve, the sympathetic nerve, inferior laryngeal nerve, and arising from the fourth, fifth, and sixth ; the medius from all the cervical vertebrse ; and the posticus from the fifth and sixth. I have always had a difficulty in separa- ting the medius and posticus. — G. * In a subject dissected in the school of tlie Middlesex Hospital during the last winter, by Mr. Joseph Rogers, the subclavian artery of the left side was placed with the vein in front of the scalenus anticus muscle. 172 MUSCLES OF THE TRUNK. inferior thyroid artery. By its posterior surface it rests upon the cervical and upper dorsal vertebrae. Actions. — The rectus anticus major and minor preserve the equi- librium of the head upon the atlas ; and acting conjointly with the lonpus colli, they flex and rotate the head and the cervical portion of the vertebral column. The scaleni muscles, taking their fixed point from below, are flexors of the vertebral column ; and, from above, elevators of the ribs, and therefore inspiratory muscles. Eighth Group. — Muscles of the Larynx. These muscles are described with the anatomy of the larynx, in Chapter X. MUSCLES OF THE TRUNK. The muscles of the trunk may be subdivided into four natural groups ; viz. 1. Muscles of the back. 2. Muscles of the thorax. 3. Muscles of the abdomen. 4. Muscles of the perineum. 1. Muscles of the back. — The region of the back, in consequence of its extent, is common to the neck, the upper extremities, and the abdomen. The muscles of which it is composed are numerous, and may be arranged into six layers. First Layer. Transversalis colli, Trapezius, Trachelo-mastoideus, Latissimus dorsi. Complexus. Second Layer. Fifth Layer. Levator anguli scapulae, (Dorsal Group.) Rhomboideus minor, Semi-spinalis dorsi, Rhomboideus major. Semi-spinahs colli. Third Layer. (Cervical Group.) Serratus posticus superior. Rectus posticus major, Serratus posticus inferior, Rectus posticus minor, Splenius capitis, Rectus laterahs, Splenius colli. Obhquus inferior, Fourth Layer. Obhquus superior. (Dorsal Group). ^^^^^ ^^y^""' Sacro lumbalis, Multifidus spinas, Longissimus dorsi, Levatores costarum, Spinalis dorsi. Supra-spinalcs, (Cervical Group.) Inter-spinales, Cervicalis ascendens, Inter-transversales. MUSCLES OF THE BACK. 173 First Layer. Dissection. — The muscles of this layer are to be dissected by making an incision along the middle line of the back, from the tubercle on the occipital bone to the coccyx. From the upper point of this incision carry a second along the side of the neck, to the middle of the clavicle. Inferiorly, an incision must be made from the extremity of the sacrum, along the crest of the ilium, to about its middle. For convenience of dissection, a fourth may be carried from the middle of the spine to the acromion process. The integument and superficial fascia, together, are to be dissected off the muscles, in the course of their fibres, over the whole of this region. The trapezius muscle (trapezium, a quadrangle with unequal sides) arises from the superior curved line or semicircular ridge, of the occipital bone, from the ligamentum nucha;, supra-spinous ligament, and spinous processes of the last cervical and all the dorsal vertebrae. The fibres converge from these various points, and are inserted into the scapular third of the clavicle, the acromion process, and the whole length of the upper border of the spine of the scapula. The inferior fibres become tendinous near to the scapula, and glide over the triangular surface at the posterior extremity of its spine, upon a bursa mucosa. When the trapezius is dissected on both sides, the two muscles resemble a trapezium, or diamond- shaped quadrangle, on the posterior part of the shoulders : hence the muscle was formerly named cucuUaris (cucullus, a monk's cowl.) The cervical and upper part of the dorsal portion of the muscle is tendinous at its origin, and forms, with the muscle of the opposite side, a kind of tendinous ellipse. Relations. — By its superficial surface with the integument and superficial fascia, to which it is closely adherent by its cervical por- tion, loosely by its dorsal portion. By its deep surface, from above downwards, with the complexus, splenius, levator anguli scapulae, supra-spinatus, a small portion of the serratus posticus superior, rhomboideus minor, rhomboideus major, intervertebral aponeurosis which separates it from the erector spinas, and with the latissimus dorsi. The anterior border of the cervical portion of this muscle forms the posterior boundary of the posterior triangle of the neck. The clavicular insertion of the muscle sometimes advances to the middle of the clavicle, or as far as the outer border of the sterno- mastoid, and occasionally it has been seen to overlap the latter. This is a point of much importance to be borne in mind in the operation for ligature of the subclavian artery. The spinal accessory nerve passes beneath the anterior border, near to the clavicle, pre- viously to its distribution to the muscle. The Ugamentum nuchge is a thin cellulo-fibrous layer extended from the tubercle and spine of the occipital bone, to the spinous process of the seventh cervical vertebra, where it is continuous 174 LATISSIMUS DORSI RHOMBOIDETJS MINOR, with the supra-spinous hgament. It is connected with the spinous processes of the rest of the cervical vertebrje, with the exception of the atlas, by means of a small fibrous slip which is sent off by each. It is the analogue of an important elastic ligament in animals. The Utissmus dorsi muscle covers the whole of the lower part of the back and loins. It arises from the spinous processes of the six inferior dorsal vertebrae,* from all the lumbar and sacral spinous processes, from the posterior third of the crest of the ilium, and from the three lower ribs; the latter origin takes place by mus- cular slips, which indigitate with the external oblique muscle of the abdomen. The fibres from this extensive origin converge as they ascend, and cross the inferior angle of the scapula; they then curve around the lower border of the teres major muscle, and terminate in a short quadrilateral tendon,f which lies in front of the tendon of the teres, and is inserted into the bicipital groove. A synovial bursa is interposed between the muscle and the lower angle of the scapula, and another between its tendon and that of the teres major. The muscle frequently receives a small fasciculus from the scapula as it crosses its inferior angle. Relations. — By its superficial surface with the integument and superficial fascia ; the latter is very dense and fibrous in the lumbar region ; and with the trapezius. By its deep surface, from below upwards, with the erector spinee, serratus posticus inferior, inter- costal muscles and ribs, rhomboideus major, inferior angle; of the scapula and teres major. The latissimus dorsi with the teres major forms the posterior border of the axilla. Second Layer. Dissection. — This layer is brought into view by dividing the two preceding muscles near to their insertion, and turning them to the opposite side. The levator anguli scapulce arises by distinct slips, from the pos- terior tubercles of the transverse processes of the four upper cervical vertebrse, and is inserted into the upper angle and posterior border of the scapula, as far as the triangular smooth surface at the root of its spine. Relations. — By its superficial surface with the trapezius, sterno- mastoid, and integument. By its deep surface with the splenius colli, transversahs colli, cervicahs ascendens, scalenus posticus, and serratus posticus superior. The tendons of origin are interposed between the attachments of the scalenus posticus in front and the splenius colli behind. The rhomboideus minor (rhombus, a parallelogram with four equal sides) is a narrow slip of muscle, detached from the rhomboi- * Horner says seven. — G. t A small muscular fasciculus from the pectoralis major is sometimes found connected with this tendon. MUSCLES OF THE BACK. 175 deus major by a slight cellular interspace. It arises from the spi- nous process of the last cervical vertebra and ligamentum nuchas, and is inserted into the edge of the triangular surface, on the pos- terior border of the scapula. Fig. 76.* I ^^^x; * The first and second and part of the third layer of muscles of the back ; the first layer being- shown upon the right, and the second on the left side. 1. The trapezius muscle. 2. The tendinous portion which, with a corresponding portion in the opposite muscle, forms the tendinous ellipse on the back of the neck. 3. The acromion pro- cess and spine of the scapula. 4. The latissimus dorsi muscle . 5. The deltoid. 6. The muscles of the dorsum of the scapula, infra-spinatus, teres minor, and teres major, 7. The external oblique muscle. 8. The gluteus medius. 9. The glutei maximi. 10. The levator anguli scapulae. 11. The rhomboidcus minor. 12. The rhomboideus major. 13. The splenius capitis ; the muscle immediately above, and overlaid by the splcnius, is the complexus. 14. The splenius colli, only partially seen ; the common origin of the_splenius is seen attaclied to the spinous processes below the lower border of the rhomboideus major. 15. The vertebral aponeurosis. 16. The serratus posticus inferior. 17. The supra-spinatus muscle. 18. TJie infra-spinatus. 19. The teres minor muscle. 20. The teres major. 21. The long head of the triceps, passing between the teres minor and major to the upper arm. 22. The serratus magnus, pro- ceeding forwards from its origin at the base of the scapula. 23. The internal oblique muscle. 176 EHOMBOIDEI SERRA.TI. The rliomhoideus major arises from the spinous processes of the four upper dorsal vertebrae and from the supra-spinous hgament ; it is inserted into the posterior border of the scapula as far as its inferior angle. The upper and middle portion of the insertion is effected by means of a tendinous arch. Relations. — By their superficial surface the two rhomboid mus- cles are in relation with the trapezius, and the rhomboideus major with the latissimus dorsi and integument. By their deep' sujfiace they cover in the serratus posticus superior, part of the erector spinse, the intercostal muscles and ribs. Third Layer. Dissection. — The third layer consists of muscles which arise from the spinous processes of the vertebral column, and pass outwards. It is brought into view by dividing the levator anguli scapulae near its insertion, and reflecting the two rhomboid muscles upwards from their insertion into the scapula. The latter should be removed altogether. The serratus posticus superior is situated at the upper part of the thorax ; it arises from the ligamentum nuchas, and from the spinous process of the last cervical and two upper dorsal vertebrae ; it is inserted by four serrations into the upper border of the second, third, fourth, and fifth ribs. Relations. — By its superficial surface with the trapezius, rhom- boideus major and minor, and serratus magnus. By its deep sur- face with the splenius, the upper part of the erector spinae, the intercostal muscles and ribs. The serratus posticus inferior arises from the spinous processes of the two last dorsal and two upper lumbar vertebras, and is inserted by four serrations into the lower border of the four lower ribs. Relations. — By its superficial surface with the latissimus dorsi, its tendinous origin being inseparably connected with the aponeurosis of that muscle. By its deep surface with the aponeurosis of the obli- quus internus, with which it is also closely adherent ; with the erector spinae, the intercostal muscles and lower ribs. The upper border is continuous with a thin tendinous layer, the vertebral aponeurosis. This aponeurosis consists of longitudinal and trans- verse fibres, and extends the whole length of the thoracic region. It is attached mesially to the spinous processes of the dorsal verte- bras, and externally to the angles of the ribs ; superiorly it is con- tinued upwards beneath the serratus posticus superior, with the lower border of which it is sometimes connected. It serves to bind down the erector spinae, and separates it from the superficial muscles. The serratus posticus superior must ha removed from its origin and turned outwards, to bring into view the whole extent of the splenius muscle. The splenius muscle is single at its origin, but divides soon after into two portions, which are destined to distinct insertions. It MUSCLES OP THE BACK. 177 arises from the lower half of the ligamentum nuchas, from the spinous process of the last cervical vertebra, and from the spinous processes of the six upper dorsal* and supra-spinous ligament ; it divides as it ascends the neck into the splenius capitis and colli. The splenius capitis is inserted into the rough surface of the occi- pital bone between the two semicircular ridges, and into the mas- toid portion of the temporal bone. The splenitis colli is inserted into the posterior tubercles of the transverse processes of the three or four upper cervical vertebrae. Relations. — By its superficial surface with the trapezius, sterno- mastoid, levator anguli scapula;, rhomboideus minor and major, and serratus posticus superior. By its deep surface with the spinahs dorsi, longissimus dorsi, semi-spinahs colli, complexus, trachelo-mastoid, and transversalis colli. The tendons of insertion of the splenius colli are interposed between the insertions of the levator anguli scapulae in front, and the transversaUs colli behind. The splenii of opposite sides of the neck leave between them a triangular interval, in which the complexus is seen. Fourth Layer. Dissection. — The two serrati and two splenii must be removed by cutting them away from their origins and insertions, to bring the fourth layer into view. Three of these muscles, viz. sacro-lumbalis, longissimus dorsi, and spinalis dorsi, are associated under the name of erector spinse. They occupy the lumbar and dorsal portion of the back. The remaining four are situated in the cervical region. The sacro-lumbalis and longissimus dorsi arise by a common origin from the posterior third of the crest of the ihum, from the posterior surface of the sacrum, and from the lumbar vertebrae: opposite the last rib a hne of separation begins to be perceptible between the two muscles. The sacro-lumhalis is inserted by sepa- rate tendons into the angles of the six lower ribs. On turning the muscle a little outwards, a number of tendinous sHps will be seen taking their orgin from the ribs, and terminating in a muscular fasciculus, by which the sacro-lumbalis is prolonged to the upper part of the thorax. This is the musculus accessorius ad sacro-lum- balem : it arises from the angles of the six lower ribs, and is inserted by separate tendons into the angles of the six upper ribs. The longissimus dorsi is inserted into all the ribs, between their tubercles and angles.f The spinalis dorsi arises from the spinous processes of the two upper lumbar and two lower dorsal vertebrae, and is inserted into the spinous processes of all the upper dorsal vertebrae ; the two muscles form an ellipse, which appears to enclose the spinous pro- cesses of all the dorsal vertebrae. * Horner makes it to arise but from four dorsal vertebras. — G. t It is also inserted into the ends of the transverse processes of all the dorsal verte- brae. — G, 23 178 FOURTH LAYER. Fiff. 77 * i^t Relations. — The erector spinse muscle is in relation by its super- ficial surface (in the lumbar region) with the conjoined aponeurosis of the transversalis and internal oblique muscle, which separates it from the apo- neurosis of the serratus posticus inferior, and longissimus dorsi; (in the dorsal region) with the vertebral aponeurosis, which separates it from the latissimus dorsi, trapezius, and serratus posticus superior, and with the splenius. By its deep surface (in the lumbar region) with the multifidus spinoe, transverse processes of the lumbar vertebras, and with the middle layer of the aponeurosis of the transversalis abdominis, which separates it from the quadratus lumborum ; (in the dorsal region) with the multifidus spinse, semi-spinalis dorsi, levatores costarum, intercostal muscles, and ribs as far as their angles. Internally or mesially with the multifidus spinse, and semi-spinalis dorsi, which separate it from the spinous processes and arches of the vertebrae. The two layers of aponeurosis of the transversalis abdominis, together with the spinal column in the lumbar region, and the vertebral aponeurosis with the ribs and spinal column in the dorsal region, form a complete osseo-aponeurotic sheath for the erector spinas. Cervical Group. — The cervicalis as- cendensf is the continuation of the sacro- lumbalis upwards into the neck. It arises from the angles of the four upper ribs, and is inserted by slender tendons into the posterior tubercles of the transverse processes of the four lower cervical vertebra;. Relations. — By its superficial surface with the levator anguli sca- pulae ; by its deep surface with the upper intercostal muscles and ribs, and with the intertransverse muscles ; externally with the * The fourth and fifth, and part of the sixth layer of the muscles of the back. 1. The common origin of the erector spinoe muscle. 2. The sacro-lumbalis. 3. The longissi- mus dorsi. 4. The spinalis dorsi. 5. The cervicalis ascendcns. 6. The transversalis colli. 7. The trachclo-mastoideus. 8. The complcxus. 9. The transversalis colli, showing- its origin. 10. The semispinalis dorsi. 11. The semjspinalis colli. 12. The rectus posticus minor. 13. The rectus posticus major. 14. The obliquus superior. 1.5. The obliquus inferior. Ifi. The multifidus spina3. 17. The levatores costarum. 18. Intertransversales. 19. The quadratus lumborum. + Called commonly the cervicalis desccndens. — G. MUSCLES OF THE BACK. 179 scalenus posticus ; and internally with the transversalis colli. The tendons of insertion are interposed between the attachments of the scalenus posticus and transversalis colli. The transversalis colli would appear to be the continuation up- wards into the neck of the longissimus dorsi ; it arises from the transverse processes of the third, fourth, fifth, and sixth dorsal ver- tebrse, and is inserted into the posterior tubercles of the transverse processes of the four or five inferior cervical vertebrae. Relations. — By its superficial surface with the levator anguli sca- pulae, splenius and longissimus dorsi. By its deep surface with the complexus, trachelo-mastoideus and vertebras ; externally with the musculus accessorius ad sacro-lumbalem, and cervicalis ascendens; internally with the trachelo-mastoideus and complexus. The tendons of insertion of this muscle are interposed between the tendons of in- sertion of the cervicalis ascendens on the outer side, and of origin of the trachelo-mastoid on the inner side. The trachelo-mastoid is likewise a continuation upwards from the longissimus dorsi. It is a very slender and delicate muscle, arising from the transverse processes of the four upper dorsal, and four lower cervical vertebrse, and inserted into the mastoid process to the inner side of the digastric fossa. Relations. — The same as those of the preceding muscle, except- ing that it is interposed between the transversahs colli and the com- plexus. Its tendons of attachment are the most posterior of those which are connected with the posterior tubercles of the transverse processes of the cervical vertebrae. The complexus is a large muscle, and with the splenius forms the great bulk of the back of the neck. It crosses the direction of the splenius, arising from the transverse processes of the four upper dorsal,* and from the transverse and articular processes of the four lower cervical vertebrae, and is inserted into the rough surface on the occipital bone between the two curved lines, near to the occipital spine. A portion of the complexus muscle is named hiventer cervicis, from consisting of a central tendon, with two fleshy bellies. Relations. — By its superficial surface with the trapezius, splenius, trachelo-mastoid, transversalis colli, and longissimus dorsi. By its deep surface with the semi-spinahs dorsi and colli, the recti and obliqui. It is separated from its fellow of the opposite side by the iigamentum nuchae, and from the semi-spinalis colli by the profunda cervicis artery, and princeps cervicis branch of the occipital, and by the posterior cervical plexus of nerves. Fifth Layer. Dissection. — The muscles of the preceding layer are to be re- moved by dividing them transversely through the middle, and turn- * Horner describes its origin from seven dorsal and four cervical. — G. 180 FIFTH LAYER. ing one extremity upwards, the other downwards. In this way the whole of the muscles of the fourth layer may be got rid of, and the remaining muscles of the spine brought into a state to be examined. The semi-spinales muscles are connected with the transverse and spinous processes of the vertebras, spanning one-half of the vertebral column, hence their name semi-spinales. The semi-spinalis dorsi arises from the transverse processes of the six lower dorsal vertebrae, and is inserted into the spinous processes of the four upper dorsal, and two lower cervical vertebrae. The semi-spinalis colli arises from the transverse processes of the four upper dorsal vertebrae, and is inserted into the spinous processes of the four upper cervical vertebrae, commencing with the axis. Relations. — By their superficial surface the semi-spinales are in re- lation from below upwards with the spinalis dorsi, longissimus dorsi, complexus, splenius, and with the profunda cervicis and princeps cervicis artery, and posterior cervical plexus of nerves. By their deep surface with the raultifidus spinas muscle. Occipital Group. — This group of small muscles is intended for the varied movements of the cranium on the atlas, and the atlas on the axis. They are extremely pretty in appearance. The rectus posticus major arises from the spinous process of the axis, and is inserted into the inferior curved line, on the occipital bone. The rectus posticus minor arises from the spinous tubercle of the atlas, and is inserted into the rough surface on the occipital bone, beneath the inferior curved line. The rectus latercdis is extended between the transverse process of the atlas and the occipital bone ; it arises from the transverse pro- cess of the atlas, and is inserted into the rough surface of the occi- pital bone, external to the condyle. The ohliquus inferior arises from the spinous process of the axis, and passes obliquely outwards to be inserted into the extremity of the transverse process of the atlas. The ohliquus superior arises from the extremity of the transverse process of the atlas, and passes obliquely inwards to be inserted into the rough surface of the occipital bone, between the curved lines. Relations. — By their superficial surface the recti and obliqui are in relation with a strong aponeurosis which separates them from the complexus. By their deep surface with the atlas and axis, and their articulations. The rectus posticus major partly covers in the rectus minor. The rectus lateralis is in relation by its anterior surface with the internal jugular vein, and by its posterior surface with the vertebral artery. Sixth Layer. Dissection. — The semi-spinales muscles must both be removed to obtain a good view of the multifidus spinae which lies beneath them, MUSCLES OF THE BACK. 181 and fills up the concavity between the spinous and transverse pro- cesses, the whole length of the vertebral column. The multifidus spines consists of a great number of fleshy fasciculi, extending between the transverse and spinous processes of the verte- brae, from the sacrum to the axis. Each fasciculus ai^ises from a transverse process, and is inserted into the spinous process of the first or second vertebra above. Relations. — By its sufeijicial surface with the longissimus dorsi, semi-spinalis dorsi, and semi-spinalis colU. By its deep surface with the arches and spinous processes of the vertebral column, and in the cervical region with the ligamentum nuchse. The levatores costarum, twelve in number on each side, arise from the transverse processes of the dorsal vertebrse, and pass obliquely outwards and downwards to be inserted into the rough surface be- tween the tubercle and angle of the rib below them. The first of these muscles arises from the transverse process of the last cervical vertebra, and the last from that of the eleventh dorsal. Relations. — By their superficial surface with the longissimus dorsi and sacro-lumbalis. By their deep surface with the intercostal muscles and ribs. The supra- spinales are little fleshy bands lying on the spinous processes of the vertebrse in the cervical region. The inter-spinales are a succession of little pairs of muscles, lying between the bifid tubercles of the spinous processes of the cervical vertebrse. There are five pairs of these muscles ; the first being situated between the axis and third vertebra, and the last between the last cervical and first dorsal. The inter-transversales are also arranged in pairs, and pass be- tween the bifid tubercles of the transverse processes of the cervical vertebrse. The inter-transversales, situated between the atlas and the occipi- tal bone, are the recti laterales. They are sometimes found in the lumbar regions. Relations. — In front with the rectus anticus major and longus colli ; and behind by the muscles of the back of the neck. They are separated from each other by the anterior branch of the cervical nerves, and by the vertebral artery and veins. With regard to the origin and insertion of the muscles of the back, the student should be informed that no regularity attends their at- tachments. At the best, a knowledge of their exact connexions, even were it possible to retain it, would be but a barren information, if not absolutely injurious, as tending to exclude more valuable learning. I have therefore endeavoured to arrange a plan, by which they may be more easily recollected, by placing them in a tabular form, that the student may see at a single glance, the origin and in- sertion of each, and compare the natural grouping and similarity of attachments of the various layers. In this manner also their actions will be better comprehended, and learnt with greater facility. 182 SIXTH LAYER. Actions. — The upper fibres of the. trapezius draw the shoulder up- wards and backwards ; the middle fibres, directly backwards ; and the lower, downwards and backwards. The lower fibres also act by .producing rotation of the scapula upon the chest. If the shoulder be fixed the upper fibres will flex the spine towards the correspond- ing side. The latissimus dorsi is a muscle of the arm, drawing it backwards and downwards, and at the same time rotating it in- wards ; if the arm be fixed, the latissimus dorsi will draw the spine to that side, and raising the lower ribs be an inspiratory muscle ; and if both arms be fixed, the two muscles will draw the whole trunk forwards, as in climbing or walking on crutches. The levator anguli scapula lifts the upper angle of the scapula, and with it the entire shoulder, and the rhomboidei carry the scapula and shoulder upwards and backwards. The serrati are respiratory muscles acting in opposition to each other — the serratus posticus superior drawing the ribs upwards, and thereby expanding the chest ; and the inferior, drawing the lower ribs downwards and diminishing the cavity of the chest. The former is an inspiratory, the latter an expiratory muscle. The splenii muscles of one side draw the vertebral column backwards and to one side, and rotate the head towards the corresponding shoulder. The muscles of opposite sides acting together, will draw the head directly backwards. They are the natural antagonists of the sterno- mastoid muscles. The sacro-lumhalis with its accessory muscle, the longissimus dorsi and spinalis dorsi, are known by the general term of erector spince, which sufficiently expresses their actions. They keep the spine, supported in the vertical position by their broad origin from below, and by means of their insertion by distinct tendons into the ribs and spinous processes. Being made up of a number of distinct fasciculi, which alternate in their actions, the spine is kept erect without fatigue, even when they have to counterbalance a corpulent abdomi- nal developement. The continuations upwards of these muscles into the neck preserve the steadiness and uprightness of that region. When the muscles of one side act alone, the neck is rotated upon its axis. The complexus, by being attached to the occipital bone, draws the head backwards, and counteracts the muscles on the anterior part of the neck. It assists also in the rotation of the head. The semi-spinales and multifidus spince muscles act directly on the vertebra;, and contribute to the general action of supporting the vertebral column erect. The four little muscles situated between the occiput and the two first vertebroe, effect the various movements between these bones ; the recti producing the antcro-postcrior actions, and the ohliqui the rotary motions of the atlas on the axis. The actions of the remaining muscles of the spine, the supra and inter-spinales and inter-transversales, are expressed in tlieir names. They approximate tlicir attachments and assist tlic more powerful muscles in preserving the erect position of the body. MUSCLES OF THE BACK. 183 The levatores costarum raise the posterior parts of the ribs, and are probably more serviceable in preserving the articulation of the ribs from dislocation, than in raising them in inspiration. In examining the following table, the student will observe the constant recurrence of the number four in the origin and insertion of the muscles. Sometimes the four occurs at the top or bottom of a region of the spine, and frequently includes a part of two regions, and takes two from each, as in the case of the serrati. Again, he will perceive that the muscles of the upper half of the table take their origin from spinous processes, and pass outwards to transverse, whereas the lower half arise mostly from transverse processes. To the student, then, we commit these reflections, and leave it to the peculiar tenor of his own mind to make such arrangements as will be best retained by his memory. 184 TABLE OF THE ORIGIN AND INSERTION ORIGIN. Layers. Spinous Processes. Transverse Processes. 1st Layer. Trapezius . . < Latissiraus dorsi < 2d Layer. Levator anguli ) scapulse . . \ Rhomboideus / minor ^ Rhomboideus major 3d Layer. Serratus posticus / superior . . C Serratus posticus ) inferior . . J Splenius capitis / Splenius colli . ) ilh Layer. Sacro-lumbalis . . accessorius ad sacro-lurabalem Longissimus dorsi Spinalis dorsi . Cervicalis ascendens Transversalis colli Trachelo-mas- j toideus ... J Complexus . . . 5th Layer. Semi-spinalis dorsi Semi-spinalis colli Rectus posticus maj. Ref:tus posticus min licctiis litoralis . . OhliquuK inferior . Obliquus superior . 6 situated deeply between the gemellus inferior and the upper border of the quadratus femoris. To expose this muscle fully, it is necessary to dissect it from the anterior part of the thigh, after the removal of the pectineus and adductor longus and brevis muscles. The Obturator externus muscle (obturare, to stop up) arises from the obturator membrane, and from the surface of bone immediately surrounding it, viz. from the body and ramus of the os pubis and ischium : its tendon passes behind the neck of the femur, to be in- serted with the external rotator muscles, into the trochanteric fossa of the femur. Relations. — By its superficial or anterior surface with the tendon of the psoas and iliacus, pectineus, adductor brevis and magnus, the obturator vessels and nerve. By its deep or posterior surface with the obturator membrane and the margin of bone which surrounds it, the lower part of the capsule of the hip-joint and the quadratus femoris. The Quadratus femoris (square-shaped) arises from the external border of the tuberosity of the ischium, and is inserted into a rough ANTERIOR FEMORAL REGION. 227 line on the posterior border of the trochanter major, which is thence named linea quadrati. Relations. — By its posterior surface with the gluteus maximus, and ischiatic vessels and nerves. By its anterior surface with the tendon of the obturator externus and trochanter minor, a synovial bursa often separating it from the latter. By its upper bolder with the gemellus inferior; and by the loiver border with the adductor magnus. Actions. — The glutei muscles are abductors of the thigh, when they take their fixed point from the pelvis. Taking their fixed point from the thigh, they steady the pelvis on the head of the femur — this action is peculiarly obvious in standing on one leg ; they assist also in carrying the leg forward, in progression. The gluteus minimus being attached to the anterior border of the trochanter major, rotates the limb slightly inwards. The gluteus medius and maximus, from their insertion into the posterior aspect of the bone, rotate the limb outwards ; the latter is, moreover, a tensor of the fascia of the thigh. The other muscles rotate the limb outwards, everting the knee and foot ; hence they are named external rotators. Anterior Femoral Region. Tensor vaginae femoris, Sartorius, Rectus, Vastus internus, Vastus externus, Crureus. Dissection. — Make an incision along the line of Poupart's ligament, from the anterior superior spinous process of the ilium to the spine of the OS pubis ; and a second, from the middle of the preceding down the inner side of the thigh, and across the inner condyle of the femur, to the head of the tibia, where it may be bounded by a trans- verse incision. Turn back the integument from the whole of this region, and examine the superficial fascia ; which is next to be re- moved in the same manner. After the deep fascia has been well considered, it is likewise to be removed, by dissecting it oflf in the course of the fibres of the muscles. As it might not be convenient to the junior student to expose so large a surface at once as ordered in this dissection, the vertical incision may be crossed by one or two transverse incisions, as may be deemed most proper. The Tensor vagincE femoris (stretcher of the sheath of the thigh) is a short flat muscle, situated on the outer side of the hip. It arises from the crest of the ilium, near to its anterior superior spinous pro- cess, and is inserted between two layers of the fascia lata at about one-fourth down the thigh. Relations. — By its superficial surface with the fascia lata and in- tegument. By its deep surface with the internal layer of the fascia 223 SARTORIUS AND RECTUS. Fig. 90.» lata, gluteus medius, rectus and vastus externus. By its innei^ border, near its origin, "^vith the sartorius. The Sartorius (tailor's muscle) is a long riband-like muscle, arising from the anterior superior spinous pro- cess of the ilium, and from the notch imme- diately below that process ; it crosses obliquely the upper third of the thigh, descends behind the inner condyle of the femur, and is inserted by an aponeurotic expansion into the inner tuberosity of the tibia. This expansion covers in the inser- tion of the tendons of the gracilis and semi-ten- dinosus muscles. The inner border of the sartorius muscle is the guide to the operation for tying the femoral artery in the middle of its course. Relations. — By its superficial surface with the fascia lata and some cutaneous nerves. By its deep surface with the psoas and iliacus, rectus, sheath of the femoral vessels and saphenous nerves, vastus internus, adductor longus, adduc- tor magnus, gracilis, long saphenous nerve, internal lateral ligament of the knee-joint. By its expanded insertion with the tendons of the gracihs and semi-tendinosus, a synovial bursa being interposed. At the knee-joint its posterior border is in relation with the internal saphenous vein. At the upper third of the thigh the sar- torius forms, with the lower border "of the adductor longus, an isosceles triangle, whereof the base corresponds with Poupart's ligament. A perpendicular line, drawn from the middle of the base to the apex of this triangle, immediately overlies the femoral artery with its sheath. The Rectus (straight) muscle is fusiform in its shape and bipenni- form in the disposition of its fibres. It arises by two round tendons — one from the anterior inferior spinous process of the ilium, the other from the upper lip of the acetabulum. It is inserted by a broad and strong tendon, into the upper border of the patella. It is more correct to consider the patella as a sesamoid bone, developed within the tendon of the rectus ; and the ligamentum patellae as the continuation of the tendon to its insertion into the spine of the tibia. Relations. — By its superficial surface with the gluteus medius, psoas and iliacus, sartorius ; and for the lower three-fourths of its extent, with the fascia lata. By its deep surface with the capsule * The muscles of the anterior femnral region. 1. The crest of the ilium. 2. Its anterior superior spinous process. 3. The gluteus medius. 4. The tensor vagintP femoris ; its insertion into the fascia lata is shown inferiorly. 5. The sartorius. 6. The rectus. 7. The vastus externus. 8. The vastus internus. 9. The patella. 10. The iliaeus internus. 11. The psoas magnus. 12. The pectineus. 13, Tlie adductor longus. I*!. Part of the adductor magnus. l.'J. The gracilis. VASTI AND ORUREUS. 229 of the hip-joint, the external circumflex vessels, crureus, and vastus internus and externus. The rectus must now be divided through its middle, and the two ends turned aside, to bring clearly into view the next muscles. The three next muscles are generally considered collectively under the name of triceps extensor cruris. Adopting this view, the muscle surrounds the whole of the femur, excepting the rough line (linea aspera) upon its posterior aspect. Its division into three parts is not well defined ; the fleshy mass upon each side being distinguished by the names of vastus internus and externus, the middle portion by that of crureus. The Vastus externus, narrow below and broad above, arises from the outer border of the patella, and is inserted into the femur and outer side of the linea aspera, as high as the base of the trochanter major. Relations. — By its superficial surface with the fascia lata, rectus, biceps, semi-membranosus and gluteus maximus, a synovial bursa being interposed. By its deej) surface with the crureus and femur. The Vastus internus, broad below and narrow above, arises from the inner border of the patella, and is inserted into the femur and inner side of the Hnea aspera as high up as the anterior inter-trochan- teric line. Relations. — By its superficial surface with the psoas and iliacus, rectus, sartorius, femoral artery and vein and saphenous nerves, pectineus, adductor longus, brevis, and magnus, and fascia lata. By its deep surface with the crureus and femur. The Crureus (crus, the leg) arises from the upper border of the patella, and is inserted into the front aspect of the femur, as high as the anterior inter-trochanteric line. When the crureus is divided from its insertion, a small, muscular fasciculus is often seen upon the lower part of the femur, which is inserted into the pouch of synovial membrane, that extends upwards from the knee-joint, behind the patella. This is named, from its situation, sub-crureus, and would seem to be intended to support the synovial membrane. Relations. — By its superficial surface with the external circumflex vessels, the rectus, and vastus internus and externus. By its deep surface with the femur, the sub-crureus, and synovial membrane of the knee-joint. Actions. — The tensor vaginae femoris renders the fascia lata tense, and slightly inverts the limb. The sartorius flexes the leg upon the thigh, and, continuing to act, the thigh upon the pelvis, at the same time carrying the leg across that of the opposite side, into the posi- tion in which tailors sit ; hence its name. Taking its fixed point from below, it assists the extensor muscles in steadying the leg, for the support of the trunk. The other four muscles have been collec- tively named quadriceps extensor, from the similarity of action. They extend the leg upon the thigh, and obtain a great increase of power by their attachment to the patella, which acts as a fiilcrum. 230 INTERNAL FEMORAL REGION. Taking their fixed point from the tibia, they steady the femur upon the leg, and the rectus, by being attached to the pelvis, serves to balance the trunk upon the lower extremity. Internal femoral Region. Iliacus internus, Psoas magnus, Pectineus, Adductor longus. Adductor brevis. Adductor magnus, Gracilis. Dissection. — These muscles are exposed by the removal of the inner flap of integument recommended in the dissection of the anterior femoral regioil. The iliacus and psoas arising from within the abdomen can only be seen in their entire extent after the removal of the viscera from that cavity. The Iliacus internus is a flat radiated muscle. It arises from the inner concave surface of the ilium ; and, after joining with the tendon of the psoas, is inserted into the trochanter minor of the femur. Relations. — By its anterior surface, within the pelvis, with the external cutaneous nerve, and with the iliac fascia, which separates the muscle from the peritoneum, on the right from the caecum, and on the left from the sigmoid flexure of the colon ; externally to the pelvis with the fascia lata, rectus, and sartorius. By its posterior surface with the iliac fossa, margin of the pelvis, and with the cap- sule of the hip-joint, a synovial bursa of large size being interposed, which is sometimes continuous with the synovial membrane of the articulation. By its inner border with the psoas magnus and crural nerve. The Psoas magnus (-^oa, lumbus, a loin), situated by the side of the vertebral column in the loins, is a long fusiform muscle. It arises from the intervertebral substances, part of the bodies and bases of the transverse processes, and from a series of tendinous arches, thrown across the constricted portion of the last dorsal and four upper lumbar vertebrce. These arches are intended to protect the lumbar arteries and sympathetic filaments of nerves from pressure, in their passage beneath the muscle. The tendon of the psoas magnus unites with that of the iliacus, and the conjoined tendon is inserted into the posterior part of the trochanter minor, a bursa being interposed. Relations. — By its anterior surface with the ligamentum arcuatum internum of the diaphragm, the kidney, the psoas parvus, genito- crural nerve, sympathetic nerve, its proper fascia, the peritoneum and colon, and along its pelvic border with the common and external iliac artery and vein. By its posterior surface with the lumbar ver- tebrae, the lumbar arteries, quadratus lum?x>rum, from which it is INTERNAL FEMORAL REGION. 231 separated by the anterior layer of the aponeurosis of the transver- salis, and with the crural nerve, which near Poupart's ligament gets to its outer side. The lumbar plexus of nerves is situated in the substance of the posterior part of the muscle. In the thigh the muscle is in relation with the fascia lata in front ; the border of the pelvis and hip-joint, from which it is separated by the synovial mem- brane, common to it and the preceding muscle, behind ; with the crural nerve, and iliacus to the outer side ; and with the femoral artery, by which it is sUghtly overlapped to the inner side. The Pectineus is a flat and quadrangular muscle ; it arises from the pectineal hne (pecten, a crust) of the os pubis, and is inserted into the line leading from the anterior inter-trochanteric line to the linea aspera of the femur. Relations. — By its anterior surface with the pubic portion of the fascia lata, which separates it from the femoral artery and vein and internal saphenous nerve, and lower down with the profunda artery. By its posterior surface with the capsule of the hip-joint, and with the obturator externus and adductor brevis, the obturator vessels being interposed. By its external border with the psoas, the femoral artery resting upon the line of interval. By its internal border with the outer edge of the adductor longus. Obturator hernia is situated directly behind this muscle, which forms one of its coverings. The Adductor longus (adducere, to draw to), the most superficial of the three adductors, arises by a round and thick tendon from the angle of the os pubis ; and, assuming a flattened form, is inserted into the middle third of the linea aspera. Relations. — By its anterior surface with the pubic portion of the fascia lata, and near its insertion with the femoral artery and vein. By its posterior surface with the adductor brevis and magnus, the anterior branches of the obturator vessels and nerves, and near its insertion with the profunda artery and vein. By its 07Uer border with the pectineus, and by the inner border with the gracilis. The pectineus must be divided near its origin and turned out- wards, and the adductor longus through its middle, turning its ends to either side, to bring into view the adductor brevis. The Adductor brevis, placed beneath the pectineus and adductor longus, is fleshy, and thicker than the adductor longus ; it arises from the body and ramus of the os pubis, and is inserted into the upper third of the linea aspera. Relations. — By its anterior surface with the pectineus, adductor longus, and anterior branches of the obturator vessels and nerve. By its posterior surface with the adductor magnus, and posterior branches of the obturator vessels and nerve. By its outer border with the obturator externus, and conjoined tendon of the psoas and iliacus. By its inner border with the gracilis and adductor magnus. The adductor brevis is pierced near its insertion by the middle per- forating artery. The adductor brevis may now be divided from its origin and turned outwards, or its inner two-thirds may be cut away entirely. 232 POSTERIOR FEMORAL REGION. when the adductor magnus muscle will be exposed in its entire extent. The Adductor magnus is a broad triangular muscle, forming a septum of division between the muscles situated on the anterior and those oh the posterior aspect of the thigh. It arises by fleshy fibres from the ramus and side of the tuberosity of the ischium ; and rad lat- ino- in its passage outwards is insei^ted into the whole length of the linea aspera, and inner condyle of the femur. The adductor magnus is pierced by five openings : the three superior, for the three perfo- rating arteries ; and the fourth, for the termination of the profunda. The fifth is the large oval opening in the tendinous portion of the muscle, that gives passage to the femoral vessels. Relations. — By its anterior surface with the pectineus, adductor brevis, adductor longus, femoral artery and vein, profunda artery and vein, with their branches, and with the posterior branches of the obturator vessels and nerve. By its posterior surface with the semi-tendinosus, semi-membranosus, biceps, and gluteus maximus. By its inner border with the gracilis and sartorius. By its upper border with the obturator externus, and quadratus femoris. The Gracilis (slender) is situated along the inner border of the thigh. It arises by a broad but very thin tendon, from the edge of the ramus of the os pubis and ischium ; and is inserted by a rounded tendon into the inner tuberosity of the tibia, beneath the expansion of the sartorius. Relations. — By its inner or superficial surface with the fascia lata, and below with the sartorius and internal saphenous nerve ; the in- ternal saphenous vein crosses it lying superficially to the fascia lata. By its outer or deep surface with the adductor longus, brevis, and magnus, and the internal lateral Hgament of the knee-joint, from which it is separated by a synovial bursa common to the tendons of the gracilis and semi-tendinosus. Actions. — The ihacus, psoas, pectineus, and adductor longus muscles bend the thigh upon the pelvis, and, at the same time, from the obliquity of their insertion into the lesser trochanter and linea aspera, rotate the entire limb outwards ; the pectineus and adductors adduct the thigh powerfully ; and, from the manner of their insertion into the linea aspera, they assist in rotating the limb outwards. The gracilis is likewise an adductor of the thigh ; but contributes also to the flexion of the leg, by its attachment to the inner tuberosity of the tibia. Posterior femoral Region. Biceps, Semi-tendinosus, Semi-membranosus. Dissection. — llcmove the integument and fascia on the posterior part of the thigh by two flaps, as on the anterior region, and turn aside the gluteus maximus from the upper part ; the muscles may then be examined. POSTERIOR FEMORAL REGION. 233 Fio-. 91 * The Biceps Jlexor cruris (bis, double, xs^aXii, head) arises by two heads, one by a common tendon with the semi-tendinosus ; the other muscular, and much shorter, from the lower two-thirds of the external border of the linea aspera. This muscle forms the outer hamstring, and is inserted by a strong tendon into the head of the fibula. Relations. — By its superficial or posterior surface with the gluteus maximus and fascia lata. By its deep or an- terior surface with the semi-membranosus, ad- ductor magnus, vastus externus, the great sciatic nerve, popliteal artery and vein, and near its insertion with the external head of the gastrocnemius, and plantaris. By its inner border with the semi-tendinosus, and in the popliteal space with the popliteal artery and vein. The Semi-tendinosus, remarkable for its long tendon, arises in common with the long head of the biceps, from the tuberosity of the ischium. It is inserted into the inner tubero- sity of the tibia. Relations. — By its superficial surface with the gluteus maximus, fascia lata, and at its insertion with the synovial bursa which sepa- rates its tendon from the expansion of the sartorius. By its deep surface with the semi- membranosus, adductor magnus, internal head of the gastrocnemius, and internal lateral liga- ment of the knee-joint, the synovial bursa com- mon to it, and the tendon of the gracilis being mterposed. By its inner border with the gra- cilis ; and by its outer border with the biceps. These two muscles must be dissected from the tuberosity of the ischium, to bring into view the origin of the next. The Semi-membranosus, remarkable for the tendinous expansion upon its anterior and posterior surface, arises from the tuberosity of the ischium, in front of the common origin of the two preceding muscles. It is inserted into the posterior part of the inner tuberosity of the tibia ; at its insertion the tendon splits into three portions, one of which is inserted in a groove on the inner side of the head of the tibia, * The muscles of the posterior femoral and gluteal region. 1. The gluteus medius. 2. The gluteus maximus. 3. The vastus externus covered in by fascia lata. 4. The head of the biceps. 5. Its short head. 6. The semi-tendinosus. 7. The semi-mem- branosus. 8. The gracilis. 9. A part of the inner border of the adductor magnus. 10. The edge of the sartorius. 11. The popliteal space. 12. The gastrocnemius mus- cle ; its two heads. The tendon of the biceps forms the outer hamstring ; and the sar- torius with the tendons of the gracilis, semi-tendinosus, and semi-membranosus, the inner hamstring. 30 234 ANTERIOR TIBIAL REGION. beneath the internal lateral ligament. The second is continuous with an aponeurotic expansion that binds down the popliteus muscle — the popliteal fascia ; and the third turns upwards and out- wards to the external condyle of the femur, forming the middle por- tion of the posterior ligament of the knee-joint (ligamentum posticum Winslowii). The tendons of the two last muscles, viz. the semi-tendinosus and semi-membranosus, with those of the gracilis and sartorius, form the inner hamstring. Relations. — By its superficial surface with the gluteus maximus, biceps, semi-tendinosus, fascia lata, and at its insertion with the tendi- nous expansion of the sartorius. By its deep surface with the quad- ratus femoris, adductor magnus, internal head of the gastrocnemius, the knee-joint, from which it is separated by a synovial membrane, and the popliteal artery and vein. By its inner border with the gra- cilis. By its outer harder with the great ischiatic nerve, and in the popliteal space, with the popliteal artery and vein. If the semi-membranosus muscle be turned down from its origin, the student will bring into view the broad and radiated expanse of the adductor magnus, upon which the three flexor muscles above described rest. Actions. — These three hamstring muscles are the direct flexors of the leg upon the thigh ; and, by taking their origin from below, they balance the pelvis on the lower extremities. The biceps from the obliquity of its direction everts the leg when partly flexed, and the semi-tendinosus turns the leg inwards when in the same state of flexion. Anterior tibial Region. Tibialis anticus. Extensor longus digitorum, Peroneus tertius, Extensor proprius pollicis. Dissection. — The dissection of the anterior tibial region is to be commenced by carrying an incision along the middle of the leg, mid- way between the tibia and the fibula, from the knee to the ankle, and bounding it inferiorly by a transverse incision, extending from one malleolus to the other. And to expose the tendons on the dor- sum of the foot, the longitudinal incision may be carried onwards to the outer side of the base of the great toe, and be terminated by another incision directed across the heads of the metatarsal bones. The Tibialis anticus muscle (flexor tarsi tibialis) arises from the upper two-thirds of the tibia, from the interosseous membrane, and from the deep fascia; its tendon passes through a distinct sheath in the annular ligament, and is inserted into the inner side of the internal cuneiform bone, and base of the metatarsal bone of the great toe. Relations. — By its anterior surface with the deep fascia, from which many of its superior fibres arise, and with the anterior annu- EXTENSOR PROPRIUS POLLICIS. 235 lar ligament. 6y its ■posterior surface with the interosseous mem- brane, tibia, ankle-joint, and bones of the tarsus with their articula- tions. By its internal surface with the tibia. By the external sur- face with the extensor longus digitorum, extensor proprius pollicis, and with the anterior tibial vessels and nerve. The Extensor longus digitorum arises from the head of the tibia, from the upper three-fourths of the fibula, from the interosseous membrane, and from the deep fascia. Below, it divides into four tendons, which pass beneath the annular ligament, to be inserted into the second and third phalanges of the four lesser toes. The mode of insertion of the extensor tendons, both in the hand and in the foot, is remarkable ; each tendon spreads into a broad aponeu- rosis over the first phalanx ; this aponeurosis divides into three sHps, the middle one is inserted into the base of the second phalanx, and the two lateral slips are continued onwards, to be inserted into the base of the third. Relations. — By its anterior surface with the deep fascia of the leg and foot, and with the anterior annular ligament. By its posterior surface with the interosseous membrane, fibula, ankle-joint, extensor brevis digitorum, which separates its tendons from the tarsus, and with the metatarsus and phalanges. By its inner surface with the tibiahs anticus, extensor proprius pollicis, and anterior tibial vessels. By its outer border with the peroneus longus and brevis. The Peroneus tertius (flexor tarsi fibularis) arises from the lower fourth of the fibula, and is inserted into the base of the metatarsal bone of the little toe. Although apparently but a mere division or continuation of the extensor longus digitorum, this muscle may be looked upon as analogous to the flexor carpi ulnaris of the fore-arm. Sometimes it is altogether wanting. The Extensor proprius 'pollicis lies between the tibialis anticus and extensor longus digitorum. It arises from the lower two-thirds of the fibula and interosseous membrane. Its tendon passes through a distinct sheath in the annular ligament, and is inserted into the base of the last phalanx of the great toe. Relations. — By its anterior surface with the deep fascia of the leg and foot, and with the anterior annular ligament. By its posterior surface with the interosseous membrane, the fibula, the tibia, the ankle-joint, the extensor brevis digitorum, and the bones and articu- lations of the great toe. It is crossed upon this aspect by the ante- rior tibial vessels and nerve. By its outer side with the extensor longus digitorum, and in the foot with the dorsalis pedis artery and veins ; the outer side of its tendon upon the dorsum of the foot being the guide to these vessels. By its inner side with the tibialis anti- cus, and with the anterior tibial vessels. Actions. — The tibialis anticus and peroneus tertius are direct flexors of the tarsus up'on the leg; acting in conjunction with the tibialis posticus they direct the foot inwards, and with the peroneus longus and brevis outwards. They assist also in preserving the flatness of the foot during progression. The extensor longus digitorum and 236 POSTERIOR TIBIAL REGION. extensor proprius poUicis, are direct extensors of the phalanges ; but continuing- their action, they assist the tibiahs anticus and peroneus tertius, in flexing the entire foot upon the leg. Taking their origin from below, they increase the stabihty of the ankle-joint. Posterior tibial Region. Superficial Group. Gastrocnemius, Plantaris, Soleus. Dissection. — Make an incision from the middle of the popliteal space down the middle of the posterior part of the leg to the heel, bounding it inferiorly by a transverse incision passing between the two malleoli. Turn aside the flaps of integument and remove the fasciae from the whole of this region; the gastrocnemius muscle will then be exposed. The Gasti^ocnemius (/ao'TgoxvPjixiov, the beUied part of the leg) arises by two heads from the two condyles of the femur, the' inner head being the longest. They unite to form the beautiful muscle so cha- racteristic of this region of the Hmb. It is inserted, by means of the tendo Achillis, into the lower part of the posterior tuberosity of the OS calcis, a synovial bursa being placed between that tendon and the upper part of the tuberosity. The gastrocnemius must be removed from its origin, and turned down, in order to expose the next muscle. Relations. — By its supei^cial surface with the deep fascia of the leg which separates it from the external saphenous vein, and with the external saphenous nerve. By its deep surface with the lateral portions of the posterior ligament of the knee-joint, the popliteus, plantaris, and soleus. The internal head of the muscle rests against the posterior surface of the internal condyle of the femur; the exter- nal head against the outer side of the external condyle. In the lat- ter a sesamoid bone is sometimes found. The Plantaris (planta, the sole of the foot), an extremely diminu- tive muscle situated between the gastrocnemius and soleus, arises from the outer condyle of the femur ; and is inserted, by its long and delicately slender tendon, into the inner side of the posterior tube- rosity of the OS calcis, by the side of the tendo Achilhs; having crossed obliquely between the two muscles. The Soleus (solea, a sole) is the broad muscle upon which the plantaris rests. It arises from the hearl and upper third of the fibula, from the oblique line and middle third of the tibia. Its fibres con- verge to the tendo Achillis, by which it is inserted into the posterior tuberosity of the os calcis. Between tlie fibular and tibial origins of this muscle is a tendinous arch, beneath which the popliteal vessels and nerve pass into the leg. Relations. — By its superficial surface with the gastrocnemius and POSTERIOR TIBIAL REGION. 237 plantaris. By its deep surface with the intermuscular fascia, which separates it from the flexor longus digitorum, tibiahs posticus, flexor longus polUcis, from the posterior tibial vessels and nerve, and from the peroneal vessels. Fig. 92 * Actions. — The three muscles of the calf draw powerfully on the OS calcis, and lift the heel ; continuing their action, they raise the entire body. This action is attained by means of a lever of the second power, the fulcrum (the toes) being at one end, the weight * The muscles of the anterior tibial region. 1. The extensor muscles inserted into the patella. 2. The subcutaneous surface of the tibia. 3. The tibialis anticus. 4. The extensor communis digitorum. 5. The extensor proprius pollicis. 6. The pero- neus tertius. 7. The peroneus longus. 8. The pcroneus brcvis. 9, 9. The borders of the soleus muscle. 10. A part of the inner belly of the gastrocnemius. 11. The extensor brevis digitorum; the tendon in front of this number is tliat of the peroneus tertius ; and that behind it, the tendon of the pcroneus brevis. t The superficial muscles of the posterior aspect of the leg. 1. The biceps muscle forming the outer hamstring. 2. The tendons forming the inner hamstring. 3. The popliteal space. 4. The gastrocnemius muscle. 5, 5. Tlie soleus. 6. The tcndo Achillis. 7. The posterior tuberosity of the os calcis, 8. Tlie tendons of the pcroneus longus and brevis muscles passing behind the outer ankle. 9. The tendons of the deep layer passing into the foot behind the inner ankle. 238 POSTERIOR TIBIAL REGION. (the body supported on the tibia) in the middle, and the power (these muscles) at the other extremity. They are, therefore, the walking muscles, and perform all move- ments that i-equire the support of the whole body from the ground, as dancing, leaping, &c. Taking their fixed point from below, they steady the leg upon the foot. Deep layer. ' Popliteus, Flexor longus pollicis, Flexor longus digitorum, Tibialis posticus. Dissection. — After the removal of the soleus, the deep layer will be found bound down by an inter-muscular fascia, which is to be dis- sected away ; the muscles may then be examined. The Popliteus muscle (poples, the ham of the leg) forms the floor of the popliteal region at its lower part, and is bound tightly down by a strong fascia derived from the middle slip of the tendon of the semi-membranosus muscle. It mnses by a rounded tendon from a deep groove on the outer side of the external condyle of the femur, beneath the external lateral ligament ; and spreading obliquely over the head of the tibia, is inserted into the surface of bone above its oblique line. This line is often called, from being the limit of inser- tion of the popliteus muscle, the popliteal line. Relations. — By its superficial surface with a thick fascia which separates it from the two heads of the gastrocnemius, the plantaris, and the popliteal vessels and nerve. By its deepj surface with the articulation of the knee-joint and with the upper part of the tibia. The Flexor longus pollicis is the most superficial of the three next muscles. It arises from the lower two-thirds of the fibula, passes through a groove in the astragalus and os calcis, which is converted by tendinous fibres into a distinct sheath lined by a synovial mem- brane into the sole of the foot ; it is inserted into the base of the last phalanx of the great toe. Relations. — By its superfixial surface with the intermuscular fascia, which separates it from the soleus and tendo Achillis. By its deep surface with the tibialis posticus, fibula, fibular vessels, inter- osseous membrane, and ankle-joint. By its 07iter border with the peroneus longus and brevis. By its inner border with the flexor longus digitorum. In the foot, the tendon of the flexor longus pol- licis is connected with that of the flexor longus digitorum by a short tendinous slip. The Flexor longus digitorum (pcrforans) arises from the surface of the tibia, immediately below the popliteal line. Its tendon passes through a shoatli common to it and the tibialis posticus behind the inner malleolus; it then passes through a second sheath which is connected with a groove in the astragalus and os calcis, into the sole of the foot, where it divides into four tendons, which are inserted TIBIALIS POSTICUS. 239 into the base of the last phalanx of the four lesser toes, perforating the tendons of the flexor brevis digitorurn. Relations. — By its sicpey-ficial surface with the intermuscular fascia, which separates it from the soleus, and with the posterior tibial vessels and nerve. By its deep surface with the tibia and tibialis posticus. In the sole of the foot its tendon is in relation with the abductor polhcis and flexor brevis digitorurn, which lie superfi- cially to it, and it crosses the tendon of the flexor longus polUcis. At the point of crossing it receives the tendinous slip of communi- cation from the latter. The flexor longus polhcis must now be removed from its origin, and the flexor longus digitorum drawn aside, to bring into view the entire extent of the tibialis posticus. The Tibialis posticus (extensor tarsi tibiahs) lies upon the interos- seous membrane, between the two bones of the leg. It arises by two heads from the adjacent sides of Fig. 94.* the tibia and fibula their whole length, and from the interosseous membrane. Its tendon passes inwards beneath the tendon of the flexor lono;us digitorum, and runs in the same sheath; it then #'i ?= .V passes through a proper sheath over the deltoid liga- ment, and beneath the calcaneo-scaphoid articula- ^ [l^^vl^] T | tion, to be inserted into the tuberosity of the '^^"t^^- .^- scaphoid and internal cuneiform bone. While in the common sheath behind the internal malleolus, the tendon of the tibiahs posticus lies internally to that of the flexor longus digitorum, from which it is separated by a thin fibrous partition. A sesamoid bone is usually met with in the tendon close to its insertion. Relations. — By its superficial surface with the in- termuscular septum, the flexor longus pollicis, flexor longus digitorum, posterior tibial vessels and nerve, peroneal vessels, and in the sole of the foot with the abductor pollicis. By its deep surface with the interosseous membrane, the fibula and tibia, the ankle joint, and the astragalus. - The anterior tibial artery passes between the two heads of the muscle. The student will observe that the two latter mus- cles change their relative position to each other in r' ^-^ their course. Thus, in the leg, the position of the " y three muscles from within outwards, is — flexor * The deep layer of muscles of the posterior tibial region. 1. The lower extremity of the femur. 2. The ligamentum posticum Winslowii. 3. The tendon of the semi- membranosus muscle dividing into its three slips. 4. The internal lateral ligament of the knee-joint. 5. The external lateral ligament. 6. Tlie popliteus muscle. 7. Tlie flexor longus digitorum. 8. The tibialis posticus. 9. The flexor longus pollicis. 10. The peroneus longus muscle. 11. The peroneus brevis. 12. The tendo Achillis divided at its insertion into the os calcis. 1.3. The tendons of the tibialis posticus and flexor longus digitorum muscles, just as they are about to pass beneath the internal annular ligament of the ankle ; the interval between the latter tendon and the tendon of the flexor longus pollicis is occupied by the posterior tibial vessels and nerve. 240 FIBULAR REGION. longus digitorum, tibialis posticus, flexor longus pollicis. At the inner malleolus, the relation of the tendons is — tibiahs posticus, flexor longus digitorum, both in the same sheath ; then a broad groove, which lodges the posterior tibial artery, venae comites, and nerve ; "and lastly, the flexor longus pollicis. Actions. — The popliteus is a flexor of the tibia upon the thigh, carrying it at the same time inwards so as to invert the leg. The flexor longus polhcis, and flexor longus digitorum are the long flexors of the toes ; their tendons are connected in the foot by a short tendinous band, hence they necessarily act together. The tibialis posticus is an extensor of the tarsus upon the leg, and an antagonist to the tibialis anticus. It combines with the tibalis anticus in adduction of the foot. Fibular Region. Peroneus longus, Peroneus brevis. Dissection. — These muscles are exposed by continuing the dissec- tion of the anterior tibial region outwards beyond the fibula, to the border of the posterior tibial region. The Peroneus longus ('tts^ovt), fibula, extensor tarsi fibularis longior) muscle arises from the upper third of the outer side of the fibula, and terminates in a long tendon, which passes behind the external malleolus, and obliquely across the sole of the foot, through the groove in the cuboid bone, to be inserted into the base of the meta- tarsal bone of the great toe. Its tendon is thickened when it glides behind the external malleolus, and a sesamoid bone is developed in that part which plays upon the cuboid bone. Relations. — By its superficial surface with the fascia of the leg and foot. By its deep surface with the fibula, peroneus brevis, os calcis, and cuboid bone, and near the head of the fibula with the fibular nerve. By its anterior border it is separated from the extensor longus digitorum by the attachment of the fascia of the leg to the fibula ; and by the posterior border by the same medium from the soleus and flexor longus pollicis. The peroneus longus is furnished with three tendinous sheaths and as many synovial membranes ; the first is situated behind the external malleolus, and is common to this muscle and the peroneus brevis, the second on the outer side of the OS calcis, and the third on the cuboid bone. The Peroneus brevis (extensor tarsi fibularis brevier) lies beneath the peroneus longus ; it arises from the lower two-thirds of the fibula, and terminates in a tendon which passes behind the external mal- leolus and through a groove in the os calcis, to be inserted into the base of tlic metatarsal bone of the little toe. Relations. — By its superficial surface with the peroneus longus and fascia of the leg and foot. By its deep surface with the fibula, the OS calcis, and cuboid bone. The lateral relations are the same as those of the peroneus longus. The tendon of the peroneus brevis MUSCLES OF THE FOOT. 241 has but two tendinous sheaths and two synovial membranes ; — one behind the external malleolus and common to both peronei, the other upon the side of the os calcis. Actions. — The peronei muscles are extensors of the foot, con- jointly with the tibialis posticus. They antagonise the tibialis anticus and peroneus tertius, which are flexors of the foot. The whole of these muscles acting together, tend to maintain the flatness of the foot, so necessary to security in walking. Foot. Dorsal Region. Extensor brevis digitorum, Interossei dorsales. The Extensor brevis digitorum muscle arises from the outer side of the OS calcis, crosses the foot obHquely, and terminates in four tendons, the innermost of which is inserted into the base of the first phalanx of the great toe, and the other three into the sides of the long extensor tendons of the second, third, and fourth toes. Relations. — By its upper surface with the tendons of the extensor longus digitorum, peroneus brevis, and with the deep fascia of the foot. By its under surface with the tarsal and metatarsal bones. Its inner border is in relation with the dorsalis pedis artery, and the innermost tendon of the muscle crosses that artery just before its division. The Dorsal interossei muscles are placed between the metatarsal bones ; they resemble the analogous muscles in the hand in arising by two heads from the adjacent sides of the metatarsal bones ; their tendons are inserted into the base of the first phalanx, and into the digital expansion of the tendons of the long extensor. The first dorsal interosseous is inserted into the inner side of the second toe, and is therefore an adductor ; the other three are inserted into the outer side of the second, third, and fourth toes, and are con- sequently abductors. Relations. — By their upper surface with a strong fascia which separates them from the extensor tendons. By their under surface with the plantar interossei. Each of the muscles gives passage to a small artery (posterior perforating) which communicates with the external plantar artery. And between the heads of the first interos- seous muscle the communicating artery of the dorsahs pedis takes its course. Plantar Region. First Layer. Abductor polUcis, Abductor minimi digiti, Flexor brevis digitorum. 31 242 3IUSCLES OF THE SOLE OF THE FOOT. Dissection. — The sole of the foot is best dissected by caiTying an incision around the heel, and along the inner and outer borders of the foot, to the great and little toes. This incision should divide the integument and superficial fascia, and both together should be dis- sected from the deep fascia, as far forward as the base of the pha- langes, where they may be removed from the foot altogether. The deep fascia should then be removed, and the first layer of muscles will be brought into view. Fig. 95.^ Fig. 96.t The Abductor pollicis lies along the inner border of the foot ; it arises by two heads, between which the tendons of the long flexors, arteries, veins, and nerves enter the sole of the foot. One head arises from the inner tuberosity of the os calcis, the other from the internal annular ligament and plantar fascia. Insertion, into the base of the first phalanx of the great toe, and into the internal sesa- moid bone. * The first layer of muscles in the sole of the foot ; this layer is exposed by the removal of tlie plantar fascia, 1. The os calcis. 2. The posterior part of the plantar fascia divided transversely. 3. The abductor pollicis. 4. The abductor minimi digiti. 5. The flexor brevis digitorum. 6. The tendon of the flexor longus pollicis muscle. 7,7. The lumbricalcs. On the second and third toes, the tendons of the flexor longus digi- torum are seen passing through the bifurcation of the tendons of the flexor brevis digitorum. t Tlie tijird and a i>art of the second layer of muscles of the sole of the foot. 1. The divided edge of the pbintar fascia. 2. Tlio musculus accessorius. 3. The tendon of the flexor longus digitorum, previously to its division. 4. The tendon of the flexor longus pollicis. 5. The flexor brevis pollicis. 6. Tlic adductor pollicis. 7. The flexor brevis minimi digiti. 8. The transversus pedis. !i. Intcrossci muscles, plantar and dorsal. 10. A convex ridge formed by the tendon of the peroneus longus muscle in its oblique course across the foot. MUSCLES OF THE SOLE OF THE FOOT. 243 Relations. — By its superficial surface with the internal portion of the plantar fascia. By its deep surface with the flexor brevis poUicis, musculus accessorius, tendons of the flexor longus digitorum and flexor longus pollicis, tendons of the tibialis anticns and posticus, the plantar vessels and nerves and the tarsal bones. On its outer border with the flexor bi'evis digitorum, from which it is separated by a vertical septum of the plantar fascia. The Abductor minimi digiti lies along the outer border of the foot. It arises from the outer tuberosity of the os calcis, and from the base of the metatarsal bone of the little toe, and is inserted into the base of the first phalanx of the little toe. Relations. — By its superficial surface with the external portion of the plantar fascia. By its deep surface with the musculus acces- sorius, flexor brevis minimi digiti, with the tarsal boneS; and with the metatarsal bone of the little toe. By its inner side with the flexor brevis digitorum, from which it is separated by the vertical septum of the plantar fascia. The Flexor brevis digitorum (perforatus) is placed between the two preceding muscles. It arises from the under surface of the os calcis and plantar fascia, and is inserted by four tendons into the base of the second phalanx of the four lesser toes. Each tendon divides, previously to its insertion, to give passage to the tendon of the long flexor ; hence its cognomen perforatus. Relations. — By its superficial surface with the plantar fascia. By its deep surface with a thin layer of fascia which separates it from the musculus accessorius, tendons of the flexor longus digitorum and flexor longus pollicis, and plantar vessels and nerves. By its borders with the vertical septa of the plantar fascia, which separate the muscle, on the one side from the abductor pollicis, and on the other from the abductor minimi digiti. Second Layer. Musculus accessorius, Lumbricales. Dissection. — The three preceding muscles must be divided from their origin, and anteriorly through their tendons, and removed, in order to bring into view the second layer. The Musculus accessorius arises by two slips from either side of the under surface of the os calcis ; the inner slip being fleshy, the outer tendinous. The muscle is inserted into the outer side of the tendon of the flexor longus digitorum. Relations. — By its superficial surface with the thi-ee muscles of the superficial layer, from which it is separated by their fascial sheaths, and with the external plantar vessels and nerves. By its deep surface with the under surface of the os calcis and the long calcaneo-cuboid ligament. The Lumbricales (lumbricus, an earthworm) are four little muscles arising from the tibial side of the tendons of the flexor longus digi- 244 MUSCLES OF THE SOLE OF THE FOOT. torum, and inserted into the expansion of the extensor tendons, and into the base of the first phalanx of the four lesser toes. Relations. — By their superficial surface with the tendons of the flexor longus digitorum. By their deep surface with the third layer of muscles of the sole of the foot. They pass between the digital slips of the deep fascia to reach their insertion. Third Layer. Flexor brevis poUicis, Adductor poUicis, Flexor brevis minimi digiti, Transversus pedis. Dissection. — The tendons of the long flexors and the muscles con- nected with them must be removed, to see clearly the attachments of the third layer. The Flexor hrevis poUicis arises by a pointed tendinous process from the os calcis, the side of the cuboid, and from the external and middle cuneiform bones ; and is inserted by two heads into the base of the first phalanx of the great toe. Two sesamoid bones are de- veloped in the tendons of insertion of these two heads, and the tendon of the flexor longus poUicis lies in the groove between them. Relations. — By its superficial surface with the abductor pollicis, tendon of the flexor longus pollicis, and plantar fascia. By its deep surface with the tarsal bones and their ligaments, the metatarsal bone of the great toe, and the insertion of the tendon of the peroneus longus. By its inner border with the abductor polhcis. By its outer harder with the adductor pollicis. The Adductor pollicis arises from the cuboid bone, from the sheath of the tendon of the peroneus longus, and from the base of the third and fourth metatarsal bones. It is inserted into the base of the first phalanx of the great toe. Relations. — By its superficial surface with the tendons of the flexor longus and flexor brevis digitorum, the musculus accessorius, and lumbricales. By its deep surface with the tarsal bones and liga- ments, the external plantar artery and veins, the interossei muscles, tendon of the peroneus longus, and metatarsal bone of the great toe. By its inner border with the flexor brevis pollicis. The Flexor brevis minimi digiti arises from the base of the meta- tarsal bone of the little toe, and from the sheath of the tendon of the peroneus longus. It is inserted into the base of the first phalanx of the little toe. Relations. — By its superficial surface with the tendons of the flexor longus and flexor brevis digitorum, the fourth lumbricalis, abductor minimi digiti, and plantar fascia. By its deep surface with the plantar interosseous muscle of the fourth metatarsal space, and the metatarsal bone. The Transversus pedis arises by fleshy slips, from the heads of the metatarsal bones of the four lesser toes. Its tendon is inserted into the base of the first phalanx of the great toe. ACTION OF MUSCLES OF THE FOOT. 245 Relations. — By its superficial surface with the tendons of the flexor longus and flexor brevis digitorum, and the kimbricales. By its deep surface with the interossei, and heads of the metatarsal bones. Fourth Layer. Interossei plantares. The Plantar interossei muscles are three in number, and are placed iLpon rather than between the metatarsal bones. They arise from the base of the metatarsal bones of the three outer toes, and are inserted into the inner side of the extensor tendon and base of the first phalanx of the same toes. In their action they are all adductors. Relations. — By their swperficicd surface with the dorsal interossei and the metatarsal bones. By their deej) surface with the external plantar artery and veins with their branches, the adductor pollicis, transversus pedis, and flexor minimi digiti. Actions. — All the preceding muscles act upon the toes ; and the movements which they are capable of executing may be referred to four heads, viz. flexion, extension, adduction, and abduction. In these actions they are grouped in the following manner : — Flexion. Extension. Flexor longus digitorum, Extensor longus digitorum, Flexor brevis digitorum. Extensor brevis digitorum. Flexor accessorius, Flexor minimi digiti. Adduction. Abduction. •r , . ( one dorsal, Interossei, three dorsal, ' \ three plantar. Abductor minimi digiti. The great toe, like the thumb in the hand, enjoys an independent action, and is provided with distinct muscles to perform its move- ments. These movements are precisely the same as those of the other toes, viz. : Flexion. Extension. Flexor longus pollicis. Extensor proprius pollicis, Flexor brevis poUicis, Extensor brevis digitorum. Adduction. Abduction. Adductor polhcis. Abductor pollicis. The only muscles excluded from this table are the lumbricales, four small muscles, which from their attachments to the tendons of the long flexor, appear to be assistants to their action ; and the transversus pedis, a small muscle placed transversely in the foot across the heads of the metatarsal bones, which has for its office the drawing together of the toes. CHAPTER IV. ON THE FASCIA. Fascia (fascia, a bandage,) is the name assigned to laminae of various extent and thickness, which are distributed through the dif- ferent regions of the body, for the purpose of investing or protecting the softer and more dehcate organs. From a consideration of their structure, these fasciae may be arranged in three classes : — cellular fasciae, cellulo-fibrous fasciae, and tendino-fibrous fasciae. The cellular fascia is best illustrated in the common subcutaneous investment of the entire body, the superficial fascia. This structure is situated immediately beneath the integument over every part of the frame, and is the medium of connexion between that layer and the deeper parts. It is composed of cellular tissue containing in its areolae a considerable abundance of adipose vesicles. The fat, being a bad conductor of caloric, serves to retain the warmth of the body; while it forms at the same time a yielding tissue, through which the minute vessels and nerves may pass to the papillary layer of the skin, without incurring the risk of obstruction from injury or pres- sure upon the surface. By dissection, the superficial fascia may be separated into two layers, between which are found the superficial or cutaneous vessels and nerves ; as, the superficial epigastric artery, the saphenous veins, the radial and ulnar veins, the superficial lymphatic vessels, also the cutaneous muscles, as the platysma myoides, orbicularis palpebrarum, sphincter ani, &c. In some situ- ations where the deposition of fat would have been injurious to the functions of the part, the cells of the cellular fascia are moistened by a serous exhalation, analogous to the secretion of serous mem- branes, as in the eyelids and scrotum. The cellulo-fLbrous fascia appears to result from a simple condens- ation of cellular tissue deprived of its fat, and intermingled with strong fibres disposed in various directions, so as to constitute an inelastic membrane of considerable strength. Of this structure is the deep fascia of the neck, some of the fasciae of the cavities of the trunk, as the thoracic and transversalis fasciae, and the sheaths of vessels. The tendino-fibrous fascia is the strongest of the three kinds of investing membrane ; it is composed of strong tendinous fibres, run- ning parallel with each other, and connected by other fibres of the same kind passing in diflferent directions. When freshly exposed, it is brilliant and nacreous, and is tough, inelastic, and unyielding. In the limbs it forms the deep fascia, enclosing and forming distinct FASCIA OF THE HEAD AND NECK. 247_ sheaths to all the muscles and tendons. It is thick upon the outer and least protected side of the limb, and thinner upon its inner side. It is firmly connected to the bones and to the prominent points of each region, as to the pelvis, knee, and ankle, in the lower, and to the clavicle, scapula, elbow, and wrist in the upper extremity. It assists the muscles in their action, by keeping up a tonic pressure on their surface ; aids materially in the circulation of the fluids in opposition to the laM^s of gravity ; and in the palm of the hand and sole of the foot is a powerful protection to the structures which enter into the formation of these regions. In some situations its tension is regulated by muscular action, as by the tensor vaginas femoris and gluteus maximus in the thigh, by the biceps in the leg, and by the biceps and palmaris longus in the arm ; in other situations it affords an extensive surface for the origin of the fibres of muscles. The fasciae may be arranged like the other textures of the body into — 1. Those of the head and neck. 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity. FASCIiE OF THE HEAD AND NECK. The temporal fascia is a strong tendino-fibrous membrane which covers in the temporal muscle at each side of the head, and gives origin by its internal surface to the superior muscular fibres. It is attached to the whole extent of the temporal ridge above, and to the zygomatic arch below ; in the latter situation it is thick and divided into two layers, the external being connected to the upper border of the arch, and the internal to its inner surface. A small quantity of fat is usually found between these two layers, together with the orbital branch of the temporal artery. The superficial cervical fascia contains between its layers the platysma myoides muscle. The deep cervical fascia is a strong cellulo-fibrous layer which invests the muscles of the neck, and retains and supports the vessels and nerves. It commences posteriorly at the ligamentum nuchas, and passes forwards at each side beneath the trapezius muscle to the posterior border of the sterno-mastoid ; here it divides into two layers which embrace that muscle and unite upon its anterior border to be prolonged onwards to the middle line of the neck, where it becomes continuous with the fascia of the opposite side. Besides thus constituting a sheath for the sterno-mastoid, it also forms sheaths for the other muscles of the neck over which it passes. If the super- ficial layer of the sheath of the sterno-mastoid be traced upwards, it will be found to pass over the parotid gland and masseter muscle, and to be inserted into the zygomatic arch; and if it be traced downwards, it will be seen to pass in front of the clavicle and be- come lost upon the pectoralis major muscle. If the deep layer of the sheath be examined superiorly, it will be found attached to the styloid process, from which it is reflected to the angle of the lower 248 FASCIA OF THE TRUNK. jaw, Fiff. 97* forming the stylo-maxillary ligament; and if it be followed downwards, it will be found con- nected with the tendon of the omo- hyoid muscle, and may thence be traced behind the clavicle where it encloses the subclavius muscle, and being extended from the cai'- tilage of the first rib to the cora- coid process, constitutes the costo- coracoid membrane. In front of the sterno-mastoid muscle, the deep fascia is attached to the border of the lower jaw and os hyoides, and forms a distinct sheath for the sub- maxillary gland. Inferiorly it di- vides into two layers, one of which passes in front of the sternum, while the other is attached to its superior border. FASCIA OF THE TRUNK. The thoracic fasciaj is a dense layer of cellulo-fibrous membrane stretched horizontally across the superior opening of the thorax. It is firmly attached to the concave margin of the first rib, and to the inner surface of the sternum. In front it leaves an opening for the connexion of the cervical with the thoracic portion of the thymus gland, and behind it forms an arch across the vertebral column, to give passage to the oesophagus. At the point where the great vessels and trachea pass through the thoracic fascia, it divides into an ascending and descending layer. The ascending layer is attached to the trachea, and becomes con- tinuous with the sheath of the carotid vessels, and with the deep cervical fascia ; the descending layer descends upon the trachea to * A transverse section of the neck, showing the deep cervical fascia and its numerous proloni,''ations, forming sheaths for the different muscles. As the figure is symmetri- cal, the figures of reference are placed only on one side. 1. The platysma myoides. 2. Tlie trapezius. 3. The ligamentum nucha?, from which the fascia may be traced forwards beneath the trapezius, enclosing the other muscles of the neck. 4. The point at which the fascia divides, to form a sheath for the sterno-mastoid muscle. 6. The point of reunion of the two layers of the sterno-mastoid slieath. 7. The point of union of the dec]) cervical fascia of opposite sides of the neck. 8. Section of the sterno-hyoid, 9. Omo-hyoid. 10. Sterno-tiiyroid. 11. The lateral lobe of the thyroid gland. 12. The trachea. 1.3. The oesophagus. 14. The slieath containing the common carotid artery, internal jugular vein, and pneumogastric nerve. 1.5. The longus colli. The nerve in front of the sheath of tliis muscle is the sympathetic. 16. The rectus anticus major. 17. Scalenus anticus. 18. Scalenus posticus. 19. The splenius capitis. 20. Splcnius colli. 21. Iiovator anguli scapulte. 22. Complexus. 23. Trachelo-mastoid. 24. Transversalis colli. 2.5. Cerviealis ascendcns. 2(i. The semi-spinalis colli. 27. The multifidus spiniE. 28. A cervical vertebra. Tlie transverse processes are seen to be traversed by the vertebral artery and vein. t For an excellent description of this fascia, see Sir Astley Cooper's work on the " Anatomy of the Thymus Gland." ABDOMINAL FASCIA. 249 its bifurcation, surrounds the large vessels arising from the arch of the aorta, and the upper part of the arch itself, and is continuous with the fibrous layer of the pericardium. It is connected also with the vense innominatse and superior cava, and is attached to the cellular capsule of the thymus gland. " The thoracic fascia," writes Sir Astley Cooper, " performs three important offices : — ■ " 1st. It forms the upper boundary of the chest, as the diaphragm does the lower. " 2nd. It steadily preserves the relative situation of the parts which enter and quit the thoracic opening. " 3d. It attaches and supports the heart in its situation, through the medium of its connexion with the aorta and large vessels which are placed at its curvature." ABDOMINAL FASCIA. The lower part of the parietes of the abdomen, and the cavity of the pelvis, are strengthened by a layer of fascia which lines their inter- nal surface, and at the bottom of the latter cavity is reflected in- wards to the sides of the bladder. This fascia is continuous through- out the whole of the surface ; but for convenience of description it is considered under the several names of transversalis fascia, iliac fascia, and pelvic fascia ; the two former meet at the crest of the ilium, and Poupart's ligament, and the latter is confined to the cavity of the true pelvis. The fascia transversalis (Fascia Cooperi)* is a cellulo-fibrous lamella which lines the inner surface of the transversalis muscle. It is thick and dense below, near the lower part of the abdomen; but becomes thinner as it ascends, and is gradually lost in the sub- serous cellular tissue. It is attached inferiorly to the reflected margin of Poupart's ligament and to the crest of the ilium ; internally, to the border of the rectus muscle ; and at the inner third of the femoral arch, is continued beneath Poupart's ligament, and forms the ante- rior segment of the crural canal, or sheath of the femoral vessels. The internal abdominal ring is situated in this fascia, at about midway between the spine of the os pubis, and the anterior superior spine of the ilium, and half an inch above Poupart's ligament ; it is bounded upon its inner side by a well-marked falciform border, but is ill defined around its outer margin. From the circumference of this ring is given off" an infundibiUform process which surrounds the testicle and spermatic cord, constituting the fascia propria of the latter, and forms the first investment to the sac of oblique inguinal hernia. It is the strength of this fascia, in the interval between the head of the rectus and the internal abdominal ring, that defends this * Sir Astley Cooper first described this fascia in its important relation to inguinal hernia. 32 250 INGUINAL HERNIA. portion of the parietes from the frequent occurrence of direct in- guinal hernia. INGUINAL HERNIA. Ino-Liinal hernia is of two kinds, obUque, and direct. In obUque inguinal hernia the intestine escapes from the cavity of the abdomen into the spermatic canal, through the internal abdo- minal ring, pressing before it a pouch of peritoneum which consti- tutes the hernial sac, and distending the infundibiliform process of the transversalis fascia. After emerging through the internal abdo- minal ring, it passes frst beneath the lower and arched border of the transversalis muscle ; then beneath the lower border of the in- ternal oblique muscle ; and finally through the external abdominal rino- in the aponeurosis of the external oblique. From the trans- versalis muscle it receives no investment ; while passing beneath the lower border of the internal oblique it obtains the cremaster muscle ; and, upon escaping at the external abdominal ring, receives the in- tercolumnar fascia. So that the coverings of an oblique inguinal hernia, after it has emerged through the external abdominal ring, are, from the surface to the intestine, the Integument, Superficial fascia, Intercolumnar fascia, Cremaster muscle, Transversalis, or infundibiliform fascia, Peritoneal sac. The spermatic canal, which, in the normal condition of the abdo- minal parietes serves for the passage of the spermatic cord in the male, and the round hgament with its vessels in the female, is about one inch and a half in length. It is bounded in front by the aponeu- rosis of the external oblique muscle ; heliind by the transversalis fascia, and by the conjoined tendon of the internal oblique and trans- versahs muscle ; above by the arched borders of the internal oblique and transversalis ; below by the grooved border of Poupart's liga- ment; and at each extremity by one of the abdominal rings, the in- ternal ring at the inner termination, the external ring at the outer extremity. These relations may be more distinctly illustrated by the following plan — Above. Lower borders of internal oblique and transversalis muscle. In Front. Behind. Transversalis fascia. Con- joined lendon of internal oblique and transversalis. Aponeurosis of external Spermatic canal. oblique. * Below. Grooved border of Poupart's ligament, DIRECT INGUINAL HERNIA. 251 There are three varieties of oblique inguinal hernia : — common, congenita], and encysted. Common oblique hernia is that which has been described above. Congenital hernia results from the nonclosure of the pouch of peri- toneum carried downwards into the scrotum by the testicle, during its descent in the foetus. The intestine at some period of life is forced into this canal, and descends through it into the tunica vaginalis where it lies in contact with the testicle ; so that congenital hernia has no proper sac, but is contained within the tunica vaginalis. The other coverings are the same as those of common inguinal hernia. Encysted heniia (hernia infantihs, of Hey) is that form of pro- trusion in which the pouch of peritoneum forming the tunica vagi- nalis, being only partially closed, and remaining open externally to the abdomen, admits of the hernia passing into the scrotum, behind the tunica vaginalis. So that the surgeon in operating upon this variety, requires to divide three layers of serous membrane ; the first and second layers being those of the tunica vaginalis ; and the third, the true sac of the hernia. Direct inguinal hernia* has received its name from passing directly through the external abdominal ring, and forcing before it the opposing parietes. This portion of the wall of the abdomen is strengthened by the conjoined tendon of the internal oblique and transversalis muscle, which is pressed before the hernia, and forms one of its investments. Its coverings are, the Integument, Superficial fascia, Intercolumnar fascia, Conjoined tendon, Transversalis fascia. Peritoneal sac. • Direct inguinal hernia differs from oblique in never attaining the same bulk, in consequence of the resisting nature of the conjoined tendon of the internal oblique and transversalis and of the transver- salis fascia ; in its direction, having a tendency to protrude from the middle line rather than towards it. Thirdly, in making for itself a new passage through the abdominal parietes, instead of following a natural channel ; and fourthly, in the relation of the neck of its sac to the epigastric artery ; that vessel lying to the outer side of the opening of the sac of direct hernia, and to the inner side of oblique hernia. All the forms of inguinal hernia are designated scrotal, when they have descended into that cavity. The fascia iliaca is the tendino-fibrous investment of the psoas and iliacus muscles ; and, hke the fascia transversalis, is thick below, and becomes gradually thinner as it ascends. It is attached superiorly along the edge of the psoas, to the anterior lamella of the * Known in America by the name ventro-inguinal hernia. — G. 252 PELVIC LAYEK OK FASCIA. aponeurosis of the transversalis muscle, to the ligamentum arcuatum internum, and to the bodies of the kimbar vertebrae, leaving arches corresponding with the constricted portions of the vertebrae for the passage of the lumbar vessels. Lower down it passes beneath the external iliac vessels, and is attached along the margin of the true pelvis ; externally, it is connected to the crest of the ilium ; and, infe- riorly, to the outer two-thirds of Poupart's ligament, where it is con- tinuous with the fascia transversalis. Passing beneath Poupart's hgament, it surrounds the psoas and iliacus muscles to their termi- nation, and beneath the inner third of the femoral arch forms the posterior segment of the sheath of the femoral vessels. The fascia pelvica is attached to the inner surface of the os pubis and along the margin of the brim of the pelvis, where it is continu- ous with the iliac fascia. From this extensive origin it descends into the pelvis, and divides into two layers, the pelvic and obturator. Fig. 98.* The pelvic layer or fascia, when traced from the internal surface of the OS pubis near to the symphysis, is seen to be reflected inwards to the neck of the bladder, so as to form the anterior vesical liga- ments. Traced backwards, it passes between the sacral plexus of nerves and the internal iliac vessels, and is attached to the anterior surface of the sacrum ; and followed from the sides of the pelvis, it descends to the base of the bladder and divides into three layers, one ascending, is reflected to the side of that viscus, encloses the * A transverse section of the pelvis, showing the distribution of the pelvic fascia. 1. The bladder. 2. The vesiculse seminales divided across. 3. The rectum. 4. The iliac fascia coverin/j in the iliacus and psoas muscles (5) ; and forming a sheath for the external iliac vessels (6). 7. The anterior crural nerve excluded from the sheath. 8. The pelvic fascia. 9. Its ascending layer, forming the lateral ligament of the bladder of one side, and a sheath to the vesical plexus of veins. 10. The recto-vesical fascia of Mr. Tyrrell formed by the middle layer. 11. The inferior layer surrounding the rectum and meeting at the middle line with the fascia of the opposite side. 12. The levator arii muscle. 13. The obturator intcrnus muscle, covered in by the obturator fascia, which also forms a sheath for the internal pudic vessels and nerve (14). 15. The layer cf fascia which invests the under surface of the levator ani muscle, the anal faBcia. OBTURATOR FASCIA— rPERINEAL FASCIA. 253 vesical plexus of veins, and forms the lateral ligaments of the blad- der. A middle layer passes inwards betv/een the base of the blad- der and the upper surface of the rectum, and is named by Mr. Tyr- rell the recto-vesical fascia; and an inferioi^ layer passes behind the rectum, and, with the layer of the opposite side, completely invests that intestine. The obturator fascia passes directly downwards from the splitting of the layers of the pelvic fascia, and covers in the obturator inter- nus muscle and the internal pudic vessels and nerve ; it is attached to the ramus of the os pubis and ischium in front, and below to the falciform margin of the great sacro-ischiatic ligament. Lying be- tween these two layers of fascia is the levator ani muscle, which arises from their angle of separation. The levator ani is covered in inferiorly by a third layer of fascia, wliich is given off by the obtu- rator fascia, and is continued downwards upon the inferior surface of the muscle to the extremity of the rectum, where it is lost. This layer may be named from its position and inferior attachment the anal fascia. Fig. 99.* In the perineum there are two fascias of much importance, the superficial and deep perineal fascia. The superficial perineal fascia is a thin tendino-fibrous layer, which covers in the muscles of the genital portion of the perineum and the root of the penis. It is firmly attached at each side to the ramus of * The pubic arch with the attachments of the perineal fascice. 1, 1, 1. The superfi- cial fascia divided by a V shaped incision into three flaps ; the lateral flaps are turned over the ramus of the os pubis and ischium at each side, to which they are firmly attached ; the posterior flap is continuous with the deep perineal fascia. 2. The deep perineal fascia. 3. The opening- for the passage of the membranous portion of the urethra, previously to entering the bulb. 4. Two projections of the anterior layer of the deep perineal fascia, corresponding with Cowper's glands. 254 DEEP PERINEAL FASCIA. the OS pubis and ischiam ; posteriorly it is reflected backwards be- neath the transversus perinei muscles to become connected with the deep perineal fascia ; while anteriorly it is continuous with the dartos of the scrotum. The deep perineal fascia (Camper's ligament, triangular liga- ment) is situated behind the root of the penis, and is firmly stretched across between the ramus of the os pubis and ischium of each side so as to constitute a strong septum of defence to the outlet of the pelvis. At its inferior border it divides into two layers, one of which is continued forwards, and is continuous with the superficial perineal fascia ; while the other is prolonged backwards to the rectum, and joining with the anal fascia assists in supporting the extremity of that intestine. The deep perineal fascia is composed of two layers, which are separated from each other by several important parts, and traversed by the membranous portion of the urethra. The ante- * A side view of the viscera of the pelvis, showing the distribution of the perineal and pelvic fascite. 1. The symphysis pubis. 2. The bladder. 3. The recto-vesical fold of peritoneum, passing- from the anterior surface of the rectum to the posterior part of the bladder ; from the upper part of the fundus of the bladder it is reflected upon the abdominal parietes. 4. The ureter. 5. The vas deferens crossing- the direction of the ureter. 6. The vesicula scminalis of the right side. 7, 7. The prostate gland divided by a longitudinal section. 8, 8. The section of a ring of clastic tissue encir- cling the prostatic portion of the urethra at its commencement. 9. TJie prostatic por- tion of the urethra. 10. The membranous portion, enclosed by the compressor urethra; muscle. 11. The commencement of the corpus spongiosum penis, the bulb. 12. The anterior ligaments of the bladder formed liy the reflection of the pelvic fascia, from the internal surface of the os pubis to tlic neck of the bladder. 13. Tiie edge of the pelvic fascia at the point where it is reflected upon the rectum. H. An interval between the pelvic fascia and deep perineal fascia, occupied by a plexus of veins. 15. The deep perineal fascia; its two layers. 16. Cowpcr's gland of the right side situated between the two layers below the membranous portion of tlie urethra. 17. The superficial perineal fascia ascending in front of tlic root of the penis to become continuous with the dartos of tlie scrotum (18). 19. The layer of the deep fascia which is prolonged to the rectum. 20. Tlie lower part of the levator ani ; its fibres arc concealed by the anal fascia. 21. The inferior segment of the fimncl-shapcd process given off" from the posterior layer of the deep perineal fascia, whieii is continuous with the recto-vcsical fiiKcia of Tyrrell. The attachment of this fascia to the recto-vcsical fold of peritoneum is seen at 22. PASCIiE OF THE UPPER EXTREMITY. 255 rior layer is nearly plane in its direction, and sends a sheath for- wards around the anterior termination of the membranous urethra to be attached to the posterior part of the bulb. The posterior layer is oblique and sends a funnel-shaped process backwards, which invests the commencement of the membranous urethra and the pro- state gland. The inferior segment of this funnel-shaped process is continued backwards beneath the prostate gland and the vesiculoB seminales, and is continuous with the recto-vesical fascia of Tyrrell, which is attached posteriorly to the recto-vesical fold of peritoneum, and serves the important oifice of retaining that duplicature in its proper situation. Between the two layers of the deep perineal fascia are situated, therefore, the whole extent of the membranous portion of the urethra, the compressor urethra muscle, Cowper's glands, the internal pudic and bulbous arteries, and a plexus of veins. Mr. Tyrrell considers the anterior lamella alone as the deep perineal fascia, and the pos- terior lamella as a distinct layer of fascia covering in a considerable plexus of veins. FASCIiE OF THE UPPER EXTREMITY. The superficial fascia of the upper extremity contains between its layers the superficial veins and lymphatics, and the superficial nerves. The deep fascia is thin over the deltoid and pectoralis major muscles, and in the axillary space, but thick upon the dorsum of the scapula, where it binds down the infra-spinatus muscle. It is at- tached to the clavicle, acromion process, and spine of the scapula. In the upper arm it is somewhat stronger, and is inserted into the condyloid ridges, forming the intermuscular septa. In the fore-arm it is very strong, and at the bend of the elbow its thickness is aug- mented by a broad band, which is given off from the inner side of the tendon of the biceps. It is firmly attached to the olecranon process, to the ulna, and to the prominent points about the wrist. Upon the front of the wrist it is continuous with the anterior annular ligament, which is considered by some anatomists to be formed by the deep fascia, but which I am more disposed to regard as a liga- ment of the wrist. On the posterior aspect of this joint it forms a strong transverse band, the fosterior annular ligament, beneath which the tendons of the extensor muscles pass, in distinct sheaths. The tendons as they pass beneath the annular ligaments are surrounded by synovial bursse. The dorsum of the hand is invested by a thin fascia, which is continuous with the posterior annular ligament. The palmar fascia is divided into three portions. A central por- tion, which occupies the middle of the palm, and two lateral por- tions, which spread out over the sides of the hand, and are continuous with the dorsal fascia. The central portion is strong and tendinous : it is narrow at the wrist, where it is attached to the annular liga- 256 FASCI-E OF THE LOWER EXTREMITY. ment, and broad over the heads of the metacarpal bones, where it divides into eight slips, which are inserted into the sides of the bases of the phalanges of each finger. The fascia is strengthened at its point of division into slips by strong fasciculi of transverse fibres. and the arched interval left between the slips gives passage to the tendons of the flexor muscles. The arches between the finsrers transmit the digital vessels and nerves, and lumbricales muscles. FASCIA OF THE LOWER EXTREMITY. The superficial fascia contains between its two layers the super- ficial vessels and nerves of the lower extremity. At the groin these two layers are separated from each other by the superficial lymphatic glands, and the deeper layer is attached to Poupart's ligament, while the superficial layer is continuous with the superficial fascia of the abdomen. The deep fascia of the thigh is named, from its great extent, the fascia lata ; it is thick and strong upon the outer side of the limb, and thinner upon its inner and posterior side. That portion of fascia which invests the gluteus maximus is very thin, but that which covers in the gluteus medius is excessively thick, and gives origin, by its inner surface, to the superficial fibres of that muscle. The fascia lata is attached superiorly to Poupart's ligament, the crest of the ilium, sacrum, coccyx, tuberosity of the ischium, ramus of the ischium and os pubis and body of the os pubis ; in the thigh it is inserted into the linea aspera, and around the knee is connected with the prominent points of that joint. It possesses also two muscular attachments, — by means of the tensor vaginae femoris, which is inserted between its two layers on the outer side, and the gluteus maximus which is attached to it behind. In addition to the smaller openings in the fascia lata which trans- mit the small cutaneous vessels and nerves, there exists at the upper and inner extremity of the thigh an obUque foramen, which gives passage to the superficial lymphatic vessels, and the large subcu- taneous vein of the lower extremity, the internal saphenous vein, and is thence named the saphenous opening. The existence of this opening has given rise to the division of the upper part of the fascia lata into two portions, an iliac portion and a pubic portion. The iliac portion is situated upon the iliac side of the opening. It is attached to the crest of the ilium, and along Poupart's ligament to the spine of the os pubis, whence it is reflected downwards and outwards in an arched direction, and forms a falciform border, which constitutes the outer boundary of the say)hcnous opening. The edge of this border immediately overlies, and is reflected upon, the sheath of the femoral vessels, and the lower extremity of the curve is con- tinuous with the pubic portion. The pubic portion, occupying the pubic side of the saphenous opening, is attached to the spine of the os pubis and pectineal line ; and, passing outvv^ards behind the sheath of the femoral vessels, FASCIA LATA FEMORAL RING. 257 divides into two layers ; the anterior layer is continuous with that portion of the iliac fascia which forms the sheath of the iliacus and psoas muscles, and the posterior layer is lost upon the capsule of the hip-joint. The interval between the falciform border of the iliac portion and the opposite surface of the pubic portion is closed by a fibrous layer, which is pierced by numerous openings for the passage of lymphatic vessels, and is thence named cribrifoi-m fascia. The cribriform fascia is connected with the sheath of the femoral vessels, and forms one of the coverings of femoral hernia. When the iliac portion of the fascia lata is removed from its attachment to Poupart's ligament and is turned aside, the sheath of the femoral vessels (the femoral or crural canal) is brought into view ; and if Poupart's Ugament be Fig. 101.* carefully divided, the sheath may be isolated, and its continuation with the transversahs and iliac fascia clearly demonstrated. In this view the sheath of the femoral vessels is an infundibiliform continua- tion of the abdominal fasciae, closely adherent to the vessels, a little way down the thigh, but much larger than the vessels it contains at * A section of the structures wiiich pass beneath the femoral arch. 1. Poupart's ligament. 2, 2. The iliac portion of the fascia lata, attached along the margin of the crest of the ilium, and along Poupart's ligament, as far as the spine of the os pubis (3). 4. The pubic portion of the fascia lata, continuous at 3 with the iliac portion, and pass- ing outwards behind the sheath of the femoral vessels to its outer border at 5, where it divides into two layers ; one is continuous with the sheath of the psoas (6) and iliacus (7); the other (8) is lost upon the capsule of the hip-joint (9). 10. The femoral nerve, enclosed in the sheath of the psoas and iliacus. 11. Gimbernat's ligament. 12. The femoral ring, within the femoral sheath. 13. The femoral vein. 14. The femoral artery: the two vessels and the ring are surrounded by the femoral sheath, and thin septa are sent between the anterior and posterior wall of the sheath, dividing the artery from the vein, and the vein from the femoral ring. 33 258 FEMORAL HERNIA. Poupart's ligament. If the sheath be opened, the artery and vein will be found lying side by side, and occupying the outer two-thirds of the sheath, leaving an infundibiliform interval between the vein and the inner wall of the sheath. The superior opening of this space is- named X\\e femoral ring; it is bounded in front by Poupart's lio-ament, behind by the os pubis, internally by Gimbernat's ligament, and externally by the femoral vein. The interval itself serves for the passage of the superficial lymphatic vessels from the saphenous opening to a lymphatic gland, which generally occupies the femoral rino- ; and from thence they proceed into the current of the deep lymphatics. The femoral ring is closed merely by a thin layer of subserous cellular tissue,* which retains the lymphatic gland in its position, and is named septum crurale ; and by the peritoneum. It follows from this description, that the femoral ring must be a weak point in the parietes of the abdomen, particularly in the female, where the femoral arch, or space included between Poupart's liga- ment and the border of the pelvis, is larger than in the male, while the structures which pass through it are smaller. It happens con- sequently, that if violent or continued pressure be made upon the abdominal viscera, a portion of intestine may be forced through the femoral ring into the infundibiliform space in the sheath of the femoral vessels, carrying before it the peritoneum and the septum crurale, — this constitutes femoral hernia. If the causes which give rise to the formation of this hernia continue, the intestine, unable to extend further down the sheath, from its close connexion to the ves- sels, will in the next place be forced forwards through the saphenous opening in the fascia lata, carrying before it two additional cover- ings, the sheath of the vessels, or fascia propria, and the cribriform fascia, and then curving upwards over Poupart's ligament, will become placed beneath the superficial fascia and integument. The direction which femoral hernia takes in its descent is at first downwards, then forwards, and then upwards; and in endeavouring to reduce it, the application of the taxis must have reference to this course, and be directed in precisely the reverse order. The cover- ings of femoral hernia are the Integument, Superficial fascia, Cribriform fascia, Fascia propria. Septum crurale, Peritoneal sac. The fascia of the leg is strong in the anterior tibial region, and gives origin by its inner surface to the upper part of the tibialis anti- cus, and extensor longus digitorum muscles. * This cellular tissue is sometimes very considerably thickened by a deposit of fat within its cells, and forms a thick stratum over the hernial sac. FASCIA OF THE LEG. 259 It is firmly attached to the tibia and fibula at each side, and be- comes thickened inferiorly into a narrow band, the anterior annular ligament, beneath which the tendons of the extensor muscles pass into the dorsum of the foot in distinct sheaths, Uned by synovial bursse. Upon the outer side it forms a distinct sheath which enve- lopes the peronei muscles, and ties them to the fibula. The anterior annular ligament is attached by one extremity to the outer side of the OS calcis, and divides in front of the joint into two bands,; one of which is inserted into the inner malleolus, while the other spreads over the inner side of the foot, and becomes continuous with the internal portion of the plantar fascia. The fascia of the dorsum of the foot is a thin layer given off from the lower border of the anterior annular ligament ; it is continuous at each side with the lateral portions of the plantar fascia. The fascia of the posterior part of the leg is much thinner than the anterior, and consists of two layers, superficial and deep. The supeifcial layer is continuous with the posterior fascia of the thigh, and is increased in thickness upon the outer side of the leg by an expansion derived from the tendon of the biceps ; it terminates infe- riorly in the external and internal annular ligaments. The deep layer is stretched across between the tibia and fibula, and forms the intermuscular fascia between the superficial and deep layer of mus- cles. It covers in superiorly the popliteus muscle, receiving a tendi- nous expansion from the semi-membranosus muscle, and is attached to the oblique line of the tibia. The internal annular ligament is a strong fibrous band attached above to the internal malleolus, and below to the side of the inner tuberosity of the os calcis. It is continuous above with the posterior fascia of the leg, and below with the plantar fascia, forming sheaths for the passage of the flexor tendons and vessels, into the sole of the foot. The external annular ligament, shorter than the internal, extends from the extremity of the outer malleolus to the side of the os calcis, and serves to bind down the tendons of the peronei muscles in their passage beneath the external ankle. The plantar fascia consists of three portions, a middle and two lateral. The middle portion is thick and dense, and is composed of strong tendinous fibres, closely interwoven with each other. It is attached posteriorly to the inner tuberosity of the os calcis, and terminates under the heads of the metatarsal bones in five fasciculi. Each of these fasciculi divides into two slips, which are inserted into each side of the bases of the first phalanges of the toes, leaving an interval between them for the passage of the flexor tendons. The point of division of this fascia into fasciculi and slips, is strengthened by transverse bands, which preserve the solidity of the fascia at its broadest part. The intervals between the toes give passage to the digital arteries and nerves and the lumbricales muscles. 260 PLANTAR FASCIA. The lateral 'portions are thin, and cover the sides of the sole of the foot ; they are continuous behind with the internal and external an- nular ligaments ; on the inner side with the middle portion, and ex- ternally with the dorsal fascia. Besides constituting a strong layer of investment and defence to the soft parts situated in the sole of the foot, these three portions of fascia send processes inwards, which form sheaths for the different muscles. A strong septum is given off from each side of the middle portion of the plantar fascia, which is attached to the tarsal bones, and divides the muscles into three groups, a middle and two lateral; and transverse septa are stretched between these to separate the layers. The superficial layer of muscles derive a part of their ori- gin from the plantar fascia. CHAPTER V. ON THE ARTERIES. The arteries are the cylindrical tubes which convey the blood from the ventricles of the heart to every part of the body. They are dense in structure, and preserve for the most part the cyhndrical form when emptied of their blood, which is their condition after death : hence they were considered by the ancients, as the vessels for the transmission of the vital spirits,* and were therefore named arteries (d^f tyj^sTv, to contain air). The artery proceeding from the left ventricle of the heart contains the pure or arterial blood, which is distributed throughout the entire system, and constitutes with its returning veins the greater or sys- temic circulation. That which emanates from the right ventricle, conveys the impure blood to the lungs ; and with its corresponding veins establishes the lesser or pulmonary circulation. The whole of the arteries of the systemic circulation proceed from a single trunk, named the aorta, from which they are given off as branches, and divide and subdivide to their ultimate ramifications, constituting the great arterial tree which pervades by its minute subdivisions every part of the animal frame. The mode in which the division into branches takes place is deserving of remark. From the aorta the branches, for the most part, pass off at right angles, as if for the purpose of checking the impetus with v^hich the blood would otherwise rush along their cylinders from the main trunk ; but in the limbs a very different arrangement is adopted ; the branches are given off" from the principal artery at an acute angle, so that no impediment may be offered to the free circulation of the vital fluid. The division of arteries is usually dichotomous, as of the aorta into the two common iliacs, common carotid into the external and inter- nal, &c. ; but in some few instances a short trunk divides suddenly into several branches which proceed in different directions ; this mode of division is termed an axis, as the thyroid and cceliac axis. In the division of an artery into two branches, it is observed that the combined arose of the two branches are greater than that of the single trunk ; and if the combined areas of all the branches at the periphery of the body were compared with that of the aorta, it would be seen that the blood, in passing from the aorta into the numerous distributing branches, was flowing through a conical tube of which the apex might be represented by the aorta, and the base * To Galen is due the honour of haviug discovered tliat arteries contained blood, and not ail-. 262 STRUCTURE OP ARTERIES. by the surface of the entire body. The advantage of this important principle in faciUtating the circulation is sufficiently obvious ; for the increased channel which is thus provided for the current of the blood, serves to compensate the retarding influence of friction, resulting from the distance of the heart and the division of the vessels. Communications between arteries are very free and numerous, and increase in frequency with the diminution in the size of the branches ; so that through the medium of the minute ramifications, the entire body may be considered as one uninterrupted circle of inosculations, or anastomoses (ava between, tfTo/j-a mouth). This in- crease in the frequency of anastomosis in the smaller branches is a provision for counteracting the greater liability to impediment exist- ing in them than in the larger branches. Where freedom of circu- lation is of vital importance, this communication of the arteries is very remarkable, as in the circle of Willis in the cranium, or in the distribution of the arteries of the heart. It is also strikingly seen in situations where obstruction is most likely to occur, as in the dis- tribution to the alimentary canal, around joints, or in the hand and foot. Upon this free communication existing every where between arterial branches is founded the principle of cure in the ligature of large arteries ; the ramifications of the branches given oflf from the artery above the ligature inosculate with those which proceed from the trunk of the vessel below the ligature: these anastomosing branches enlarge and constitute a collateral circulation, in which, as is shown in the beautiful preparations made by Sir Astley Cooper, several large branches perform the office of the single obliterated trunk.* The arteries do not terminate directly in veins ; but in an inter- mediate system of vessels, which, from their minute size, are termed capillaries (capillus, a hair). The capillaries constitute a micro- scopic network, which is distributed through every part of the body, so as to render it impossible to introduce the smallest needle-point beneath the skin without wounding several of these fine vessels. It is through the medium of the capillaries that all the phenomena of nutrition and secretion are performed. They are remarkable for their uniformity of diameter, and for the constant divisions and communications which take place between them without any altera- tion of size. They inosculate on one hand with the terminal ram- usculi of the arteries ; and on the other with the minute radicles of the veins. Arteries are composed of three coats, external, middle, and in- ternal The external or cellular coat is firm and strong, and serves at the same time as the chief means of resistance of the vessel, and of connexion to surrounding parts. It consists of condensed cellular tissue, strengthened by an interlacement of ghstening fibres which * I have a preparation, showing the collaternl circulation in a dog, in whom T tied the abdorainul aorta ; the animai died from over-ffcding- nearly two years after the operation. AORTA. 263 partially encircle the cylinder of the tube in an oblique direction. Upon the surface the cellular tissue is loose, to permit of the move- ments of the artery in distension and contraction. The middle or fibrous coat is composed of yellowish fibres of elastic tissue, which are disposed in an oblique direction around the cylinder of the vessel, and cross each other in their course. This coat is elastic and fragile, and thicker than the external coat. Its elasticity enables the vessel to accommodate itself to the quantity of blood which it may contain ; its fragility is exhibited in some cases of aneurism, and in the division of the two internal coats of an artery by a ligature. The internal coat is a thin serous membrane which lines the in- terior of the artery, and gives it the smooth polish which that sur- face presents. It is continuous with the lining membrane of the heart, and through the medium of the capillaries with the venous system. The internal is connected to the fibrous coat by a close cellular tissue which is very liable to disease and depositions of various kinds ; and is the seat of the first changes which precede aneurism. The researches of Henle have demonstrated an epithe- lium, composed of vesicles and scales, with central nuclei, upon the surface of this internal coat, analogous to the epithelium of serous and mucous membranes. The arteries in their distribution through the body are included in a loose cellular investment which separates them from the sur- rounding tissues, and is called a sheath. Around the principal ves- sels the sheath is an important structure ; it is composed of cellulo- fibrous tissue, intermingled with tendinous fibres, and is continuous with the fascia of the region in which the arteries are situated, as with the thoracic and cervical fascia in the neck, transversalis and iliac fasciae, and fascia lata in the thigh, &c. The sheath of the arteries contains also their accompanying veins, and sometimes a nerve. The coats of arteries are supplied with blood like other organs of the body, and the vessels which are distributed to them are named Vasa vasorum. They are also provided with nerves ; but the mode of distribution of the nerves is at present undiscovered. In the consideration of the arteries, we shall first describe the aorta, and the branches of that trunk, with their subdivisions, which together constitute the efferent portion of the systemic circulation : and then the pulmonary artery as the efferent trunk of the pulmo- nary circulation. AORTA. The Aorta arises from the left ventricle, at the middle of the root of the heart, opposite the articulation of the fourth costal cartilage with the sternum. At its commencement it presents three dilata- tions, called the sinus aortici, which correspond with the semilunar valves. It ascends at first to the right, then curves backwards and 264 AORTA. to the left, and descends on the left side of the vertebral column to the fourth lumbar vertebra. Hence it is divided into — ascending — arch — and descending aorta. Relations. — The ascendivg aorta has in relation with it, in front, the trunk of the pulmonary artery, thoracic fascia, and pericardium ; behind, the right pulmonary veins and artery; to the right side, the right auricle and superior cava ; and to the left, the left auricle and the trunk of the pulmonary artery. Fig. 102.* * The large vessels which proceed from the root of the heart, with their relations ; the heart has been removed. 1. The ascending aorta. 2. The arch. 3. The thoracic portion of the descending aorta. 4. The arteria innominata dividing into, 5, the right carotid, which again divides at 6, into the external and internal carotid; and 7, the right subclavian artery. 8. The axillary artery : its extent is designated by a dotted line. 9. The brachial artery. 10. The right pneumogasiric nerve running by the side of the common carotid, in front of the right subclavian artery, and behind the root of tlie right lunp-. 11. The left common carotid, having to its outer side the left pneumo- gastric nerve, which crosses the arch of the aorta, and as it reaches its lower border is seen to give off the left recurrent nerve. 12. The left subclavian artery becoming axillary, and brachial in its course, like the artery of the opposite side. 13. The trunk of the pulmonary artery connected to the concavity of the arch of the aorta by a fibrous cord, the remains of the ductus arteriosus. 14. Tiie left pulmonary artery. 1.5. The right pulmonary artery. IG. The traciiea. 17. The right bronchus. 18. The left bronchus. 19, 19. The pulmonary veins. 17, l.*), and 19, on the right side, and 14, 18, and 19, on the left, constitute the roots of the corresponding lungs, and the relative position of these vessels is carefully preserved. 20. Bronchial arteries. 21,21. Inter- costal arteries; the branches from the front of the aorta above and below the number 3 are pericardiac and oesophageal branches. ASCENDING AORTA — ARCH. 265 Plan of the relations of the ascending Aorta. In Front. Pericardium, Thoracic fascia, Pulmonary artery. Right Side, Superior cava. Right auricle. Ascending Aorta. Left Side. Pulmonary artery, Left auricle. Behind. Right pulmonary artery, Right pulmonary veins. Arch. — The upper border of the arch is parallel with the upper border of the second sterno-costal articulation of the right side in front, and the second dorsal vertebra behind, and terminates opposite the lower border of the third. The anterior surface of the arch is crossed by the left pneumo- gastric nerve, and by the cardiac branches of that nerve, and of the sympathetic. The posterior surface of the arch is in relation with the bifurca- tion of the trachea and great cardiac plexus, the cardiac nerves, left recurrent nerve, and the thoracic duct. The superior border gives off the three great arteries, viz. the in- nominata, left carotid, and left subclavian. The inferior border, or concavity of the arch, is in relation with the remains of the ductus arteriosus, the cardiac ganglion and left recurrent nerve, and has passing beneath it the right pulmonary artery and left bronchus. Plan of the relations of the arch of the Aorta. Above. Arteria innorainata. Left carotid, Left subclavian. In Front. Left pneumogastric nerve. Cardiac nerves. Arch of the Aorta. Behind, Bifurcation of the trachea, Great cardiac plexus. Cardiac nerves. Left recurrent nerve, Thoracic duct. Below. Cardiac ganglion. Remains of ductus arteriosus, Left recurrent nerve, Right pulmonary artery. Left bronchus. The descending aorta is subdivided, in correspondence with the two great cavities of the trunk, into the thoracic and abdominal aorta. The thoracic aorta is situated to the left side of the vertebral 34 266 THORACIC AORTA ABDOMINAL AORTA. column, but approaches the middle line as it descends, and at the aortic opening of the diaphragm is altogether in front of the column. After entering the abdomen it again falls back to the left side. Relations. — It is in relation, behind with the vertebral column and lesser vena azygos ; in front with the oesophagus and right pneumogastric nerve ; to the left side with the pleura ; and to the right with the thoracic duct. Plan of the relations of the thoracic Aorta. In Front. CEsophagus, Right pneumogastric nerve. Right Side. Thoracic duct. Thoracic Aorta. Left Side. Pleura. Behind. Lesser vena azygos, Vertebral column. The abdominal aorta enters the abdomen through the aortic open- ing of the diaphragm, and descends, lying rather to the left side of the vertebral column, to the fourth lumbar vertebra, where it divides into the two common iliac arteries. Relations. — It is crossed, in front by the left renal vein, pancreas, transverse duodenum, and mesentery, and is embraced by the aortic plexus ; behind it is in relation with the thoracic duct, receptaculum chyli, and left lumbar veins. ' On its left side is the left semilunar ganglion and sympathetic nerve ; and on the right the vena cava, right semilunar ganglion, and the commencement of the vena azygos. Plan of the relations of the abdominal Aorta. In Front. Left renal vein. Pancreas, Transverse duodenum, Mesentery, Aortic plexus. Right Side. Vena cava, Right semilunar ganglion. Vena azygos. Behind. Thoracic duct, Receptaculum chyli. Left lumbar veins. Left Side. Left semilunar gan- glion. Sympathetic nerve. ARTERIA. INNOMINATA. 267 Branches.- are — -The branches of the aorta, arranged in a tabular form, Ascending aorta Arch of the aorta Thoracic aorta Right carotid, Right subclavian. Abdominal aoj^ta Coronary. Arteria innominata, Left carotid, Left subclavian. Pericardiac, Bronchial, 1 (Esophageal, Intercostal. Phrenic, C Gastric, Coeliac axis, < Hepatic, ( Splenic. Supra-renal, or capsular, Renal, or emulgent, Superior mesenteric, Spermatic, Inferior mesenteric, Lumbar, Sacra media, Common iliacs. The coronary arteries arise from the aortic sinuses at the com- mencement of the ascending aorta, immediately above the free margin of the semilunar valves. The left, or anterior coronary passes forwards, between the pulmonary artery and left appendix auriculae, and divides into two branches ; one of which winds around the base of the left ventricle, in the auriculo-ventricular groove, and inosculates with the right coronary, forming an arterial circle around the base of the heart, while the other passes along the line of union of the two ventricles, upon the anterior aspect of the heart, to its apex, where it anastomoses with the descending branch of the right coronary. It supplies the left auricle and the adjoining sides of both ventricles. The right, or posterior coronary passes forwards, between the root of the pulmonary artery and the right auricle, and winds along the auriculo-ventricular groove, to the posterior median furrow, where it descends upon the posterior aspect of the heart to its apex, and inosculates with the left coronary. It is distributed to the right auricle and to the posterior surface of both ventricles, and sends a large branch along the sharp margin of the right ventricle to the apex of the heart. ARTERIA INNOMINATA. The Arteria innominata (fig. 102, No. 4,) is the first artery given off by the arch of the aorta. It is an inch and a half in length, 268 COMMON CAROTID ARTERIES. and ascends obliquely to the right sterno-clavicular articulation, where it divides into the right carotid and right subclavian artery. Relations. — It is in relation, in front with the left vena innomi- nata, the thymus gland, and the origins of the sterno-thyroid and sterno-hyoid muscles, which separates it from the sternum. Behind with the trachea, pneumogastric nerve and cardiac nerves ; exter- nally with the right vena innominata and pleura; and internally with the origin of the left carotid. Plan of the relations of the Arteria Innominata. In Front, Left vena innominata, Thymus gland, Sterno-thyroid, Sterno-hyoid. Right Side. Right vena innominata, Pleura. Arteria innominata. Left Side. Left carotid. Behind. Trachea, Pneumogastric nerve. Cardiac nerves. The arteria innominata occasionally gives off a small branch which ascends along the middle of the trachea to the thyroid gland. This branch was described by Neubauer, and Dr. Harrison names it the middle thyroid artery. A knowledge of its existence is ex- tremely important in performing the operation of tracheotomy. COMMOKr CAROTID ARTERIES. The common carotid arteries (xapa, the head) arise, the right from the bifurcation of the arteria innominata opposite the right sterno- clavicular articulation, the left from the arch of the aorta. It fol- lows, therefore, that the right carotid is shorter than the left; it is also more anterior; and, in consequence of proceeding from a branch instead of from the main trunk, it is larger than its fellow. The Right common carotid artery (fig. 102, No. 5) ascends the neck perpendicularly, from the right sterno-clavicular articulation to a level with the upper border of the thyroid cartilage, where it divides into the external and internal carotid. The Left common carotid (fig. 102, No. 11) passes somewhat ob- liquely outwards from the arch of the aorta to the side of the neck, and thence upwards to a level with the upper border of the thyroid cartilage, where it divides like the right common carotid into the external and internal carotid. Relations. — The right common carotid rests, first, upon the longus colli muscle, then upon the rectus anticus major, the sympathetic nerve being interposed. The inferior thyroid artery and recurrent laryngeal nerve pass behind it at its lower part. To its inner side is the trachea, recurrent laryngeal nerve, and larynx; to its outer side, and enclosed in the same sheath, the jugular vein and pneumo- EXTERNAL CAROTID ARTERY. 269 gastric nerve; and in front the sterno-thyroid, sterno-hyoid, sterno- mastoid, omo-hyoid, and platysma muscles, and the descendens noni nerve. The left common carotid, in addition to the relations just enumerated, which are common to both, is crossed near its com- mencement by the left vena innominata; it lies upon the trachea; then gets to its side, and is in relation with the oesophagus and tho- racic duct : to facilitate the study of these relations, I have arranged them in a tabular form. Plan of relations of the Common Carotid Artery. In Front. Platysma, Descendens noni nerve, Omo-hyoid, Sterno-mastoid, Sterno-hyoid, Sterno-thyroid. Externally. Internal jugular vein, Pneumogastric nerve. Common Carotid Artery. Internally. Trachea, Larynx, Recurrent laryngeal Behind. Longus colli. Rectus anticus major. Sympathetic, Inferior thyroid artery. Recurrent laryngeal nerve. Additional relations of the Left Common Carotid. In Front. Left vena innominata. Behind. Trachea, Thoracic duct. Internally. Arteria innominata, (Esophagus. Externally. Pleura. EXTERN.'IL CAROTID ARTERY. The External carotid artery ascends nearly perpendicularly from opposite the upper Itorder of the thyroid cartilage, to the space be- tween the neck of the lower jaw and the meatus auditorius, where it divides into the temporal and internal maxillary artery. Relations. — In front it is crossed by the posterior belly of the digastricus, stylo-hyoideus, and platysma myoides muscles; by the lingual nerve near its origin; higher up it is situated in the sub- stance of the parotid gland, and is crossed by the facial nerve. Be- hind it is separated from the internal carotid by the stylo-pharyngeus and stylo-glossus muscles, glosso-pharyngeal nerve, and part of the parotid gland. 270 SUrEKIOR THYROID ARTERY. Plan of the relations of the External Carotid Artery. In Front. ' Platysma, Digastricus, Stylo-h)'oid, Lingual nerve, Facial nerve, Parotid gland. Behind. Stylo-pharyngeus, Stylo-glossus, Glosso-pharyngeal nerve, Parotid gland. Branches. — The branches of the external carotid are eleven in number, and may be arranged into four groups, viz. Anterior. Posterior. 1. Superior thyroid, 4. Mastoid, 2. Lingual, 5. Occipital, 3. Facial. 6. Posterior auricular. Superior. Terminal. 7. Parotidean, 10. Temporal. 8. Ascending pharyngeal, 1 1 . Internal maxillary. 9. Transverse facial. The anterior branches arise from the commencement of the exter- nal carotid, within a short distance of each other. The lingual and facial bifurcate, not unfrequently, from a common trunk. 1. The Superior Thyroid Artery (the first of the branches of the external carotid) curves downwards to the thyroid gland to which it is distributed, anastomosing with its fellow of the opposite side, and with the inferior thyroid arteries. In its course it passes be- neath the omo-hyoid, sterno-thyroid, and sterno-hyoid muscle. Branches. Hyoid, Superior laryngeal, Inferior laryngeal. Muscular. The Hyoid branch passes forwards beneath the thyro-hyoideus, and is distributed to the insertion of the depressor muscles^ into the OS hyoidcs. The Superior laryngeal pierces the thyro-hyoidcan membrane, in company with the superior laryngeal nerve, and supplies the mucous membrane and muscles of the larynx, sending a branch upwards to the epiglottis. LINGUAL ARTEEY. 271 The Inferior laryngeal is a small branch which crosses the crico- thyroidean membrane along the lower border of the thyroid cartilage. It sends branches through the membrane to supply the mucous lining of the larynx, and inosculates with its fellow of the opposite side. Fig. 103.* The muscular branches are distributed to the depressor muscles of the OS hyoides and larynx. One of these branches crosses the sheath of the common carotid to the under surface of the sterno-mastoid muscle. 2. The Lingual Artery ascends obliquely from its origin, it then passes forwards parallel with the os hyoides ; thirdly, it ascends to the under surface of the tongue ; and fourthly, runs forward in a serpentine direction to its tip, under the name of ranine artery, where it terminates by inosculating with its fellow of the opposite side. Relations. — The ^rs^ part of its course rests upon the middle con- strictor muscle of the pharynx, being covered in by the tendon of the digastricus and the stylo-hyoid muscle ; the second is situated between the middle constrictor and hyo-glossus muscle, the latter separating it from the lingual nerve ; in the third part of its course * The carotid arteries with the branches of the external carotid. 1. The common carotid. 2. The external carotid. 3. The internal carotid. 4. The carotid foramen in the petrous portion of the temporal bone. 5. The superior tliyroid artery. 6. The lingual artery. 7. The facial artery. 8. The mastoid artery. 9. The occipital. 10. The posterior auricular. 11. The transverse facial artery. 12. The internal ma.xil- lary. 13. The temporal. 14. The ascending pharyngeal artery. 272 FACIAL ARTERY. it lies between the hyo-glossus and genio-hyo-glossus ; and in the fourth (ranine) rests upon the HnguaUs to the tip of the tongue. Branches. Hyoid, Dorsalis hngua3, Sublingual. The Hyoid branch runs along the upper border of the os hyoides, and is distributed to the origins of the elevator muscles of the os hyoides, inosculating with its fellow of the opposite side. The Do7'saIis linguce ascends along the posterior border of the hyo-glossus muscle to the dorsum of the tongue, and is distributed to the tongue, the fauces and epiglottis, anastomosing with its fellow of the opposite side. The Sublingual branch, frequently considered as a branch of bifurcation of the lingual, runs along the anterior border of the hyo- glossus, and is distributed to the sublingual gland and to the muscles of the tongue. It is situated between the mylo-hyoideus and genio- hyo-glossus, generally accompanies Wharton's duct for a part of its course, and sends a branch to the fraenum Hnguse. It is the latter branch which affords the considerable haemorrhage which some- times accompanies the operation of snipping the froenum in children. 3. Facial Artery. — The Facial artery arises a little above the great cornu of the os hyoides and ascends obliquely to the submax- illary gland, in which it lies embedded. It then curves around the body of the lower jaw, close to the anterior inferior angle of the massetcr muscle, ascends to the angle of the mouth, and thence to the angle of the eye, where it is named the angular artery. The facial artery is very tortuous in its course over the buccinator mus- cle, to accommodate itself to the movement of the jaws. Relations. — Below the jaw it passes beneath the digastricus and stylo-hyoid muscles ; on the body of the lower jaw it is covered by the platysma myoides, and at the angle of the mouth by the depressor anguli oris and zygomatic muscles. It rests upon the submaxillary gland, the lower jaw, buccinator, orbicularis oris, levator anguli oris, levator labii superioris proprius,.and levator labii supcrioris alseque nasi. Its branches are divided into those which are given off below the jaw and those on the face : they may be thus arranged : — Below the Jaw. Inferior palatine, Submaxillary, Submental, Pterygoid. FACIAL OCCIPITAL. 273 On the Face. Masseteric, Inferior labial, Inferior coronary, Superior coronary, Lateralis nasi. The Inferior- palatine branch ascends between the stylo-glossus and stylo-pharyngeus muscles, to be distributed to the tonsil and soft palate, and anastomoses with the posterior palatine branch of the internal maxillary artery. The Submaxillary are four or five branches which supply the sub- maxillary gland. The Submental branch runs forwards upon the mylo-hyoid muscle, under cover of the body of the lower jaw, and anastomoses with branches of the sublingual and inferior dental artery. The Pterygoid branch is distributed to the internal pterygoid muscle. The Masseteric branches are distributed to the masseter and buc- cinator muscles. The Inferior labial branch is distributed to the muscles and integu- ment of the lower lip. The Inferior coronary runs along the edge of the lower lip, between the mucous membrane and labial glands, and the orbicu- laris oris ; it inosculates with the corresponding artery of the oppo- site side. The Superior coronary follows the same course along the upper lip, inosculating with the opposite superior coronary artery, and at the middle of the Up it sends a branch upwards to supply the septum of the nose and the mucous membrane. The Lateralis nasi is distributed to the ala and septum of the nose. The Inosculations of the facial artery are very numerous : thus it anastomoses with the sublingual branch of the lingual, with the ascending pharyngeal and posterior palatine arteries, with the inferior dental as it escapes from the mental foramen, infra-orbital at the infra-orbital foramen, transverse facial on the side of the face, and at the angle of the eye with the nasal and frontal branches of the ophthalmic artery. The facial artery is subject to considerable varieties in its extent ; it not unfrequently terminates at the angle of the nose or mouth, and is rarely symmetrical on both sides of the face. 4. The Mastoid Artery turns downwards, to be distributed to the sterno-mastoid muscle, and to the lymphatic glands of the neck ; sometimes it is replaced by two small branches. 5. The Occipital Artery, smaller than the preceding branches, passes backwards beneath the posterior belly of the digastricus, the trachelo-mastoid and sterno-mastoid muscles, to the occipital groove 35 274 POSTERIOR AURICULAR TEMPORAL. in the mastoid portion of the temporal bone. It then ascends between the splenius and complexus muscles, and divides into two branches which are distributed upon the occiput, anastomosing with the opposite occipital, the posterior auricular, and temporal artery. The lingual nerve curves around this artery near to its origin from the external carotid. Branches. — It gives off only two branches deserving of name, the inferior meningeal and princeps cervicis. The Inferior meningeal ascends by the side of the internal jugular vein, and passes through the foramen lacerum posterius, to be dis- tributed to the dura mater. The Arteria prince'ps cervicis is a large and irregular branch. It descends the neck between the complexus and semi-spinahs coUi, and inosculates with the profunda cervicis of the subclavian. This branch is the means of estabhshing a very important collateral cir- culation between the branches of the carotid and subclavian, in liga- ture of the common carotid artery. 6. The Posterior Auricular Artery arises from the external carotid, above the digastric and stylo-hyoid muscles, and ascends beneath the lower border of the parotid gland, and behind the concha, to be distributed by two branches to the external ear and side of the head, anastomosing with the occipital and temporal arteries ; some of its branches pass through fissures in the fibro-cartilage, to be dis- tributed to the anterior surface of the pinna. The anterior auricular arteries are branches of the temporal. Branches. — The posterior auricular gives off but one named branch, the styh-mastoid, which enters the stylo-mastoid foramen to be distributed to the aquseductus Fallopii and tympanum. 7. The Parotidean Arteries are four or five large branches which are given off" from the external carotid whilst that vessel is situated in the parotid gland. They are distributed to the structure of the gland, their terminal branches reaching the integument and the side of the face. 8. The Ascending Pharyngeal Artery, the smallest of the branches of the external carotid, arises from that trunk near to its bifurcation, and ascends between the internal carotid and the side of the pharynx to the base of the skull, where it divides into two branches ; meningeal, which enters the foramen lacerum posterius, to be distributed to the dura mater ; and pharyngeal. It supplies the pharynx, tonsils, and Eustachian tube. 9. The Transversalis Faciei arises from the external carotid whilst that trunk is lodged within the parotid gland ; it crosses the masseter muscle, lying parallel with and a little above Stenon's duct ; and is distributed to the temporo-maxillary articulation, and to the muscles and integument on the side of the face, inosculating with the infra-orbital and facial artery. This artery is not unfrequently a branch of the temporal. 10. The Temporal Artery is one of the two terminal branches of the external carotid. It ascends over the root of the zygoma ; INTERNAL MAXILLARY ARTERY. 275 and at about an inch and a half above the zygomatic arch, divides into an anterior and a posterior temporal branch. The anterior temporal is distributed over the front of the temple and arch of the skull, and anastomoses with the opposite anterior temporal, and with the supra-orbital and frontal artery. The posterior temporal curves upwards and backwards, and inosculates with its fellow of the oppo- site side, with the posterior auricular and occipital artery. The trunk of the temporal artery is covered in by the parotid gland and by the attrahens aurem muscle, and rests upon the tem- poral fascia. Branches. Orbitar, Anterior auricular. Middle temporal. The Orbitar artery is a small branch, not always present, which passes forwards immediately above the zygoma, between the two layers of the temporal fascia, and inosculates beneath the orbicularis palpebrarum with the palpebral arteries. The Anterior auricular arteries are distributed to the anterior por- tion of the pinna. The Middle temporal branch passes through an opening in the temporal fascia immediately above the zygoma, and supplies the temporal muscle inosculating with the deep temporal arteries. 11. The Internal Maxillary Artery, the other terminal branch of the external carotid, has next to be examined. Dissection. — The Internal maxillary artery passes inwards behind the neck of the lower jaw to the deep structures in the face ; we require, therefore, to remove several parts for the purpose of seeing it completely. To obtain a good view of the vessel, the zygoma should be sawn across in front of the external ear, and the malar bone near to the orbit. Turn down the zygomatic arch with the masseter muscle. In doing this, a small artery and nerve will be seen crossing the sigmoid arch of the lower jaw, and entering the masseter muscle (the masseteric). Cut away the tendon of the tem- poral muscle from its insertion into the coronoid process, and turn it upwards towards its origin ; some vessels will be seen entering its under surface ; these are the deep temporal. Then saw the ramus of the jaw across its middle, and dislocate it from its articulation with the temporal bone. Be careful in doing this to carry the blade of the knife close to the bone, lest any branches of nerves should be injured. Next raise this portion of bone, and with it the external pterygoid muscle. The artery, together with the deep branches of the inferior maxillary nerve, will be seen lying upon the pterygoid muscles. These are to be carefully freed of fat and cellular tissue, and then examined. This artery (fig. 103, No. 12) commences in the substance of the parotid gland, opposite the meatus auditorius externus, it passes in the first instance horizontaUv forwards behind the neck of the lower 276 INTERNAL MAXILLARY ARTERY. jaw ; next, curves around the lower border of the external pterygoid muscle near its origin, and ascends obliquely forwards upon the outer side of that muscle ; it then passes between the two heads of the external pterygoid and enters the pterygo-maxillary fossa. Occa- sionally it passes between the two pterygoid muscles, without appear- ing on the outer surface of the external pterygoid. In consideration of its course this artery may be divided into three portions: maxillary, pterygoid, and spheno-maxillary. Relations. — The Maxillary portion is situated between the ramus of the jaw and the internal lateral ligament, lying parallel with the auricular nerve ; the pterygoid portion between the external ptery- goid muscle, and the masseter and temporal muscle. The pterygo- maxillary portion lies between the two heads of the external ptery- goid muscle, and in the spheno-maxillary fossa is in relation with Meckel's ganglion. Branches. Tympanic, nr -1, J- J Inferior dental, Maxillary pai^tion ^ ^^^^^.-^ meningea magna, Arteria meningea parva. Deep temporal branches. External pterygoid. Pterygoid portion . <^ Internal pterygoid, Masseteric, Buccal. Superior dental, Infra-orbital, Pterygo-maxillary ) Pterygo-palatine, portion j Spheno-palatine, Posterior palatine. Vidian. The Tympanic branch is small and not likely to be seen in an ordinary dissection ; it is distributed to the temporo-maxillary articu- lation and meatus, and passes into the tympanum through the fissura Glaseri. The Inferior dental descends to the dental foramen, and enters the canal of the lower jaw in company with the dental nerve. Opposite the bicuspid teeth it divides into two branches, one of which is continued onwards within the bone as far as the symphysis, to supply the incisor teeth, while the other escapes with the nerve at the mental foramen, and anastomoses with the inferior labial and submental branch of the facial. It supplies the teeth of the lower jaw, sending small branches along the canals in their roots. The Arteria meningea magna ascends behind the temporo-maxil- lary articulation to the foramen spinosum in the spinous process of the sphenoid bone, and entering the cranium divides into an anterior and a posterior branch. The anterior branch crosses the great ala INTERNAL MAXILLARY ARTERY. 277 of the sphenoid to the groove or canal in the anterior inferior angle of the parietal bone, and divides into branches, v^hich ramify upon the external surface of the dura mater, and anastomose with corre- sponding branches from the opposite side. The posterior branch crosses the squamous portion of the temporal bone, to the posterior part of the dura mater and cranium. The branches of the arteria meningea magna are distributed chiefly to the bones of the skull ; and in the middle fossa it sends a small branch through the hiatus Fallopii to the facial nerve. The Meningea parva is a small branch which ascends to the foramen ovale, and passes into the skull to be distributed to the Casserian ganglion and dura mater. It gives off a small branch to the nasal fossae and soft palate. The Muscular branches are distributed, as their names imply, to the five muscles of the maxillary region ; the temporal branches are two in number. The Superior dental artery is given off from the internal maxil- lary, just as that vessel is about to make its turn into the spheno- maxillary fossa. It descends upon the tuberosity of the superior maxillary bone, and sends its branches through several small fora- mina to supply the posterior teeth of the upper jaw, and the antrum. The terminal branches are continued forwards upon the alveolar process, to be distributed to the gums and to the sockets of the teeth. The Infra-orbital would appear, from its size, to be the proper continuation of the artery. It runs along the infra-orbital canal with the superior maxillary nerve, sending branches into the orbit and downwards through canals in the bone, to supply the mucous lining of the antrum and the teeth of the upper jaw, and escapes from the infra-orbital foramen. The branch which supplies the in- cisor teeth is the anterior dental artery ; on the face it inosculates with the facial and transverse facial arteries. The Pterygo-palatine is a small branch which passes through the pterygo-palatine canal, and supplies the upper part of the pharynx and Eustachian tube. The Spheno-palatine, or nasal, enters the superior meatus of the nose through the spheno-palatine foramen in company with the nasal branches of Meckel's ganglion, and divides into two branches ; one of which is distributed in the mucous membrane of the septum, while the other supplies the mucous membrane of the lateral wall of the nares, together with the sphenoid and ethmoid cells. The Posterior palatine artery descends along the posterior pala- tine canal, in company with the posterior palatine branches of Meckel's ganglion, to the posterior palatine foramen ; it then curves forwards lying in a groove upon the bone, and is distributed to the palate, while in the posterior palatine canal it sends a small branch backwards, through the small posterior palatine foramen to supply the soft palate, and anteriorly it supplies a branch to the anterior palatine canal, which reaches the nares and inosculates with the branches of the spheno-palatine artery. 278 IjVTErnal carotid artery. The Vidian branch passes backwards along the pterygoid canal, and is distributed to the sheath of the Vidian nerve, and to the Eus- tachian tube. INTERNAL CAROTID ARTERY. The internal carotid artery curves slightly outwards from the bifurcation of the common carotid, and then ascends nearly perpen- dicularly through the maxillo-pharyngeal space* to the carotid fora- men in the petrous bone. It next passes inioards along the carotid c^iidX, forioards by the side of the sella turcica, and upwards by the anterior clinoid process, where it pierces the dura mater and divides into three terminal branches. The course of this artery is remark- able from the number of angular curves which it forms ; one or two of these flexures are sometimes seen in the cervical portion of the vessel near to the base of the skull ; and by the side of the sella tur- cica it resembles the italic letter s, placed horizontally. Relations. — In consideration of its connections, the artery is divi- sible into a cervical, petrous, cavernous, and cerebral portion. The Cervical portion is in relation 'posteriorly with the rectus anticus major, sympathetic nerve, pharyngeal and laryngeal nerves which cross behind it, and near the carotid foramen with the glosso-pharyn- geal, pneumogastric and lingual nerves, and partially with the inter- nal jugular vein. Internally it is in relation with the side of the pharynx, the tonsil, and the ascending pharyngeal artery. Externally with the internal jugular vein, glosso-pharyngeal, pneumogastric, and lingual nerves, and in front with the stylo-glossus, and stylo- pharyngeus muscle, glosso-pharyngeal nerve, and parotid gland. Plan of the relations of the cervical portion of the internal carotid artery. In Front. Parotid gland, Stylo-glossus muscle, Stylo-pharyngeus muscle, Glosso-pharyngeal nerve. Internally, P^^'^y,"''' I Internal i°"^''' , Carotid Artery. Ascendmg pharyn- ' geal artery. Externally, Jugular vein, Glosso-pharyngeal, Pneumogastric, Lingual nerve. Behind, Superior cervical ganglion, Pneumogastric nerve, Glosso-pharyngeal, Pharyngeal nerve, Superior laryngeal nerve. Sympathetic nerve, Rectus anticus major. The Petrous portion is separated from the bony wall of the carotid canal by a lining of dura mater ; it is in relation with the carotid plexus, and is covered in by the Casserian ganglion. * For tlie boundaries of this space bcc page IGG. INTERNAL CAROTID ARTERY. 279 The Cavernous 'portion is situated in the inner wall of the caver- nous sinus, and is in relation by its outer side with the lining mem- brane of the sinus, the sixth nerve, and the ascending branches of the carotid plexus. The third, fourth, and ophthalmic nerves are placed in the outer wall of the cavernous sinus, and are separated from the artery by the lining membrane of the sinus. The Cerebral portion of the artery is enclosed in a sheath of the arachnoid, and is in relation with the optic nerve. At its point of division it is situated in the fissure of Sylvius. Branches. — The cervical portion of the internal carotid gives oif no branches : from the other portions are derived the following : — Tympanic, Anterior meningeal. Ophthalmic, Anterior cerebral. Middle cerebral. Posterior communicating, Choroidean. The Tympanic is a small branch which enters the tympanum through a minute foramen in the carotid canal. The Anterior meningeal is distributed to the dura mater and Cas- serian ganglion. The Ophthalmic artery arises from the cerebral portion of the in- ternal carotid, and enters the oi'bit through the foramen opticum, immediately to the outer side of the optic nerve. It then crosses the optic nerve to the inner wall of the orbit, and runs along the lower border of the superior oblique muscle, to the inner angle of the eye, where it divides into two terminal branches, the frontal and nasal. Branches. — The branches of the ophthalmic artery may be arranged into two groups : — first, those distributed to the orbit and surrounding parts ; and secondly, those which supply the muscles and globe of the eye. They are — First Group. Second Group. Lachrymal, Muscular, Supra-orbital, Anterior ciliary, Posterior ethmoidal. Ciliary short and long, Anterior ethmoidal. Centralis retinae. Palpebral, Frontal, Nasal. The Lachrymal is the first branch of the ophthalmic artery, and is usually given off immediately before that artery enters the optic foramen. It follows the course of the lachrymal nerve, along the upper border of the external rectus muscle, and is distributed to the 280 OPHTHALMIC ARTERY. lachrymal gland. The small branches which escape from the gland supply the conjunctiva and upper eyelid. The lachrymal artery gives off a malar branch, which passes through the malar bone into the temporal fossa and inosculates with the deep temporal arteries, while some of its branches become subcutaneous on the cheek and anastomose with the transverse facial. The Supra-orbital artery follows the course of the frontal nerve, resting on the levator palpebrse muscle : it passes through the supra- orbital foramen, and divides into a superficial and deep branch which are distributed to the muscles and integument of the forehead and to the pericranium. At the supra-orbital foramen it sends a branch inwards to the diploe. The Ethmoidal arteries, posterior and anterior, pass through the ethmoidal foramina, and are distributed to the falx cerebri and to the ethmoidal cells and nasal fossss. The latter accompanies the nasal nerve. The Palpebral arteries, superior and inferior, are given off from the ophthalmic, near to the inner angle of the orbit ; they encircle the eyelids, forming a superior and inferior arch near to the borders of the lids, between the orbicularis palpebrarum and tarsal cartilage. At the outer angle of the eyelids the superior palpebral inosculates with the orbital branch of the temporal artery. The inferior palpe- bral artery sends a branch to the nasal duct. The Frontal artery, one of the terminal branches of the ophthalmic, 'emerges from the orbit at its inner angle, and ascends along the middle of the forehead. It is distributed to the integument, muscles, and pericranium. The JVasal artery, the other terminal branch of the ophthalmic, passes out of the orbit above the tendo oculi, and divides into two branches ; one of which inosculates with the angular artery, while the other, the dorsalis nasi, runs along the ridge of the nose and is distributed to its entire surface. The nasal artery sends a small branch to the lachrymal sac. The Muscular branches, usually two in number, superior and inferior, supply the muscles of the orbit; and upon the anterior aspect of the globe of the eye give off the anterior ciliary arteries, which pierce the sclerotic near its margin of connection with the cornea, and are distributed to the iris. It is the congestion of these vessels that gives rise to the vascular zone around the cornea in iritis. The Ciliary arteries are divisible into three groups, — short, long, and anterior. The Short ciliary are very numerous ; they pierce the sclerotic around the entrance of the optic nerve, and supply the choroid coat and ciliary processes. The long ciliary, two in number, pierce the sclerotic upon opposite sides of the globe of the eye, and pass for- wards between it and the choroid to the iris. They form an arterial circle around the circumference of the iris by inosculating with each other, and from this circle branches are given off which ramify SUBCLAVIAN ARTERY, 281 in the substance of the iris, and form a second circle around the pupil. The anterior ciliary are branches of the muscular arteries ; they terminate in the great arterial circle of the iris. The Centralis retince artery pierces the optic nerve obliquely, and passes forwards in the centre of its cylinder to the retina, where it divides into branches, which ramify in the inner layer of that membrane. It supplies the retina, hyaloid membrane, and zonula ciliaris ; and, by means of a branch sent forwards through the centre of the vitreous humour in a tubular sheath of the hyaloid membrane, the capsule of the lens. The Anterior cerebral artery passes forwards in the great longi- tudinal fissure between the two hemispheres of the brain; then curves backwards along the corpus callosum to its posterior extre- mity. It gives branches to the olfactory and optic nerves, to the under surface of the anterior lobes, the third ventricle, the corpus callosum, and the inner surface of the hemispheres. The two ante- rior cerebral arteries are connected soon after their origin by a short anastomosing trunk, the anterior communicating. The Middle cerebral artery, larger than the preceding, passes out- wards along the fissure of Sylvius, and divides into three principal branches, which supply the anterior and middle lobes, and the island of Reil. Near to its origin it gives off the numerous small branches which enter the substantia perforata, to be distributed to the corpus striatum. The Posterior Communicating artery, very variable in size, some- times double, and sometimes altogether absent, passes backwards and inosculates with the posterior cerebral, a branch of the basilar artery. Occasionally it is so large as to take the place of the pos- terior cerebral artery. The Choroidean is a small branch which is given off from the internal carotid, near to the origin of the posterior communicating artery, and passes beneath the edge of the middle lobe of the brain to enter the descending cornu of the lateral ventricle. It is distri- buted to the choroid plexus, and to the walls of the middle cornu. SUBCLAVIAN ARTERY. The Subclavian artery, on the right side, arises from the arteria innominata, opposite the sterno-clavicular articulation, and on the left, from the arch of the aorta. The right is consequently shorter than the left, and is situated nearer to the anterior wall of the chest ; it is also somewhat greater in diameter, from being a branch of a branch, in place of a division from the main trunk. The course of the subclavian artery is divisible, for the sake of precision and surgical observation, into three portions. The first portions of the right and left arteries differ in their course and rela- tions in correspondence with their dissimilarity of origin. The other two portions are precisely alike on both sides. The first portion, on the rig/it side, ascends obliquely outwards to the inner border of the scalenus anticus. On the left side it ascends 3G 282 SUBCLAVIAN ARTERY RELATIONS. perpendicularly to the inner border of that muscle. The second portion curves outwards behind the scalenus anticus ; and the third portion passes downwards and outwards beneath the clavicle, to the lower border of the jfirst rib, where it becomes the axillary artery. Relations. — The first portion, on the rigid side, is in relation in frotit with the internal jugular and subclavian vein at their point of junction, and is crossed by the pneumogastric nerve, cardiac nerves, and phrenic nerve. Behind and beneath it is invested by the pleura, is crossed by the right recurrent laryngeal nerve and vertebral vein, and is in relation with the transverse process of the seventh cervical vertebra. The first portion on the left side is in relation in front with the pleura, the vena innominata, the pneumogastric and phrenic nerves (which lie parallel to it), and the left carotid artery. To its ijiner side is the oesophagus ; to its outer side the pleura ; and hehiiid, the thoracic duct, longus colli, and vertebral column. Plan of the relations oUhe first portion of the Right Subclavian Artery. In Front. Internal jugular vein, Subclavian vein, Pneumogastric nerve, Cardiac nerves, Phrenic nerve. Behind and beneath. Pleura, Recurrent laryngeal nerve. Vertebral vein, Transverse process of 7th cervical vertebra. Plan of the relations of the first portion of the Left Subclavian Artery. In Front. Pleura, Vena innominata, Pneumogastric nerve, Phrenic nerve, Left carotid artery. Inner Side. (Esophagus. Left Subclavian Artery. Outer Side. Pleura. Behind. Thoracic duct, Longus colli, Vertebral column. The Second portion is situated between the two scaleni, and is supported by the margin of the first rib. The scalenus anticus separates it from the subclavian vein and j)hrenic nerve. Behind it is in relation with the brachial plexus. The 7'hyroid portion is in relation, in front with the subclavian vein and subclavius muscle; behind w'lih the brachial plexus and scalenus posticus; below with the first rib; and above with the supra-scapular artery and platysma. VERTEBRAL ARTERY, 283 Plan of the relations of the third portion of the Subclavian Artery, Above. Supra-scapular artery, Platysma myoides. In Front. Subclavian vein, Subclavius. Subclavian Artery, Third portion. Behind. Brachial plexus, Scalenus posticus. Below. First rib. Thyroid axis, Fig. 104.t Branches. — The greater part of the branches of the subclavian are given off from the artery before it arrives at the margin of the first rib. The profunda cervicis and superior intercostal frequently encroach upon the second portion, and not unfrequently a branch or branches may be found proceeding from the third portion. The primary branches are five in number, the three first being ascending, and the latter descending ; they are the — Vertebral, Inferior thyroid. Supra-scapular,* Posterior scapular, Superficialis cervicis. Profunda cervicis, Superior intercostal, Internal mammary. The Vertebral Artery is the first and the largest of the branches of the subclavian artery; it ascends through the foramina in the transverse processes of all the cervical vertebrae, excepting the last ; then winds back- wards around the articulating process of the atlas ; and piercing the dura mater enters the skull through the foramen magnum. The two arteries unite at the lower border of the pons Varolii, to form the basilar artery. In the foramina of the transverse processes of the vertebrae the artery lies in front of the cervical nerves. Dr. John DavyJ has observed that, when the vertebral arteries differ in size, the left is generally the larger : thus in ninety-eight cases he found the * This is usually described as arising' from the axillary, but I have most frequently found it to arise from the subclavian. — G. t The branches of the right subclavian artery. 1. The arteria innominata. 2. The right carotid. 3. Tlic first portion of the subclavian artery. 4. The second por- tion, o. The tiiird portion. 6. The vertebral artery. 7. The inferior thyroid. 8. The thyroid axis. 9. The superficialis cervicis. 10. The profunda cervicis. 11. Tlie posterior scapular or transversalis colli. 12. The supra-scapular, 13. Tlie internal mammary artery. 14. The superior intercostal. t Edinburgh Medical and Surgical Journal, 1839. 284 BASILAR ARTERY BRANCHES. left vertebral the larger twenty-six times, and the right only eight. In the same number of cases he found a small band stretching across the cylinder of the basilar artery, near the junction of the two vertebral arteries, seventeen times, and in a few instances a small communicating trunk between the two vertebral arteries pre- viously to their union. I have several times seen this communicating branch, and have a preparation now before me . in which it is ex- hibited. The Basilar Artery, so named from its position at the base of the brain, runs forwards to the anterior border of the pons Varolii, where it divides into four ultimate branches, two to either side. Brandies. — The branches of the vertebral and basilar arteries are tlie following : — Lateral spinal, Posterior meningeal, Vertebral, ^ Anterior spinal. Posterior spinal, Inferior cerebellar. ( Transverse, Basilar^ < Superior cerebellar, ( Posterior cerebral. The Lateral spinal branches enter the intervertebral foramina, and are distributed to the spinal cord and to its membranes. Where the vertebral artery curves around the articular process of the atlas, it gives ofl' several muscular branches. The Posterior meningeal are one or two small branches, which enter the cranium through the foramen magnum, to be distributed to the dura mater of the cerebellar fossee, and to the falx cerebelli. One branch, described by Soemmering, passes into the cranium along the first cervical nerve. The Anterior spinal is a small branch which unites with its fellow of the opposite side, on the front of the medulla oblongata. The artery formed by the union of these two vessels descends along the anterior aspect of the spinal cord, to which it distributes branches. The Posterior spinal winds around the medulla oblongata to the posterior aspect of the cord, and descends on either side, communi- cating very freely with the spinal branches of the intercostal and lumber arteries. Near its commencement it sends a branch upwards to the fourth ventricle. The Inferior cerebellar arteries wind around the upper part of the medulla oblongata to the under surface of the cerebellum, to which they are distributed. They pass between the filaments of origin of the hypoglossal nerve in their course, and anastomose with the superior cerebellar arteries. The Transverse branches of the basilar artery supply the pons Varolii, and adjacent parts of the brain. One of these branches, THYROID AXIS BRANCHES. 285 larger than the rest, passes along the crus cerebelli to be distributed to the anterior border of the cerebellum. This may be called the middle cerebellar artery. The Superior cerebellar arteries, two of the terminal branches of the basilar, wind around the crus cerebri on each side in relation with the fourth nerve, and are distributed to the upper surface of the cerebellum inosculating with the inferior cerebellar. This artery gives off a small branch which accompanies the seventh pair of nerves into the meatus auditorius internus. The Posterior cerebral arteries, the other two terminal branches of the basilar, wind around the crus cerebri at each side, and are distributed to the posterior lobes of the cerebrum. They are sepa- rated from the superior cerebellar artery, near the origin, by the third pair of nerves, and are in close relation with the fourth pair in their course around the crura cerebrL Anteriorly, near their origin, they give off a tuft of small vessels, which enter the locus perforatus, and they receive the posterior communicating arteries from the internal carotid. They also send a branch to the velum interpositum and plexus choroides. The communications established between the anterior cerebral arteries in front, and the internal carotids and posterior cerebral arteries behind, by the communicating arteries, constitute the circle of Willis. This remarkable communication at the base of the brain is formed by the anterior communicating branch, anterior cerebrals, and internal carotid arteries in front, and by the posterior communicating, posterior cerebrals, and basilar artery behind. The Thyroid Axis is a short trunk which divides almost imme- diately after its origin into four branches, some of which are occa- sionally branches of the subclavian artery itself. The I\FERioR Thyroid Artery ascends obliquely in a serpentine course behind the sheath of the carotid vessels, to the inferior part of the thyroid gland, to which it is distributed, and sends branches to the trachea, lower part of the larynx, and oesophagus. It is in relation with the middle cervical ganglion of the sympathetic, which lies in front of it. The Supra-scapular artery (transversalis humeri) passes ob- liquely outwards behind the clavicle, and over the ligament of the supra-scapular notch, to the supra-spinatus fossa. It crosses in its course the scalenus anticus muscle, phrenic nerve and subclavian artery, is distributed to the muscles on the dorsum of the scapula, and inosculates with the posterior scapular, and beneath the acro- mion process with the dorsal branch of the subscapular artery. At the supra-scapular notch it sends a large branch to the trape- zius muscle. The supra-scapular artery is not unfrequently a branch of the subclavian. The Posterior Scapular Artery (transversalis colli) passes transversely across the subclavian triangle at the root of the neck, to the superior angle of the scapula. It then descends along the posterior border of that bone to its inferior angle, where it inoscu- 286 CIRCLE OF WILLIS. lates with the subscapular artery, a branch of the axillary. In its course across the neck it passes in front of the scalenus anticus, and across the brachial plexus; in the rest of its course it is covered in by the trapezius, levator anguli scapulae, rhomboideus minor, and rhomboideus major muscles. Sometimes it passes behind the scalenus anticus, and between the nerves wliich constitute the brachial plexus. This artery, which is very irregular in its origin, proceeds more frequently from the third portion of the subclavian artery than from the first. Fiff. 105.* The posterior scapular gives branches to the neck, and opposite the angle of the scapula inosculates with the profunda cervicis. It supplies the muscles along the posterior border of the scapula, and establishes an important anastomotic communication between the branches of the external carotid, subclavian, and axillary arteries. * The circle of Willis. The branches of tlie arteries have references only on one side, on account of their symmetrical distribution. 1. The vertebral arteries. 2. The two anterior spinal branches uniting to form a single vessel. 3. One of tlic posterior spinal arteries. 4. The posterior meningeal. 5. Tlie inferior cerebellar. G. The basilar artery giving off its transverse branches to either side. 7. The superior cere- bellar artery. 8. The posterior cerebral. 9. Tlic posterior communicating branch of the internal carotid. 10. The internal carotid, showing tlie curvatures it makes witliin the skull. 11. The ophthalmic artery divided across. 12. The middle cerebral artery. 13. The anterior cerebral arteries connected by, 14. The anterior communicating artery. INTERNAL MAMMARY ARTERY. 287 The SuPERFiciALis Cervicis Artery (cervicalis anterior) is a small vessel, which ascends upon the anterior tubercles of the transverse processes of the cervical vertebrtE, lying in the groove between the scalenus anticus and rectus anticus major. It is distributed to the deep muscles and glands of the neck, and. sends branches through the intervertebral foramina to supply the spinal cord and its membranes. The Profunda Cervicis (cervicalis posterior) passes backwards between the transverse processes of the seventh cervical and first dorsal vertebra, and then ascends the back part of the neck, between the complexus and semi-spinalis colli muscles. It inoscu- lates above with the princeps cervicis of the occipital artery, and below, by a descending branch, with the posterior scapular. The Superior Intercostal Artery descends behind the pleura upon the necks of the first two ribs, and inosculates with the first aortic intercostal. It gives off two branches which supply the two first intercostal spaces. The Internal Mammary Artery descends by the side of the sternum, resting upon the costal cartilages, to the diaphragm : it then pierces the anterior fibres of the diaphragm, and enters the sheath of the rectus, where it inosculates with the epigastric artery, a branch of the external iliac. In the upper part of its course it is crossed by the phrenic nerve, and lower down lies between the triangularis sterni and the internal intercostal muscles. The Branches of the internal mammary are, — Anterior intercostal. Mammary, Comes nervi phrenici, Mediastinal, Pericardiac, Musculo-phrenic. The Anterior intercostals supply the intercostal muscles of the front of the chest, and inosculate with the aortic intercostal arteries. Each of the three first anterior intercostals gives ofi" a large branch to the mammary gland, which anastomoses freely with the thoracic branches of the axillary artery ; the corresponding branches from the remaining intercostals supply the integument and pectoralis major muscle. There are usually two anterior intercostal arteries in each space. The Comes nervi phrenici is a long and slender branch which accompanies the phrenic nerve. The mediastinal and fericardiac branches are small vessels dis- tributed to the anterior mediastinum, the thymus gland, and peri- cardium. The Musculo-phrenic artery winds along the attachment of the' diaphragm to the ribs, supplying that muscle and sending branches to the inferior intercostal spaces. " The mammary arteries," says 288 AXILLARY ARTERY. Dr. Harrison, " are remarkable for the number of their inosculations, and for the distant parts of the arterial system which they serve to connect. They anastomose with each other, and their inosculations, with the thoracic aorta, encircle the thorax. On the parietes of this cavity their branches connect the axillary and subclavian arteries ; on the diaphragm they form a link in the chain of inosculations be- tween the subclavian artery and abdominal aorta, and in the parietes of the abdomen they form an anastomosis most remarkable for the distance between those vessels which it serves to connect ; namely, the arteries of the superior and inferior extremities," Varieties of the Subclavian Arteries. — Varieties in these arteries are rare ; that which most frequently occurs is the origin of the right subclavian, from the left extremity of the arch of the aorta, below the left subclavian artery. The vessel, in this case, curves behind the oesophagus and right carotid artery, and sometimes between the oesophagus and trachea, to the upper border of the first rib, on the right side of the chest, where it assumes its ordinary course. In a case* of subclavian aneurism on the right side, above the clavicle, which happened during the present summer, Mr. Liston proceeded to perform the operation of tying the carotid and subclavian arteries at their point of division from the innominata. Upon reaching the point where the bifurcation should have existed, he found that there was no subclavian artery. With that admirable self-possession which distinguishes this eminent surgeon in all cases of emergency, he continued his dissection more deeply, towards the vertebral column, and succeeded in securing the artery. It was ascertained after death, that the arteria innominata was extremely short, and that the subclavian was given off within the chest from the posterior aspect of its trunk, and pursued a deep course to the upper mar- gin of the first rib. In a preparation which was shown to me in Heidelberg some years since by Professor Tiedemann, the right subclavian artery arose from the thoracic aorta, as low down as the fourth dorsal vertebra, and ascended from that point to the border of the first rib. Varieties in the branches of the subclavian are not unfrequent ; the most interesting is the origin of the left vertebral, from the arch of the aorta, of which I possess several preparations. AXILLARY ARTERY. The axillary artery forms a gentle curve through the middle of the axillary space from the lower border of the first rib to the lower border of the latissimus dorsi, where it becomes the brachial. Relations. — After emerging from beneath the margin of the costo- coracoid membrane, it is in relation with the axillary vein, which lies at first to the inner side and then in front of the artery. Near the middle of the axilla it is embraced by the two heads of the median nerve, and is covered in by the pectoral muscles. Upon the * This caae is recorded in the Lancet, Vol. I. 1839-40, pp. 37 and 419. AXILLARY ARTERY. 280 inner or thoracic side it is in relation, first, with the first intercostal muscle ; it next rests upon the first serration of the serratus magnus ; and is then separated from the chest by the brachial plexus of nerves. By its outer or humeral side it is at first separated from the brachial plexus by a triangular cellular interval ; it next rests against the tendon of the subscapularis muscle ; and thirdly upon the coraco-bra- chialis muscle. The relations of the axillary artery may be thus arranged : — In front. Inner or thoracic Side. Outer or humeral Side. Pectoralis major, First intercostal muscle, Plexus of nerves, Pectoralis minor. First serration of ser- Tendon of sub- Pectoralis major. ratus magnus, ■ scapularis, Plexus of nerves. Coraco-brachialis. Branches. — The branches of the Axillary artery are seven in number : — Thoracica acromiahs, Superior thoracic, Inferior thoracic, Thoracica axillaris, Subscapular, Circumflex anterior. Circumflex posterior. The thoracica acromialis and superior thoracic are found in the triangular space above the pectoralis minor. The inferior thoracic and thoracica axillaris, below the pecto- ralis minor. And the three remaining branches below the lower border of the subscapularis. The Thoracica acromialis is a short trunk which ascends to the space above the pectoralis minor muscle, and divides into three branches, — thoracic, which is distributed to the pectoral muscles and mammary gland; acromial, which passes outwards to the acromion, and inosculates with branches of the supra-scapular artery ; and descending, which follows the interspace between the deltoid and pectorahs major muscles, and is in relation with the cephalic vein. The Superior thoracic (short), very frequently arises by a common trunk with the preceding ; it runs along the upper border of the pectoralis minor, and is distributed to the pectoral muscles and mammary gland, inosculating with the intercostal and mammary arteries. The Inferior thoracic (long external mammary) descends along the lower border of the pectoralis minor to the side of the chest. It is distributed to the pectoralis major and minor, serratus magnus, and subscapularis muscle, to the axillary glands and mammary gland ; inosculating with the superior thoracic, intercostal, and mammary arteries. 37 290 BRANCHES OF THE AXILLARY ARTERY. Fig. 106.* The Thoracica axillaris is a small branch distributed to the plexus of nerves and glands in the axilla. It is frequently derived from one of the other thoracic branches. • The Subscajndar artery, the largest of the branches of the axillary, runs along the lower border of the subsca- pularis muscle, to the inferior angle of the scapula, where it inosculates with the posterior scapular, a branch of the subclavian. It supphes, in its course, the muscles on the under surface, and inferior border of the scapula, and the side of the chest. At about an inch and a half from the axillary, it gives off a large branch, the dorsalis scapulcs, which passes backwards through the triangular space bounded by the teres minor, teres major, and scapular head of the triceps, and beneath the infra- spinatus to the dorsum of the scapula, ■^ where it is distributed, inosculating \ with the supra-scapular and posterior ;A scapular arteries. The Cirmmjlex arteries'wmdB.i'ound the neck of the humerus. The anterior very small, passes beneath the coraco- brachialis and short head of the biceps, and sends a branch upwards along the bicipital groove to supply the shoulder-joint. The Posterior circumjiex, of larger size, passes backwards through the quadrangular space bounded by the teres minor and major, the scapular head of the triceps and the humerus, and is distributed to the deltoid muscle and joint. Sometimes this artery is a branch of the superior profunda of the brachial. It then ascends behind the tendon of the teres major, and is distributed to the deltoid without passing through the quadrangular space. The posterior circumflex artery sends branches to the shoulder-joint. * The axillary and brachial artery, with their branches. ]. The deltoid muscle. 2. The biceps. 3. The tendinous process given off from the tendon of the biceps, to the deep fascia of the fore-arm. It is this process which separates the median basilic vein from the brachial artery. 4. The outer border of the brachialis anticus muscle. 5. The supinator longus. 6. The coraco-brachialis. 7. Tlio middle portion of tlie triceps muscle. 8. Its inner head. 9. The a,\illary artery. 10. The brachial artery ; — a dark line marks the limit between these two vessels. 11. The thoracica acro- mialis artery dividing into its three branches ; the number rests upon the coracoid pro- cess. 12. The superior and inferior thoracic arteries. 1.3. The scrratus magnus mus- cle, 14. The subscapular artery. The posterior circumflex and thoracica axillaris branches are seen in the figure between the inferior thoracic and subscapular. The anterior circumflex is observed, between the two heads of the biceps, crossing the neck of the humerus. 15. The superior profunda artery. JG. The inferior profunda. 17. The anastomotica magna inosculating inferiorly, with the anterior ulnar recurrent. 18. The termination of the superior profunda, inosculating with the radial recurrent in the interspace between the brachialis anticus and supinator longus. BRACHIAL ARTERY BRANCHES. 291 Varieties of the Axillary Artery. — The most frequent peculiarity of this kind is the division of the vessel into two trunks of equal size : a muscular trunk, which gives off some of the ordinary axil- lary branches and supplies the upper arm, and a continued trunk, which represents the brachial artery. The next most frequent variety is the high division of the ulnar which passes down the arm by the side of the brachial artery, and superficially to the muscles proceed- ing from the inner condyle, to its ordinary distribution in the hand. In this course it Kes immediately beneath the deep fascia of the fore- arm, and may be seen and felt pulsating beneath the integument. The high division of the radial from the axillary is rare. In one instance, I saw the axillary artery divide into three branches of nearly equal size, which passed together down the arm, and at the bend of the elbow resolved themselves into radial, ulnar, and interosseous. But the most interesting variety, both in a physiological and surgical sense, is that described by Dr. Quain, in his " Elements of Anatomy." " I found in the dissecting-room, a few years ago, a variety not hitherto noticed : it was at first taken for the ordinary high division of the ulnar artery. The two vessels descended from the point of division at the border of the axilla, and lay parallel with one another in their course through the arm ; but instead of diverging, as is usual, at the bend of the elbow, they converged, and united so as to form a short trunk which soon divided again into the radial and ulnar arteries in the regular way." In a subject, dissected during the past winter in Sydenham College, this variety existed in both arms ; and I have seen several other instances of a similar kind. BRACHIAL ARTERY. The Brachial artery passes down the inner side of the arm, from the lower border of the latissimus dorsi to the bend of the elbow, where it divides into the radial and ulnar arteries. Relations. — In its course downwards, it rests upon the coraco- brachialis muscle, internal head of the triceps, brachialis anticus, and the tendon of the biceps. To its inner side is the ulnar nerve ; to the outer side, the coraco-brachialis and biceps muscles ; in front it has the basilic vein, and is crossed by the median nerve. Its relations, within its sheath, are the vense comites. Plan of the relations of the Brachial Artery. In Front. Basilic vein, Deep fascia, Median nerve. Inner Side. Ulnar nerve. Brachial Artery. Outer Side. Coraco-brachialis, Biceps. Behind. Short head of triceps Coraco-brachialis, Brachialis anticus, Tendon of biceps. 292 BRACHIAL ARTERY BRANCHES. The branches of the brachial artery are, the — Superior profunda, Inferior profunda, Anastomotica magna, Muscular. The Superior profunda arises opposite the lower border of the latissimus dorsi, and winds around the humerus, between the triceps and the bone, in the space between the brachialis anticus and supinator longus, where it inosculates with the radial recurrent branch. It accompanies the musculo-spiral nerve. In its course it gives off the posterior articular artery, which descends to the elbow-joint, and a more superficial branch which inosculates with the interosseous articular artery. The Inferior profunda arises from about the middle of the brachial artery, and descends to the space between the inner condyle and olecranon in company with the ulnar nerve, where it inosculates with the posterior ulnar recurrent. The Anastomotica magna is given off nearly at right angles from the brachial, at about two inches above the joint. It passes directly inwards, and divides into two branches which inosculate with the anterior and posterior ulnar recurrent arteries and with the inferior profunda. The Muscular branches are distributed to the muscles in the course of the artery, viz. to the coraco-brachialis, biceps, deltoid, brachialis anticus and triceps. Varieties of the Brachial Artery, — The most frequent peculiarity in the distribution of branches from this artery is the high divi- sion of the radial, which arises generally from about the upper third of the brachial artery and descends to its normal position at the bend of the elbow. The ulnar artery sometimes arises from the brachial at about two inches above the elbow, and pursues either a superficial or deep course to the wrist ; and in more than one instance I have seen the interosseous artery arise from the bra- chial a little above the bend of the elbow. The two profunda arte- ries occasionally arise by a common trunk, or there may be two superior profundse. RADIAL ARTERY. The Radial artery, one of the divisions of the brachial, appears from its direction to be the continuation of that trunk. It runs along the radial side of the fore-arm, from the bend of the elbow to the wrist ; it there turns round the base of the thumb, beneath its extensor tendons, and passes between the two heads of the first dorsal interosseous muscle, into the palm of the hand. It then crosses the metacarpal bones to the ulnar side of the hand, forming the deep palmar arch, and terminates by inosculating with the super- ficial palmar arch. RADIAL ARTERY. 293 In the upper half of its course, the radial artery is situated between the supinator longus muscle, by which it is overlapped superiorly, and the pronator radii teres ; in the lower half, between the tendons of the supinator longus and flexor carpi radialis. It rests in its course downwards, upon the supinator brevis, pronator radii teres, radial origin of the flexor sublimis, flexor longus pollicis, and pro- nator quadratus ; and is covered in by the integument and fasciae. At the wrist it is situated in contact with the dorsal carpal liga- ments and beneath the extensor tendons of the thumb ; and in the palm of the hand, beneath the flexor tendons. It is accompanied by vensB comites throughout its course, and for its middle third is in close relation with the radial nerve. Plan of the relations of the Radial Artery in the fore-arm. In Front. Deep fascia, Supinator long^us. Inner Side, Pronator radii teres, Flexor carpi radialis. Radial Artery. Outer Side. Supinator longus, Radial nerve (middle third of its course). Behind, Supinator brevis, Pronator radii teres, Flexor sublimis digitorum, Flexor longus pollicis, Pronator quadratus, Wrist-joint. The Branches of the radial artery may be arranged into three groups, corresponding with the three regions, the fore-arm, the wrist, and the hand ; they are — Recurrent radial, Muscular. Superficialis vote, Carpalis anterior, Carpalis posterior, or dorsalis carpi, Metacarpalis, Dorsales pollicis. Princeps, or magna pollicis, Radialis indicis, Interosseas, Perforantes. Fore-arm, Wrist, Hand, The Recurrent branch is given ofl^ immediatly below the elbow ; it ascends in the space between the supinator longus and brachialis anticus to supply the joint, and inosculates with the terminal branches of the superior profunda. This vessel gives off" numerous muscular branches. The Muscular branches are distributed to the muscles on the radial side of the fore-arm. The Superficialis vola is given off from the radial artery while at 294 RADIAL ARTERY BRANCHES. Fig. 107.* the wrist. It passes between the fibres of the abductor pollicis muscle, and inosculates with the termination of the ulnar artery, completing the superficial palmar arch. This artery is very variable in size, being some- times as large as the continuation of the radial, and at other times a mere muscular ramusculus, or entirely wanting ; when of large size it supphes the palmar side of the thumb and the radial side of the index finger. The Carp«Z branches are intended for the supply of the wrist, the anterior carpal in front, and the posterior, the larger of the two, behind. The carpqlis posterior crosses the carpus transversely to the ulnar border of the hand, where it inosculates with the posterior carpal branch of the ulnar artery. Superiorly it sends branches which inoscu- late with the termination of the anterior interosseous artery ; inferiorly, it gives off posterior interosseous branches, which anas- tomose with the perforating branches of the deep palmar arch, and then run forwards upon the dorsal interossei muscles. The Metacarpal branch runs forwards on the second dorsal interosseous muscle, and inosculates with the digital branch of the superficial palmar arch, which supplies the adjoining sides of the index and middle fingers. Sometimes it is of large size, and the true continuation of the radial artery. The Dorsales 'pollicis are two small branches which run along the sides of the dorsal aspect of the thumb. The Princeps pollicis descends along the border of the metacarpal bone, between the abductor indicis and adductor pollicis to the base of the first phalanx, where it divides into two branches, which are distributed to the two sides of the palmar aspect of the thumb. * The arteries of the fore-arm. 1. The lower part of the biceps muscle. 2. The inner condyle of the humerus with tlie humeral origin of the pronator radii teres and flexor carpi radialis divided across. 3. The deep portion of the pronator radii teres. 4. The supinator longus muscle. 5. The flexor longus pollicis. 6. The pronator quadratiis. 7. The flexor profundus digitorum. 8. The flexor carpi ulnaris. 9. The annular ligament with the tendons passing beneath it into the palm of the hand ; the figure is placed on the tendon of the palmaris longus muscle, divided close to its inser- tion. 10. The brachial artery. 11. The anastomotiea magna inosculating superiorly with the inferior profunda, and inferiorly with the anterior ulnar recurrent. 19. The radial artery. 13. The radial recurrent artery inosculating with the termination of the superior profunda. 14. The superfieialis vola;. 15. The ulnar artery. 16. Its superficial palmar arch giving off digital branches to three fingers and a half. 17. The magna pollicis and radialis indicis arteries. 18. The posterior ulnar recurrent. 19. The anterior interosseous artery. 20. The posterior interosseous, as it is passing through the interosseous membrane. ULNAR ARTERY, 295 The Radialis indicis is also situated between the abductor indicis and adductor poUicis, and runs along the radial side of the index finger, forming its collateral artery. This vessel is frequently a branch of the princeps pollicis. The InterossecB, three or four in number, are branches of fhe deep palmar arch ; they pass forwards upon the interossei muscles and inosculate w^ith the digital branches of the superficial arch, opposite the heads of the metacarpal bones. The Perforantes, three in number, pass directly backwards be- tween the heads of the dorsal interossei muscles, and inosculate with the posterior interosseous arteries. ULNAR ARTERY. The Ulnar artery^, the other division of the brachial artery, crosses the arm obliquely to the commencement of its middle third; it then runs down the ulnar side of the fore-arm to the wrist, crosses the annular ligament, and forms the superficial palmar arch, which terminates by inosculating with the superficialis volas. Relations. — In the upper or obhque portion of its course, it hes upon the brachialis anticus, and flexor profundus digitorum ; and is covered in by the superficial layer of muscles of the fore-arm and the median nerve. In the second part of its course, it is placed upon the flexor profundus, and pronator quadratus, lying between the flexor carpi ulnaris and flexor sublimis digitorum. While cross- ing the annular hgament it is protected from injury by a strong ten- dinous arch thrown over it from the pisiform bone ; and in the palm it rests upon the tendons of the flexor sublimis, being covered in by the palmaris brevis muscle and palmar fascia. It is accompanied in its course by the venae comites, and is in relation with the ulnar nerve for the lower two-thirds of its extent. Plan of the relations of the Ulnar Artery : In front. Deep fascia, Superficial layer of muscles, Median nerve. In the Hand. Tendinous arch from the pisiform bone, Palmaris brevis muscle, Palmar fascia. Inner side. i Outer side. Flexor carpi ulnaris, Ulnar Arlerv Flexor sublimis digilo- Ulnar nerve (lower two- ' ' | rum. tliirds.) Behind. Brachialis anticus. Flexor profundus digitorum. Pronator quadratus. In the Hand. Annular ligament. Tendons of the flexor sublimis digitorum. 296 fLNAR ARTERY BRANCHES. The Branches of the idnar artery jna.y be arranged like those of the radial into three groups : — Anterior ulnar recurrent, Posterior ulnar recurrent, Pny-e n^m J T ^ { A nterlor interosseous, ±oie-arm < Interosseous -n ^ • • . Muscular. Posterior interosseous, T^ • . \ Carpalis anterior, vvrist . ^ Carpalis posterior, or dorsaUs manus. Hand . Digitales. The Anterior ulnar recurrent arises immediately below the elbow, and ascends in front of the joint between the pronator radii teres and brachialis anticus, where it inosculates with anastomotica magna and inferior profunda. The two recurrent arteries frequently arise by a common trunk. The Posterior ulnar recurrent, larger than the preceding, arises immediately below the elbow-joint, and passes backwards beneath the origins of the superficial layer of muscles; it thena scends be- tween the two heads of the flexor carpi ulnaris, and beneath the ulnar nerve, and inosculates with the inferior profunda and anasto- motica magna. The Common interosseous artery is a short trunk which arises from the ulnar, opposite to the bicipital tuberosity of the radiu^. It divides into two branches, the anterior and posterior interosseous arteries. The Anterior interosseous passes down the fore-arm upon the inter- osseous membrane, between the flexor profundus digitorum and flexor longus pollicis, and behind the pronator quadratus it pierces that membrane and descends to the back of the wrist, where it inos- culates with the posterior carpal branches of the radial and ulnar. It is retained in connexion with the interosseous membrane by means of a thin aponeurotic arch. The anterior interosseous artery sends a branch to the median nerve, which it accompanies into the hand. The median artery is sometimes of large size, and I have seen it take the place of the superficial palmar arch. The Posterior interosseous artery passes backwards through an openincr between the upper part of the interosseous membrane and the oblique ligament, and is distributed to the muscles on the poste- rior aspect of the fore-arm. It gives off a recurrent branch, which returns upon the elbow between the anconeus, extensor carpi ulnaris and supinator brevis muscles, and anastomoses with the posterior terminal branches of the superior profunda. The Muscular branches supply the muscles situated along the ulnar border of the fore-arm. The Carpal branches, anterior and posterior, are distributed to the BRANCHES OF THE THORACIC AORTA. 297 anterior and posterior aspects of the wrist-joint, where they inoscu- late with corresponding branches of the radial artery. The Digital branches are given off from the superficial palmar arch, and are four in number. The first and smallest is distributed to the ulnar side of the little finger. The other three are short trunks, which divide between the heads of the metacarpal bones, and form the collateral branch of the radial side of the little finger, the collateral branches of the ring and middle fingers, and the col- lateral branch of the ulnar side of the index finger. The Superficial palmar arch receives the termination of the deep palmar arch from between the abductor minimi digiti and flexor brevis minimi digiti near to their origins, and terminates by inoscu- lating with the superficialis volas upon the ball of the thumb. The communication between the superficial and deep arch is generally described as the communicating branch of the ulnar artery. The mode of distribution of the arteries to the hand is subject to great variety. BRANCHES OF THE THORACIC AORTA. Bronchial, (Esophageal, Intercostal. The Bronchial Arteries are four in number, and vary both in size and origin. They are distributed to the bronchial glands and tubes, and send branches to the oesophagus, pericardium, and left auricle of the heart. These are the nutritious vessels of the lungs. The (Esophageal Arteries are numerous small branches ; they arise from the anterior part of the aorta, are distributed to the oeso- phagus, and estabUsh a chain of anastamosis along that tube : the superior inosculate with the bronchial arteries, and with oesophageal branches of the inferior thyroid arteries ; and the inferior with similar branches of the phrenic and gastric arteries. The Intercostal, or posterior intercostal arteries, arise from the posterior part of the aorta ; they are nine in number on each side, the two superior spaces being supplied by the superior intercostal artery, a branch of the subclavian. The right intercostals are longer than the left, on account of the position of the aorta. They ascend somewhat obliquely from their origin, and cross the vertebral column behind the thoracic duct, vena azygos major, and sympathetic nerve, to the intercostal spaces, the left passing beneath the superior inter- costal vein, the vena azygos minor and sympathetic. In the inter- costal spaces, or rather, upon the external intercostal muscles, each artery gives off a dorsal branch, which passes back between the transverse processes of the vertebrse, lying internally to the middle costo-transverse ligament, and divides into a spinal branch, which supplies the spinal cord and vertebrae, and a muscular branch which is distributed to the muscles and integument of the back. It then comes into relation with its vein and nerve, the former being above, and the latter below, and divides into two branches which run along 38 298 BRANCHES OF THE ABDOMINAL AORTA. the borders of the contiguous ribs between the two planes of inter- costal muscles, and anastomose with the anterior intercostal arteries, branches of the internal mammary. The branch corresponding with the lower border of each rib is the larger of the two. They are protected from pressure during the action of the intercostal muscles, by little tendinous arches thrown across and attached by each extremity to the bone. BRANCHES OF THE ABDOMINAL AORTA. Phrenic, C Gastric, Coeliac axis < Hepatic, ( Splenic, Superior mesenteric, Spermatic, Inferior mesenteric, Supra-renal, or capsular, Renal, or emulgent, Lumbar, Sacra media. The Phrenic Arteries are given off from the anterior part of the aorta as soon as that trunk has passed through the aortic opening. Passing obliquely outwards upon the under surface of the diaphragm, each artery divides into two branches, an internal hrancli which runs forwards and inosculates with its fellow of the opposite side in front of the oesophageal opening ; and an external branch which proceeds outwards towards the great circumference of the muscle, and sends branches to the supra-renal capsules. The phrenic arte- ries inosculate with branches of the internal mammary, inferior intercostal, epigastric, oesophageal, gastric, hepatic, and supra-renal arteries. They are frequently derived from the coeliac axis, or from one of its divisions, and sometimes they give off the supra- renal arteries. The CcELiAc Axis {y-oikla ventriculus) is the first single trunk given off from the abdominal aorta. It arises opposite the upper border of the first lumbar vertebrae, is about half an inch in length, and divides into three large branches — gastric, hepatic, and splenic. Relations. — The trunk of the coeliac axis has in relation with it, in front the lesser omentum ; on the right side the right semilunar ganghon and lobulus Spigelii of the liver ; on the left side the left semilunar ganglion and cardiac portion of the stomach ; and below the upper border of the pancreas and lesser curve of the stomach. It is completely surrounded by the solar plexus. The Gastric Artery (coronaria vcntriculi), the smallest of the three branches of the coeliac axis, ascends between the two layers of the lesser omentum to the cardiac orifice of the stomach, then runs along the lesser curvature to the pylorus, and inosculates with the pyloric brancii of the hepatic. It is distributed to tiie lower ABDOMINAL AORTA. 299 extremity of the oesophagus and lesser curve of the stomach, and anastomoses with the oesophageal arteries and vasa brevia of the splenic artery. Fiff. 108.* The Hepatic Artery curves forwards, and ascends along the right border of the lesser omentum to the liver, where it divides into two branches (right and left), which enter the transverse fissure, and are distributed along the portal canals to the right and left lobcs.f It is in relation in the right border of the lesser omentum, with the ductus communis choledochus and portal vein, and is surrounded by the * The abdominal aorta with its branches. 1. The phrenic arteries. 2. The coeliac axis. 3. The gastric artery. 4. The hepatic artery, dividing into the right and left hepatic branches. 5. The splenic artery, passing outwards to the spleen. 6. The supra-renal artery of the right side. 7. Tiie right renal artery, which is longer than the left, passing outwards to the right kidney. 8. Tlic lumbar arteries. 9. Thc'superior mesenteric artery. 10. The two spermatic arteries. 11. The inferior mesenteric artery. 12. The sacra media. 13. The common iliacs. 14. The internal ihao of the right side. 15. The external iliac artery. 16. The epigastric artery. 17. The cir- cumflexa ilii artery. 18. The femoral artery. t For the mode of distribution of the hepatic artery within the liver, see the " Minute Anatomy" of that organ in tlie Chajjtcr on the Viscera. 300 SPLENIC ARTERY BRANCHES. hepatic plexus of nerves and numerous lymphatics. There are some- times two iiepatic arteries, in which case one is derived from the superior mesenteric artery. The Branches of the hepatic artery are the Pyloric, ^ , J J ,. ( Gastro-epiploica dextra, Gastro-duodenahs, < -d 5 j ] r { rancreatico-duodenahs. Cystic. The Pyloric branch given off from the hepatic near to the pylorus, is distributed to the commencement of the duodenum and to the lesser curve of the stomach, where it inosculates with the gastric artery. The Gastro-duodenaUs artery is a short but large trunk, which descends behind the pylorus, and divides into two branches, the gastro-epiploica dextra, and pancreatico-duodenalis. Previously to its division, it gives off some inferior pyloric branches to the small end of the stomach. The Gastro-epiploica dextra runs along the great curve of the stomach lying between the two layers of the great omentum, and inosculates at about its middle with the gastro-epiploica sinistra, a branch of the splenic artery. It supplies the great curve of the stomach and the great omentum ; hence the derivation of its name. The Pancreatico-duodenalis curves along the fixed border of the duodenum, partly concealed by the attachment of the pancreas, and is distributed to the pancreas and duodenum. It inosculates infe- riorly with the first jejunal and with the pancreatic branches of the superior mesenteric artery. The Cystic artery, generally a branch of the right hepatic, is of small size, and ramifies between the coats of the gall bladder, pre- viously to its distribution to the mucous membrane. The Splenic Artery, the largest of the three branches of the coeliac axis, passes horizontally to the left along the upper border of the pancreas, and divides into five or six large branches which enter the hilum of the spleen and are distributed to its structure. In its course it is tortuous and serpentine, and frequently makes a com- plete turn upon itself It lies in a narrow groove in the upper border of the pancreas, and is accompanied by the splenic vein, and by the splenic plexus of nerves. The Branches of the splenic artery are — Pancreaticffi parvce, Pancreatica magna, Vasa brevia, Gastro-epiploica sinistra. The Pancrenticai parvce arc numerous small branches distributed to the pancreas, as the splenic artery runs along its upper border. SUPERIOR MESEPTTERIC ARTERY. 301 One of these, larger than the rest, follows the course of the pancre- atic duct, and is called pancreatica magna. The Fasa hrevia are five or six branches of small size which pass from the extremity of the splenic artery and its terminal branches, between the layers of the gastro-splenic omentum, to the great end of the stomach, to which they are distributed, inosculating wdth branches of the gastric artery and of the gastro-epiploica sinistra. The Gastro-epiploica sinistra appears to be the continuation of the splenic artery ; it passes forwards from left to right, along the great curve of the stomach, lying between the layers of the great omentum, and inosculates with the gastro-epiploica dextra. It is distributed to the greater curve of the stomach and to the great omentum. Fig. 109.* The Superior Mesenteric Artery, the second of the single trunks, and next in size to the coeUac axis, arises from the aorta im- * The distribution of the branches of the coeliac axis. 1. The liver. 2. Its trans- verse fissure. 3. The gall bladder. 4. The stomach. 5. The entrance of the oeso- phagus. 6. The pylorus. 7. The duodenum, its descending portion. 8. The trans- verse portion of the duodenum. 9. The pancreas. 10. The spleen. 11. The aorta. 12. The coehac axis. 13. The gastric artery. 14. The hepatic artery. 15. Its pyloric branch. 16. The gastro-duodenalis. 17. The gastro-epiploica dextra. 18. The pancreatico-duodenalis, inosculating with a brancli from the superior mesenteric artery. 19. The division of the liepatic artery into its right and left branches; the right giving off the cystic branch. 20. The splenic artery, traced by dotted lines behind the stomach to the spleen. 21. The gastro-epiploica sinistra, inosculating along the great curva- ture of the stomach with the gastro-epiploica. dextra. 22. The pancreatica magna. 23. The vasa brevia to the great end of the stomach, inosculating with branches of the gastric artery. 24. The superior mesenteric artery, emerging from between the pan- creas and the transverse portion of the duodenum. 302 SUPERIOR 3IESENTERIC ARTERY. mediately below that vessel, and behind the pancreas. It passes for- wards betv/een the pancreas and transverse duodenum, and descends within the layers of the mesentery, to the right iliac fossa, where it terminates very much diminished in size. It forms a curve in its course, the convexity being directed towards the left, and the con- cavity to the right. It is in relation near its commencement with the portal vein ; and is accompanied by two veins, and the superior mesenteric plexus of nerves. The brandies of the superior Mesenteric Artery are — Vasa intestini tenuis, Ileo-colica, Colica dextra, Colica media. Fig. 110* * The course and distribution of the superior mesenteric artery. J. The descending portion of the duodenum. 2. The transverse portion. 3. TJic pancreas. 4. The jejunum. 5. The ileum. 6. The ccecum from which the ap[)endix vermiformis is seen projecting. 7. The ascending colon. 8. Tiic transverse colon. 9. The com- mencement of ^the descending colon. 10. The superior mesenteric artery. 11. The colica media. 12. The branch vi^hich inosculates with the colica sinistra. 13. The branch of the superior mesenteric artery, whicii inoscidates with the pancreatico- duodenalis. 14. The colica dextra. 15. The ileo-coliea. IG, IG. Tiic branches from the convexity of the superior mesenteric t»thc small intestines. SPERMATIC ARTERIES. 303 The Vasa intestini tenuis arise from the convexity of the superior mesenteric artery. They vary from fifteen to twenty in number, and are distributed to the small intestine from the duodenum to the termination of the ileum. In their course between the layers of the mesentery, they form a series of arches by the inosculation of their larger branches; from these are developed secondary arches, and from the latter a third series of arches, from which the branches arise which are distributed to the coats of the intestine. From the middle branches a fourth and sometimes even a fifth series of arches is produced. By means of these arches a direct communication is established between all the branches given off from the convexity of the superior mesenteric artery ; the superior branches moreover sup- ply the pancreas and duodenum, and inosculate with the pancreatico- duodenalis ; and the inferior with the ileo-colica. The Ileo-colic arterij is the last branch given off from the conca- vity of the superior mesenteric. It descends to the right iliac fossa, and divides into branches which communicate and form arches, from which branches are distributed to the termination of the ileum, the cEecum, and the commencement of the colon. This artery inoscu- lates on the one hand with the last branches of the vasa intestini tenuis, and on the other with the colica dextra. The Colica dextra arises from about the middle of the concavity of the superior mesenteric, and divides into branches which form arches, and are distributed to the ascending colon. Its descending branches inosculate with the ileo-colica, and the ascending with the colica media. The Colica media arises from the upper part of the concavity of the superior mesenteric, and passes forwards between the layers of the transverse mesocolon, where it forms arches, and is distributed to the transverse colon. It inosculates on the right with the colica dextra ; and on the left with the colica sinistra, a branch of the infe- rior mesenteric artery. The Spermatic Arteries are two small vessels which arise from the front of the aorta below the superior mesenteric ; from this origin each artery passes obliquely outwards, and accompanies the corre- sponding ureter along the front of the psoas muscle to the border of the pelvis, where it is in relation with the external iliac artery. It is then directed outwards to the internal abdominal ring, and follows the course of the spermatic cord along the spermatic canal, and through the scrotum to the testicle, to which it is distributed. The right spermatic artery lies in front of the vena cava, and both ves- sels are accompanied by their corresponding veins and by the sper- matic plexuses of nerves. The spermatic arteries in the female descend into the pelvis and pass between the two layers of the broad ligaments of the uterus, to be distributed to the ovaries, Fallopian tubes, and round ligaments; along the latter they are continued to the inguinal canal and labium at each sid?. They inosculate with the uterine arteries. 304 lA^FERIOR MESENTERIC ARTERY. The Inferior Mesenteric Artery, smaller than the superior, arises from the abdominal aorta, about two inches below the origin of- that vessel, and descends between the layers of the left mesocolon, to the left iliac fossa, where it divides into three branches: Colica sinistra, superior, Sigmoidese, or colica sinistra media and inferior. Superior ha;morrhoidal. The Colica sinistra is distributed to the descending colon, and ascends to inosculate with the colica media. This is the largest arterial inosculation in the body. Fig. 11] * * The distribution and brandies of the inferior mesenteric artery. 1, ]. The supe- rior artery with its brandies and the small intestines turned over to the right side. 2. The cxcum and ap])endix ca;ci. 3. The ascending- colon. 4. The transverse colon raised upwards. r>. Tlie descending colon. G. Its sigmoid flexure. 7. The rectum. 8. The aorta. 9. Tiie inferior mesenteric artery. 10. The eoliea sinistra, inosculating with 11. The colica media, a branch of the superior mesenteric artery. 12, 12. Sig- moid branches. 13. The fiuiierior ha-morrhoidal artcu'y. 14. The pancreas. 15, The descending portion of the duodentmi. RENAL ARTERIES- — LUMBAR ARTERIES. 305 The Sigmoidece are several large branches which are distributed to the sigmoid flexure of the descending colon. They form arches, and inosculate above with the colica sinistra, and below with the superior hsemorrhoidal artery. The Superior hcEmorrhoidal artery is the continuation of the inferior mesenteric. It crosses the ureter and common iliac artery of the left side, and descends between the two layers of the meso- rectum as far as the middle of the rectum to which it is distributed, anastomosing with the middle and external hsemorrhoidal arteries. The Supra-Rexal are two small vessels which arise from the aorta immediately above the renal arteries, and are distributed to the supra-renal capsules. They are sometimes branches of the phrenic or of the renal arteries. The Reival Arteries (emulgent) are two large trunks given off from the sides of the aorta immediately below the superior mesen- teric artery ; the right is longer than the left on account of the posi- tion of the aorta, and passes behind the vena cava to the kidney of that side. The left is somewhat higher than the right. They divide into several large branches previously to entering the kidney, and ramify very minutely in its vascular portion. The renal arteries supply several small branches to the supra-renal capsules. The Lumbar Arteries correspond with the intercostals in the chest ; they are four or five in number on each side, and curve around the bodies of the lumbar vertebras beneath the psoas muscles, and divide into two branches ; one of which passes backwards between the transverse processes and is distributed to the vertebra3 and spinal cord and to the muscles of the back, whilst the other takes its course behind the quadratus lumborum muscle and supplies the abdominal muscles. The first lumbar artery runs along the lower border of the last rib, and the last along the crest of the ilium. In passing between the psoas muscles and the vertebra?, they are protected by a series of tendinous arches, which defend them and the communicating branches of the sympathetic nerve from pressure during the action of the muscle. The Sacra Media arises from the posterior part of the aorta at its bifurcation, and descends along the middle of the anterior surface of the sacrum to the first piece of the coccyx where it terminates by inosculating with the lateral sacral arteries. It distributes branches to the rectum and anterior sacral nerves, and inosculates on either side with the lateral sacral arteries. Varieties in the Brandies of the abdominal Aorta. — The phrenic arteries are very rarely both derived from the aorta. One or both may be branches of the cceliac axis ; one may proceed from the gastric artery, from the renal, or from the upper lumbar artery. There are occasionally three or more phrenic arteries. The coeliac axis is very variable in length, and gives otT its branches irregularly. There are sometimes two or even three hepatic arteries, one of which may be derived from the gastric or even from the superior mesenteric. The colica media is sometimes derived from the hepatic 39 306 COMMON ILIAC ARTERIES. arteiy. The spermatic arteries are very variable both in origin and number. The right spermatic may be a branch of the renal artery, and the left a branch of the inferior mesenteric. The supra-renal arteries may be derived from the phrenic or renal arteries. The renal arteries present several varieties in number ; there may be three or even four arteries on one side and one only on the other. When there are several renal arteries on one side, one may arise from the common iliac artery, from the front of the aorta near its lower part, or from the internal iliac. COMMOIV ILIAC ARTERIES. The abdominal aorta divides opposite the fourth lumbar vertebras into the two common iliac arteries. Sometimes the bifurcation takes place as high as the third, and occasionally as low as the fifth lum- bar vertebra. The common iliac arteries are about two inches and a half in lengtli ; they diverge from the termination of the aorta, and pass downwards and outwards on each side to the margin of the pelvis opposite the sacro-iliac symphysis, where they divide into the internal and external iliac arteries. In old persons the common iliac arteries are more or less dilated and curved in their course. The Right common iliac is somewhat longer than the left and forms a more obtuse angle with the termination of the aorta ; the angle of bifurcation is greater in the female than in the male. Relations. — The relations of the two arteries are different on the two sides of the body. The right common iliac is in relation in front with the peritoneum, and is crossed at its bifurcation by the ureter. It is in relation posteriorly with the two common iliac veins, and externally with the psoas magnus. The left is in relation in front with the peritoneum, and is crossed by the rectum and superior ha;morrhoidal artery, and at its bifurcation by the ureter. It is in relation behind with the left common iliac vein, and externally with the psoas magnus. INTERNAL ILIAC ARTERY. The Internal Iliac Artery is a short trunk, varying in length from an inch to two inches. It descends obliquely to a point opposite the upper margin of the great sacro-ischiatic foramen, where it divides into an anterior and a posterior trunk. Relations. — This artery rests externally upon the sacral plexus and upon the origin of the pyriformis muscle ; posteriorly it is in relation with the internal iliac vein, and anteriorly with the ureter. Branches. — The branches of the anterior trunk are the — Umbilical, Ischiatic, Middle vesical. Internal pudic. Middle ha^morrhoidal. And in the female the — Uterine, Vaginal. INTERNAL ILIAC ARTERY. 307 And of the posterior trunk the — Iho-lumbar, Lateral sacral, Obturator, Gluteal. The umbilical artery is the commencement of the fibrous cord into which the umbilical artery of the foetus is converted after birth. In after life, the cord remains pervious for a short distance and con- stitutes the umbilical artery of the adult, from which the superior vesical artery is given off to the fundus and anterior aspect of the bladder. The cord may be traced forwards by the side of the fundus of the bladder to near its apex, whence it ascends by the side of the linea alba and urachus to the umbilicus. Fig. 112.* The Middle vesical artery is generally a branch of the umbilical, and sometimes of the internal iliac. It is somewhat larger than the superior vesical, and is distributed to the posterior part of the body of the bladder, the vesiculse seminales, and prostate gland. The Middle ha^morrhoidal artery is as frequently derived from the ischiatic or internal pudic as from the internal iliac. It is of variable size, and is distributed to the rectum, base of the bladder, vesiculse seminales, and prostate gland ; and inosculates with the superior and external hasmorrhoidal arteries. * Tlie distribution and branches of the iliac arteries. 1. Tlic aorta. 2. The left common iliac artery. 3. The external iliac. 4. The epigastric artery. 5. The cir- cumflcxa ilii. 6. The internal iliac artery. 7. Its anterior trunk. 8. Its posterior trunk. !). The umbilical artery giving olF (10) the superior vesical artery. After the origin of this branch, the umbilical artery becomes converted into a fibrous cord — the umbilical ligament. 11. The internal pudic artery passing behind the spine of the ischium (12) and lesser sacro-ischiatic ligament. 13. Tlic middle hajmorrlioidal artery. 14. The ischiatic artery, also passing behind the anterior sacro-ischiatic ligament to escape from tlie pelvis. 15. Its inferior vesical branch. 16. Tlie ilio-lumbar, the fust brancli of the posterior trunk (8) ascending to inosculate with tlie circumflcxa ilii arlery (5) and form an arcli along the crest of the ilium. 17. The obturator artery. 18. The lateral sacral. 19. The gluteal artery escaping from tlic pelvis through the upper part of the great sacro-ischiatic foramen. 20. The sacra media. 21. The right common iliac artery cut short. 22. The femoral artery. 308 ISCHIATIC ARTERY, The IscHiATic Artery is the larger of the two terminal branches of the anterior division of the internal iliac. It passes dowmvards between the posterior border of the levator ani, and the pyriformis, resting upon the sacral plexus of nerves and lying behind the internal pudic artery, to the lower border of the great ischiatic notch, where it escapes from the pelvis below the pyriformis muscle. It then descends in the space between thetrochanter major and the tube- rosity of the ischium in company with the ischiatic nerves, and divides into branches. Fig. 113* Its branches within the pelvis are the inferior hmmorrlioidal which supplies the rectum conjointly with the middle hsemorrhoidal and sometimes takes the place of that artery, and the inferior vesical which is distributed to the base and neck of the bladder, the vesiculse seminales, and prostate gland. The branches external to the pelvis, are four in number — coccygeal, inferior gluteal, comes nervi ischia- tici, and muscular branches. The Coccygeal branch pierces the great sacro-ischiatic ligament, and is distributed to the coccygcus and levator ani muscles, and to the integument around the anus and coccyx. * The arteries of the perineum ; on the rijrlit side the superficial arteries are seen, and on the left the deep. 1. The penis, consisting' of corpus spongiosum and corpus cavernosum. The /;rus penis on the Icfl side is cut througli. 2. The accclcratores urinoB muscles, enclosing the bulbous portion of the cori)us spongiosum. 3. The erector penis, spread out upon the crus penis of the right side. 4. TJic anus, surrounded by the sphincter ani muscle. .5. The ramus of the ischium and os pubis. G. The tube- rosity of the ischium. 7. The lesser sacro-ischiatic ligament, attached by its small extremity to the si)iue of the ischium. 8. The coccyx, y. Tlio internal jjudic artery, crossing tiic spine of tlie ischium, and entering tiic perineum. 10. Inferior liremor- rhoidal branch. 11. The supcrticialis perinci artery, giving oil' a small branch, transversalis perinci, upon the transvcrsus perinci muscle. 12. The same artery on the left side cut. off. 13. The artery of the l>ulb. 14. TJie two terminal branches of the internal pudic artery; one is seen entering tlio divided extremity of the crus penis, the artery of the corpus cavernosum ; the oilier, the dorsalis penis, ascends upon the dorsum of the organ. INTERNAL PUDIC ARTERY. 309 The Inferior gluteal branches supply the gkiteus maximus muscle. The Comes nervi iscliiatici is a small but regular branch, which accompanies the great ischiatic nerve to the lower part of the thigh. The Muscular branches supply the muscles of the posterior part of the hip and thigh, and inosculate with the internal and external circumflex arteries, with the obturator, and with the superior per- forating artery. The Internal Pudic Artery, the other terminal branch of the anterior trunk of the internal iliac, descends in front of the ischiatic artery to the lower border of the great ischiatic foramen. It emerges from the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, crosses the spine of the ischium, and re-enters the pelvis through the lesser sacro-ischiatic foramen ; it then crosses the internal obturator muscle to the ramus of the iscliium, being situated at about an inch from the margin of the tuberosity, and bound down by the obturator fascia ; it next ascends the ramus of the ischium, enters between the two layers of the deep perineal fascia lying along the border of the ramus of the os pubis, and at the symphysis, pierces the anterior layer of the deep perineal fascia, and very much diminished in size reaches the dorsum of the penis along which it runs, supplying that organ under the name of the dorsalis penis. Branches. — The branches of the internal pudic artery within the pelvis are several small ramuscules to the base of the bladder, the vesicute seminales, and the prostate gland; and the hcBmorrlioidal branch which supplies the middle of the rectum, and frequently takes the place of the middle hcemorrhoidal branch of the internal ihac. The branches, external to the pelvis, are the Inferior htemorrhoidal, Superficialis perinei, Transversahs perinei, Arteria bulbosa, Arteria corporis cavernosi, Arteria dorsalis penis. The Inferior hcBmorrhoidal artery is given off by the internal pudic while behind the tuberosity of the ischium. It is distributed to the anus, and to the muscles, the fascia, and the integument in the anal region of the perineum. The Superficial perineal arterij is given off near the attachment of the crus penis; it pierces the connecting layer of the superficial and deep perineal fascia, and runs forwards across the transversus perinei muscle, and along the groove between the accelerator uringe and erector penis to the septum scroti, upon which it ramifies under the name of arteria septi. It distributes branches to the scrotum, and to the perineum in its course fonvards. One of the latter, larger than the rest, crosses the perineum, resting on the transversus peri- nei muscle, and is named the transversalis perinei. 310 UTERINE, VAGINAL, AND OBTTIRATOE ARTERIES. The Artery of the hulh is given off from the pudic nearly opposite the opening for the transmission of the urethra; it passes nearly transversely inwards between the two layers of the deep perineal fascia, and pierces the anterior layer to enter the corpus spongiosum at its bulbous extremity. It is distributed to the corpus spongiosum. The Artery of ike corpus cavernosum pierces the crus penis, and runs forward in the interior of the corpus cavernosum, by the side of the septum pectiniforme. It ramifies in the parenchyma of the venous structure of the corpus cavernosum. The Dorsal artery of the penis ascends between the two crura and symphysis pubis to the dorsum penis, and runs forward through the suspensory ligament in the groove of the corpus cavernosum to the glans, distributing branches in its course to the body of the organ and to the integument. The Internal pudic artery in the female is smaller than in the male ; its branches, with their distribution, are in principle the same. The superficial perineal artery supphes the analogue of the lateral half of the scrotum, viz. the greater labium. The artery of the bulb supphes the meatus urinarius, and the vestibule ; the artery of the corpus cavernosum, the cavernous body of the clitoris, and the arte- ria dorsalis clitoridis, the dorsum of that organ. The Uterine and Vaginal arteries of the female are derived either from the internal iliac, or from the umbilical, internal pudic, or ischiatic arteries. The former are very tortuous in their course, and ascend between the layers of the broad ligament, to be distri- buted to the uterus. The latter ramify upon the exterior of the vagina, and supply its mucous membrane. Branches of the posterior trunk. The lUo-lumhar artery ascends beneath the external ihac vessels and psoas muscle, to the posterior part of the crest of the ihum, where it divides into two branches, a lumbar branch wliich supplies the psoas and iliacus muscles, and sends a ramuscule through the fifth intervertebral foramen to the spinal cord and its membranes ; and an iliac branch which passes along the crest of the ilium dis- tributing branches to the iliacus and abdominal muscles, and inos- culating with the lumbar and gluteal arteries, and with the circum- llexa ilii. The Obturator Artery is exceedingly variable in point of origin ; it generally proceeds from the posterior trunk of the internal iliac artery, and passes forwards a little below the brim of the pelvis to the upper border of the obturator foramen. It there escapes from the pelvis through a tendinous arch formed by the obturator membrane, and divides into two branches; an internal branch which curves inwards around the bony margin of the obturator foramen, between the obturator cxtcrnus muscle and the ramus of Ihe ischium, and distributes branches to the obturator muscles, the pectineus, the adductor muscles, and to the organs of generation, GLUTEAL ARTERY. 311 and inosculates with the internal circumflex artery. And an external branch which pursues its course along the outer margin of the obturator foramen to the space between the gemellus inferior and quadratus femoris, where it inosculates with the ischiatic artery. In its course backwards it anastomoses with the internal circumflex, and sends a branch through the notch in the acetabulum to the hip- joint. Within the pelvis the obturator artery gives off a branch to the ihacus muscle, and a small ramuscule which inosculates with the epigastric artery. The Lateral Sacral Arteries are generally two in number on each side ; superior and inferior. The superior passes inwards to the first sacral foramen and is distributed to the contents of the spinal canal, from which it escapes by the posterior sacral foramen, and supplies the integument on the dorsum of the sacrum. The inferior passes down by the side of the anterior sacral foramina to the coccyx ; it first pierces and then rests upon the origin of the pyri- formis, and sends branches into the sacral canal to supply the sacral nerves. Both arteries inosculate with each other and with the sacra media. The Gluteal Artery is the continuation of the posterior trunk of the internal iliac : it passes backwards between the lumbo-sacral and first lumbar nerve through the upper part of the great sacro- ischiatic foramen, and above the pyriformis muscles, and divides into three branches — superficial, deep superior, and deep inferior. The Superficial branch is directed forwards between the gluteus maximus and medius, and divides into numerous branches, which are distributed to the upper part of the gluteus maximus and to the integument of the gluteal region. The Deep superior branch passes along the superior curved line of the ilium, between the gluteus medius and minimus to the ante- rior superior spinous process, where it inosculates with the superfi- cial circumflexa ilii and external circumflex artery. There are frequently two arteries which follow this course. The Deep inferior branches are several large arteries which cross the gluteus minimus obliquely to the trochanter major, where they inosculate with branches of the external circumflex artery, and send branches through the gluteus minimus to supply the capsule of the hip-joint. Varieties in the Branches of the internal iliac. — The most impor- tant of the varieties occurring among these branches is the origin of the dorsal artery of the penis from the internal iliac or ischiatic. The artery in this case passes forv^^ards by the side of the prostate gland, and through the upper part of the deep perineal fascia. It would be endangered in the operation for lithotomy. The dorsal artery of the penis is sometimes derived from the obturator, and sometimes from one of the external pudic arteries. The artery of the bulb, in its normal course, passes almost transversely inwards to the corpus spongiosum. Occasionally, however, it is so oblique in its direction as to render its division in lithotomy unavoidable. 312 EXTERNAL ILIAC AKTERY, The obturator artery may be very small or altogether wanting, its place being supplied by a branch from the external iliac or epigas- tric. EXTERNAL ILIAC ARTERY. The external iliac artery of each side passes obliquely downwards along the inner border of the psoas muscle, from opposite the sacro- ihac symphysis to the femoral arch, where it becomes the femoral artery. Relations. — It is in relation in front with the spermatic vessels, the peritoneum, and a thin layer of fascia, derived from the iliac fascia, which surrounds the artery and vein. At its commence- ment it is crossed by the ureter, and near its termination by the crural branch of the genito-crural nerve and the circumflexa ilii vein. Externally it lies against the psoas muscle, from which it is sepa- rated by the iliac fascia ; and 'posteriorly it is in relation with the external iliac vein, which, at the femoral arch, becomes placed to its inner side. The artery is surrounded throughout the whole of its course by lymphatic vessels and glands. Branches. — Besides several small branches which supply the glands surrounding the artery, the external iliac gives off two branches, the — Epigastric, Circumflexa ilii. The Epigastric artery arises from the external iliac near to Pou- part's ligament ; and passing forwards between the peritoneum and transversalis fascia, ascends obliquely to the border of the sheath of the rectus. It enters the sheath near to its lower third, passes upwards behind the rectus muscle, to which it is distributed, and in the substance of that muscle it inosculates near the ensiform cartilage with the termination of the internal mammary artery. It lies internally to the internal abdominal ring, and immediately above the femoral ring, and is crossed near its origin by the vas deferens in the male, and by the round ligament in the female. The only branches of the epigastric artery worthy of distinct notice are the Cremasteric, which accompanies the spermatic cord and supplies the cremaster muscle; and the ramusculus which inos- culates with the obturator artery. The Epigastric artery forms a projection of the peritoneum which divides the iliac fossa into an internal and an external portion ; it is from the former that direct inguinal hernia issues, and from the latter, oblique inguinal hernia. The Circumflexa ilii arises from the outer side of the external iliac, nearly opposite to the epigastric artery. It ascends obhquely along Poupart's ligament, and curving around the crest of the ilium between the attachments of the internal oblique and transversalis FEMORAL ARTERY. 313 Fig. 114* muscle, inosculates with the ilio-lumbar and inferior lumbar artery. Opposite the anterior superior spinous process of the ilium, it gives off a large ascending branch which passes up- wards between the internal oblique and trans- versalis, and divides into numerous branches which supply the abdominal muscles, and in- osculates with the inferior intercostal and with the lumbar arteries. Varieties in the branches of the external iliac. — The epigastric artery not unfrequent- ly gives off the obturator,-]- which descends in contact with the external ihac vein, to the obturator foramen. In this situation the artery would lie to the outer side of the femoral ring, and would not be endangered in the operation for dividing the stricture of femoral i^^ hernia. But occasionally the obturator passes along the free margin of Gimbernat's liga- ment in its course to the obturator foramen, and would completely encircle the neck of the hernial sac ; a position in which it could scarcely escape the knife of the operator. In a preparation in my anatomical collec- tion the branch of communication between the epigastric and obturator arteries is very much enlarged, and takes this dangerous course. FEMORAL ARTERY. Emerging from beneath Poupart's ligament, the external iliac artery enters the thigh and * A view of the anterior and inner aspect of the thigh, showing the course and branches of the femoral artery. 1. The lower part of the aponeurosis of the external oblique muscle ; its inferior margin is Poupart's ligament. 2. The external abdominal ring. 3, 3. The upper and lower part of the sartorius muscle; its middle portion hav- ing been removed. 4. The rectus. 5. The vastus internus. 6. The patella. 7. The iliacus and psoas ; the latter being nearest the artery. 8. The pectineus. 9. The adductor longus. 10. The tendinous canal for the femoral artery formed bj' the ad- ductor magnus, and vastus internus muscles. 11. The adductor magnus. 12. The gracilis. 13. The tendon of the semi-tendinosus. 14. The femoral artery. 15. The superficial circumflexa ilii artery taking its course along the line of Poupart's ligament, to the crest of the ilium. 2. The superficial epigastric artery. 1 6. The two external pudic arteries, superficial and deep. 17. The profunda artery giving off 1 8, its external circumflex branch ; and lower down the three perforantes. A small bend of the inter- nal circumflex artery (8) is seen behind the inner margin of the femoral, just below the deep external pudic artery. 19. The anastoinotica magna, descending to the knee, upon which it ramifies (6). t The proportion in which high division of the obturator artery from the epigastric occurs, is stated to be one in three. In two hundred and fifty subjects examined by Cloquet with a view to ascertain how frequently the high division took place, he found the obturator arising from the epigastric on both sides one hundred and fift;y times ; on one side twenty-eight times, and six times it arose from the femoral artery. 40 •314 FE3I0RAL AETERV. becomes the femoral. The femoral artery passes down the inner side of the thigh, from Poupart's ligament, at a point midway be- tween the anterior superior spinous process of the ilium and the symphysis pubis, to the hole in the adductor magnus, at the junction of the middle with the inferior third of the thigh, where it becomes the pophteal artery. The femoral artery and vein are enclosed in a strong sheath, femoral or crural canal, which is formed for the greater part of its extent by fibrous and cellular tissue, and by a process of fascia sent inwards from the fascia lata. Near Poupart's ligament this sheath is much larger than the vessels it contains, and is continuous with the fascia transversalis, and iliac fascia. If the sheath be opened at this point, the artery will be seen to be situated in contact with the outer wall of the sheath. The vein lies next to the artery, being separated from it by a fibrous septum, and between the vein and the inner wall of the sheath, and divided from the vein by another thin fibrous septum, is a triangular interval, into which the sac is protruded in femoral hernia. This space is occupied in the normal state of the parts by loose cellular tissue, and by lymphatic vessels which pierce the inner wall of the sheath to make their way to a gland, situated in the femoral ring. Relations. — The upper third of the femoral artery is superficial, being covered only by the integument, inguinal glands and by the superficial and deep fascia. The lower two-thirds are covered by the sartorius muscle. To its outer side the artery is first in relation with the psoas, next with the rectus, and then with the vastus in- ternus. Behind it rests upon the inner border of the psoas muscle ; it is next separated from the pectineus by the femoral vein, profunda vein and artery, and then lies on the adductor longus to its termina- tion: near the lower border of the adductor longus, it is placed in an aponeurotic canal, formed by an arch of tendinous fibres, thrown from the border of the adductor longus, and the border of the opening in the adductor magnus, to the side of the vastus internus. To its inner side it is in relation at its upper part with the femoral vein, and lower down with the pectineus, the adductor longus, and sar- torius. The immediate relations of the artery are the femoral vein, and two saphenous nerves. The vein at Poupart's ligament lies to the inner side of the artery ; but lower down gets altogether behind it. The short saphenous nerve lies to the outer side, and somewhat upon the sheath for the lower two-thirds of its extent ; and the long saphenous nerve is situated within the sheath for the same extent. FEMORAL ARTKRY BRANCHES. 315 Plan of the relations of the Femoral Artery. Front. Fascia lata, Saphenous nerves, Sartorius, Arch of the tendinous canal. Inner Side. Femoral vein, Pectineus, Adductor longus, Sartorius. Femoral artery. Outer Side. Psoas, Rectus, Vastus internus. Behind. Psoas muscle. Femoral vein. Adductor longus. Branches. — The branches of the Femoral Artery are the- Siiperficial circumflexa ilii, Superficial epigastric, Superficial external pudic, Deep external pudic, ( External circumflex, Profunda < Internal circumflex, Muscular, Three perforating. Anastomotica magna. The Superficial circumflexa ilii artery arises from the femoral, immediately below Poupart's ligament, pierces the fascia lata, and passes obliquely towards the umbilicus between the two layers of superficial fascia. It distributes branches to the inguinal glands and integument, and inosculates with branches of the deep epigastric and of the internal mammary artery. The Superficial external pudic arises near to the superficial epi- gastric artery ; it pierces the fascia lata, at the saphenous opening, and passes transversely inwards crossing the spermatic cord, to be distributed to the integument of the penis and scrotum in the male, and to the labia in the female. The Deep external pudic arises from the femoral, a little lower down than the preceding ; it crosses the femoral vein immediately below the termination of the internal saphenous vein, and piercing the pubic portion of the fascia lata passes beneath that fascia to the inner border of the thigh, where it again pierces the fascia ; having become superficial, it is distributed to the integument of the scrotum and perineum. The Profuivda Femoris arises from the femoral artery at two inches below Poupart's ligament : it passes downwards and back- wards, and a little outwards, behind the adductor longus muscle, pierces the adductor magnus, and is distributed to the flexor muscles on the posterior part of the thigh. 316 PROFUNDA ARTERY. Relations. — In its course doM^nwards it rests successively upon the pectineus, the conjoined tendon of the psoas and iUacus, ad- ductor brevis and adductor magnus muscles. To its outer side the tendinous insertion of the vastus internus muscle intervenes between it and the femur; and in front it is separated from the femoral artery, above by the profunda vein and femoral vein ; and below by the ad- ductor longus muscle. Plan of the relations of the Profunda artery. In Front. Profunda vein, Adductor longus. Outer Side. Vastus internus, Femur. Behind, Pectineus, Tendons of psoas and iliacus. Adductor brevis, Adductor magnus. Branches. — The branches of the profunda artery are the external circumflex, internal circumflex, and three perforating arteries. The External circumflex artery passes outwards between the divisions of the crural nerve, then between the rectus and crureus muscle, and divides into three branches ; ascending, which inos- culates with the terminal branches of the gluteal artery ; descending which inosculates with the superior external articular artery ; and middle, which continues the original course of the artery around the thigh, and anastomoses with branches of the ischiatic, internal cir- cumflex, and superior perforating artery. It supplies the muscles on the anterior and outer side of the thigh. The Internal circumflex artery is larger than the external; it winds around the inner side of the neck of the femur, passing be- tween the pectineus and psoas, and along the border of the external obturator muscle, to the space betv/een the quadratus femoris and upper border of the adductor magnus, where it anastomoses with the ischiatic, external circumflex, and superior perforating artery. It supplies the muscles on the upper and inner side of the thigh, anastomosing with the obturator artery, and sends a small branch through the notch in the acetabulum into the hip-joint. The Superior perforating artery passes backwards between the pectineus and adductor brevis, pierces the adductor magnus near to the femur, and is distributed to the posterior muscles of the thigh ; inosculating freely with the circumflex and ischiatic artery, and with the branches of the middle perforating artery. The Middle perforating artery pierces the tendons of the adductor brevis and magnus, and is distributed like the superior ; inosculating POPLITEAL ARTERY. 317 with the superior and inferior perforantes. This branch frequently gives off the nutritious artery of the femur. The Inferior ferf orating artery is given off below the ad ductor brevis, and pierces the tendon of the adductor magnus, supplying it and the flexor muscles and inosculating with the middle perforating artery above, and with the articular branches of the popliteal below. It is through the medium of these branches that the collateral cir- culation is maintained in the Umb after ligature of the femoral * artery. The Muscular branches are given off by the femoral artery throughout the whole of its course. They supply the muscles in immediate proximity with the artery, particularly those of the ante- rior aspect of the thigh. One of these branches larger than the rest, arises from the femoral immediately below the origin of the pro- funda, and passing outwards between the rectus and sartorius divides into branches which are distributed to all the muscles of the anterior aspect of the thigh. It may be named the superior muscular artery. The Anastomotica magna arises from the femoral while in the tendinous canal formed by the adductors and vastus internus. It runs along the tendon of the adductor magnus to the inner condyle, and inosculates with the superior internal articular artery : some of its branches are distributed to the vastus internus muscle and to the crureus, and terminate by anastomosing with the branches of the external circumflex and superior external articular artery. POPLITEAL ARTERY. The popliteal artery commences from the termination of the femoral at the opening in the adductor magnus muscle, and passes obliquely outwards through the middle of the popliteal space to the lower border of the popliteus muscle, where it divides into the ante- rior and posterior tibial artery. Relations. — In its course downwards it rests first on the femur, then on the posterior ligament of the knee-joint, then on the fascia, covering the popliteus muscle. Superficially it is in relation with the semimembranosus muscle, next with a quantity of fat which sepa- rates it from the deep fascia, and near its termination with the gas- trocnemius, plantaris, and soleus ; superficial and external to it is the popliteal vein, and still more superficial and external, the popli- teal nerve. By its inner side it is in relation with the semimem- branosus, internal condyle of the femur, and inner head of the gastrocnemius ; and by its outer side with the biceps, external condyle of the femur, the outer head of the gastrocnemius, the plantaris and the soleus. 318 ANTERIOR TIBIAL ARTERY. Plan of the relations of the PopHteal Artery. Snperjicially. Semimembranosus, Popliteal nerve, Popliteal vein, Gastrocnemius, Plantaris. Soleus. Inner Side. Semimembranosus, Internal condyle. Gastrocnemius. Popliteal Artery. Outer Side. Biceps, External condyle, Gastrocnemius, Plantaris, Soleus. Deeply. Femur, Ligamentum posticum Winslowii, Popliteal fascia. Branches. — The branches of the popHteal artery are the — Superior external articular, Superior internal articular, Azygos articular, Inferior external articular. Inferior internal articular. Sural. The Superior articular arteries, external and internal, wind around the femur immediately above the condyles, to the front of the knee-joint, anastomosing with each other, with the external cir- cumflex, the anastomotica magna, the inferior articular, and the recurrent of the anterior tibial. The external passes beneath the tendon of the biceps, and the internal through an arched opening beneath the tendon of the abductor magnus. They supply the knee- joint and the lower part of the feriiur. The Azygos articular artery pierces the posterior ligament of the joint, the ligamentum posticum Winslowii, and supplies the synovial membrane in its interior. There are frequently several posterior articular arteries. The Inferior articular arteries wind around the head of the tibia immediately below the joint, and anastomose with each other, the superior articular arteries, and the recurrent of the anterior tibial. The external passes beneath the two external lateral ligaments of the joint, and the internal beneath the internal lateral ligament. They supply the knee-joint and the heads of the tibia and fibula. The Sural arteries (sura, the calf) are two large muscular branches, which are distributed to the two heads of the gastrocne- mius muscle. ANTERIOR TIBIAL ARTERY. The anterior tibial artery passes forwards between the two heads of the tibiahs posticus muscle, and through the opening in the upper ANTERIOR TIBIAL ARTERY, 319 part of the interosseous membrane, to the anterior tibial region. It then runs down the anterior aspect of the leg to the ankle-joint, where it becomes the dorsalis pedis. Relations. — In its course downwards it rests upon the interosseous membrane (to which it is connected by a little tendinous arch which is thrown across it), the lower part of the tibia, and the anterior ligament of the joint. In the upper third of its course it is situated between the tibialis anticus and extensor longus digitorum, lower down between the tibialis anticus and extensor proprias pollicis ; and just before it reaches the ankle it is crossed by the tendon of the extensor proprius pollicis, and becomes placed between that tendon and the tendons of the extensor longus digitorum. Its immediate relations are the venaB comites and the anterior tibial nerve, which lies at first to its outer side, and at about the middle of the leg be- comes placed superficially to the artery. Plan of the relations of the Anterior Tibial Artery. Front. Deep fascia. Tibialis anticus, Extensor longus digitorum, Extensor proprius pollicis, Anterior tibial nerve. Inner Side. Tibialis anticus, Tendon of the extensor pro- prius pollicis. Anterior Tibial Artery. Outer Side. Anterior tibial nerve, Extensor longus digitorum. Extensor proprius pollicis, Tendons of the extensor longus digitorum. Behind. Interosseous membrane. Tibia (lower fourth), Ankle joint. Branches. — The branches of the Anterior Tibial Artery are the — Recurrent, Muscular, External malleolar, Internal malleolar. The Recurrent branch passes upwards beneath the origin of the tibialis anticus muscle to the front of the knee-joint, upon which it is distributed, anastomosing with the articular arteries. The Muscular branches are very numerous, they supply the mus- cles of the anterior tibial region. The Malleolar arteries are distributed to the ankle-joint; the external passing beneath the tendons of the extensor longus digi- torum and peroneus tertius, inosculates with the anterior peroneal artery and with the branches of the dorsalis pedis ; the internal beneath the tendons of the extensor proprius pollicis and tibialis 320 DORSA.L ARTERIES OP THE FOOT. anticus, inosculates with branches of the posterior tibial and of the internal plantar artery. They supply branches to the ankle-joint. The DoRSALis Pedis Artery is continued forwards along the tibial side of the dorsum of the foot, from the ankle to the base of the metatarsal bone of the great toe, where it divides into two branches, the dorsalis hallucis and communicating. Relations. — The dorsalis pedis is situated along the outer border of the tendon of the extensor proprius pollicis ; on its fibular side is the innermost tendon of the extensor longus digitorum, and near to its termination it is crossed by the inner tendon of the extensor brevis digitorum. It is accompanied by venae comites, and has the con- tinuation of the anterior tibial nerve to its outer side. Plan of the relations of the Dorsalis Pedis Artery. In Front. Integument, Deep fascia, Inner tendon of the extensor brevis digitorum. Inner Side, Tendon of the ex- tensor proprius pollicis. Dorsalis Pedis Artery. Outer Side. Tendon of the extensor longus digitorum, Border of the extensor brevis disfitorum muscle. Behind. Bones of the tarsus, with their ligaments. Branches. — The branches of this artery are the — Tarsea, Metatarsea, — interosseas, Dorsalis hallucis, — collateral digital, Communicating. The Tarsea arches transversely across the tarsus, beneath the extensor brevis digitorum muscle, and supplies the articulations of the tarsal bones and the outer side of the foot ; it anastomoses with the external malleolar, the peroneal arteries, and with the external plantar. The Metatarsea forms an arch across the base of the metatarsal bones, and supplies the outer side of the foot, anastomosing with the tarsea and with the external plantar artery. The metatarsea gives off three branches, the interossecu, which pass forwards upon the dorsal interossei muscles, and divide into two collateral branches for the adjoining toes. At their commencement these interosseous branches receive the posterior perforating arteries from the plantar arch, and opposite the heads of the metatarsal bones they are joined by the anterior perforating branches from the digital arteries. ANTERIOR AND POSTERIOR TIBIALS. Fig. 115.* Fig. 116.t 321 * The anterior aspect of the leg and foot, showing the anterior tibial and dorsalis pedis arteries, with their branches. ]. The tendon of insertion of the quadriceps ex- tensor muscle. 2. The insertion of the ligamentum patellae into the lower border of the patella. 3. The tibia. 4. The extensor proprius pollicis muscle. 5. The extensor longus digitorum. G. The peronei muscles. 7. The inner belly of the gastrocnemius and the soleus. 8. The annular ligament beneath which the extensor tendons and the anterior tibial artery pass into the dorsum of tlie foot. 9. The anterior tibial artery. 10. Its recurrent branch inosculating with (2) the inferior articular, and (1) the superior articular artery, branches of the popliteal. 11. The internal malleolar artery. 17. ijThe external malleolar inosculating with the anterior peroneal artery 12. 13. The dorsalis pedis artery. 14. The tarsea and metatarsea arteries ; the tarsea is nearest the ankle, the metatarsea is seen giving off the interosseaj. 15. The dorsalis hallucis artery. ] 6. The communicating branch. + A posterior view of the leg, showing the popliteal and posterior tibial artery. 1. The tendons forming the inner hamstring. 2. The tendon of the biceps forming the outer hamstring. 3. The popliteus muscle. 4. Tlie flexor longus digitorum. 5. The tibialis posticus. 6. The fibula ; immediately below the figure is the origin of the flexor longus pollicis ; the muscle has been removed in order to expose the peroneal artery. 7. The peronei muscles, longus and brevis. 8. The lower part of the flexor longus pollicis muscle with its tendon. 9. The popliteal artery giving off its articular and muscular branches ; the two superior articular are seen in the upper part of the popliteal space passing above the two heads of the gastrocnemius muscle, which are cut through near to their origin. The two inferior are in relation with the popliteus muscle. 10. The anterior tibial artery passing througli the angular interspace between the two heads of the tibialis posticus muscle. 11. The posterior tibial artery. 12. The relative position of the tendons and artery at the inner ankle from within outwards, previously to their passing beneath the internal annular ligament. 13. The peroneal artery, dividing into two branches ; the anterior peroneal is seen piercing the inter- osseous membrane, 14. The posterior peroneal. 41 322 POSTERIOE TIBIAL ARTERY. The Dorsalis hallucis runs forward upon the first dorsal interosse- ous muscle, and at the base of the first phalanx divides into two branches, one of which passes inwards beneath the tendon of the extensor proprius pollicis, and is distributed to the inner border of the great toe, while the other bifurcates for the supply of the adja- cent sides of the great and second toes. The Communicating artery passes into the sole of the foot between the two heads of the first dorsal interosseous muscle, and inosculates with the termination of the external plantar artery. Besides the preceding, numerous branches are distributed to the bones and articulations of the foot, particularly along the inner bor- der of the latter. POSTERIOR TIBIAL ARTERY. The posterior tibial artery passes obliquely downwards along the tibial side of the leg from the lower border of the popliteus muscle to the concavity of the os calcis, where it divides into the internal and external plantar artery. Relations. — In its course downwards it lies upon the tibialis pos- ticus, next upon the flexor longus digitorum, and then upon the tibia ; it is covered in by the intermuscular fascia which separates it above from the soleus, and below from the deep fascia of the leg and the integument. It is accompanied by its venae comites, and by the posterior tibial nerve, which lies at first to its outer side, then super- ficially to it, and again to its outer side. Plan of the relations of the Posterior Tibial Artery. Superficially, Soleus, Deep fascia, The intermuscular fascia. Inner Side. Vein, Posterior Tibial Artery. Outer Side. Posterior tibial nerve, Vein. Deeply. Tibialis posticus, - Flexor longus digitorum, Tibia. . Branches. — The branches of the posterior tibial artery are the — Peroneal, Nutritious, Muscular, Internal calcanean, Internal plantar. External plantar. The Peroneal artery is given off from the posterior tibial at about two inches below the lower border of the popliteus muscle ; it is nearly as large as the anterior tibial artery, and passes obli(]ucly out- PLANTAR ARTERIES. 323 wards to the fibula. It then runs downwards along the inner border of the fibula to its lower third, where it divides into the anterior and posterior peroneal artery. Relations. — The peroneal artery rests upon the tibialis posticus muscle, and is covered in by the soleus, the intermuscular fascia, and the flexor longus pollicis, having the fibula to its outer side. , Plan of the relations of the Peroneal Artery. In Front. Soleus, Intermuscular fascia, Flexor longus pollicis. Outer Side. Fibula. Behind, Tibialis posticus. Branches. — The branches of the peroneal artery are muscular to the neighbouring muscles, particularly to the soleus, and the two terminal branches anterior and posterior peroneal. The Anterior peroneal pierces the interosseous membrane at the lower third of the leg, and is distributed on the front of the outer malleolus, anastomosing with the external malleolar and tarsal artery. This branch is very variable in size. The Posterior 'peroneal continues onwards along the posterior aspect of the outer malleolus to the side of the os calcis, to which and to the muscles arising from it, it distributes external calcanean branches. It anastomoses with the anterior peroneal, tarsal, exter- nal plantar, and posterior tibial artery. The JVutritious artery of the tibia arises from the trunk of the tibial, frequently above the origin of the peroneal, and proceeds to the nutritious canal which it traverses obliquely from below upwards. The Muscular brandies of the posterior tibial artery are distributed to the soleus and to the deep muscles on the posterior aspect of the leg. One of these branches is deserving of notice, a recurrent 5mnc/?, which -arises from the posterior tibial above the origin of the peroneal artery, pierces the soleus and is distributed upon the inner side of the tibia, anastomosing with the inferior internal articular. The Internal calcanean branches, three or four in number, proceed from the posterior tibial artery immediately before its division ; they are distributed to the inner side of the os calcis, to the integument, and to the muscles which arise from its inner tuberosity, and they anastomose with the external calcanean branches, and with all the neighbouring arteries. PLANTAR ARTERIES. The Internal plantar artery proceeds from the bifurcation of the posterior tibial at the inner malleolus and passes along the inner 324 PLANTAR ARTERIES. border of the foot between the abductor pollicis and flexor brevis digitorum muscles, supplying the inner border of the foot and greaftoe. The External plantar artery, much larger than the internal, passes obliquely outwards between the first and second layers of the plantar muscles, to the fifth metatarsal space. It then turns hori- zontally inwards between the second and third layers, to the first metatarsal space, where it inosculates with the communicating branch from the dorsalis pedis. The horizontal portion of the artery describes a slight curve, having the convexity forwards; this is the plantar arch. Branches. — The branches of the external Fig. 117.* plantar artery are the — Muscular, Articular, Digital, — anterior perforating, Posterior perforating. The Muscular branches are distributed to the muscles in the sole of the foot. The Articular branches supply the ligaments of the articulations of the tarsus, and their synovial membranes. The Digital branches are four in number: — the first is distributed to the outer side of the little toe ; the three others pass forwards to the cleft between the toes, and divide into collateral branches, which supply the adjacent sides of the three external toes and the outer side of the second. At the bifurcation of the toes, a small branch is sent upwards from each digital artery, to inosculate with the inter- osseous branches of the metatarsea; these are the anterior perforating arteries. The Posterior perforating are three small branches which pass upwards between the heads of the three external dorsal interossei muscles, to inosculate with the arch formed by the metatarsea artery. Varieties in the Arteries of the lower Extremity. — The femoral artery occasionally divides at Poupart's ligament into two branches, and sometimes into three ; the former is an instance of the high division of the profunda artery ; and in a case of the latter kind * The arteries of the sole of the foot; the first and a part of the second layer of mus- cles havinjr been removed. 1. The under and posterior i)art of the os calcis; to whicii the origins of the first layer of niuscles remain attached. 2. The musculus accesso- rius. 3. Tlic long flexor tendons. 4. The tendon of the peroneus long-us. .5. The termination of the posterior tibial artery. G. Tlie internal plantar. 7. The external plantar artery. 8. The plantar arcli ffivinj( off four digital branches, which pass for- wards on the interossei muscles to divide into collatf:ral branches. PULMONARY ARTERY. 325 which occurred during my dissections, the branches were the pro- funda, the superficial femoral, and internal circumflex artery. Dr. Quain in his " Elements of Anatomy," records an instance of a high division of the femoral artery, in which the two vessels became again united in the popliteal region. The point of origin of the pro- funda artery varies considerably in different subjects, being some- times nearer to and sometimes farther from Poupart's ligament, but more frequently the former. The branches of the popliteal artery are very liable to variety in size ; and in all these cases the com- pensating principle, so constant in the vascular system, is strikingly manifested. When the anterior tibial is of small size, the peroneal is large ; and, in place of dividing into two terminal branches at the lower third of the leg, descends to the lower part of the inter- osseous membrane, and emerges upon the front of the ankle, to supply the dorsum of the foot : or the posterior tibial and plantar arteries are large, and the external plantar is continued between the heads of the first dorsal interosseous muscle, to be distributed to the dorsal surface of the foot. Sometimes the posterior tibial artery is small and thread-like; and the peroneal, after descending to the ankle, curves inwards to the inner malleolus, and divides into the two plantar arteries. If in this case the posterior tibial be suffi- ciently large to reach the ankle, it inosculates with the peroneal previously to its division. The internal plantar artery sometimes takes the distribution of the external plantar, which is short and diminutive, and the latter not unfrequently replaces a deficient dor- salis pedis. The varieties of arteries are interesting in the practical applica- tion of a knowledge of their principal forms to surgical operations ; in their transcendental anatomy, as illustrating the normal distribu- tion in animals ; or in many cases, as diverticula permitted by Nature, to teach her observers two important principles •.—first, in respect to herself, that, however, in her means she may indulge in change, the end is never overlooked, and a hmb is as surely sup- plied by a leash of arteries, various in their course, as by those which we are pleased to consider normal in distribution ; and secondly, with regard to us ; that we should ever be keenly alive to what is passing beneath our observation, and ever ready in the most serious operation to deviate from our course and avoid, — or give eyes to our knife, that it may see — the concealed dangers which it is our pride to be able to contend with and vanquish. PULMONARY ARTERY. The pulmonary artery arises from the left side of the base of the right ventricle in front of the origin of the aorta, and ascends obliquely to the under surface of the arch of the aorta, where it divides into the right and left pulmonary arteries. In its course upwards and backwards it inclines to the left side, crossing the commencement of the aorta, and is connected to the under surface 326 PULMONARY AKTERY. of the arch by a hgamentous cord, the remains of the ductus arte- riosus. Relations. — It is enclosed for one half of its extent by the pericar- dium, and receives the attachment of the fibrous portion of the peri- cardium by its upper portion. Behind, it rests against the ascend- ing aorta ; on either side is the appendix of the corresponding auricle and a coronary artery ; and above, the cardiac ganglion and the remains of the ductus arteriosus. The Right pulmonary artery passes beneath the arch and behind the ascending aoita, and in the root of the lungs divides into three branches for the three lobes. The Left pulmonary artery, rather larger than the right, passes in front of the descending aorta, to the root of the left lung to which it is distributed. These arteries divide and subdivide in the structure of the lungs, and terminate in capillary vessels which form a net- work around the bronchial cells, and become continuous with the radicles of the pulmonary veins. Relations. — In the root of the right lung examined trom above downwards, the pulmonary artery is situated between the bronchus, and pulmonary veins ; the former being above, the latter below ; while in the left lung the artery is the highest, next the bronchus, and then the veins. On both sides, from before backwards, the artery is situated between the veins and bronchi, the former being in front, and the latter behind. CHAPTER VI. ON THE VEINS. The veins are the vessels which return the blood to the auricles of the heart, after it has been circulated by the arteries through the various tissues of the body. They are much thinner in structure than the arteries, so that when emptied of their blood they become flattened and collapsed. The veins of the systemic circulation convey the dark-coloured and impure or venous hloocl from the capillary system to the right auricle of the heart, and they are found after death to be more or less distended with that fluid. The veins of the pulmonary circulation resemble the arteries of the systemic circulation in containing during hfe the pure or arterial blood, which they transmit from the capillaries of the lungs to the left auricle. The veins commence by minute radicles in the capillaries which are every where distributed through the textures of the body, and converge to constitute larger and larger branches, till they termi- nate in the large trunks which convey the venous blood directly to the heart. In diameter they are much larger than the arteries, and like those vessels their combined areas would constitute an imagi- nary cone, whereof the apex is placed at the heart, and the base at the surface of the body. It follows from this arrangement, that the blood in returning to the heart is passing from a larger into a smaller channel, and therefore increases in rapidity during its course. Veins admit of a threefold division, into superficial, deep, and sinuses. The Superficial veins return the blood from the integument and superficial structures, and take their course between the layers of the superficial fascia ; they then pierce the deep fascia in the most convenient and protected situations, and terminate in the deep veins. They are unaccompanied by arteries, and are the vessels usually selected for venesection. The Deep veins are situated among the deeper structures of the body and generally in relation with the arteries ; in the limbs they are enclosed in the same sheath with those vessels, and they return the venous blood from the capillaries of the deep tissues. In com- pany with all the smaller, and also with the secondary arteries, as the brachial, radial, and ulnar in the upper, and the tibial and pero- neal in the lower extremity, there are two veins, placed one on each 328 STRUCTURE OF VEINS. side of the artery, and named vencB comites. The larger arteries, as the axillary, subclavian, carotid, popliteal, femoral, &c., are accom- panied by a single venous trunk. Sinuses differ from veins in their structure, and also in their mode of distribution, being confined to especial organs, situated within their substance. The principal venous sinuses are those of the dura mater, of the diploe, of the cancellous structure of bone, and of the uterus. The communications between veins are even more frequent than those of arteries, and they take place between the larger as well as among the smaller vessels ; the vense comites communicate with each other very frequently in their course, by means of short trans- verse branches which pass from one to the other. These communi- cations are strikingly exhibited in the frequent inosculations of the spinal veins, and in the various venous plexuses, as the spermatic plexus, vesical plexus, &c. The office of these inosculations is very apparent, as tending to obviate the obstructions to wliich the veins are particularly liable from the thinness of their coats, and from their inability to overcome much impediment by the force of their current. Veins are composed of three tunics, external, middle, and in- ternal. The External or Cellular coat is dense and resisting, and resem- bles the cellular tunic of arteries. The middle coat is fibrous like that of arteries, but extremely thin ; so that its existence is ques- tioned by some anatomists. The internal coat is serous, and also similar to that of arteries ; it is continuous with the lining membrane of the heart at one extremity, and with the lining of the capillaries at the other. At certain intervals the internal coat forms folds or duplicatures, which constitute valves. The valves of veins are generally composed of two semilunar folds, one on each side of the cylinder of the vessel, occasionally of a single duplicature, having a spiral direction, and in rare instances of three. The free extremity of the valvular folds is concave, and directed forwards, so that while the current of blood would be permitted to flow freely towards the heart, the valves would become distended and the current intercepted if the stream became retrograde in its course. Upon the cardiac side of each valve the vein is expanded into two pouches (sinuses), corresponding with the segments of the valves, which give to the distended or injected vein a knotted appearance. The valves are most numerous in the veins of the extremities, particularly in the deeper veins, and they are generally absent in the smaller veins, and in the veins of the viscera, as in the portal and cerebral veins : they are also absent in the large trunks, as in the venge cavse, vena) azygos, innominata), and iliac veins. Sinuses are venous channels, excavated in the structure of an organ, and lined by the internal coat of the veins ; of this structure are the sinuses of the dura matter, whose external covering is the fibrous tissue of the membrane, and the internal, the serous layer of VEINS OF THE HEAD AND NECK. 329 the veins. The external investment of the sinuses of the uterus is the tissue of that organ ; and that of the bones, the hning membrane of the cells and canals. Veins, like arteries, are supplied with nutritious vessels, the vasa vasorum ; and it is to be presumed that nervous filaments are dis- tributed to their coats. I shall describe the veins according to the primary division of the body ; taking first, those of the head and neck ; next those of the upper extremity ; then those of the lower extremity ; and lastly, the veins of the trunk. VEINS OF THE HEAD AND NECK. The veins of the head and neck may be arranged into three groups, viz. 1. Veins of the exterior of the head. 2. Veins of the diploe and interior of the cranium. 3. Veins of the neck. The veins of the exterior of the head are the — Facial, Internal maxillary, Temporal, Temporo-maxillary, Posterior auricular, Occipital. The Facial vein commences upon the anterior part of the skull in a venous plexus, formed by the communications of the branches of the temporal, and descends along the middle line of the fore- head, under the name oi frontal vein, to the root of the nose, where it is connected with its fellow of the opposite side by a communi- cating trunk which constitutes the nasal arch. There are usually two frontal veins which communicate by a transverse inosculation ; but sometimes the vein is single and bifurcates at the root of the nose, into the two angular veins. From the nasal arch, the frontal is continued downwards by the side of the root of the nose, under the name of the angular vein ; it then passes beneath the zygomatic muscles and becomes the facial vein, and descends along the ante- rior border of the masseter muscle, crossing the body of the lower jaw, by the side of the facial artery, to the submaxillary gland, and from thence to the internal jugular vein in which it ter- minates. The branches which the facial vein receives in its course are, the supra- orbital, which joins the frontal vein ; the dorsal veins of the nose which terminate in the nasal arch ; the ophthalmic, which com- municates with the angular vein ; the palpebral and nasal, which also open into the angular vein ; a considerable trunk, the alveolar, which returns the blood from the spheno-maxillary fossa, from the infra-orbital, palatine, vidian and spheno-palatinc, and joins the facial beneath the zygomatic process of the superior maxillary 42 830 VEINS OF THE DIPLOE. bone, and the veins corresponding with the branches of the facial artery. The Internal maxillary vein receives the branches from the zygomatic and pterygoid fossoe ; these are so numerous and com- municate so freely as to constitute a pterygoid plexus. Passing backwards behind the neck of the lower jaw, the internal maxillary joins with the temporal vein, and the common trunk resulting from this union constitutes the temforo-maxillary vein. The Temporal vein commences on the vertex of the head by a plexiform network which is continuous with the frontal, the tem- poral, auricular, and occipital veins. The ramifications of this plexus form an anterior and a posterior branch which unite imme- diately above the zygoma ; the trunk is here joined by another large vein, the middle temporal, which collects the blood from the temporal muscle, and around the outer segment of the orbit, and pierces the temporal fascia near the root of the zygoma. The temporal vein then descends between the meatus auditorius externus and the con- dyle of the lower jaw, and unites with the internal maxillary vein, to form the temporo-maxillary. The Temporo-maxillary vein formed by the union of the temporal and internal maxillary, passes downwards in the substance of the parotid gland to its lower border, where it becomes the external jugular vein. It receives in its course the anterior auricular, masse- teric, transverse facial, and parotid veins, and near its termination is joined by the posterior auricular vein. The Posterior auricular vein communicates with the plexus upon the vertex of the head, and descends behind the ear to the temporo- maxillary vein, immediately before that vessel merges in the external jugular. It receives in its course the veins from the external ear and the stylo-mastoid vein. The Occipital vein commencing posteriorly in the plexus of the vertex of the head, follows the direction of the occipital artery, and passing deeply beneath the muscles of the back part of the neck, terminates in the external jugular vein. This vein communicates with the lateral sinus by means of a large branch which passes through the mastoid foramen, the mastoid vein. VEINS OF THE DIPLOE. The diploe of the bones of the head is furnished in the adult with irregular sinuses, which are formed by a continuation of the sei'ous membrane of the veins into the osseous canals in which they are lodged. At the middle period of life these sinuses are confined to the particular bones ; but in old age, after the ossification of the sutures, they may be traced from one bone to the next. They receive their blood from the capillaries supplying the cellular structure of the diploe, and terminate externally in the veins of the pericranium, and internally in the veins and sinuses of tlie dura mater. These CEREBRAL AND CEREBELLAR VEINS. 331 veins are separated from the bony walls of the canals by a thin layer of, marrow. CEREBRAL AND CEREBELLAR VEINS. The cerebral veins are remarkable for the absence of valves, and for the extreme tenuity of their coats. They may be divided into the superficial, and deep or ventricular veins. The Superficial cerebral veins are situated upon the surface of the hemispheres, lying in the grooves formed by the convexities of the convolutions. They are named from the position which they may chance to occupy upon the surface of this organ, either superior or inferior, internal or external, anterior or posterior. The Superior cerebral veins, seven or eight in number on each side, pass obliquely forwards, and terminate in the superior longitu- dinal sinus, in the opposite direction to the course of the stream of blood in the sinus. The Deep or Ventricular veins commence within the lateral ven- tricles by two vessels, the vena corporis striati and the veins of the choroid plexus, which unite to form the two vense Galeni. The VencB Galeni pass backwards in the structure of the velum interpositum ; and escaping through the fissure of Bichat, terminate in the straight sinus. The Cerebellar veins are disposed, like those of the cerebrum, on the surface of the lobes of the cerebellum ; they are situated some upon the superior, and some upon the inferior surface, while others occupy the borders of the organ. They terminate in the lateral and petrosal sinuses. SINUSES OF THE DURA MATER. The sinuses of the dura mater are irregular channels, formed by the splitting of the layers of that membrane, and fined upon their inner surface by a continuation of the serous layer of the veins. They may be divided into two groups: — 1. Those situated at the upper and back part of the skull. 2. The sinuses at the base of the skull. The former are, the — Superior longitudinal sinus, Inferior longitudinal sinus, Straight sinus, or sinus quartus, Occipital sinuses. Lateral sinuses. The Superior longitudinal sinus, is situated in the attached margin of the falx cerebri, and extends along the middle line of the arch of the skull, from the foramen ca3cum in the frontal, to the inner tube- rosity of the occipital bone, where it divides into the two lateral sinuses. It is triangular in form, is small in front, and increases gradually in size as it passes backwards ; it receives the superior cerebral veins which open into it obliquely, numerous small veins 332 INFERIOR LONGITUDINAL SINUS, from the diploe, and near the posterior extremity of the sagittal sutm'e the parietal veins, from the pericranium and scalp. Examined upon its interior, it presents numerous transverse fibrous bands, the chordae Willisii, which are stretched across its inferior angle ; and some small white granular masses, the glandular Pacchioni ; the oblique openings of the cerebral veins, with their valve-Uke margin, are also seen upon the walls of the sinus. The termination of the superior longitudinal sinus in the two lateral sinuses forms a considerable dilatation, into which the straight sinus opens from the front, and the occipital sinuses from below. This dilatation is named the torcular He?-ophili,* and is the point of communication of six sinuses — the superior longitudinal, tv/o lateral, two occipital, and the straight. Fig. iiat The Inferior longitudinal sinus is situated in the free margin of the falx cerebri ; it is cylindrical in form, and extends from near the crista galli to the anterior border of the tentorium, where it termi- nates in the straight sinus. It receives in its course several veins from the falx. The Straight or fourth sinus is the sinus of the tentorium ; it is situated at the line of union of the falx with the tentorium ; is prismoid in form, and extends across the tentorium, from the termina- * Torcular (a pi-ess), from a supposition entertained by the older anatomists that the columns of blood, coming in different directions, compressed each other at this point, t Tiie sinuses of the upper and back part of the skull. 1. The superior longitudinal sinus. 2, 2. The cerebral veins opening into tlie sinus from btihind forwards. 3. The falx cerebri. 4. The inferior longitudinal sinus. 5. The straight or fourth sinus. 6. The vcnaj Galeni. 7. The torcular Herophili. 8. The two lateral sinuses, with the occipital sinuses between them. 9. The termination of the inferior petrosal sinus of one side. 10. The dilatations corresponding with the jugular fossae. 11. The internal jugular veins. LATERAL SINUSES. 333 tion of the inferior longitudinal sinus to the torcular Herophili. It receives the venag Galeni, the cerebral veins from the inferior part of the posterior lobes, and the superior cerebellar veins. The Occipital sinuses are two canals of small size, situated in the attached border of the falx cerebelli ; they commence by several small veins around the foramen magnum, and terminate by separate openings in the torcular Herophili. They not unfrequently commu- nicate with the termination of the lateral sinuses. The Lateral sinuses, commencing at the torcular Herophili, pass horizontally outwards, in the attached margin of the tentorium, and curve downwards and inwards along the base of the petrous portion of the temporal bone, at each side, to the foramina lacera posteriora, where they terminate in the internal jugular veins. Each sinus rests successively in its course upon the transverse groove of the occipital bone, posterior inferior angle of the parietal, mastoid portion of the temporal, and again on the occipital bone. They receive the cerebral veins from the inferior surface of the posterior lobes, the inferior cerebellar veins, the superior petrosal sinuses, the mastoid, and pos- terior condyloid veins, and, at their termination, the inferior petrosal sinuses. These sinuses are often unequal in size, the right being much larger than the left. The sinuses of the base of the skull are the — Cavernous, Inferior petrosal, Circular, Superior petrosal, Transverse. The Cavernous sinuses are named from presenting a cellular struc- ture in their interior. They are situated on each side of the sella turcica, receiving, anteriorly, the ophthalmic veins through the sphenoidal fissures, and terminating posteriorly in the inferior petrosal sinuses. In the internal wall of each cavernous sinus is the internal carotid artery, accompanied by several filaments of the carotid plexus, and crossed by the sixth nerve ; and, in its external wall, the third, fourth, and ophthalmic nerves. These structures are separated from the blood flowing through the sinus, by the tubular lining membrane. The cerebral veins from the under surface of the anterior lobes, open into the cavernous sinuses. They communicate by means of the ophthalmic veins with the facial veins, by the circular sinus with each other, and by the superior petrosal with the lateral sinuses. The Inferior petrosal sinuses are the continuations of the cavern- ous sinuses backwards along the lower border of the petrous por- tion of the temporal bone at each side of the base of the skull, to the foramina lacera posteriora, where they terminate with the lateral sinuses in the commencement of the internal jugular veins. The Circular sinus is situated in the sella turcica, surrounding the pituitary gland, and commimicates on each side with the cavernous sinus. 334 VEINS or THE NECK. The Sifperior petrosal sinuses pass obliquely backwards along the attached border of the tentorium, on the upper margin of the petrous portion of the temporal bone, and establish a communication between the cavernous and lateral sinus at each side. They receive one or two cerebral veins from the inferior part of the middle lobes, and a cerebellar vein from tiie anterior border of the cerebellum. Fig-. 119.* The Transverse sinus (basilar, anterior occipital) passes trans- versely across the basilar process of the occipital bone, forming a communication between the two inferior petrosal sinuses. VEINS OF THE NECK. The veins of the neck which return the blood from the head are the— External jugular, Anterior jugular. Internal jugular, Vertebral. The External jugular vein is formed by the union of the pos- terior auricular vein with the temporo-maxillary, and commences * The sinuses of the base of the skull, 1. The ophthalmic veins. 2. The cavernous sinus of one side. 3. The circular sinus; the figure occupies the position of the pitui- tary {fland in the sella turcica. 4. The inferior petrosal sinus. .'>. Tlic transverse or anterior occipital sinus. 6. TIic superior petrosal sinus. 7. Tlic internal jugular vein. 8. The foramen magnum. 9. The occipital sinuses. 10. The torcular Hero- phili. 11,11. The lateral sinuses. VEINS OF THE NECK. 335 at the lower border of the parotid gland, in front of the sterno-mas- toid muscle. It descends the neck in the direction of a line drawn from the angle of the lower jaw to the middle of the clavicle, crosses the sterno-mastoid, and terminates near the posterior and inferior attachment of that muscle in the subclavian vein. In its course downwards it lies upon the anterior lamella of the deep cervical fascia, which separates it from the sterno-mastoid muscle, and is covered in by the platysma myoides and superficial fascia. At the root of the neck it pierces the deep cervical fascia ; it is accompa- nied, for the upper half of its course, by the auricularis magnus nerve. The branches which it receives are the occipital and pos- terior cervical cutaneous, and, near its termination, the supra and posterior scapular. The external jugular vein is very variable in size, and is occa- sionally replaced by two veins. In the parotid gland it receives a large communicating branch from the internal jugular vein. The Anterior jugular vein is a trunk of variable size, which col- lects the blood from the integument and superficial structures on the fore part of the neck. It passes downwards along the anterior bor- der of the sterno-mastoid muscle, and opens into the subclavian vein, near to the termination of the external jugular. The two veins communicate with each other, with the external and with the inter- nal jugular vein. The Internal jugular vein, formed by the convergence of the lateral and inferior petrosal sinus, commences at the foramen lacerum posterius on each side of the base of the skull, and descends the side of the neck, lying, in the first instance, to the outer side of the in- ternal carotid, and then upon the outer side of the common carotid artery to the root of the neck, where it unites with the subclavian, and constitutes the vena innominata. At its commencement, the internal jugular vein is posterior and external to the internal carotid artery, and to the eighth and ninth pairs of nerves ; lower down, the vein and artery are on the same plane, the glosso-pharyngeal and hypoglossal nerves passing forwards between them, the pneumo- gastric being between and behind in the same sheath, and the nervus accessorius crossing obliquely behind the vein. The Branches which the internal jugular receives in its course are, the facial, the lingual, the inferior fharyngeal, the occipital, and the superior and inferior thyroid veins. The Vertebral vein descends by the side of the vertebral artery in the canal formed by the foramina in the transverse processes of the cervical vertebrae, and terminates at the root of the neck in the commencement of the vena innominata. In the lower part of the vertebral canal it frequently divides into two branches, one of which advances forwards, while the other passes through the foramen in the transverse process of the seventh cervical vertebra, before opening into the vena innominata. The Branches which it receives in its course arc the posterior 336 VEINS OF THE UPPER EXTREMITY. condyloid vein, muscular branches, the cervical meningo-rachidian veins, and, near its termination, the superficial and deep cervical veins. The Inferior thyroid veins, two, and frequently more in number, are situated on one side of the trachea, and receive the venous blood from the thyroid gland. They communicate with each other and with the superior thyroid veins, and form a plexus upon the front of the trachea. The risht vein terminates in the right vena innominata, just at its union with the superior cava, and the left in the left vena innominata. VEINS OF THE UPPER EXTREMITY. The veins of the upper extremity are the deep and superficial. The deep veins accompany the branches and trunks of the arteries, and constitute their vence comites. The venae comites of the radial and ulnar arteries are enclosed in the same sheath with those ves- sels, and terminate at the bend of the elbow in the brachial veins. The brachial venae comites are situated one on each side of the artery, and open into the axillary vein ; the axillary becomes the subclavian, and the subclavian unites with the internal jugular to form the vena innominata. The Superficial veins of the fore-arm are the — Anterior ulnar vein, Posterior ulnar vein, Basilic vein, Radial vein, Cephalic vein, Median vein, Median basihc. Median cephalic, The Anterior idnar vein collects the venous blood from the inner border of the hand, and from the vein of the little-finger, vena sal- vatella, and ascends the inner side of the fore-arm to the bend of the elbow, where it becomes the basilic vein. The Posterior ulnar vein, irregular in size and frequently absent, commences also upon the inner border and posterior aspect of the hand, and, ascending the fore-arm, terminates in front of the inner condyle, in the anterior ulnar vein. The Basilic vein (/SatfiXixog, royal, or principal) ascends from the common ulnar vein, formed by the two preceding, along the inner side of the upper arm, and near its middle pierces the fascia ; it then passes upwards to the axilla, and becomes the axillary vein. The Radial vein commences in the large vein of the thumb, on the outer and posterior aspect of the hand, and ascends along the outer border of the fore-arm to the bend of the elbow, where it becomes the cephalic vein. CEPHALIC VEIN AXILLAKY VEIN. 337 Fig. 120.^ The Cephalic vein (xs^akri, the head) ascends along the outer side of the arm to its upper third ; it then enters the groove between the pectorahs major and deltoid muscles, where it is in relation with the descending branch of the thoracico-acromialis artery, and ter- minates beneath the clavicle in the subcla- vian vein. A large communicating branch sometimes crosses the clavicle between the external jugular and this vein, which gives it the appearance of being derived directly from the head — hence its appellation. The Median vein is intermediate between the anterior ulnar and radial vein ; it collects the blood from the anterior aspect of the fore-arm, communicating with the two pre- ceding. At the bend of the elbow it receives a branch from the deep veins, and divides into two branches, the median cephalic and median basilic. The Median cephalic vein, generally the smaller of the two, passes obliquely outwards, in the groove between the biceps and the supinator longus, to join the cephalic vein. The branches of the external cutaneous nerve pass behind it. The Median basilic vein passes obliquely inwards, in the groove between the biceps and pronator radii teres, and terminates in the basilic vein. This vein is crossed by one or two filaments of the internal cutaneous nerve, and is separated from the brachial artery by the aponeurotic slip given off by the tendon of the biceps. AXILLARY VEIN. The axillary vein is formed by the union of the vense comites of the brachial artery with the basilic vein. It lies in front of the artery, and receives numerous branches from the collateral veins of the branches of the axillary artery, and, at the lower border of the first rib, becomes the subclavian vein. * The veins of the fore-arm and bend of the elbow. 1. The radial vein. 2. The cephalic vein. 3. The anterior ulnar vein. 4. The posterior ulnar vein. 5. 'I'he trunk formed by their union. 6. The basilic vein, piercing the deep fascia at 7. 8. Tlic median vein. 9. A communicating branch between the deep veins of the fore-arm and tlie upper part of the median vein. 10. The median cephalic vein. 11. Tiie median basilic. 12. A slight convexity of the deep fascia, formed l)y the brachial artery. 13. The process of fascia, derived trom the tendon of the biceps, and separating the median basilic vein from the brachial artery. 14. The external cutaneous nerve, piercing tlie deep fascia, and dividing into two branches, which pass behind the median cephalic vein. 15. The in- ternal cutaneous nerve, dividing into branches, which pass in front of ihe median basilic vein. 16. The intercosto humeral cutaneous nerve. 17. The spiral cutaneous jiervCj a branch of the musculo-sjiiral. 43 338 SUBCLAVIAN VEIN FEMORAL VEIN. SUBCLAVIAN VEIN. The subclavian vein crosses over the first rib and beneath the clavicle, and unites with the internal jugular vein to form the vena innominata. It lies at first in front of the subclavian artery, and then in front of the scalenus anticus, which separates it from that vessel. The phrenic and pneumogastric nerves pass between the artery and vein. The veins opening into the subclavian are the cephalic below the clavicle, and the external and anterior jugulars above ; occasionally some small veins from the neighbouring parts also terminate in it. VEINS OF THE LOWER EXTREMITY. The veins of the lower extremity are the deep and superficial. The deep veins accompany the branches of the arteries in pairs, and form the venae comites of the anterior and posterior tibial and pero- neal arteries. These veins unite in the popliteal region to form a single vein of large size — the popliteal — which successively becomes in its course the femoral and the external iliac vein. POPLITEAL VEIN. The popliteal vein ascends through the popliteal region, lying, in the first instance, directly upon the artery, and then getting some- what to its outer side. It receives several muscular and articular veins, and the external saphenous vein. The valves in this vein are four or five in number. FEMORAL VEIN. The femoral vein, passing through the opening in the adductor magnus muscle, ascends the thigh in the sheath of the femoral artery, and entering the pelvis beneath Poupart's ligament, becomes the external iliac vein. In the lower part of its course it is situated upon the outer side of the artery; it then becomes placed behind that ves- sel, and, at Poupart's ligament, lies to its inner side. It receives the muscular veins, and the profunda, and, through the saphenous opening, the internal saphenous vein. The valves in this vein are four or five in number. The Profunda vein is formed by the convergence of the numerous small veins which accompany the branches of the artery; it is a vein of large size, lying in front of the profunda artery, and ter- minates in the femoral at about an inch and a half below Poupart's ligament. The Superficial veins are the external or short, and the internal or long saphenous. The External saphenous vein collects the blood from the outer SUPERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. 339 side of the foot and leg. It passes behind the outer ankle, ascends along the posterior aspect of the leg, lying in the groove between the two bellies of the gastrocnemius muscle, and pierces the deep fascia in the pophteal region to join the popliteal vein. It receives several cutaneous branches in the popliteal region before passing through the deep fascia, and is accompanied in its course by the external saphenous nerve. The Internal saphenous vein commences upon the dorsum and inner side of the foot. It ascends in front of the inner ankle, and along the inner side of the leg; it then passes behind the inner con- dyle of the femur, and along the inner side of the thigh to the saphe- nous opening, where it pierces the sheath of the femoral vessels, and terminates in the femoral vein, at about one inch and a half below Poupart's ligament. It receives in its course the cutaneous veins of the leg and thigh, and communicates freely with the deep veins. At the saphenous opening it is joined by the superficial epigastric and circumflexa ilii veins, and by the external pudic. The situation of this vein in the thigh is not unfrequently occupied by two or even three trunks of nearly equal size. VEINS OF THE TRUNK. The veins of the trunk may be divided into 1. The superior vena cava, with its formative branches. 2. The inferior vena cava, with its formative branches. 3. The azygos veins. 4. The vertebral and spinal veins. 5. The cardiac veins. 6. The portal vein. 7. The pulmonary veins. SUPERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. VencB InnominatcB. The VencB innominatcB are two large trunks, formed by the union of the internal jugular and subclavian vein, at each side of the root of the neck. The Right ve7iainjiominata, about Q,ninch and a quarter in length, lies superficially and externally to the arteria innominata, and descends almost vertically, to unite with its fellow of the opposite side in the formation of the superior cava. At the junction of the jugular and subclavian veins it receives from behind the ductus lymphaticus dexter, and lower down it has opening into it the right vertebral, right internal mammary, and right inferior thyroid vein. The Left vena innominata, considerably longer than the right, ex- tends almost horizontally across the roots of the three arteries arising from the arch of the aorta, to the right side of the mediastinum, where it unites with the right vena innominata, to constitute the superior cava. 340 SUPERIOR VENA CAVA. Fig. 121.* It is in relation in front with the left sterno-clavicular articulation and the first piece of the sternum. At its com- mencement it receives the thoracic duct which opens into it from behind, and in its course is joined by the left vertebral, left inferior thyroid, left mam- mary, and by the superior intercostal vein. It also receives some small veins from the mediastinum and thymus gland. There are no valves in the venae innomi- natas. SUPERIOR VENA CAVA. The superior cava is a short trunk about three inches in length, formed by the junction of the two vense innominate. It descends perpendicularly on the right side of the mediastinum, and entering the pericardium terminates in the upper part of the right auricle. It is in relation in front with the tho- racic fascia, which separates it from the thymus gland, and with the pericardium; behind with the right pulmonary artery, and the right superior pulmonary vein ; internally with the ascending aorta ; ex- ternally with the right phrenic nerve, and right lung. Immediately before entering the pericardium it receives the vena azygos major. INFERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. Iliac Veins. The External iliac vein lies to the inner side of the corresponding artery at the os pubis; but gradually gets behind it as it passes * TJie veins of tlir; trunk and neck. 1. The superior vena cava. 2. The left vena innominata. 3. Tlie right vena innominata. 4. Tlie right subclavian vein. 5. The internal jugular vein. 6. Tiic external jugular. 7. The anterior jugular. 8. The inferior vena cava. 9. The external iliac vein. 10. The internal iliac vein. 11. The common iliac veins; the small vein betw^ecn these is the vena sacra media. 12, 12. Lumbar veins. 1.'3. The right spermatic vein. 14. The left spermatic, opening into the left renal vein. l.'j. The right renal vein. 1 (I. The trunk of the hepatic veins. 17. The greater vena azygos, commencing inferiorly in tlie lumbar veins. 18. The lesser vena azygos, also commencing in the lumbar veins. 19. A branch of communi- cation with the left renal vein. 20. The termination of the lesser in the greater vena azygos. 21. The superior intercostal vein; communicating inferiorly with the lesser vena azygos, and terminating superiorly in the loft vena innominata. INFERIOR VENA CAVA. 341 upwards along the brim of the pelvis, and terminates opposite the sacro-iliac symphysis by uniting with the internal iliac, to form the common iliac vein. Immediately above Poupart's ligament it receives the epigastric and the circumflexa ihi veins ; it has no valves. The Internal iliac vein is formed by vessels which correspond with the branches of the internal iliac artery; it receives the return- ing blood from the gluteal, ischiatic, internal pudic, and obturator veins, externally to the pelvis ; and from the vesical and uterine plexuses within the pelvis. The vein lies to the inner side of the internal iliac artery, and terminates by uniting with the external ihac vein, to form the common ihac. The Vesical and -prostatic plexus is an important plexus of veins which surrounds the neck and base of the bladder and prostate gland, and receives its blood from the great dorsal vein of the penis, and from the veins of the external organs of generation. It is retained in connexion with the sides of the bladder by a reflection of the pelvic fascia. The Uterine plexus is situated around the vagina, and upon the sides of the uterus, between the two layers of the broad ligaments. The veins forming the vesical and uterine plexus are very subject to the production of phlebolitis. The Common iliac veins are formed by the union of the external and internal iliac vein on each side of the pelvis. The right conmion iliac, shorter than the left, ascends obliquely behind the correspond- ing artery ; and upon the intervertebral substance between the fourth and fifth lumbar vertebra3, unites with the vein of the opposite side, to form the inferior cava. The left common iliac, longer and more oblique than the right, ascends behind, and a little internally to the corresponding artery, and passes beneath the right common iliac artery, near to its origin, to unite with the right vein in the formation of the inferior vena cava. The right common iliac vein has no branch opening into it; the left receives the vena sacra media. These veins have no valves. INrERIOR VENA CAVA. The inferior vena cava is formed by the union of the two common iliac veins, upon the intervertebral substance between the fourtli and fifth lumbar vertebra. It ascends along the front of the vertebral column, on the right side of the abdominal aorta, and passing through the fissure in the posterior border of the hver and the quadrilateral opening in the tendinous centre of the diaphragm, terminates in the inferior and posterior part of the right auricle. There are no valves in this vein. It is in relation from below upwards, in front with the mesentery, transverse duodenum, portal vein, pancreas, and liver which nearly and sometimes completely surrounds it; behind it rests upon the vertebral column and right crus of the diaphragm, from which it is 342 BRANCHES OF INFERIOR CAVA. separated by the right renal and lumbar arteries ; to the right it has the peritoneum and sympathetic nerve ; and to the left the aorta. The Branches which the inferior cava receives in its course, are the— Lumbar. Right spermatic, Renal, Supra-renal, Phrenic, Hepatic. The Lumhar veins, three or four in number on each side, collect the venous blood from the muscles and integument of the loins, and from the spinal veins ; the left are longer than the right from the position of the vena cava. The Right spermatic vein is formed by the two veins which re- turn the blood from the venous plexus, situated in the spermatic cord. These veins follow the course of the spermatic artery, and unite to form the single trunk which opens into the inferior vena cava. The left s-pei-matic vein terminates in the left renal vein. The Ovarian veins represent the spei'matic veins of the male, and collect the venous blood from the ovaries, round ligaments, and Fallopian tubes, and communicate with the uterine sinuses. They terminate as in the male. The Renal or emulgent veins return the blood from the kidneys ; their branches are situated in front of the divisions of the renal arteries, and the left opens into the vena cava somewhat higher than the right. The left is longer than the right in consequence of the position of the vena cava, and crosses the aorta immediately below the origin of the superior mesenteric artery. It receives the left spermatic vein, which terminates in it at right angles : hence the more frequent occurrence of varicocele on the left than on the right side. The Supra-renal veins terminate partly in the renal veins, and partly in the inferior vena cava. The Phrenic veins return the blood from the ramifications of the phrenic arteries ; they open into the inferior cava. The Hepatic veins form two principal trunks and numerous smaller veins which open into the inferior cava, while that vessel is situated in the posterior border of the liver. The hepatic veins commence in the liver by minute venules, the intralobular veins in the centre of each lobule ; these pour their blood into larger vessels, the sublobular veins ; and the sublobular veins constitute by their convergence and union, the hepatic trunks, which terminate in the inferior vena cava. AZYGOS VEINS. The azygos veins form a system of communication between the superior and inferior vena cava, and serve to return the blood from VERTEBRAL AND SPINAL VEINS. 343 that part of the trunk in which those vessels are deficient, on account of their connexion with the heart. This system consists of three vessels, the — Vena azygos major, Vena azygos minor, Superior intercostal vein. The Vena azygos major commences in the lumbar region by a communication with the lumbar veins ; sometimes it is joined by a branch directly from the inferior vena cava, or by one from the renal vein. It passes through the aortic opening in the diaphragm, and ascends upon the right side of the vertebral column to the third dorsal vertebra, where it arches forwards over the right bronchus, and terminates in the superior cava. It receives all the intercostal veins of the right side, the vena azygos minor, and the bronchial veins. The Vena azygos minor commences in the lumbar region, on the left side, by a communication with the lumbar or renal veins. It passes beneath the border of the diaphragm, and ascending upon the left side of the vertebral column crosses the fifth or sixth dorsal vertebra to open into the vena azygos major. It receives the six or seven lower intercostal veins of the left side. The azygos veins have no valves. The Superior intercostal vein is the trunk formed by the union of the five or six upper intercostal veins of the left side. It communi- cates below with the vena azygos minor, and ascends to terminate in the left vena innominata. VERTEBRAL AND SPINAL VEINS. The numerous venus plexuses of the vertebral column and spinal cord may be arranged into three groups : — Dorsi-spinal, Meningo-rachidian, MeduUi-spinal. The Dorsi-spinal veins form a plexus around the spinous, trans- verse and articular processes and arches of the vertebrag. They receive the returning blood from the dorsal muscles and surrounding structures, and transmit it, in part to the meningo-rachidian, and in part to the vertebral, intercostal, lumbar, and sacral veins. The Meningo-rachidian veins are situated between the theca ver- tebralis and the vertebra. They communicate freely with each other by means of a complicated plexus. In front they form two longitudinal trunks, which extend the whole length of the column on each side of the posterior common ligament, and are joined on the body of each vertebra by transverse trunks, which pass beneath the ligament, and receive the large vertebral veins from the interior of each vertebra. They pour their blood into the vertebral veins in 344 PORTAIi SYSTEM. the neck, into the intercostal veins in the thorax, and into the lumbar and sacral veins in the loins and pelvis, by means of communicating trunks, which escape at the intervertebral foramina. The Medulli-spinul veins are situated between the pia mater and arachnoid ; they communicate freely with each other, and form plexuses, and send branches through the intervertebral foramina with each of the spinal nerves, to join the veins of the trunk. CARDIAC VEINS. The veins returning the blood from the substance of the heart, are the — Great cardiac vein. Posterior cardiac veins. Anterior cardiac veins, Venae Thebesii. The Great cardiac vein (coronary) commences at the apex of the heart, and ascends along the anterior ventricular groove to the base of the ventricles ; it then curves around the left auriculo-ventricular groove to the posterior part of the heart, where it terminates in the right auricle. It receives in its course the left cardiac veins from the left auricle and ventricle, and the posterior cardiac veins from the posterior ventricular groove. The Posterior cardiac vein, frequently two in number, commences also at the apex of the heart, and ascends along the posterior ven- tricular groove, to teminate in the great cardiac vein. It receives the veins from the posterior aspect of the two ventricles. The Anterior cardiac veins collect the blood from the anterior sur- face of the right ventricle ; one larger than the rest runs along the right border of the heart and joins the trunk formed by these veins, which curves around the right auriculo-ventricular groove, to termi- nate in the great cardiac vein near to its entrance into the right auricle. The Fence. Thebesii are numerous minute venules which convey the venous blood directly from the substance of the heart into its four cavities. Their existence is denied by some anatomists. PORTAL SYSTEM. The portal system is composed of four large veins which return the blood from the chylopoietic viscera ; they are the — Inferior mesenteric vein, Superior mesenteric vein, Splenic vein. Gastric veins. The Inferior mesenteric vein receives its blood from the rectum by means of the ha-jmorrhoidal veins, and from the sigmoid flexure and descending colon, and ascends beneath the transverse duodenum and SPLENIC VEIN. 345 pancreas, to terminate in the splenic vein. Its haemorrhoidal branches inosculate with the branches of the internal ihac vein, and thus establish a communication between the portal and general venous system. The Swperior mesenteric vein is formed by branches which col- lect the venous blood from the capillaries of the superior mesenteric artery ; they constitute by their junction a large trunk which ascends by the side of the corresponding artery, crosses the trans- verse duodenum, and unites behind the pancreas with the splenic in the formation of the portal vein. Fig. 122.* The Splenic vein commences in the structure of the spleen, and quits that organ by several lai-ge veins ; it is larger than the splenic artery, and perfectly straight in its course. It passes horizontally inwards behind the pancreas, and terminates near its greater end by uniting with the superior mesenteric and forming the portal vein. It * The portal vein. 1. The inferior mesenteric vein; it is traced by means of dotted lines behind the pancreas (2) to terminate in the splenic vein (3). 4. TJie spleen. 5. Gastric veins, opening into the splenic vein. 6. The superior mesenteric vein. 7. The descending- portion of the duodenum. 8. Its transverse portion, which is crossed by the superior mesenteric vein and by a part of the trunk of the superior mesenteric artery. 9. The portal vein. 10. The hepatic artery. 11. The ductus communis choledochus. 12. The divisions of the duct and vessels at the transverse fissure of the liver. 13. The cystic duct leading to the gall-bladder. 44 346 PULMONARY VEINS. receives in its course the gastric and pancreatic veins, and near its termination the inferior mesenteric vein. The Gastric veins correspond with the gastric, gastro-epiploic, and vasa brevia arteries, and terminate in the splenic vein. The Vexa PoRTiE, formed by the union of the splenic and supe- rior mesenteric vein behind the pancreas, ascends through the right border of the lesser omentum to the transverse fissure of the hver, where it divides into two branches, one for each lateral lobe. In the right border of the lesser omentum it is situated behind and be- tween the hepatic artery and ductus communis choledochus, and is surrounded by the hepatic plexus of nerves and lymphatics. At the transverse fissure each primary branch divides into numerous secondary branches which ramify through the portal canals, and give off vaginal and interlobular veins, which terminate in the lobular venous plexus of the lobules of the liver. The portal vein within the liver receives the venous blood from the capillaries of the hepatic artery. PULMONARY VEINS. The pulmonary veins, four in number, return the arterial blood from the lungs to the left auricle of the heart ; they differ from the veins in general, in the area of their cylinders, being very little larger than the corresponding arteries, and in accompanying singly each branch of the pulmonary artery. They commence in the capilla- ries upon the parietes of the bronchial cells, and unite to form a single trunk for each lobe. The vein of the middle lobe of the right lung unites with the superior vein so as to form the two trunks which open into the left auricle. Sometimes they remain separate, and then there are three pulmonary veins on the right side. The right pulmonary veins pass behind the superior vena cava to the left auricle, and the left behind the pulmonary artery ; they both pierce the pericardium. Within the lung the branches of the pul- monary veins are behind the bronchial tubes, and those of the pul- monary artery in front ; but at the root of the lungs the veins are in front, next the arteries, and then the bronchi. There are no valves in the pulmonary veins. CHAPTER VII ON THE LYMPHATICS. The lymphatic vessels, or absorbents, have received their double appellation from certain phenomena which they present ; the former name is derivable from the peculiar limpid fluid (lympha, water,) which they convey ; and the latter, from their supposed property of absorbing foreign substances into the system. They are minute and delicate vessels, having a knotted appearance, and are distri- buted through every part of the body. Their office is to collect the products of digestion, and the detrita of nutrition, and to convey them into the venous circulation near to the heart. Lymphatic vessels commence in a delicate network which is dis- tributed upon the cutaneous surface of the body, upon the various surfaces of organs and throughout their internal structure ; and from this network the lymphatic vessels proceed, nearly in straight lines, in a direction towards the root of the neck. In their course they are intercepted by numerous small oval or rounded bodies — lymphatic glands — in which the entering or inferent vessels ramify to an extreme minuteness, and from which proceed the escaping or efferent vessels somewhat larger in size and fewer in number, to be again and again subdivided into other glands, and each time to be a little more increased in size. Lymphatic vessels admit of a threefold division into superficial, deep, and lacteals. The superficial lymphatic vessels, upon the sur- face of the body, follow the course of the veins, and pierce the deep fascia in convenient situations, to join the deep lymphatics. Upon the surface of organs they converge to the nearest lymphatic trunks. The Superficial lymphatic glands are placed in the most protected situations of the superficial fascia, as in the hollow of the ham and groin in the lower extremity, and upon the inner side of the arm in the upper extremity. The deep lymphatics accompany the deeper veins ; those from the lower parts of the body converging to the numerous glands seated around the iliac veins and inferior vena cava, and terminating in a large trunk situated upon the vertebral column — the thoracic duct. From the upper part of the trunk on the left side, and from the left side of the head and neck, they also proceed to the thoracic duct. Those on the right side of the head, and neck, right upper extremity, and right side of the thorax, form a distinct duct which terminates at the point of junction of the sub- 348 XYMPHATICS OF THE HEAD AND NECK. clavian with the internal jugular vein on the right side of the root of the neck. The lacteah are the lymphatics of the small intestines ; they have i-eceived their distinctive appellation from conveying the milk- hke product of digestion — the chyle — to the great centre of the lym- phatic system — the thoracic duct. They are situated in the mesen- tery, and pass through the numerous mesenteric glands in their course. The communications between lymphatic vessels are less frequent than those of arteries or veins; their anastomoses take place by means of branches of equal calibre that unite at acute angles, and con- stitute a combined trunk which is scarcely larger than either of the single branches by which it is formed. Lymphatic vessels are composed of two coats ; an external or cellular, and an internal or serous. The External coat resembles the external tunic of veins and arte- ries, bat is extremely thin and dense. The Internal coat is continuous with the internal hning of the veins; and, like that membrane, is most probably provided with an ephhelium. At short intervals this coat forms semilunar folds which are disposed in pairs in the cylinder of the vessel and constitute the valves. It is to these valves, which are extremely numerous in lymphatics, that their peculiar knotted appearance is due, when filled with injection. The lymphatic glands are small oval and somewhat flattened or rounded bodies, composed of a plexus of minute lymphatic vessels, associated with a plexus of blood-vessels, and enclosed in a thin cellular capsule. The larger glands have a lobed or cellular appearance. The lymphatic vessels and glands are supplied with arteries, veins, and nerves, like other structures. I shall describe the lymphatic vessels and glands according to the arrangement adopted for the veins, commencing with those of the head and neck, and proceeding next to those of the upper extremity, lower extremity, and trunk. LYMPHATICS OF THE HEAD AND NECK. The Superficial lymphatic glands of the head and face are small and few in number ; they are the occipital, which are situated near the origin of the occipito-frontalis muscle; posterior auricular, behind the ear; parotid, in the parotid gland; zygomatic, in the zygomatic fossa; buccal, upon the buccinator muscle; and sub- maxillary, beneath the margin of the lower jaw. There are no deep lymphatic glands within the cranium. The Sit-perficial cervical lymphatic glands are few in number ; they are situated in the course of the external jugular vein, between the sterno-mastoid and trapezius muscles, at the root of the neck and about the larynx. The Deep cervical glands are very numerous and of large size ; they are situated around the internal jugular vein and sheath of the LYMPHATICS OF THE UPPER EXTREMITY. 349 arteries, by the side of the pharnyx, oesophagus, and trachea, and extend from the base of the skull to the root of the neck, where they are in communication with the lymphatic vessels and glands of the thorax. The Swperjicial lymphatic vessels of the head and face are disposed in three groups; occipital, which take the course of the occipital vein to the occipital and deep cervical glands; temporal, which fol- low the branches of the temporal vein to the parotid and deep cer- vical glands; and frtc/aZ, which accompany the facial vein to the submaxillary lymphatic glands. The Deep lymphatic vessels of the head are the meningeal and cerebral; the former are situated in connexion with the meningeal veins, and escape through foramina at the base of the skull, to join the deep cervical glands. The cerebral lymphatics, according to Fohmann, are situated upon the surface of the pia mater. They pass most probably through the foramina at the base of the skull, to terminate in the deep cervical glands. The Deep lymphatic vessels of the face proceed from the nasal fossae, mouth, and pharynx, and terminate in the submaxillary and deep cervical glands. The Supeificial and deep cervical lymphatic vessels accompany the jugular veins, passing from gland to gland, and at the root of the neck communicate with the thoracic lymphatic vessels, and termi- nate, on the right side, in the ductus lymphaticus dexter, and, on the left, in the thoracic duct, near to its termination. LYMPHATICS OF THE UPPER EXTREMITY. The Superficial lymphatic glands of the arm are not more than four or five in number, and of very small size. One or two are situated near the median basilic, and cephalic veins, at the bend of the elbow; and one or two near to the basilic vein, on the inner side of the upper arm, immediately above the elbow. The Deep glands in the fore-arm are excessively small and infre- quent; two or three may generally be found in the course of the radial and ulnar vessels. In the upper arm there is a chain of small glands, accompanying the brachial artery. The Jlxillary glands are numerous and of large size. Some are closely adherent to the vessels, others are dispersed in the loose cel- lular tissue of the axilla, and a small chain may be observed extend- ing along the lower border of the pectoralis major to the mammary gland. Two or three subclavian glands are situated beneath the clavicle, and serve as the medium of communication betvv^een the axillary and deep cervical lymphatic glands. The Superficial lymphatic vessels of the upper extremity commence at the extremities of the fingers, and pass along the borders of the fingers to the dorsum of the hand; they next ascend the fore-arm, some on its posterior and some on its anterior aspect, observing par- ticularly the direction of the veins. At the bend of the elbow they 350 LYMPHATICS OF THE LOWER EXTREMITY. converge, to form two groups which accompany the basiUc and cephaUc veins. The lymphatics of the basihc group communicate with the glands situated immediately above the elbow, and ascend to join tlie axillary gland. Those of the cephaUc group for the most part cross the upper part of the biceps muscle, and also enter the axillary glands, while two or three are continued onwards along the cephalic vein, in the interspace between the pectoralis major and deltoid muscle, to communicate with the subclavian glands. The Deep lymphatics accompany the vessels of the upper extre- mity, and communicate occasionally with the superficial lymphatics. They enter the axillary and subclavian glands, and at the root of the neck terminate on the left side in the thoracic duct, and on the right side in the ductus lymphaticus dexter. LYMPHATICS OF THE LOWER EXTREMITY. The Superficial lymphatic glands of the lower extremity are those of the groin, the inguinal, and one or two situated in the superficial fascia of the posterior aspect of the thigh, just above the popliteal region. The Inguinal glands are divisible into two groups, a superior group of small size, situated along the course of Poupart's ligament, and receiving the lymphatic vessels from the parietes of the abdo- men and genital organs ; and an inferior group of larger glands clustered around the internal saphenous vein near to its termination, and receiving the superficial lymphatic vessels from the lower extremity. The Deep lymphatic glands are the anterior tibial, popliteal, deep inguinal, gluteal, and ischiatic. The Anterior tibial is generally a single gland, placed on the inter- osseous membrane, by the side of the anterior tibial artery in the upper part of its course. The Popliteal glands, four or five in number, are embedded in the loose cellular tissue and fat of the popliteal space. The Deep inguinal glands, less numerous and smaller than the superficial, are situated near the femoral vessels in the groin, beneath the fascia lata. The Gluteal and ischiatic glands are placed above and below the pyriformis muscle at the great ischiatic foramen. The Superficial lymphatic vessels are divisible into two groups, internal and external ; the internal and principal group commencing on the dorsum and inner side of the foot, ascend the leg by the side of the internal saphenous vein, and passing behind the inner condyle of the femur, follow the direction of that vein to the groin, where they join the saphenous group of superficial inguinal glands. The greater part of the efferent vessels from these glands pierce the cribriform fascia of the saphenous opening and the sheath of the femoral vessels, to join the lymphatic gland situated in the femoral ring, which serves to establish a communication between the lym- LYMPHATICS OF THE TRUNK. 351 phatics of the lower extremity and those of the trunk. The other efferent vessels pierce the fascia lata to join the deep glands. The vessels which pass upwards from the outer side of the dorsum of the foot, ascend upon the outer side of the leg, and curve inwards just below the knee, to unite with the lymphatics of the inner side of the thigh. The external grouj) consists of a few lymphatic vessels which commence upon the outer side of the foot and posterior part of the ankle, and accompany the external saphenous vein to the popliteal region, where they enter the popliteal glands. The Dee]) lymphatic vessels accompany the deep veins, and com- municate with the various glands in their course. After joining the deep inguinal glands they pass beneath Poupart's ligament, to com- municate with the numerous glands situated around the iliac vessels. The deep lymphatics of the gluteal region follow the course of the branches of the gluteal and ischiatic arteries. The former join the glands situated upon the upper border of the pyriformis muscle, and the latter after communicating with the lymphatics of the thigh, enter the ischiatic glands. LYMPHATICS OF THE TRUNK. The lymphatics of the trunk may be arranged under three heads, superficial, deep, and visceral. The Superficial lymphatic vessels of the upper half of the trunk pass upwards and outwards on each side, and converge, some to the axillary glands, and others to the glands at the root of the neck. The lymphatics from the mammary glands follow the lower border of the pectoralis major, communicating by means of a chain of lymphatic glands, with the axillary glands. The superficial lymph- atic vessels of the lower half of the trunk, of the gluteal region, perineum, and external organs of generation, converge to the supe- rior group of superficial inguinal glands. Some small glands are situated on each side of the dorsal vein of the penis, near to the suspensory ligament ; from these, as from the superficial lymphatics, the efferent vessels pass into the superior group of superficial inguinal glands. The Deep lymphatic glands of the thorax are the intercostal, in- ternal mammary, anterior mediastinal, and posterior mediastinal. The Intercostal glands are of small size, and are situated on each side of the vertebral column, near to the articulations of the heads of the ribs, and in the course of the intercostal arteries. The Internal mammary glands, also very small, are placed in the intercostal spaces, by the side of the internal mammary arteries. The Anterior mediastinal glands occupy the loose cellular tissue of the anterior mediastinum, resting some on the diaphragm, but the greater number upon the large vessels at the root of the heart. The Posterior mediastinal glands are situated along the course of the aorta and oesophagus in the posterior mediastinum, and com- 352 LYMPHATICS OF THE VISCERA. municate above with the deep cervical glands, on each side with the intercostal, and below with the abdominal glands. The Deep lymphatic vessels of the thorax are the intercostal, in- ternal mammary, and diaphragmatic. The Intercostal lymphatic vessels follow the course of the arteries of the same name ; and reaching the vertebral column curve down- wards, to terminate in the thoracic duct. The Internal mammary lymphatics commence in the parietes of the abdomen, communicating with the epigastric lymphatics. They ascend by the side of the internal mammary vessels, being joined in their course by the anterior intercostals, and terminate on the right side in the tributaries of the ductus lymphaticus dexter; and on the left side in the thoracic duct. The diaphragmatic lymphatics pur- sue the direction of their corresponding veins, and terminate, some in front in the internal mammary vessels, and some behind, in the posterior mediastinal lymphatics. The Deep lymphatic glands of the abdomen are the lumbar glands; they are very numerous, and are seated around the common iliac vessels, the aorta and vena cava. The deep lymphatic glands of the pelvis are the external iliac, internal iliac, and sacral. The External iliac are placed around the external iliac vessels, being in continuation by one extremity with the femoral lymphatics, and by the other with the lumbar glands. The Internal iliac glands are situated in the course of the internal iliac vessels, and the sacral glands are supported by the concave surface of the sacrum. The Deep lymphatic vessels are continued upwards from the thigh, beneath Poupart's ligament, and along the external iliac vessels to the lumbar glands, receiving in their course the epigastric, circum- flex ilii, and ilio-lumbar lymphatic vessels. Those from the parietes of the pelvis, and from the gluteal, ischiatic, and obturator vessels, follow the course of the internal iliac arteries, and unite with the lumbar lymphatics. And the lumbar lymphatic vessels, after re- ceiving all the lymphatics from the lower extremities, pelvis, and loins, terminate by several large trunks in the receptaculum chyli. LYMPHATICS OF THE VISCERA. The Lymphatic vessels of the lungs are distributed over every part of the surface, and through the texture of these organs ; they converge to the numerous glands situated around the bifurcation of the trachea and roots of the lungs — the bronchial glands. Some of these glands of small size, may be traced in connexion with the bronchial tubes for some distance into the lungs. The efferent vessels from the bronchial glands unite with the tracheal and oeso- phageal glands, and terminate principally in the thoracic duct at the root of the neck, and partly in the ductus lymphaticus dexter. The bronchial glands, in the adult, present a variable tint of brown. , LYMPHATICS OF THE LIVER. 353 and in old age a deep black colour. In infancy they have none of this pigment, and are not to be distinguished from lymphatic glands in other situations. The Lymphatic vessels of the heart originate in the subserous cel- lular tissue of the surface, and in the deeper tissues of the organ, and follow the course of the vessels, principally, along the right border of the heart to the glands situated around the arch of the aorta and bronchial glands, whence they proceed to the thoracic duct. The Pericardiac and thymic lymphatic vessels proceed to join the anterior mediastinal and bronchial glands. The Lymphatic vessels of the liver are divisible into the deep and superficial. The former take their course through the portal canals, and through the right border of the lesser omentum, to the lymphatic glands, situated in the course of the hepatic artery and along the lesser curve of the stomach. The superficial lymphatics are situated in the cellular structure of the proper capsule, over the whole sur- face of the liver. Those of the convex surface are divided into two sets; — 1. Those which pass from before backwards; 2. Those which advance from behind forwards. The former unite to form trunks, which enter between the folds of the lateral ligaments at the right and left extremities of the organ, and of the coronary ligament in the middle. Some of these pierce the diaphragm and join the posterior mediastinal glands ; others converge to the lymphatic glands situated around the inferior cava. Those which pass from behind forwards consist of two groups : one ascends between the folds of the broad ligament, and perforates the diaphragm, to terminate in the anterior mediastinal glands ; the other curves around the anterior margin of the liver to its concave surface, and from thence to the glands in the right border of the lesser omentum. The lymphatic vessels of the concave surface are variously distributed, according to their position ; those from the right lobe terminate in the lumbar glands ; those from the gall-bladder which are large and form a remarkable plexus, enter the glands in the right border of the lesser omentum ; and those from the left lobe converge to the lymphatic glands, situated along the lesser curve of the stomach. The Lymphatic glands of the spleen are situated around its hilus, and those of the pancreas in the course of the splenic vein. The lymphatic vessels of these organs pass through their respective glands, and join the aortic glands, previously to terminating in the thoracic duct. The Lymphatic glands of the stomach are of small size, and are situated along the lesser and greater curves of that organ. The lymphatic vessels, as in other viscera, are superficial and deep, the former originating in the subserous and the latter in the submucous tissue ; they pass from the stomach in four different directions : some ascend to the glands situated along the lesser curve, — others descend to those occupying the greater curve, — a third set passes outwards 45 354 THORACIC DUCT. to the splenic glands, and a fourth to the glands situated near the pylorus and to the aortic glands. The Lympliatic glands of the small intestine are situated between the layei-s of the mesentery, in the meshes formed by the superior mesenteric artery, and thence named mesenteric glaiids. These glands are most numerous and largest, superiorly, near to the duodenum ; and, inferiorly, near to the termination of the ileum. The Lymphatic vessels of the small intestines are of two kinds : those of the structure of the intestines, which ramify upon its sur- face previously to entering the mesenteric glands ; and those which commence in the villi, upon the surface of the mucous membrane, and are named lacteals. The Lacteals according to the most recent and best researches — those of Dr. Henle of Berlin — commence in the centre of each villus as a ccecal tubulus, which opens into a fine network, situated in the submucous tissue. From this areolar network the lacteal vessels proceed to the mesenteric glands, and from thence to the thoracic duct, in which they terminate. The Lymphatic glands of the large intestines are situated along the attached margin of the intestine, in the meshes formed by the arteries previously to their distribution. The lymphatic vessels take their course in two different directions ; those of the coecum, ascend- ing and transverse colon, after traversing their proper glands, pro- ceed to the mesenteric, and those of the descending colon and rectum to the lumbar glands. The Lymphatic vessels of the hidney follow the direction of the blood-vessels to the lumbar ganglia situated around the aorta and inferior vena cava ; those of the supra-renal capsules, which are very large and numerous, terminate in the renal lymphatics. The Lymphatic vessels of the viscera of the pelvis terminate in the sacral and lumbar ganglia. The Lymphatic vessels of the testicle take the course of the sper- matic cord where they are of large size, as is shown in the beautiful injections made by Sir Astley Cooper ; they terminate in the lumbar ganglia. THORACIC DUCT. The thoracic duct commences in the abdomen, by a considerable and somewhat triangular dilatation, the receptaculum chyli, which is situated upon the front of the body of the second lumbar vertebra, behind and between the aorta and inferior vena cava, and close to the tendon of the right crus of the diaphragm. From the upper part of the receptaculum chyli, the thoracic duct ascends through the aortic opening in the diaphragm, and along the front of the ver- tebral column, lying between the thoracic aorta and vena azygos, to the fourth, dorsal vertebra. It then inclines to the left side, passes behind the arch of the aorta, and ascends by the side of the op.so- THORACIC DUCT. 355 Fig. 123* phagus and behind the perpendicular portion of the left subclavian artery to the root of the neck opposite the seventh cervical vertebra, where it makes a sudden curve forwards and downwards, and ter- minates at the point of junction of the left subclavian with the left internal jugular vein. The thoracic duct is equal in size to the diameter of a goose- quill at its commencement from the receptaculum chyh, diminishes consi- derably in diameter towards the middle of the posterior mediastinum, and again becomes dilated near its termination. At about the middle of its course it fre- quently divides into two branches of equal size, which reunite after a short course ; and sometimes it gives off se- veral branches, which assume a plexi- form arrangement in this situation. Oc- casionally the thoracic duct bifurcates at the upper part of the thorax into two branches, one of which opens into the point of junction between the right sub- clavian and jugular veins, while the other proceeds to the normal termina- tion of the duct on the left side. In rare instances the duct has been found to terminate in the vena azygos which is its normal destination in some Mam- malia. The thoracic duct presents fewer valves in its course than lymphatic vessels generally ; at its termination it is provided with a pair of semilunar valves which prevent the admission of venous blood into its cylinder. Branches. — The thoracic duct re- ceives at its commencement four or five large lymphatic trunks which unite to form the receptaculum chyli ; it next receives the trunks of the * The course and termination of the thoracic duct. 1. The arch of llic aorta. 2. The thoracic aorta. 3. The abdomhial aorta ; showing- its principal branches divided near their origin. 4. The arteria innominata, dividing into the right carotid and right subclavian arteries. 5. The left carotid. 6. The left subclavian. 7. The superior cava, formed by the union of 8, tlie two venEB innominataj ; and these by the junction 9, of the internal jugular and subclavian vein at each side. 1 0. The greater vena azygos. 11. The termination of the lesser in the greater vena azygos. 12. The re- ceptaculum chyli; several lymphatic trunks are seen opening into it. 13. The tho- racic duct, dividing opposite the middle of the dorsal vertebrtE into two branches which soon reunite ; the course of the duct behind the arch of the aorta and left sub- clavian artery is shown by a dotted line. 14. The duct making its turn at the root of the neck and receiving several lymphatic trunks previously to terminating in the pos- terior aspect of the junction of the internal jugular and subclavian vein. 15. Tiie termination of the trunk of the ductus lymphaticus de.xter. 356 RIGHT THORACIC DUCT. lacteal vessels. Within the thorax it is joined by a large lymphatic trunk from the Uver, and in its course through the posterior medias- tinum, receives the lymphatic vessels both from the viscera and from the parietes of the thorax. At its curve forwards in the neck it is joined by the lymphatic trunks from the left side of the head and neck, left upper extremity, and from the upper part of the thorax, and thoracic viscera. The Ductus lymp/iaticus dexter is a short trunk which receives the lymphatic vessels from the right side of the head and neck, right upper extremity and right side of the thorax, and terminates at the junction of the right subclavian with the right internal jugular vein, at the point where these veins unite to form the right vena innominata. It is provided at its termination with a pair of semi- lunar valves, which prevent the entrance of blood from the veins. CHAPTER VIII. ON THE NERVOUS SYSTEM. The nervous system consists of a central organ, the cerebro- spinal centre of axis, and of numerous rounded and flattened white cords, — the nerves, which are connected by one extremity with the cerebro-spinal centre, and by the other are distributed to all the textures of the body. The sympathetic system is an exception to this description ; for in place of one it has many small centres which are called ganglia, and which communicate very freely with the cerebro-spinal axis and with its nerves. The cerebro-spinal axis consists of two portions, the brain, an organ of large size, situated within the skull, and the spinal cord, a lengthened portion of the nervous centre continuous with the brain, and occupying the canal of the vertebral column. The most superficial examination of the brain and spinal cord shows them to be composed of fibres, which in some situations are ranged side by side or collected into bundles or fasciculi, and in other situations are intei'laced at various angles by cross fibres. The fibres are connected and held together by a delicate cellular web, which forms the bond of support to the entire organ. It is also observed that the cerebro-spinal axis presents two substances differing from each other in density and colour ; a gray or cineri- tious or cortical substance, and a white or medullary substance. The gray substance forms a thin lamella over the entire surface of the convolutions of the cerebrum, and the laminas of the cerebellum : hence it has been named cortical ; but the gray substance is not confined to the surface of the brain, as this term would imply, it is likewise situated in the centre of the spinal cord its entire length, and may be thence traced through the medulla oblongata, crura cerebri, thalami optici, and corpora striata ; it enters also into the composition of the lobus perforatus,- tuber cinereum, commissura mollis, pineal gland, and corpus rhomboideum. The fibres of the cerebro-spinal axis are arranged into two classes, diverging and converging. The diverging fibres proceed from the medulla oblongata, and diverge to every part of the surface of the brain ; while the converging commence upon the surface, and pro- ceed inwards towards the centre so as to connect the diverging fibres of opposite sides. In certain parts of their course the diverging fibres are separated by the gray substance, and increase 358 ?;ERvors system — developement. in number so as to form a body of considerable size, which is called a o-ancrlion. The position and mutual relations of these fibres and ganglia may be best explained by reference to the mode of developement of the cerebro-spinal axis in animals and in man. The centre of the nervous system in the lowest animals possessed of a lengthened axis, presents itself in the form of a double cord. A step higher in the animal scale, and knots or ganglia are developed upon one extremity of this cord ; such is the most rudi- mentary condition of the brain in the lowest forms of vertebrata. In the lowest fishes the anterior extremity of the double cord dis- plays a succession of five pairs of ganglia. The higher fishes and amphibia appear to have a different disposition of these primitive ganglia. The first two have become fused into a single ganglion, and then follow only three pairs of symmetrical ganglia. But if the lai'ger pair be unfolded after being hardened in alcohol, it will then be seen that the whole number of ganglia exists, but that four have become concealed by a thin covering that has spread across them. This condition of the brain carries us upwards in the animal scale even to Mammalia ; e. g., in the dog or cat we find, first a single ganglion, the cerebellum, then three pairs following each other in succession ; and if we unfold the middle pair, we shall be at once convinced that it is indeed composed of two pairs of pri- mitive ganglia concealed by an additional developement. Again it will be observed, that the primitive ganglia of opposite sides, at first separate and disjoined, become connected by means of trans- verse fibres of communication {commissures, commissura, a joining). The office of these commissures is the association in function of the two symmetrical portions. Hence we arrive at the general and important conclusion, that the brain among the lower animals con- sists of pnmiiive cords, primitive ganglia upon those cords, and commissures which connect the substances of the adjoining ganglia, and associate their functions. In the developement of the cerebro-spinal axis in man, the earliest indication of the spinal cord is presented under the form of a pair of minute longitudinal filaments placed side by side. Upon these, towards the anterior extremity, five pairs of minute swellings are observed, not disposed in a straight line as in fishes, but curved upon each other so as to correspond with the direction of the future cranium. The posterior pair soon becomes cemented upon the middle line; forming a single ganglion ; the second pair also unite with each other ; the third and fourth pairs, at first distinct, are speedily veiled by a lateral developement, which arches backwards and conceals them ; the anterior pairs, at first very small, decrease in size and become almost lost in the increased developement of the preceding pairs. We sec here a chain of resemblances corresponding with the pro- gressive developement observed in the lower animals; the human brain is passing through the ])hasos of improving developement, which distinguish the higher from the lower creatures : and we are NERVOUS SYSTEM STRUCTURE, 359 naturally led to the same conclusion with regard to the architecture of the human brain, that we were led to estabUsh as the principle of developement in the inferior creatures— that it is composed of primitive cords, 'primitive ganglia upon those cords, commissures to connect those ganglia, and developements from those ganglia. In the adult, the primitive longitudinal cords have become cement- ed together, to form the spinal cord. But, at the upper extremity, they separate from each other under the name of crura cerebri. The first pair of ganglia developed from the primitive cords, have grown into the cerebellum; the second pair (the optic lobes of animals) have become the corpora guadrigemina of man. The third pair, the optic thalami, and the fourth, the cmyora striata, are the basis of the hemispheres, which, the merest lamina in the fish, has become the largest portion of the brain in man. And the fifth pair (olfactory lobes), so large in the lowest forms, have dwindled into the olfactorij bulbs of man. The white substance of the brain and spinal cord when examined with the microscope, is found to consist of fibres varying in diameter, according to Krause, from the ■^\-^ to the y|-j of a line. These fibres are composed of a thin and transparent neurilemma, en- closing a soft homogeneous nervous substance, and they possess a remarkable tendency, when compressed, to assume a varicose ap- pearance. The nervous fibres of the olfactory, optic, and auditory nerves have the same disposition to become varicose on pressure. The neurilemma of the primitive fibre, according to Fontana, con- sists of two layers, of which the internal is thin and transparent, and the external cellular and less transparent. The gray substance of the brain, according to Valentin, is com- posed of spherical globules of considerable size, having a central nucleus, and near the margin of the latter another smaller nucleus, and frequently upon the surface of the globule, patches of pigment. Numerous minute fibres have been observed by Remak to proceed from the surface of these globules, and are supposed to maintain a communication with surrounding globules. The various shades of gray observed in different parts of the brain, depend upon the greater or smaller number of globules existing in those parts. Two kinds of gray substance are described by Rolando as existing in the spinal cord ; the one {substantia cinerea spongiosa vasculosa) is the ordinary gray matter of the cord, and the other {substantia cinerea gelatinosa) forms part of the posterior cornua. The former resembles the gray matter of the brain, consisting of globules, while the latter is composed of small bodies resembling the blood corpus- cules of the frog. The nerves are divisible into two great classes, — those which proceed directly from the cerebro-spinal axis, the cranial and spinal nerves, and constitute the system of animal life ; and those which originate from a system of nervous centres, independent oi the cerebro-spinal axis, but closely associated with that centre by 360 CLASSIFICATION OF NERVES. numerous communications, the sympathetic system, or system of organic hfe. The division of nerves into cranial and spinal is purely arbitrary, and depends upon the circumstance of the former passing through the foramina of the cranium, and the latter through those of the vertebral column. With respect to origin, — all the cranial nerves, with the exception of the, first, — olfactory, proceed from the spinal cord, or from its immediate continuation into the brain. The spinal nerves arise by two roots ; anterior, which proceeds from the anterior segment of the spinal cord, and possess a motor function ; and posterior, which is connected with the posterior segment, and bestows the faculty of sensation. The motor nerves of the cranium are shown by dissection to be continuous with the motor portion of the cord, and form one system with the motor roots of the spinal cord ; while the nerves of sensation, always excepting the olfactory, are in like manner traced to the posterior segment of the cord, and form part of the system of sensation. To these two systems a third has been added by Sir Charles Bell, — the respiratory system, — ■ which consists of nerves associated in the function of respiration, and arising from the side of the upper part of the spinal cord in one continuous line, which was thence named, by that distinguished physiologist, the respiratory tract. The microscope has succeeded in making no structural distinction between the anterior and pos- terior roots of the spinal nerves ; but the latter are remarkable from possessing a ganglion near to their attachment with the cord. This ganglion is observed upon the posterior roots of all the spinal nerves, and also upon the corresponding root of the fifth cranial nerve, which is thence considered a spinal cranial nerve. Upon others of the cranial nerves a ganglion is found, which associates them in their function with the nerves of sensation, and establishes an analogy with the spinal nerves. The recent researches of Mr. Grainger have made an important addition to our knowledge of the mode of connexion of the nerves with the spinal cord ; he has shown that both roots of the spinal nerves, as well as most of the cerebral, divide into two sets of fila- ments upon entering the cord, one set being connected to the gray substance, while the other is continuous with the white or fibrous part of the cord. The former he considers to be the agents of the excito-motory system of Dr. Marshall Hall ; and the latter, the communication with the brain and the medium for the transmission of sensation and volition. He has not been able to trace the fibres which enter the gray substance to their termination ; but he thinks it probable that the ultimate filaments of the posterior root join those of the anterior root ; or in the words of Dr. Marshall Hall's system, that the incident fibres (sensitive) are continuous with the reflex (motor). The connexion of a nerve with the cerebro-spinal axis is called, for convenience of description, its origin : this term must not, how- NERVES — STRUCTURE COMMUNICATIONS. 361 ever, be received literally ; for each nerve is developed in the pre- cise situation which it occupies in the body, and with the same rela- tions that it possesses in after life. Indeed, ,we not unfrequently meet with instances in anencephalous foetuses where the nerves are beautifully and completely formed, while the brain and spinal cord are wholly wanting. The word origin must, therefore, be consi- dered as a relic of the darkness of preceding ages, when the cerebro-spinal axis was looked upon as the tree from which the nerves pushed forth as branches. In their distribution the spinal nerves for the most part follow the course of the arteries, particu- larly in the limbs, where they lie almost constantly to the outer side and superficially to the vessels, as if for the purpose of receiving the first intimation of danger and of communicating it to the mus- cles, that they may instantly remove the arteries from impending injury. The microscopic examination of a cerebro-spinal nerve shows it to be composed of minute fibres, resembling those of the brain, and consisting of a neurilemma enclosing a soft, homogeneous nervous substance. The chief difference betvt^een the fibres of the nerves and the cerebral fibres is a somewhat greater opacity and more granular appearance of the contents of the minute cylinders of the former; a greater thickness of their neurilemma, and an indisposition to the formation of varicose enlargements upon compression. The neurilemma presents the same two layers whicPi exist in the cere- bral fibres. The primitive fibres, or filaments, are assembled into small bundles and enclosed in a distinct sheath, constituting ^. funi- culus; the funiculi are collected into larger bundles or fasciculi, and a single fasciculus or a number of fasciculi connected by cellular tissue, and invested by a membranous sheath, constitute a nerve. The funiculi, when freshly exposed, present a peculiar zigzag line across their cylinder, which is most probably produced by the arrangement of the primitive fibres, or possibly by some condition of th^ neurilemma. This appearance is destroyed by making exten- sion upon the nerve. Communications between nerves take place either by means of the funiculi composing a single nerve, or of the fasciculi in a nervous plexus. In these communications there is no fusion of nervous sub- stance, the cord formed by any two funiculi is constantly enlarged, and corresponds accurately with their combined bulk. Microscopic examination substantiates this observation, and shows that the pri- ■ mitive fibre passes unchanged from one funiculus to the other, so that the primitive fibre is single and uninterrupted from its connec- tion with the cerebro-spinal axis to its terminal distribution. A nervous plexus consists in a communication between the fascicuH and funiculi composing the nerves, which are associated in their supply of a limb or of a certain region of the body. During this communication there is an interchange of funiculi, and with the funiculi an interchange of fibres. The Sympathetic system consists of numerous ganglia, of commu- 46 362 BRAIN SIE3IBRANES. nicating branches passing between the ganglia, of others passing between the gangUa and the cerebro-spinal axis, and of branches of distribution which are remarkable for their frequent and plexiform communications. The sympathetic nerves also differ from other nerves in their colour, which is of a grayish pearly tint. Examined with the microscope the sympathetic nerves are seen to be composed of an admixture of gray and white fibres ; the white fibres belong to the cerebro-spinal system: the gray are much smaller than the white, less transparent, and the neurilemma is less easily distinguish- able from its contents: some of the nerves are composed of gray fibres only, without any admixture of white. The sympathetic gan- glia contain the globules observed in the gray substance of the brain; they are firmer in structure and enclosed in a strong invest- ing capsule. The fasciculi of fibres entering the ganglion become divided and form a plexus around the globules; they then con- verge to constitute another fasciculus, by which they quit the ganglion. The nervous system may be divided for convenience of descrip- tion into 1. The brain. 2. The spinal cord. 3. The cranial nerves. 4. The spinal nerves. 5. The sympathetic system. THE BRAIiV. The brain is a collective term which signifies those parts of the nervous system, exclusive of the nerves themselves, whi'ch are con- tained within the cranium ; they are the cerebrum, cerebellum, and medulla oblongata. These are invested and protected by the mem- branes of the brain, and the whole together constitute the encephalon (ev, xs^akrj, within the head). MEMBRANES OF THE ENCEPHALON. Dissection. — To examine the encephalon with its membranep, the upper part of the skull must be removed by sawing througn the external table, and breaking the internal table with the chisel and hammer. After the calvarium has been loosened all round, it will require a considerable degree of force to tear the bone away from the dura mater. This adhesion is particularly firm at the sutures, where the dura mater is continuous with a membranous layer inter- posed between the edges of the bones ; in other situations, the con- nexion results from numerous vessels which permeate the inner table of the skull. The adhesion subsisting between the dura mater and bone is greater in the young subject than in the adult. Upon being torn away, the internal table will present the deeply grooved and ramified channels, corresponding with the branches of the arteria mcningea magna. Along the middle line will be seen a groove corresponding with the superior longitudinal sinus, and on either side may be frequently observed some depressed fossae, cor- responding with the Pacchionian bodies. DURA MATER. 363 The membranes of the encephalon are the dura mater, arachnoid membrane, and fia mater. The Dura mater* is the firm, bluish, fibrous membrane, which is exposed on the removal of the calvarium. It fines the anterior of the skufi and spinal column, and sends processes inwards for the support and protection of the difterent parts of the brain. It also sends processes externally, which form sheaths for the nerves as they quit the skull and spinal column. Its external surface is rough and fibrous, and corresponds with the internal table of the skull. The internal surface is smooth, and lined by the thin varnish-like lamella of the arachnoid membrane. The latter is a serous membrane. Hence the dura mater becomes a fibro-serous membrane, being composed of its own proper fibrous structure, and the serous layer derived from the arachnoid. There are two other instances of fibro-serous membrane in the body, formed in the same way — the pericardium and tunica albuginea of the testicle. On either side of the dura mater the branches of the middle me- ningeal artery may be seen ramifying ; and in the middle line is a depressed groove, formed by the subsidence of the upper wall of the superior longitudinal sinus. If the sinus be opened along its course, it will be found to be a triangular channel, crossed at its lower angle by numerous white bands, called chordee Willisii ;f granular bodies are also occasionally seen in its interior ; these are glandulce Pacchioni. The GlanduIcB Pacchioni'^ are small, round, whitish granulations, collected into clusters of variable size. They are found in three situations. 1. On the inner surface of the dura mater near to the superior longitudinal sinus ; when of large size they produce absorp- tion of the dura mater, and considerable indentations on the inner wall of the skull. 2. In the superior longitudinal sinus. 3. On the arachnoid membrane investing the pia mater near to the margin of the hemispheres. If the student cut through one side of the dura mater, along the line of his incision through the skull, and turn it upwards towards the middle line, he will observe the smooth internal surface of the dura mater. He will perceive also the large cerebral veins filled with dark blood, passing from behind forwards to open into the superior longitudinal sinus, and the firm connexions, by means of these veins and the Pacchionian bodies, between the opposed sur- faces of the arachnoid membrane. If he separate these with his scalpel, he will see a vertical layer * So named from a supposition that it was the source of all the fibrous membranes of the body. t Willis lived in the seventeenth century ; he was a great defender of the opinions of Harvey. t These bodies have no analogy whatsoever with glands. Their nature and use are but imperfectly known. They are not found in infancy. Tliey arc described as con- globate glands by Pacchioni, in an epistolary dissertation. "De Glandulis conglobatis DuriE Meningis indeque ortis Lymphaticis ad Piam Matrem productis," published in Rome, in 1705. 364 DURA JMATER PROCESSES. of dura mater descending between the hemispheres, and if he draw one side of the brain a httle outwards, he will distinctly perceive its extent; this is the falx cerebri. The processes of dura mater which are sent inwards towards the interior of the skull, are the falx cerebri, tentorium cerebelli, and falx cerebelli. The Falx cerebri (falx, a sickle), so named from its sickle-like appearance, narrow in front, broad behind, and forming a sharp curved edge below, is attached in front to the crista galli process of the ethmoid bone, and behind to the tentorium cerebelli. The Tentorium cerebelli (tentorium, a tent) is a roof of "dura mater, thrown across the cerebellum and attached at each side to the margin of the petrous portion of the temporal bone, behind to the transverse ridge of the occipital bone, which lodges the lateral sinuses, and to the clinoid processes in front. It supports the poste- rior lobes of the cerebrum and prevents their pressure* on the cerebellum, leaving only a small opening anteriorly, for the trans- mission of the crura cerebri. The Falx cerebelli is a small process, generally double, attached to the vertical ridge of the occipital bone beneath the lateral sinus, and to the tentorium. It is received into the indentation between the two lateral lobes of the cerebellum. The layers of the dura mater separate in several situations, so as to form irregular channels which receive the venous blood. These are the sinuses of the dura mater; they are described at page 331, in the Chapter on the Veins. The student cannot see the tentorium and falx cerebelli until the brain is removed ; but he should consider the attachments of the tentorium upon the dried skull, for he will have to divide it in the removal of the brain. He should now proceed to that operation, for which purpose the dura mater is to be incised all round, on a level with the section through the skull, and the scissors are to be cai'ried deeply between the hemispheres of the brain in front, to cut through the anterior part of the falx ; then draw the dura mater backwards, and leave it hanging by its attachment to the tentorium, liaise the anterior lobes of the brain carefully with the hand, and lift the olfactory bulbs from the cribriform fossas with the handle of the scalpel. Then cut across the two optic nerves and internal carotid arteries. Next divide the infundibulum and third nerve, and carry the knife along the margin of the petrous bone at each side, so as to divide the tentorium near its attachment. Cut across the fourth, fifth, sixth, seventh, and eighth nerves in succession with a sharp knife, and pass the scalpel as far down as possible into the vertebral canal, to sever the spinal cord, cutting first to one side and then to the other, in order to divide the vertebral arteries and first cervical nerves. Then let him press the cerebellum gently for- * In le;tpin^ animalH, as tlic feline and canine gomwa., the tentorium forms a bony tent. ARACHNOID MEMBRANE. 365 wards with the fingers of the right hand, the hemispheres being supported with the left, and the brain will roll into his hand. The Arteries of the dura mater are the anterior meningeal from the internal carotid. The middle meningeal and meningea varva from the internal maxillary. The inferior meningeal from the as- cending pharyngeal and occipital arteries ; and the posterior menin- geal from the vertebral. The Nerves are derived from the nervi molles and vertebral plexus of the sympathetic, from the Casserian gangUon, the ophthalmic nerve, and sometimes from the fourth. The branches from the two last are given off while the nerves are situated by the side of the sella turcica ; they are recurrent and pass backwards between the layers of the tentorium, to the lining membrane of the lateral sinus. Arachnoid Membrane. The Arachnoid (d^a-xyn, sTSos, like a spider's web), so named from its extreme tenuity, is the serous membrane of the cerebro-spinal centre, and, like other serous membranes, a shut sac. It envelopes the brain and spinal cord, and is reflected upon the inner surface of the dura mater, giving to that membrane its serous investment. The arachnoid is thin and transparent on the upper surface of the brain, and may be demonstrated by inserting a blowpipe, and inject- ing beneath it a stream of air. In other situations, as at the base of the brain and between the cerebellum and medulla oblongata, it is semi-transparent and dense in structure, and is rendered very evi- dent by passing across from one convexity to another, and leaving a considerable space between it and the brain.. The space which is thus formed between the arachnoid membrane and the interval of the base of the brain between the two middle lobes of the hemi- spheres, has been called by Cruveilhier the anterior suh-araclinoidean space ; and that intervening between the posterior and under part of the cerebellum and the medulla oblongata, the posterior sub-aracb- noidean space. Both these spaces communicate with each other across the crura cerebelli. In inflammation of the meninges, this membrane is often thickened and opaque. The arachnoid is attached to the pia mater of the brain by a loose cellular tissue, the sub-arachnoidean. This tissue is filamentous at the base of the brain, and between the hemispheres. Around the spinal cord the arachnoid is disposed very loosely so as to leave a considerable space between it and the spinal cord. The spinal sub- arachnoidean space is divided by a partial longitudinal septum which serves to connect the arachnoid with the posterior surface of the spinal cord. The Sub-arachnoidean cellular tissue and the sub-arachnoidean spaces are the seat of an abundant serous secretion, the sub-arach- %oidean Jiuid, which fills all the vacuities existing between the arachnoid and pia mater, and distends the arachnoid of the spinal cord so completely, as to enable it to occupy the whole of the space included in the sheath of dura mater. 366 PIA jVIATER CEREBRUM. The arachnoid also secretes a serous fluid from its inner surface, which is small in quantity compared with the sub-arachnoidean liquid. "The arachnoid does not enter into the ventricles of the brain, as imagined by Bichat, but is reflected inwards upon the vense Galeni for a short distance only, and returns upon those vessels to the dura mater of the tentorium. It surrounds the nerves as they originate from the brain, and forms a sheath around them to their point of exit from the skull. It is then reflected back upon the inner surface of the dura mater. There are no vessels in the arachnoid, and no nerves have been traced into it. Pia Mater. The Pia mater is a vascular membrane composed of innumerable vessels held together by a thin cellular layer. It invests the whole surface of the brain, dipping into its convolutions, and forming a fold in its interior called velum inter positum. It also forms folds in other situations, as in the fourth ventricle, and in the longitudinal grooves of the spinal cord. This membrane differs very strikingly in its structure in different parts of the cerebro-spinal axis. Thus, on the surface of the cere- brum, in contact with the soft gray matter of the brain, it is exces- sively vascular, forming remarkable loops of anastomoses between the convolutions, and distributing multitudes of minute straight ves- sels to the gray substance. In the substantia perforata, again, and locus perforatus, it gives off" tufts of small arteries, which pierce the white matter to reach the gray substance in the interior. But, upon the crura cerebri, pons Varolii, and spinal cord, its vascular cha- racter seems almost lost. It has become a dense fibrous membrane, difficult to tear off, and forming the proper sheath of the spinal cord. The pia mater is the nutrient membrane of the brain, and derives its blood from the internal carotid and vertebral arteries. Its JVerves are the minute filaments of the sympathetic, which accompany the branches of the arteries. CEREBRUM. The Cerebrum is divided into two hemispheres by the great longi- tudinal fissure, which lodges the falx cerebri, and marks the original developement of the brain by two symmetrical halves. Each hemisphere, upon its under surface, admits of a division hito three lobes, anterior, middle, and posterior. The anterior lobe rests upon the roof of the orbit, and is separated from the middle by the fissure of Sylvius.* The middle lobe is received into the middle * Jamos Dubois, a celebrated professor of anatomy in Paris, where he succeedecr Vidius in l.'j.'jf), although known much earlier by liis own works and discoveries, but particularly by his violence in tlio defence of Galen, His name was Latinised to Jacobus Sylvius. CENTRUM OVALE MAJUS CORPUS CALLOSUM. 367 fossa, in the base of the skull, and is separated from the posterior by a slight impression produced by the ridge of the petrous bone. The posterior lobe is supported by the tentorium. If the upper part of one hemisphere be removed with a scalpel, a centre of white surface will be observed, surrounded by a narrow border of gray, which follows the depressions of the convolutions, and presents a zigzag outline. This appearance is called centrum ovale minus. The divided surface will be seen to be studded with numerous small red points (puncta vasculosa) which are produced by the escape of blood from the divided ends of minute arteries and veins. Now separate carefully the two hemispheres of the cerebrum, and a broad band of white substance will be seen to connect them. Re; move the upper part of each hemisphere, with a knife, to a level with this white layer. The appearance resulting from this section is the centrum ovale majus. The Centrum ovale majus is the large centre of white substance presented to view on the removal of the upper part of both hemi- spheres ; it is surrounded by the thin stratum of gray substance, which follows in a zigzag line all the convolutions and the fissures between them. In the middle of the centrum ovale majus is the broad band which connects the two hemispheres to each other, the corpus callosum. The Corpus callosum (callosits, hard) is a dense layer of transverse fibres connecting the two hemispheres and constituting their great commissure. It is situated nearer to the anterior than to the poste- rior part of the brain, and terminates anteriorly in a rounded border which may be traced downwards to the base of the brain, in front of the commissure of the optic nerves. Posteriorly it forms a thick rounded fold which is continuous with the fornix. Beneath the posterior rounded border of the corpus callosum is the transverse ^ssure of the cerebrum, which extends between the hemispheres and crura cerebri from the fissure of Sylvius on one side, to that on the opposite side of the brain. It is through this fissure that the pia mater communicates with the velum interpositum. And it was here that Bichat conceived the arachnoid to enter the Ventricles; hence it is also named the fissure of Bichat. Along the middle line of the corpus callosum is the raphe, a linear depression between two slightly elevated longitudinal bands ; and, on either side of the raphe, may be seen the linecB transversce, which mark the direction of the fibres of which the corpus callosum is composed. If an incision be made through the corpus callosum on either side of the raphe, two irregular cavities will be opened, which extend from one extremity of the hemispheres to the other: these ai'e the lateral ventricles. To expose them completely the upper boundary should be removed with the scissors. Each Lateral ventricle is divided into a central cavity, and three smaller cavities called cornua. The anterior cornu curves forwards 368 LATERAL VENTRICLES. and outwards in the anterior lobe ; the middle cornu descends into the middle lobe; and the posterior cornu passes backwards in the posterior lobe, converging towards its fellow of the opposite side. The central cavity is triangular in its form, being bounded above (roof) by the corpus callosum ; internally by the septum lucidum, which separates it from the opposite ventricle; and below {fioor) by the following parts, taken in their order of position from before backwards : Corpus striatum. Tenia semicircularis. Thalamus opticus, Choroid plexus. Corpus fimbriatum. Fornix. Fig. 124.* * The lateral ventricles of the cerebrum. 1,1. T'he two hemispheres cut down to a level with the corpus callosum so as to constitute the centrum ovale majus. The sur- face is seen to be studded witli the small vascular points — puncta vasculosa ; and sur- rounded by a narrow margin which represents the gray substance. 2. A small portion of the anterior extremity of the corpus callosum. 3. Its posterior boundary ; the inter- mediate portion forming the roof of the lateral ventricles has been removed so as to completely expose those cavities. 4. A part of the septum lucidum, showing an inter- space between its layers — the fifth ventricle. 5. The anterior cornu of one side. 6. The commencement of the middle cornu. 7. The posterior cornu. 8. The corpus striatum of one ventricle. 9. The tenia semicircularis covered by the vena corporis striata and tenia Tarini. 10. A small part of the thalamus opticus. 11. The dark fringe-like body to the left of the figure is the choroid plexus. This plexus communi- cates with tliat of the opposite ventricle through the foramen of Munro; a bristle is passed through this opening, and its extremities are seen resting on the corpus striatum at each side. The figure ll rests upon the edge of the fornix, upon thut part of it which is called the corpus fimbriatum. 12. The fornix. 13. The commencement of the hippocampus major descending into the middle cornu. The rounded oblong body in the posterior cornu of the lateral ventricle, directly behind the figure 13, is the hip- pocampus minor. * CORPUS STRIATUM CHOROID PLEXUS. 369 The Corpus striatum is named from the striated Hnes of white and gray matter which are seen upon cutting into its substance. It is gray on the exterior, and of a pyriform shape. The broad end, directed forwards, rests against tlie corpus striatum of tlie opposite side : the small end, backwards, is separated from its fellow by the interposition of the thalami optici. The corpora striata are the superior ganglia of the cerebrum. The Tenia SRinicircularis (tenia, a fillet) is a narrow band of medullary substance, extending along the posterior border of the corpus striatum, and serving as a bond of connexion between that body and the thalamus opticus. The tenia is partly concealed by a large vein (vena covporis striali) formed by small vessels from the corpus striatum and thalamus opticus, and terminating in the venas Galeni. The vein is overlaid by a yellowish band, a thickening of the lining membrane of the ventricle. This was first noticed and described by Tarinus, under the name of the horny band. We may, therefore, term it tenia Tarini.^ The Thalamus opticus (thalamus, a bed) is an oblong body, hav- ing a thin coating of white substance on its surface; it has received its name from giving origin to one root of the optic nerve. It is the inferior ganglion of the cerebrum. The border only of the thalamus is seen in the floor of the lateral ventricle. We must, therefore, defer its further description until we can examine it in its entire extent. The Choroid plexus (x^'p'"^' ^'^'^°^' resembling the chorionf) is a vas- cular fringe extending obliquely across the floor of the lateral ven- tricle, and sinking into the middle cornu. Anteriorly, it is small and tapering, and communicates with the choroid plexus of the opposite ventricle, through a large oval opening, the fora?nen of Munro. This foramen may be distinctly seen by pulling sHghtly on the plexus, and pressing aside the septum lucidum with the handle of the knife. It is situated between the under surface of the fornix, and the anterior extremities of the thalami optici, and forms a transverse communi- cation between the lateral ventricles, and below with the third ventricle. The choroid plexus is variable in its appearance, and sometimes presents groups and clusters of small serous cysts, which have been mistaken for hydatids. The Corpus fimbriatum is a narrow white band, which is situated immediately behind the choroid plexus, and extends with it into the descending cornu of the lateral ventricle. It is the lateral thin edge of the fornix. The Fornix is a white layer of medullary substance, of which a portion only is seen in this view of the ventricle. The .interior cornu is triangular in its form, sweeping outwards, * Peter Tarin, a French anatomist: his work, entitled " Adversaria Anatomica," was published in 1750. t See the note appended to the description of the choroid coat of the eyeball. 47 370 coRXUA or the lateral ventricles, and terminating by a point in the anterior lobe of the brain, at a short distance only from its surface. The Posterior cornu or digital cavity curves inwards, as it extends into the posterior lobe of the brain, and likewise terminates near to the surface. An elevation corresponding with a deep sulcus between two convolutions projects into the area of this cornu, and is called the lii-ppocampus minor. The Middle or descending cornu, in descending into the middle lobe of the brain, forms a very considerable curve, and alters its direction several times as it proceeds. Hence it is described as passing backwards and outwards and downwards, and then turning forwards and inwards. This complex expression of a very simple curve has given birth to a symbol formed by the primary letters of these various terms ; and by means of this the student recollects with ease the course of the cornu, eodfi. It is the largest of the three cornua. The middle cornu should now be laid open, by inserting the little finger into its cavity, and making it serve as a director for the scalpel in cutting away the side of the hemisphere, so as to expose it completely. Its Superior boundary is formed by the under surface of the thala- mus opticus, upon which are the two projections called corpus geniculatum internum and externum ; and the inferior wall by the various parts which are often spoken of as the contents of the middle cornu : these are the — Hippocampus major. Pes hippocampi. Pes accessorius. Corpus fimbriatum. Choroid plexus, Fascia dentata, Transverse fissure. The FIippoca?npns major or coi^nu Ammonis, so called from its re- semblance to a ram's horn, the famous crest of Jupiter Ammon, is a considerable projection from the inferior wall, and extends the whole length of the middle cornu. Its extremity is likened to the club-foot of some animal, from its presenting a number of knuckle-like eleva- tions upon the surface : hence it is named pes hippocampi. The hippocampus major is the termination of the lateral edge of the hemisphere, which in this situation is very much attenuated and rolled upon itself If it be cut across, the section will be seen to re- semble the extremity of a convoluted scroll, consisting of alternate layers of white and gray substance. The hippocampus major is continuous superiorly with the fornix and corpus callosum. The Pes accessorius is a swelling somewhat resembhng the hippo- campus major, but smaller in size ; it is situated on the outer wall of the cornu, and is frequently absent. The Corpus fimbriatum is the narrow white band which is pro- FASCIA DEXTATA FORNIX. 371 longed from the central cavity of the ventricle, and is attached along the inner border of the hippocampus major to its termination. Fascia dentata: — if the corpus fimbriatum be carefully raised a narrow serrated band of gray substance will be seen beneath it ; this is the fascia dentata. Beneath the corpus fimbriatum will be likewise seen the transverse fissure of the brain, which has been before described as extending from the fissure of Sylvius on one side, across to the same fissure on the opposite side of the brain. It is through this fissure that the pia mater communicates with the choroid plexus, and the latter obtains its supply of blood. The fissure is bounded on one side by the coi-pus fimbriatum, and on the other by the under surface of the thalamus opticus. The internal boundary of the lateral ventricle is the septum luci- dum. This septum is thin and semi-transparent, and consists of two laminse of cerebral substance attached above to the under sur- face of the corpus callosum at its anterior part, and below to the fornix. Between the two layers is a narrow space, the fft/i ven- tricle, which is fined by a proper membrane. The ffth ventricle may be shown, by snipping through the septum lucidum transversely with the scissors. The corpus callosum should now be cut across towards its ante- rior extremity, and the two ends carefully dissected away. The anterior portion will be retained only by the septum lucidum, but the posterior will be found incorporated with the white layer beneath, which is the fornix. The fornix (arch) is a triangular lamina of white substance, broad behind, and extending into each lateral ventricle: narrow in front, where it terminates in two crura, which arch downwards to the base of the brain. The two crura descend through the foramen commune anterius of the third ventricle, and terminate in the cor- pora albicantia. Opening transversely beneath these two crura, just as they are about to arch downwards, is the foramen of Munro, through which the two lateral ventricles communicate, and the cho- roid plexuses are connected anteriorly. The lateral thin edges of the fornix are continuous posteriorly with the concave border of the hippocampus major at each side, and form the narrow white band called corpus fimbriatum. In the middle line the fornix is continuous with the corpus callosum, and at each side with the hippocampus major and minor. Upon the under surface of the fornix towards its posterior part, some trans- verse lines are seen passing between the diverging lateral fasciculi : this appearance is termed the lyra, from a fancied resemblance to the strings of a harp. The fornix may now be removed by dividing it across anteriorly, and turning it backwards, at the same time separating its lateral connexions with the hippocampi. If the student examine its under surface, he will perceive the lyra above described. Beneath the fornix is the velum interpositum, a rcfiection of pia mater introduced into the interior of the brain, throucjh the trons- 372 THALAMI OPTICI. verse fissure. The velum is connected at each side with the choroid plexus, and contains within its two layers, in the middle line, two large veins, the vencE Galeni, which receive the blood from the ventricles, and terminate posteriorly in the straight sinus. Upon the under surface of the velum interpositum are two fringe-like bodies which project into the third ventricle. These are the choroid plexuses of the third ventricle. Fig. 125.* If the velum interpositum be raised and turned back, an operation which must be conducted with care, particularly at its posterior part, where it invests the pineal gland, the thalami optici and the cavity of the third ventricle will be brought into view. The Thalami optici are two rounded oblong bodies, of a white colour superficially, inserted between the two diverging portions of the corpora striata. In the middle line a fissure exists between them, which is called the third ventricle. Posteriorly and inferiorly, they form the superior wall of the descending cornu, and present * The mesial surface of a longitudinal section of the brain. The incision has been carried along the middle line ; between the two liemispheres of the cerebrum, and through the middle of the cerebellum and medulla oblongata. 1. The inner surface of the left hemisphere. 2. The divided surface of the cerebellum, showing the arbor vitee. 3. The medulla oblongata. 4, The corpus callosum, rounded before to terminate in the base of the brain ; and behind, to become continuous with 5, the fornix. 6. One of the crura of the fornix descending to 7, one of the corpora albicantia. 8. The septum lucidum. 9. The velum interpositum, communicating with tlie pia mater of the convolutions through the fissure of Bichat. 10. Section of the middle commissure situated in the third ventricle. 11. Section of tlio anterior commissure. 12. Section of the posterior commissure; the commissure is somewhat above and to the left of the number. The interspace between 10 and 11 is the foramen commune anterius, in which the crus of the fornix (6) is situated. The interspace between 10 and 12 is the foramen commune postcrius. 13. The corpora quadrigemina, upon which is seen resting (he pineal gland, 14. 1.5. The iter e tcrtio ad quartum vcntriculum. IG. The fourth ventricle. 17. The pons Varolii, through which arc seen passing the diverging fibres of the corpora pyramidalia. 18. The crus cerebri of the left side, with the third nerve arising from it. 19. The tuber cinercum, from which projects the infundibulum having the pituitary gland appended to its extremity. 20. One of the optic nerves. 21. The left olfactory nerve terminating anteriorly in a rounded bulb. THIRD VENTRICLE. 373 two rounded elevations called corpus geniculatum externum and internum. The corpus geniculatum externum is the larger of the two, and of a grayish colour ; it is the principal origin of the optic nerve. Inferiorly, the thalami are connected with the corpora albi- cantia by means of two white bands, w^hich appear to originate in the white substance uniting the thalami to the corpora striata. In their interior the thalami are composed of white fibres mixed with gray substance. They are essentially the inferior ganglia of the cerebrum. The Third ventricle is the fissure between the two thalami optici. It is bounded above by the under surface of the velum interpositum, from which are suspended the choroid plexuses of the third ventricle. lis, floor is formed by the anterior termination of the corpus callosum, the tuber cinereum, corpora albicantia, and locus perforatus. Late- rally it is bounded by the thalami optici and part of the corpora striata; anteriorly by the anterior commissure and crura of the fornix ; and posteriorly by the posterior commissure and the iter e " tertio ad quartum ventriculum. The third ventricle is crossed by three commissures, the anterior, middle, and posterior ; and between these are two spaces, called foramen commune anterius and foramen commune posterius. The Anterior commissure is a rounded white cord, which enters the corpus striatum at either side ; the middle, or soft commissure consists of gray matter, and is very easily broken down ; it connects the adjacent sides of the thalami optici : and the posterior commis- sure is a flattened white cord, connecting the two thalami optici posteriorly. Between the anterior and middle commissure is the space called foramen commune anterius, which, from leading downwards into the infundibulum, is also designated iter ad infundihulum. The crura of the fornix descend through this space, surrounded by gray matter, to the corpora albicantia. Betw^een the middle and posterior com- missure is the foramen cominune posterius, from which a canal leads backwards to the fourth ventricle, the iter a tertio ad quartum ventn- culum. Behind the third ventricle is placed the quadrifid ganglion, called optic lobes in the inferior animals, and corpora quadrigemina in man. The two anterior of these bodies are the larger, and are named nates; the two posterior, testes. Their base is perforated from before backwards by a tubular canal, which serves to communicate the third and fourth ventricles, and is thence named the iter e tertio ad quartum ventriculum, or aqueduct of Sylvius. Resting upon the corpora quadrigemina and surrounded by a sheath of pia mater, obtained from the velum interpositum, with which it is liable to be torn oft' unless very great care be used, is the pineal gland. The Pineal gland consists of soft gray substance, and is of a conical form ; hence one of its synonymes, conarinm. It contains in its interior several brov/nish granules, which are composed of phosphate and carbonate of lime. It is connected to the thalami 374 CHOROID PLEXUSES. optici by two small rounded cords, called peduncles, and is very im- properly called a gland. Behind the corpora quadrigemina is the cerebellum, and beneath the cerebellum the fourth ventricle. The student must therefore divide the cerebellum down to the fourth ventricle, and turn its lobes aside to examine that cavity. The Fourth ventricle is the ventricle of the medulla oblongata, upon the posterior surface of which it is placed. It is an oblong quadrilateral cavity, hounded on each side by a thick cord passing between the cerebellum and corpora quadrigemina, called the p?'o- cessiis e cerebello ad testes, and by the corfiLS restiforme. It is covered in behind by the arch of the cerebellum, which forms three remarka- ble projections into its cavity, named, from their resemblance, uvula and tonsils: and by a thin lamella of white substance, stretched between the two processus e cerebello ad testes, termed the valve of Fieussens.* This layer is easily broken down, and requires that care be used in its demonstration. In fj-ont the fourth ventricle is bounded by the posterior surface of the medulla oblongata ; above by the corpora quadrigemina, and the termination of the iter e tertio ad quartum ventriculum ; and beloiv by a layer of pia mater and one of arachnoid, passing between the under surface of the cerebellum and the medulla oblongata, called the valve of the arachnoid. We observe within the fourth ventricle the chm-oid plexuses, the calamus scriptorius, and the linece transverscB. The Choriod plexuses resemble in miniature those of the lateral ventricles : they are formed by the pia mater, and lie against that part of the cerebellum called uvula and tonsils. The anterior wall, or floor, of the fourth ventricle is formed of gray substance, which is continuous with that contained within the spinal cord. This gray substance is separated into two bands by a median fissure, which is continuous with the calamus scriptorius. The two bands are considered by Mr. Solly as the two posterior pyramids ; and he has observed in their structure such an arrange- ment of fibres as induces him to name them the " posterior ganglia of the medulla oblongata," in opposition to the corpora oKvaria, which he describes as the " anterior ganglia of the medulla" The Calamus scriptorius is a groove upon the anterior wall, or floor, of the fourth ventricle. Its pen-like appearance is produced by the divergence of the posterior median columns, the feather by the lincoe transversse. At the point of the pen is a small cavity lined with gray substance, and called the ventricle of Arantius. The Linece transversa; are irregular transverse lines upon the an- terior wall of the ventricle, which in some degree resemble the plume of the pen. They are the filaments of origin of the auditory nerve. The existence of a communication between the fourth ventricle * Raymond Viousscns, a gniat, fllscovnrcr in tlio nnatomy of the brain nnd ncrvouf" Bystcin. His " Ncurograpliia Universalis" was puljlishcd at Lyons, in 1G85. LINING MEMBRANE OF THE VENTRICLES. 375 and the subarachnoidean space, as imagined by Magendie, is very questionable. LINING MEMBRANE OF THE VENTRICLES. The lining membrane of the ventricles is a serous layer, quite distinct from the arachnoid, and having no communication with it. This membrane lines the whole of the interior of the lateral ventri- cles, and is connected above and below to the attached border of the choroid plexus, so as to exclude completely all communication between the ventricles and the exterior of the brain. It is reflected through the foramen of Munro, on each side, into the third ventricle, which it invests throughout. From the third it is conducted into the fourth ventricle, through the iter e tertio ad quartum ventri- culum, and lines its interior, together with the layer of pia mater which forms its inferior boundary. In this manner a perfect com- munication is established between all the ventricles. It is this membrane which gives them their polished surface, and transudes the secretion which moistens their interior. When the fluid accu- mulates to an unnatural degree, it may then break down this layer and the layer of pia mater at the bottom of the fourth ventricle, and thus make its way into the subarachnoidean cellular tissue ; but in the normal condition it is doubtful whether a communication exists between the interior of the ventricles and the cavity of the subarachnoidean space. CEREBELLUM. The Cerebellum, according to Cruveilhier, is seven times smaller than the cerebrum. Like that organ, it is composed of white and gray substance, whereof the gray is larger in proportion than the white. Its surface is formed by parallel lamellcB, separated by fissures ; and at intervals deeper fissures exist, which divide it into larger segments termed lobules. The cerebellum is divided into two lateral hemispheres or lobes, two minor lobes called superior and inferior vermiform processes, and some small lobules. The Lateral lobes are separated from each other posteriorly by a depression which lodges the falx cerebelli, and above and below by the projection of the vermiform processes. The Superior vermiform, process, a slightly elevated ridge along the middle of the upper surface of the cerebellum, is all that exists of that organ in birds, and it constitutes the largest proportion of the cerebellum in many mammalia. It is situated along the middle line, and serves to connect the lateral lobes superiorly. The Inferior vermiform process forms a projection inferiorly, and is the means of connexion between the lateral lobes below. The principal lobules are the pneumogastric, the tonsils, uvula, and linguetta laminosa. 376 CEREBELLUM. The Pneumogastric lobule (flocculus) is situated on the anterior border of the cerebellum, near to the origin of the eighth pair of nerves, and is hence called pneumogastric. It is not unUke a con- voluted- shell in its form. The Tonsils and uvula resemble those organs in a swollen state very strikingly ; they project from the under surface of the cere- bellum into the fourth ventricle. The Lingueila iaminosa is a thin tonguelet of gray substance, marked by transverse furrows, which extend forwards upon the valve of Vieussens from the gray substance of the cerebellum. When cut into vertically, the cerebellum presents the appearance termed arbor vita. If the incision be made throuo-h the outer third of the organ, a gray body, surrounded by a yellow zigzag line of horny structure, will be seen in the centre of the white substance : this is the corpus rhomboideum, or ganglion of the cerebellum. The cerebellum is associated with the spinal cord and cerebrum by thiee pairs of peduncles ; the Corpora restiformia, Processus e cerebello ad testes. Crura cerebelli. The Corpora restiformia, or inferior peduncles, diverge at the upper extremity of the medulla oblongata, and enter the cerebellum, forming, by their divergence, part of the lateral boundaries of the fourth ventricle. Their fibres surround the corpus rhomboideum, and are expanded into the lamellae of the cerebellum. The Processus e cerebello ad testes are the superior peduncles : they ascend from the corpus rhomboideum, on each side, to the testis, and also form a part of the lateral boundaries of the fourth ventricle. The valve of Vieussens, by connecting the two pro- cessus e cerebello ad testes from side to side, and the cerebellum and testes from behind forwards, also contributes to the antero-pos- terior communication of the cerebellum. The Crura cerebelli are the terminations of the transverse fibres of the pons Varolii, or great commissure of the cerebellum, which serves to establish a transverse communication between the lateral lobes. BASE OF THE BRAIN. The student should now prepare to study the base of the brain : for this purpose the organ should be turned upon its incised surface; and if the dissection have hitherto been conducted with care, he will find the base perfectly uninjured. The arachnoid membrane, some parts of the pia mater, and the circle of Willis, must be care- fully cleared away in order to expose all the structures. These he will find arranged in the following order from before back- wards: — BASE OF THE BRAIN. 577 Longitudinal fissure, Olfactory nerves, Fissure of Sylvius, Substantia perforata, Commencement of the transverse fissure, Optic commissure, Tuber cinereum, Infundibulum, Corpora albicantia, Locus perforatus, Crura cerebri, Pons Varolii, Crura cerebelli. Medulla oblongata. The Longitudinal fissure is the space separating the two hemi- spheres: it is continued downwards to the base of the brain, and divides the two anterior lobes. In this fissure the anterior cerebral arteries ascend towards the corpus callosum; and, if the two lobes be slightly drawn asunder, the anterior extremity of the corpus cal- losum will be seen descending to the base of the brain. On each side of the longitudinal fissure, upon the under surface of each anterior lobe, is the olfactojy nerve, with its bulb. The Fissure of Sylvius bounds the anterior lobe posteriorly, and separates it from the middle lobe; it lodges the middle cerebral artery. If this fissure be followed outwards, a small isolated cluster of convolutions will be observed; these constitute the island of Reil. The Substantia perforata is a triangular plane of white substance, situated at the inner extremity of the fissure of Sylvius. It is named perforata, from being pierced by a number of openings for small arteries, v/hich enter the brain in this situation to supply the gray substance of the corpus striatum. Passing backwards on each side beneath the edge of the middle lobe, is the commencement of the great transverse fissure, which extends beneath the hemisphere of one side to the same point on the opposite side. The Optic commissure is situated on the middle line ; it is the point of communication between the two optic nerves. The Tuher cinereum is an eminence of gray substance immediately behind the optic commissure, and connected with its posterior bor- der. It forms part of the floor of the third ventricle. The Infundibulum is a tubular process of gray substance, opening from the centre of the tuber cinereum, and attached below to the pituitary gland, which is lodged in the sella turcica. This gland is retained within the sella turcica by the dura mater and arachnoid, and is with great difficulty removed with the brain. It is, therefore, better left in its place, where it is intended to study afterwards the base of the skull ; for any attempt at removal would injure the 48 378 BASE OF THE BRAIN. cavernous sinuses. It consists of two lobes, but presents nothing glandular, either in structure or function. -The Corpora albicantia are two rounded white bodies, placed side by side, of about the size of peas; hence their synonyme, fisiformia. They are the anterior extremities of the crura of ihe fornix, and are connected with the thalami optici by two white cords, which may be easily traced. The Locus perforatus is a layer of whitish gray substance, con- nected in front with the corpora albicantia, and on each side with the crura cerebri, between which it is situated. It is perforated by several thick tufts of arteries, which are distributed to the thalami optici and third ventricle, of which it assists in forming the floor. It is sometimes called the pons Tarini. The Crura cerebri are two thick white cords which issue from beneath the pons Varolii, and diverge to each side to enter the tha- lami optici. The third nerve will be observed to arise from the inner side of each, and the fourth nerves wind around them from above. If the crus cerebri be cut across, it will be seen to present, in the centre of the section, the locus niger. The Pons Varolii* (protuberantia annularis) is the broad transverse band of white fibres, which arches like a bridge across the upper part of the medulla oblongata ; and, contracting on each side into a thick rounded cord, enters the substance of the cerebellum under the name of crus cerebelli. There is a groove along its middle which lodges the basilar artery. The pons Varolii is the commis- sure of the cerebellum, and associates the two lateral lobes in their common function. Resting upon the pons, near its posterior border, is the sixth pair of nerves. On the anterior border of the crus cere- belli, at each side, is the thick bundle of filaments belonging to the fifth nerve, and, lying on its posterior border, the seventh pair of nerves. The Medulla oblongata is the upper enlarged portion of the spinal cord. Upon its anterior surface are seen two narrow projecting columns, the corpora pyramidalia. These bodies are broad above, and narrow below; and, at the point where they enter the pons Va- rolii, they become considerably constricted. They are connected to each other in the middle fissure, at about an inch below the pons, by a decussation of their fibres, which form small interlacing bands crossing from side to side. Externally to the corpora pyramidalia are two oblong and rounded bodies, supposed to resemble olives in their form, and hence called corpora olivaria. If these bodies be divided by a longitudinal sec- tion, a gray zigzag outline, resembling the corpus rhomboideum of * Constant Varolius, Professor of Anatomy in Bolog'na : died in 1578. He dissected the brain in the course of its fibres, beginninjr from tlic medulla oblongata: a plan which has since been perfected by Vieussens, and by Gall and Spurzheim. The work containing his mode of dissection, " De Resolutione Corporis Humani," was published after his death, in 1591. MEDULLA OBLONGATA. 379 the cerebellum, will be seen in the interior of each. This is the ganghon of the corpus olivare. Behind the corpus olivare is a narrow white band, which de- scends along the side of the medulla oblongata at the bottom of the lateral sulcus. This is the situation of the respiratory tract of Sir Charles Bell. Fig-. 126* The Corpora restiformia (restis, a rope) are the remaining columns, of the medulla oblongata; they form its posterior segment, and diverge superiorly to enter the cerebellum. Between the two corpora restiformia posteriorly are two other white bands, which diverge at the point of the calamus scriptorius, and join the cor- * The under surface or base of the brain. 1. The anterior lobe of one hemisphere of the cerebrum. 2. The middle lobe. 3. The posterior lobe almost concealed by (4) the lateral lobe of the cerebellum. 5. The inferior vermiform process of the cerebellum. 6. The pneumogastric lobule. 7. The long-itudinal fissure. 8. The olfactory nerves, with their bulbous expansions. 9. The substantia perforata at the inner termination of the fissure of Sylvius ; the three roots of the olfactory nerve arc seen upon the sub- stantia perforata. The commencement of the transverse fissure on each side is con- cealed by the inner border of the middle lobe. 10. The commissure of the optic nerves. 11. The tuber cinereum, from which the infundibulum is seen projecting-. 12. The corpora albicantia. 13. The locus perforatus bounded on each side by the crura cere- bri, and by the third nerve. 14. The pons Varolii. 15. Tlie crus cerebelli of one side. 16. The fifth nerve emerging- from the anterior border of the crus cerebelli ; the small nerve by its side is the fourth. 17. The sixth pair of nerves. 18. The seventh pair of nerves consisting of the auditory and facial. 19. The corpora pyramidalia of the medulla oblongata ; the corpus olivare and part of the corpus restiforme are seen at each side. Just below the number is the decussation of the fibres of the corpora pyra- mydalia. 20. The eighth pair of nerves. 21. The ninth or hypoglossal nerve. 22. The anterior root of the first cervical spinal nerve. 380 FIBRES OF THE BRAIN, pora restiformia : these are the posterior median fasciculi of the medulla oblongata. If a thin layer of the pons Varolii be carefully raised, or if a lon- gitudinal incision be made across it, it may easily be seen that the corpus pyramidale passes through the pons into the crus cerebri. If the crus cerebri be traced forwards, it will be found to enter the thalamus opticus, and leaving it by the opposite border to plunge into the corpus striatum, and pass from thence onwards to the con- volutions of the hemispheres. Fig. 127.* From pursuing this remarkable course, and spreading out as they advance, these fibres have been called by Gall the diverging fibres. While situated within the pons it is found that the fibres of the cor- pus pyramidale separate and spread out, and have gray substance * The base of the brain, upon which several sections have been made, showing the distribution of the diverging fibres. 1. The medulla oblongata. 2. One half of the pons Varolii. .3, The crus cerebri crossed by the optic nerve (4), and spreading out into the substance of the middle lobe. 5. The two roots of the optic nerve ; the nerves about the crus cerebri and cerebclli are the same as in the preceding figure. 6. The olfactory nerve. 7. The corpora albicantia. On the right side a portion of the brain has been removed to show the distribution of the diverging fibres. 8. The fibres of the corpus pyramidale passing through fhc substance of the pons Varolii. 9. The fibres passing through the thalamus opticus. 10. The fibres passing through the corpus striatum. 11. Their distribution to the hemispheres. 12. The fifth nerve; its two roots may be traced, the one forwards to the fibres of the corpus pyramidale, the other backwards to the corpus restiforme. 13. The fibres of the corpus pyramidale which pass outwards with the corpus restiforme into the substance of the cerebellum ; these are the arciform fibres of Solly. The number rests upon the upper part of the corpus olivarc ; the rest of that body having been cut away, the arciform fibres are below the number. 14. A section through one of the lateral lobes of the cerebellum, showing the corpus rhomboideum in the centre of its white substance; the arbor vita) is also beauti- fully seen, 15. The opposite lobe of the cerebellum. DIVERGING FIBRES. 381 interposed between them ; and that they quit the pons much increased in number and bulk, so as to form the cms cerebri. The fibres of the crus cerebri again are separated in the thalamus opticus, and are intermingled with gray matter, and they also quit that body greatly increased in number and bulk. Precisely the same change takes place in the corpus striatum, and the fibres are now so extra- ordinarily multiphed as to be capable of forming a large proportion of the hemispheres, viz., the whole of the lower part of the anterior and middle lobes. From observing this remarkable increase in the white fibres, apparently from the admixture of gray substance. Gall and Spurz- heim considered the latter as the material increase of formative substance to the white fibres, and they are borne out in this conclu- sion by several collateral facts, among the most prominent of which is the great vascularity of the gray substance ; and the larger pro- portion of the nutrient fluid circulating through it, is fully capable of effecting the increased growth and nutrition of the structures by which it is surrounded. For a like reason the bodies in which this gray substance occurs, are called by the same physiologists ^^ ganglia of increase" and by other authors simply ganglia. Thus the thalami optici and corpora striata are the ganglia of the cerebrum ; or, in other words, the formative ganglia of the hemispheres. Mr. Solly, in a recent work upon " the human brain," has desig- nated the diverging fibres of the corpus pyramidale that pursue the course above described, " the cerebral fibres ;" to distinguish them from another set of fibres discovered by that gentleman, which also proceed from the corpus pyramidale, and pass outwards beneath the corpus olivare to the cerebellum. These he names the " arciform fibres," and divides them into two layers, the superficial cerebellar and deep cerebellar fibres. They join the corpus restiforme, forming one-fourth of its whole diameter, and spread out in the structure of the cerebellum. The Corpora olivaria owe their convex olive-shaped form to a "ganglion of increase" (the anterior ganglia of the medulla oblongata of Solly), situated in the interior of each. The white fibres surrounding these ganglia form a fasciculus at each side, which is continued into the pons Varolii along with the corpora pyramidalia. Here its fibres are mixed with gray matter, and pass into the crus cerebri, forming its superior and inner seg- ment. From the crus cerebri they traverse successively the thalamus opticus and corpus striatum, and become developed into the convolu- tions of the upper part of the hemispheres and posterior lobe. The Corpora restiformia diverge as they approach the cerebellum, and leaving between them the cavity of the fourth ventricle enter the substance of the cerebellum, under the form of two rounded cords. These cords envelope the coi-pora rhomboidea, or ganglia of increase, and then expand on all sides so as to constitute the cerebellum. In addition to the diverging fibres which are thus shown to con- 382 CONVERGING FIBRES. stitute both the cerebrum and cerebellum, by then" increase and developement, another set of fibres are found to exist, which have for their otfice the association of the symmetrical halves, and distant parts of -the same hemispheres. These are called from their direction converging jihres, and from their office commissures. The commissures of the cerebrum and cerebellum are the — Corpus callosum, Fornix, Septum lucidum, Anterior commissure, Middle commissure, Posterior commissure. Peduncles of the pineal gland, Processus e cerebello ad testes, Valve of Vieussens, Pons Varolii. The Corpus callosum is the commissure of the hemispheres. It is therefore of moderate thickness in the middle, where its fibres pass directly from one hemisphere to the other ; thicker in front, where the anterior lobes are connected ; and thickest behind, where the fibres from the posterior lobes are assembled. The Fornix is an antero-posterior commissure, and serves to con- nect a number of parts. Below it is associated with the thalami optici ; on each side, by means of the corpora fimbriata, with the middle lobes of the brain ; and, above, with the corpus callosum, and consequently with the hemispheres. The Septum lucidum is a perpendicular commissure between the fornix and corpus callosum. The Anterior commissure traverses the corpus striatum, and con- nects the anterior and middle lobes of opposite hemispheres. The Middle commissure is a layer of gray substance, uniting the thalami optici. The Posterior commissure is a white flattened cord, connecting the thalami optici. The Peduncles of the pineal gland must also be regarded as com- missures, assisted in their function by the gray substance of the gland. The Processus e cerebello ad testes are the means of communica- tion between the white substance of the cerebellum and cerebrum ; and the linguetta laminosa and valve of Vieussens perform the same office to the gray substance. The Pons Varolii is the commissure to the two lobes of the cere- bellum. It consists of transverse fibres, which are split into two layers by the passage of the fasciculi of the corpora pyramidalia and olivaria. These two layers, the superior and inferior, are col- lected together on each side, in the formation of the crura cerebelli. SPINAL CORD. 383 SPINAL CORD. The dissection of the spinal cord requires that the spinal column should be opened throughout its entire length by sawing through the laminae of the vertebrae, close to the roots of the transverse processes, and raising the arches with a chisel, after the muscles of the back have been removed. The Spinal column contains the spinal cord, or medulla spinalis ; the roots of the spinal nerves ; and the membranes of the cord, viz., dura mater, arachnoid, pia mater, and memhrana dentata. The Dura mater (tlieca vertebralis) is continuous with the dura mater of the skull : it is closely attached around the border of the occipital foramen, particularly in front, where it is connected with the posterior common ligament. In the vertebral canal it is connected only by loose cellular tissue, containing an oily fluid, somewhat analogous to the marrow of long bones. On either side and below, it forms a sheath, for each of the spinal nerves, to which it is closely adherent. Upon its inner surface it is smooth, being lined by the arachnoid ; and on the sides may be seen the double openings for the two roots of each of the spinal nerves. The Jlracknoid is a continuation of the serous membrane of the brain. It encloses the cord very loosely, being connected to it only by long slender cellular filaments, and by a longitudinal lamella which is attached to the posterior aspect of the cord. It passes off on either side with the spinal nerves, to which it forms a sheath ; and is then reflected upon the dura mater, to constitute its serous surface. A connexion exists in several situations between the arach- noid of the cord and that of the dura mater. The space between the arachnoid and the spinal cord is identical with that already described as existing between the same parts in the brain, the suh-arachnoidean space. It is occupied in both by a serous fluid, sufficient in quantity to expand the arachnoid, and fill completely the cavity of the theca vertebralis. The suh-arachnoi- dean jiuid keeps up a constant and gentle pressure upon the entire surface of the brain and spinal cord, and yields with the greatest facility to the various movements of the cord, giving to those .deli- cate structures the advantage of the principles so usefully applied by Dr. Arnott in the hydrostatic bed. According to Majendie this fluid communicates with the secretion contained in the lateral ven- tricles, by means of an opening which exists in the fibrous layer of the inferior boundary of the fourth ventricle. The Pia mater is the immediate investment of the cord ; and, like the other membranes, is continuous with that of the braiin. It is not, however, like the pia mater cerebri, a vascular membrane ; but is dense and fibrous in its structure, and contains very few vessels. It invests the cord closely, and sends a duplicate into the sulcus lon- gitudinalis anterior, and another, extremely delicate, into the sulcus longitudinalis posterior. It forms a sheath for each of the filaments 384 MEDULLA SPINALIS. of the nerves, and for the nerves themselves ; and, inferiorly, at the conical termination of the cord, is prolonged downwards as a slender ligament, which descends through the centre of the cauda equina, and is attached to the dura mater lining the canal of the coccyx. This attachment is a rudiment of the original extension of the spinal cord into the canal of the sacrum and coccyx. The Memhrana dentata is a process of the pia mater sent off from each side of the cord throughout its entire length, and separating the anterior from the posterior roots of the spinal nerves. Between each of the nerves it forms a serration, which is attached to the dura mater, and unites the two layers of the arachnoid membrane at that point. The processes are about twenty in number at each side. Their use is to maintain the position of the spinal cord in the midst of the fluid by which it is surrounded. The Spinal cord of the adult extends from the pons Varolii to opposite the first or second lumbar vertebra, where it terminates in a rounded point ; in the child, at birth, it reaches to the middle of the third lumbar vertebra, and in the embryo is prolonged as far as the coccyx. It presents a difference of diameter in different parts of its extent, and exhibits three enlargements. The uppermost of these is the medulla oblongata ; the next corresponds with the origin of the nerves destined to the upper extremities ; and the lower en- largement is situated near to its termination, and corresponds with the attachment of the nerves which are intended for the supply of the lower limb. In form, the spinal cord is a flattened cylinder, and presents on its anterior surface a groove, which extends into the cord to the depth of one third of its diameter. This is the sulcus longitudinalis ante- rior. If the sides of the groove be gently separated, they will be seen to be connected at the bottom by a layer of medullary substance, the anterior commissure. On the posterior surface another fissure exists, which is so narrow as to be hardly perceptible without careful examination. This is the sulcus longitudinalis posterior. It extends much more deeply into the cord than the anterior sulcus, and terminates in the gray substance of the interior. These two fissures divide the medulla spinalis into two lateral cords, which are connected to each other merely by the white commissure which forms the bottom of the anterior longitudinal sulcus. On either side of the sulcus longitudinalis posterior is a slight line, which bounds on each side the posterior median columns. These columns are most apparent at the upper part of the cord, near to the fourth ventricle, where they are separated by the point of the cala- mus scriptorius, and where they form a bulbous enlargement at each side, called the processus clavatus. Two other lines are observed on the medulla, the anterior and posterior lateral sulci, corresponding with the attachment of the anterior and posterior roots of the spinal nerves. The anterior lateral sulcus is a mere trace, marked only by the attachment of the C0LU3INS OF THE SPINAL CORD. 385 filaments of the anterior roots. The 'posterior lateral sulcus is more evident, and is formed by a narrow grayish fasciculus derived from the gray substance of the interior. These sulci divide the medulla into four fasciculi or cords, viz. — Anterior columns. Lateral columns, Posterior columns. Median posterior columns. The Anterior are the motor columns, and give origin to the motor roots of the spinal nerves. They are continued upwards into the medulla oblongata, under the form of corpora pyramidalia. The Lateral columns are divided in their function between motion and sensation, and contain the fasciculus described by Sir Charles Bell as the respiratory tract. Some anatomists consider the ante- rior and lateral column on each side as a single column, under the name of antero-lateral The Posterior are the columns of sensation, and give origin to the sensitive roots of the spinal nerves. Their superior terminations are named corpora restiformia. The Median posterior columns have no function at present assigned to them. If a transverse section of the spinal cord be made, its internal structure may be seen and examined. It would then appear to be composed of two hollow cylinders of white matter, placed side by side, and connected by a narrow white commissure. Each cylinder is filled with gray substance, which is connected by a commissure of the same matter. The form of the gray substance, as observed in the section, is that of two half moons placed back to back, and joined by a transverse band. The horns of the moons correspond to the sulci of origin of the anterior and posterior roots of the nerves. The anterior horns do not quite reach this surface; but the posterior appear upon the surface, and form a narrow gray line. The white substance of the spinal cord is composed of parallel fibres which are collected into longitudinal laminae and extend throughout the entire length of the cord. These lamina; are various in breadth, and are arranged in a radiated manner ; one border being thick and corresponding with the surface of the cord, while the other is thin and lies in contact with the gray substance of the interior. According to Rolando the white substance constitutes a simple nervous membrane which is folded into longitudinal plaits, having the radiated disposition above described. The anterior commissure according to his description is merely the continuation of this ner- vous membrane from one lateral cord across the middle line to the other. Moreover, Rolando considers that a thin lamina of pia mater is received between each of the folds from the exterior, while a layer of the gray substance is prolonged between them from within. Cruveilhier is of opinion that each lamella is completely independent of its neighbours, and he believes this statement to be confirmed by 49 386 OLFACTORY NERVE. pathology, which shows that a single lamella may be injured or atrophied, and at the same time be surrounded by others perfectly sound. CRANIAL NERVES. There are nine pairs of cranial nerves. Taken in their order from before, backv^^ards, they are — 1st. Olfactory. 2d. Optic. 3d. Motores oculorum. 4th. Pathetici (trochleares). 5th. Trifacial (trigemini). 6th. Abducentes. ^,1 ( Facial (portio dura), ( Auditory (portio mollis), C Glosso-pharyngeal, 8th. < Pneumogastric (vagus, par vagum). ( Spinal accessory. 9th. Hypoglossal (lingual). Functionally or physiologically they are divided into four groups, and in this order we shall examine them. JVerves of ( 1st. Olfactory, 1. Special sense . - < 2d. Optic, ( 7th. Auditory. ( 3d. Motores oculorum, 2. Motion . . . < 6th. Abducentes, ( 9th. Hypoglossal. C 4th. Patheticus, 3. Respiration {Bell) . < 7th. Facial, ^8th. Glosso-pharyngeal. Pneumogastric, Spinal accessory. 4. Spinal . . . 5th. Trifacial. NERVES OF SPECIAL SENSE. 1st pair, Olfactory. — This nerve rests against the under surface of the anterior lobe of the brain, being lodged in the narrow interval between two convolutions, and retained in its place by the arachnoid membrane. It arises by three roots, I. Internal, from the substantia perforata. 2. Middle, from a papilla of gray matter embedded in the anterior OPTIC NERVE AUDITORY NERVE. 387 lobe. 3. External, from a long fasciculus which is traced for a considerable distance along the fissure of Sylvius, into the middle lobe. The union of these roots forms a grayish white nerve, pris- moid in form and soft in structure, which expands into a hulb {bulbus olfactorms), and rests upon the cribriform plate. Its branches are transmitted through the numerous foramina in the cribriform plate, to be distributed to the mucous membrane of the nr»se. The inner- most are reddish in colour and soft, and spread out upon the septum narium; the external branches are whiter and more firm, they pass through bony canals in the outer wall of the nose, and communicate freely with each other previously to their distribution in the mucous membrane of the superior and middle turbinated bones. 2d pair. Optic. — The optic nerve arises by two roots; one from the corpus geniculatum externum, the other from the anterior pair (nates) of the corpora quadrigemina or optic lobes. It winds around the crus cerebri as a flattened band, and unites with its fellow of the opposite side, to form the commissure. The two nerves then diverge from each other, to enter the orbit through the optic foramen, pierce the sclerotic and choroid coat of the eyeball, and expand in the retina. The optic commissure rests upon the processus olivaris of the sphenoid bone, and its posterior border is closely connected with the tuber cinereum, from which it receives fibres ; in its interior the innermost fibres of the two nerves cross each other, while the exter- nal proceed directly onwards in their course. On entering the orbit the nerve obtains a firm sheath from the dura mater, which is con- tinuous with the sclerotic coat of the eyeball. This sheath is formed by the splitting of the dura mater at the foramen opticum into two layers, the one surrounding the optic nerve, while the other is con- tinuous with the periosteum of the orbit. Near to the globe of the eyeball the optic nerve is pierced by the arteria centralis retinae, which runs forwards in the centre of the nerve, and reaching the retina distributes branches upon its internal surface, forming its vascular layer. 7th pair, Auditory (poriio mollis). — This nerve arises from the anterior wall or floor of the fourth ventricle, by means of the white fibres, linecE transversce, of the calamus scriptorius. It winds around the corpus restiforme, from which it receives fibres, and emerges upon the posterior border of the crus cerebelli : it then enters the meatus auditorius internus, together with the facial nerve, which lies in a groove on its superior and anterior surface, and at the bottom of the meatus divides into two branches, cochlear and vestibu- lar, which are distributed to the internal ear. It is soft and pulpy in texture, and whilst situated in the meatus auditorius sends several filaments to the facial nerve. NERVES OF MOTION. We have already seen that the corpora pyramidalia are the con- 388 MOTORES OCULORU3I ABDUCENTES. tinuations up-\vards of the anterior columns of the spinal cord, or motor tract, and that these fascicuh are prolonged onwards through the pons Varolii and crura cerebri into the ganglia of the hemi- spheres. ■ Now, the three motor nerves arise from the cerebral por- tion of the motor tract at different points of its course. 3d pair, Motores Oculorum. — The motor oculi nerve arises from the inner side of the crus cerebri, near to the pons Varoli, and passes forward between the posterior Fig. 128.* cerebral and superior cerebellar artery. It pierces the dura mater immediately in front of the posterior clinoid process ; descends obliquely along the ex- ternal wall of the cavernous sinus; and divides into two branches which enter the orbit between the two heads of the external rectus muscle. The siiferior branch ascends, and supplies the superior rectus and levator palpebrEe. The inferior sends a branch beneath the optic nerve to the internal rectus, another to the inferior rectus, and a long branch to the in- ferior oblique muscle. From the latter a short thick branch is given off to the ciliary gan- glion, forming its inferior root. The fibres of origin of this nerve may be traced into the gray substance of the crus cerebri,f into the motor tractj and as far as the superior fibres of the crus cerebri.§ In the cavernous sinus it receives one or two fila- * The anatomy of the side of the neck, showing the nerves of the tongue. 1 . A frag- ment of the temporal bone containing the meatus auditorius externus, mastoid, and styloid process. 2, Tiie stylo-hyoid muscle. 3. The stylo-glossus. 4. The stylo- pharyngcus. 5. The tanguc. 6. The hyo-glossus muscle ; its two portions. 7. The gcnio-hyo-glossus muscle. 8. The genio-hyoidcus; they both arise from the inner sur- face of the symf)hysis of the lower jaw. f). The sterno-hyoid muscle. 10. The sterno- thyroid. 11. The thyro-hyoid, u|)ori which the hyoid branch of the lingual nerve is seen ramifying. 12. The omo-iiyoid crossing the common carotid artery (13), and in- ternal jugular vein (14). 1.5. Tiie external carotid giving off its branches. 16. The internal carotid. 17. The gustatory nerve giving off a brancli to the submaxillary ganglion (18), and communicating a little further on witii tlic hypoglossal nerve. 19. The submaxillary, or Wharton's duct, passing forwards to the sublingual gland. 20. The glosso-pharyngeal nerve. 21. The hypoglossal nerve curving around the occipital artery. 22. The desccndens noni nerve, forming a loop with (23) the communicans noni, which is seen to be arising by filaments from tlic u])per cervical nerves. 24. The pneumogastric nerve, emerging from between the internal jugular vein and common carotid artery, and entering the chest. 2.5. The facial nerve, emerging from the stylo- mastoid foramen, and cro.ssing the external carotid artery. t Mayo. t Solly. § Grainger. HYPOGLOSSAL NERVE. 389 ments from the cavernous plexus, and one from the ophthalmic nerve. 6th pah% Abducentes. — The abclucens nei've arises from the upper part of the corpus jjyramidale, close to the pons Varolii, several of its filaments of origin passing between the fascicuH of the pons. It pierces the dura mater upon the basilar process of the sphenoid bone, and ascends to the cavernous sinus. It then runs forward along the inner wall of the sinus, below the other nerves ; and, resting against the internal carotid artery, passes between the two heads of the external rectus, and is distributed to that muscle. As it enters the orbit it lies upon the ophthalmic vein, from which it is separated by a lamina of dura mater. In the cavernous sinus it is joined by two filaments from the carotid plexus, and by one from the ophthal- mic nerve. Mr. Mayo has traced the origin of this nerve between the fasciculi of the corpora pyramidalia to the posterior part of the medulla oblongata ; and Mr. Grainger has pointed out its connexion with the gray substance of the spinal cord. 9th pair. Hypoglossal (lingual). — The ninth nerve, the true mo- tor nerve of the tongue, arises by eight or ten filaments from the side of the corpus pyramidale of the medulla oblongata. These filaments are disposed in two fasciculi which unite into a single nerve at the jMNteMer condyloid foramen. The lingual nerve then ^ passes forward between the internal carotid artery and internal jugular vein, and descends along the anterior and inner side of the vein to a point parallel with the angle of the lower jaw. It next curves inwards around the occipital artery, with which it forms a loop, and crosses the lower part of the hyo-glossus muscle to the genio-hyo-glossus, in which it terminates by sending filaments on- wards with the anterior fibres of this muscle as far as the tip of the tongue. It is distributed to the muscles of the tongue, and princi- pally to the genio-hyo-glossus. While resting on the hyo-glossus muscle it has a flattened appearance, and communicates beneath the mylo-hyoideus of the gustatory nerve. The Branches of the hypoglossal nerve are : — Communicating branches with the Pneumogastric, Spinal accessory, First and second cervical nerves, Sympathetic. Descendens noni, Hyoidean branch. Communicating filaments with the gustatory nerve. The Communications with the pneumogastric and spinal acces- sory take place through the medium of a plexiform interlacement of branches at the base of the skull, behind the internal jugular vein. The communications with the sympathetic nerve are derived from the superior cervical ganglion. 390 RESPIKATORY NERVES. The Descendens noni is a long slender twig, which quits the hypo- glossal just as that nerve is about to form its arch around the occipi- tal-artery, and descends upon the sheath of the carotid vessels. Just below the middle of the neck it forms a loop with a long branch (communicans noni) from the second and third cervical nerves. From the convexity of this loop branches are sent to the depressor muscles of the larynx. If the descendens noni be traced to its con- nexion with the hypoglossal nerve, and examined with care, it will be found to be formed by two filaments, one from the lingual, the other, of larger size, from the first and second cervical nerves. The Hyoidean branch is a small twig distributed to the insertions of the depressor muscles of the larynx, particularly to the thyro- hyoid. The Communicating filaments with the gustatory nerve are two or three small branches which ascend upon the anterior part of the hyo-glossus muscle, and join corresponding branches sent down- wards by the gustatory. RESPIRATORY NERVES. * Under this head are grouped, by Sir Charles Bell, certain nerves ^^ * '• which are associated in the movements of respiration. They all arise in the course of a distinct tract, situated between the corpus olivare and corpus restiforme on each side of the medulla oblongata, and which may be traced upwards to the corpora quadrigemina ; hence this portion of the brain has been named the respiratory tract. 4th pair, Pathetici (trochlearis). — The fourth is the smallest cerebral nerve ; it arises from the valve of Vieussens and testis, and winds around the crus cerebri to the extremity of the petrous por- tion of the temporal bone, where it pierces the dura mater near to the oval opening for the fifth nerve, and passes along the outer wall of the cavernous sinus to the sphenoidal fissure. In its course through the sinus it is situated at first below the motor oculi, but afterwards ascends and becomes the highest of the nerves which enter the orbit through the sphenoidal fissure. After reaching the orbit it crosses the levator palpebraj muscle near to its origin, and is distributed upon the orbital surface of the superior oblique or trochlearis muscle ; hence its synonyme ti'ocli- learis. Branches. — While in the cavernous sinus the fourth nerve gives off a recurrent branch ; some filaments of communication to the ophthalmic nerve ; and a branch to assist in forming the lachrymal nerve. The recurrent branch passes backwards between the layers of the tentorium and divides into two or three filaments, which are distributed to the lining membrane of the lateral sinus. In a prepa- ration before me this i)ranch is very distinct; but I have not always succeeded in finding it. FACIAL NERVE. 3&1 7th pair, Facial {portio dura.) The Facial nerve arises from the respiratory tract, at the upper part of the medulla oblongata close to the lower border of the pons Vai'olii, from which point its fibres may be traced deeply into the corpus restiforme. It enters the meatus auditorius internus in front of and superiorly to the auditory nerve (portio molUs), and at the bottom of the meatus passes into the canal which is expressly intended for it, the aque- ductus Fallopii. In this canal it dh'ects its course at first forwards towards the hiatus Fallopii, where it forms a gangliform swelUng, and receives the petrosal branch of the Vidian nerve. It then curves backwards towards the tympanum, and descends along its inner wall to the stylo-mastoid foramen. Emerging at the stylo-mastoid foramen it passes forwards within the parotid gland, and crosses the external jugular vein and external carotid artery to the ramus of the jaw. While situated within the gland it is joined by a branch from the auricular nerve, and divides into two trunks — the temporo-facial and cervico-facial — which communicate with each other and give off" the numerous branches which constitute the pes anserinus, and are distributed over the whole of the side of the face, supplying the muscles. The Branches of the facial nerve are — Within the aqueductus ( Tympanic, Fallopii, ( (Chorda tympani).* r Communicating, After emerging at the > Posterior auricular, stylo-mastoid foramen, j Digastric, (^ Stylo-hyoid. /-, ,7 ^ ( Temporo-facial, Un the face, ^ ^ v r • i j. ^ i Cervico-iacial.j The Tympanic branches are two small filaments, which are dis- tributed to the stapedius and tensor tympani muscle. The Chorda tympani quits the facial just before that nerve emerges from the stylo-mastoid foramen. Entering the tympanum at its posterior and superior angle, it crosses its cavity between the handle of the malleus and long process of the incus, to its anterior inferior angle. It then escapes through a distinct opening in the fissura Glaseri, and joins the gustatory nerve at an acute angle between * The chorda tympani is not considered as a branch of the facial ; but being in close connexion with it, and being given off from it like a branch I have inserted it here lest it should be overlooked. + A third series of branches is usually described, whicli arc included by Wilson in his temporo-facial branches. They are called buccal from supplying the neighbourhood of the buccinator muscle. — G. 392 FACIAL NERVE. the t^vo pterygoid muscles. Enclosed in the sheath of the gustatory nerve, it descends to the submaxillary gland, where it unites with the submaxillary ganglion. The Communicating branches are filaments which it receives from the glosso-pharyngeal and pneumogastric nerves. The Posterior auricular nerve ascends behind the ear, and crosses the mastoid process to the occipito-frontalis muscle ; it gives branches also to the attollens and retrahens muscles of the pinna. The Digastric branch Fig. 129.* supplies the posterior belly of the digastricus muscle. The Stijlo-hyoid branch is distributed to the stylo- hyoid muscle. The Temforo-facial gives off a number of branches which are dis- tributed over the temple and upper half of the face, supplying the muscles of this region, and commu- nicating with the branches of the auricular, the tem- poro-malar, and the su- pra-orbital nerve. The inferior branches, which accompany Stenon's duct, form a plexus with the terminal branches of the infra-orbital nerve. The Cervico-facial di- vides into a number of branches that are distributed to the muscles on the lower half of the face, and upper part of the neck. The cervical branches form a plexus with the superficialis colli nerve over the submaxillary gland. * The distribution of the facial nerve and the branches of the cervical plexus. 1. The facial nerve, escaping- from tlie stylo-mastoid foramen, and crossing- the ramus of the lower jaw ; the parotid gland has been removed in order to see the nerve more dis- tinctly. 2. The posterior auricular bi-anch ; tlie digastric and stylo-mastoid filaments are seen near the origin of this branch. .3. Temporal branches, comrnunicating -with (4) the branches of the frontal nerve. 5. Facial brandies, communicating -with (6) the infra-orbital nerve. 7. Facial branches, communicating with (8) tlie mental nerve. 9. Cervico-facial branches communicating with (10) the superficialis colli nerve, and -forming a plexus (11) over the submaxillary gland. The distribution of the branches of the facial in a radiated direction over the side of the face constitutes tlic pes anse- rinus, 12. The auricularis magnus nerve, one of tlie ascending brandies of the cer- vical plexus. 13. The occipitalis minor, ascending along the posterior border of the sterno-mastoid muscle. 14. The superficial and deep descending branches of the cer- vical plexus. 15. The spinal accessory nerve, giving off a braneli to the external sur- face of the trapezius muscle. 16. The occipitalis major nerve, tiio posterior branch of the second cervical nerve. GLOSSO-PHARYNGEAL NERVE. 393 The facial nerve has been named sympailieticus minor, on account of the number of communications which it maintains with other nerves. These will be best seen in a tabular arrangement : r ^t J 7 ui. Auditory nerve, In the petrous hone it petrosal branch of Vidian, communicates with ^ ^^.^ ganglion. At its exit from the ( ^, , , styh-mastoid fora- glosso-pharyngeal, ^ •,, -^ i rneumoo;astric. men, with ( ° , ,, ,- 1 T J r Anterior auricular, In the parotid gland, \ ^uricularis magnus, ivith Occipitalis minor. Supra-orbital, Infra-orbital, On the face and neck, J Temporo-malar, with \ Buccal, Mental, Superficialis colli. 8th pair. — This pair consists of three nerves, the glosso-pharyn- geal, pneumogastric, and spinal accessory. The Glosso-pharyngeal Nerve arises by several filaments from the respiratory tract, between the corpus olivare and restiforme, and escapes from the skull at the innermost extremity of the jugular foramen through a distinct opening in the dura mater, lying ante- riorly to the sheath of the pneumogastric and spinal accessory nerves, and internally to the jugular vein. It then passes for- wards between the jugular vein and internal carotid artery to the stylo-pharyngeus muscle, and descends along its inferior border to the hyo-glossus, beneath which it passes to be distributed to the mucous membrane of the base of the tongue and fauces, to the mucous glands of the mouth, and to the tonsils. While situated in the jugular fossa, the nerve presents two gangliform swellings, one superior (ganglion jugulare of Miiller) of small size, and in- volving only the posterior fibres of the nerve, the other inferior, nearly half an inch below the preceding, of larger size and occupy- ing the whole diameter of the nerve, the ganglion of Andersch* (ganglion petrosum). The fibres of origin of this nerve may be traced through the fas- ciculi of the corpus restiforme to the gray substance in the floor of the fourth ventricle. * Charles Samuel Andersch. " Tractatus Anatomico-Physiologicus de Nervis Cor- poris Humani Aliquibus, 1797." 50 394 PNEUMOOASTRIC NERVE. The Branches of the glosso-pharyngeal nerve are — Communicating branches with the Facial, Pneumogastric, Spinal accessory, Sympathetic. Tympanic, Muscular, Pharyngeal, Lingual, Tonsillitic. The Branches of communication proceed from the ganglion and from the upper part of the trunk of the nerve, and are common to the facial, eighth pair, and sympathetic ; they form a complicated plexus at the base of the skull. The Tijmpanic branch (Jacobson's nerve) enters a small bony canal in the petrous portion of the temporal bone, and divides into six branches, which are distributed upon the inner wall of the tym- panum, and establish important communications with the sympathetic and fifth pair of nerves. The branches of distribution supply the fenestra rotunda, fenestra ovalis, and Eustachian tube : those of communication join the carotid plexus, the petrosal branch of the Vidian nerve, and the otic ganglion. The Muscular branch divides into filaments, which are distributed to the stylo-pharyngeus and to the posterior belly of the digastricus and stylo-hyoideus muscle. The Pharyngeal branches are two or three filaments which are distributed to the pharynx and unite with the pharyngeal branches of the pneumogastric and of the sympathetic nerve to form the pharyngeal plexus. The Lingual branches enter the substance of the tongue beneath the hyo-glossus and stylo-glossus muscle, and are distributed to the mucous membrane of the side and base of the tongue, and to the fauces. The Tonsillitic branches proceed from the glosso-pharyngeal nerve near to its termination ; they form a plexus (circulus tonsillaris) around the base of the tonsil, from which numerous filaments are giv^en oflf to the mucous membrane of the fauces and soft palate, communicating with the posterior palatine branches of Meckel's ganglion. The Pneumogastric Nerve (vagus) arises by numerous filaments from the respiratory tract immediately below the glosso-pharyngeal, and passes out of the skull through the inner extremity of the jugular foramen in a distinct canal of the dura mater. While situated in this canal it presents a small rounded ganglion ; and having escaped from the skull, a gangliform swelling, nearly an inch in length, and surrounded by an irregular plexus of white nerves, PNEUMOOASTRIC NERVE BRANCHES. 395 which communicate with each other, with the other divisions of the eighth pair, and with the trunk of the pneumogastric below the gangUon. This second, or plexiform ganglion (ganglion of the su- perior laryngeal branch, of Sir Astley Cooper), is situated, at first, behind the internal carotid artery, and then between that vessel and the internal jugular vein. The pneumogastric nerve then descends the neck within the sheath of the carotid vessels, lying behind and between the artery and vein, to the root of the neck. Here the course of the nerve at opposite sides becomes different. The Right passes between the subclavian artery and vein to the posterior mediastinum, then behind the root of the lung to the oeso- phagus, which it accompanies to the stomach, lying on its posterior aspect. The Left enters the chest parallel with the left subclavian artery, crosses the arch of the aorta, and descends behind the root of the lung, and along the anterior surface of the oesophagus, to the stomach. The fibres of origin of the pneumogastric nerve, like those of the glosso-pharyngeal, may be traced through the fasciculi of the corpus restiforme into the gray substance of the floor of the fourth ventricle. The Branches of the pneumogastric nerve are the following : — Communicating branches with the Facial, Glosso-pharyngeal, Spinal accessory, H}TO-glossal, Sympathetic. Pharyngeal, Superior laryngeal, Cardiac, Inferior or recurrent laryngeal. Pulmonary anterior. Pulmonary posterior, CEsophageal, Gastric. The Branches of communication form part of the complicated plexus at the base of the skull. The branches to the ganglion of Andersch, and that to the facial nerve, are given oft" by the superior ganglion in the jugular fossa ; the latter passes through a minute canal in the petrous bone, to the lower part of the aqueductus Fallopii. The Pharyngeal nerve arises from the pneumogastric, immediately above the plexifarm ganglion, and descends behind the internal carotid artery to the upper border of the middle constrictor, upon which it forms the pharyngeal plexus assisted by branches from the glosso-pharyngeal, superior laryngeal, and sympathetic. The pharyn- 396 EIGHTH PAIR OF NERVES. Fig. 130.* geal plexus is distributed to the muscles and mucous membrane of the pharynx. The Superior laryngeal nerve arises from the inferior ganglion of the pneumo- gastric, of which it appears to be almost a continuation ; hence the ganglion has been named by Sir Astley Cooper, the ^^ ganglion of the superior laryngeal branch." The nerve descends behind the internal carotid artery to the opening in the thyro-hyoidean membrane, through which it passes with the superior laryngeal artery, and is dis- tributed to the mucous membrane of the larynx, communicating on the arytenoid muscle, and behind the cricoid cartilage, with the recurrent laryngeal nerve. Be- hind the internal carotid it gives off the external laryngeal branch, which sends a branch to the pharyngeal plexus, and then descends to supply the inferior constrictor and crico-thyroid muscles and thyroid gland, and communicates by two or three branches with the recurrent laryngeal and sympathetic nerve. Mr. John Hilton, demonstrator of ana- tomy in Guy's Hospital, who has made some able dissections of the nerves of the larynx, of which we refer the student to a masterly description in the 2d vol. of the Guy's Hospital Reports, concludes that the superior laryngeal nerve is the nerve of sensation to the larynx, being distributed solely (with the exception of its external laryngeal branch) to the mucous mem- brane, cellular tissue, and glands. If this fact be taken in connexion with the obser- vations of Sir Astley Cooper, and the dis- sections of the origin of the nerve by Mr. Edward Cock, we shall perceive that, both in the ganglionic origin of the nerve and in its * Orij»'in and distribution of the cijrhth pair of nerves, 1. 3, 4. The medulla oblon- gata. 1. Is the corpus pyraniidalc of one side. 3. The corpus olivare. 4. The corpus restiforme. 2. The pons Varolii. 5. The facial nci'vo. 6. The orij^in of the glosso- pharyngeal nerve. 7. The ganglion of Andcrsch. 8. Tlie trunk of tiie nerve. 9. The spinal accessory nerve. 10. The ganglion of tlic pncumogastric nerve. 11. Its plexi- form ganglion. 12. Its trunk. 13. Its pliaryngeal branch forming the pharyngeal plexus (14), assisted by a branch from the glosso-pliaryngeal (H), and one from the superior laryngeal nerve (1.5). IG. Cardiac ])ranches. 17. Recurrent laryngeal branch. IS. Anterior pulmonary branches. 19. Posterior pulmonary branches. 20. Qilsophageal plexus. 21. Gastric branches. 29. Origin of the spinal accessory nerve. 23. Its branches distributed to the stcrno-mastoid muscle. 24, Its branches to the trapezius muscle. SPINAL ACCESSORY NERVE. 397 distribution, we have striking evidence of its sensitive function. The recurrent, or inferior laryngeal nerve, is the proper motor nerve, and is distributed to the muscles of the larynx. The Cardiac branches, two or three in number, arise from the pneumogastric in the lower part of the neck, and cross the lower part of the common carotid, to communicate with the cardiac branches of the sympathetic, and with the great cardiac plexus. The Recurrent laryngeal, or inferior laryngeal nerve, curves around the subclavian artery on the right, and the arch of the aorta on the left side. It ascends in the groove between the trachea and oesophagus, and piercing the lower fibres of the inferior con- strictor muscle enters the larynx close to the articulation of the inferior cornu of the thyroid with the cricoid cartilage. It is distri- buted to all the muscles of the larynx, with the exception of the crico-thyroid, and communicates with the superior laryngeal nerve. As it curves around the subclavian artery and aorta it gives branches to the heart and root of the lungs ; and as it ascends the neck it distributes filaments to the oesophagus and trachea, and com- municates with the external laryngeal nerve and sympathetic. The Anterior fulmonary branches are distributed upon the ante- rior aspect of the root of the lungs, forming, with branches from the great cardiac plexus, the anterior 'pulmonary flexus. The Posterior pulmonary branches, more numerous than the ante- rior, are distributed upon the posterior aspect of the root of the lungs, and are joined by branches from the great cardiac plexus, forming the -posterior pulmonary plexus. Upon the oesophagus the two nerves divide into numerous branches which communicate with each other and constitute the oesophageal plexus which completely surrounds the cylinder of the oesophagus, and accompanies it to the cardiac orifice of the stomach. The Gastric branches are the terminal filaments of the two pneu- mogastric nerves ; they are spread out upon the anterior and poste- rior surfaces of the stomach, and are likewise distributed to the omentum, spleen, pancreas, liver, and gall-bladder, and communi- cate, particularly the right nerve, with the solar plexus. The Spinal Accessory Nerve arises by several filaments from the respiratory tract as low down as the fourth or fifth cervical nerve, and ascends behind the Hgamentum denticulatum, and between the anterior and posterior roots of the spinal nerves, to the foramen lacerum posterius. It communicates in its course with the posterior root of the first cervical nerve, and soon becomes applied against the ganglion of the pneumogastric and enclosed in the same canal of dura mater. In the jugular fossa it divides into two branches ; the smaller joins the pneumogastric immediately below the superior ganglion, and contributes to the formation of the pharyngeal nerve ; while the larger or true continuation of the nerve passes backwards behind the internal jugular vein, and descends obliquely to the upper part of the sterno-mastoid muscle. It then pierces the sterno-mas- toid and passes obliquely across the neck, communicating with the 398 FIFTH PAIR TRIFACIAL. cervical nerves, and is distributed to the trapezius. The spinal ac- cessory sends numerous branches to the sterno-mastoid in its pas- sage through that muscle ; its branches to the trapezius may be traced to the lower border of that muscle. The pneumogastric and spinal accessory nerves together resemble a spinal nerve, the former representing the posterior root with its ganglion, and the latter an anterior root. 5th pair. Trifacial (trigeminus). — This nerve is analogous to the spinal nerves in its origin by two roots, from the anterior and poste- rior columns of the spinal cord, and in the existence of a ganglion on the posterior root. Hence it ranges with the spinal nerves, and is considered as the cranial spinal nerve. It arises* by two roots from a tract of yellowish white matter situated in front of the floor of the fourth ventricle and the orio-in of the auditory nerve, and behind the crus cerebeUi. This tract divides inferiorly into two fasciculi which may be traced downwards into the spinal cord, one being continuous with the fibres of the anterior column, the other with the posterior column. Proceeding from this origin the two roots of the nerve pass forward, and issue from the brain upon the anterior part of the crus cerebelli, where they are separated by a slight interval. The anterior is much smaller than the posterior, and the two together constitute the fifth nerve, which in this situation consists of seventy to a hundred filaments held together by pia mater. The nerve then passes through an oval opening in the border of the tentorium, near to the extremity of the petrous bone, and spreads out into a large semilunar ganghon — the Casserian. If the ganglion be turned over, it will be seen that the anterior root lies against its under surface without having any con- nexion with it, and may be followed onwards to the inferior maxil- lary nerve. The Casserian ganglion divides into three branches, the ophthalmic, superior maxillary, and inferior maxillary. The Ophthalmic Nerve is a short trunk, being not more than three quarters of an inch in length ; it arises from the upper angle of the Casserian ganglion, beneath the dura mater, and passes forwards through the outer wall of the cavernous sinus, lying externally to the other nerves: it divides into three branches. Previously to its division it receives several filaments from the carotid plexus, and gives off a small recurrent nerve, that passes backwards with the recurrent branch of the fourth nerve between the two layers of the tentorium to the lining membrane of the lateral sinus. The Branches of the ophthalmic nerve are, the — Frontal, Lachrymal, Nasal. * I have adopted llic origin of this nerve, given by Dr. Alcock, of Dubhn, as the result of Ills dissections, in llio f"yclopa;dia of Anatomy and Physiology. Mr. Mayo also traces the anterior root of tlic nerve to a .similar origin. BRANCHES OF THE TRIFACIAL. 399 The Frontal nerve mounts above the levator palpebrse, and runs forward, resting upon that muscle, to the supra-orbital foramen, through which it escapes upon the forehead, and supplies the mus- cles and integument of that region. It gives off one small branch, the supra-trochlear, which passes inwards above the pulley of the superior oblique muscle, and ascends along the middle line of the forehead, distributing filaments to the muscles and integument at the inner angle of the eye and root of the nose. The Lachrymal nerve, the smallest of the three branches of the ophthalmic, receives a filament from the fourth nerve in the caver- nous sinus, and passes outwards along the upper border of the exter- nal rectus muscle to the lachrymal gland, where it divides into two branches. The superior branch passes over the gland and through a foramen in the malar bone, and is distributed upon the temple and cheek, communicating with the temporo-malar and facial nerves. The inferior branch supplies the lower surface of the gland, and ter- minates in the integument of the upper lid communicating with the facial nerve. The Nasal nerve passes forwards between the two heads of the external rectus muscle, crosses the optic nerve in company with the ophthalmic artery, and enters the anterior ethmoidal foramen imme- diately above the internal rectus. It then traverses the upper part of the ethmoid bone to the cribriform plate, and passes downwards through the slit-like opening by the side of the crista galh into the nose, where it divides into two branches — an internal branch supply- ing the mucous membrane, near the anterior openings of the nares; and an external branch which passes between the fibro-cartilages, and is distributed to the integument at the extremity of the nose. The Branches of the nasal nerve within the orbit are, the gangli- onic, ciliary, and infra-trochlear; in the nose it gives off one or two filaments to the anterior ethmoidal cells and frontal sinus. The ganglionic branch passes obliquely forwards to the superior angle of the ciliary ganglion, forming its superior or long root. The ciliary branches are two or three filaments which are given off by the nasal as it crosses the optic nerve. They pierce the posterior part of the sclerotic, and pass between that tunic and the choroid to be distri- buted to the iris. The infra-trochlear is given off" just as the nerve is about to enter the anterior ethmoidal foramen. It passes along the superior border of the internal rectus to the inner angle of the eye, where it communicates with the supra-trochlear nerve, and supplies the lachrymal sac, caruncula lachrymalis, conjunctiva, and inner angle of the orbit. The Superior Maxillary Nerve proceeds from the middle of the Casscrian ganglion ; it passes forwards through the foramen rotun- dum, crosses the spheno-maxillary fossa, and enters the canal in the floor of the orbit, along which it runs to the infra-orbital foramen. Emerging on the face, beneath the levator labii supcrioris muscle, it divides into a leash of branches, whicli are distributed to the 400 FIFTH PAIR OF NERVES BRANCHES. muscles and integument of tlie cheek, forming a plexus with the facial nerve. Fiff. 131.* The Branches of the superior maxillary nerve are divisible into three groups: — 1. Those which are given off in the spheno-maxil- lary fossa. 2. Those in the infra-orbital canal ; and 3. Those on the face. They may be thus arranged : — Splieno-mazillary fossa, Orbital. Two from Meckel's ganglion,t Posterior dental. * A diagram, showing the fifth pair of nerves with its branches. 1 . The origin of the nerve by two roots. 2. Tlie nerve escaping from the crus cerebelli. 3, Tin; Cas- serian ganglion. 4. Its ophthahnic division. 5. The frontal nerve, giving off the supra-trociilcar branch, and escaping on the forehead through the supra-orbital foramen, 6. The laclirymal nerve. 7. The nasal nerve, passing at 8 througli the anterior ethmoidal foramen, and giving off the infra-trochlear branch. 9. The communication of the nasal nerve with the ciliary ganglion. 10. A small portion of the third nerve with which the ganglion is seen communicating; the ganglion gives off the ciliary branches from its anterior aspect. 11. The superior maxillary nerve. 12. Its orbital branch. 13. The two branches communicating with Meckel's ganglion; the three branches given off from the lower part of the ganglion are the posterior palatine nerves. 14, 14. The superior dental nerves, posterior, middle, and anterior. 15. The infra- orbital branches distributed upon the cheek. 16. The inferior maxillary nerve. 17. Its anterior or muscular trunk. 18. The posterior tnnik ; tlie two divisions are sepa- rated by an arrow. 19. The gustatory nerve. 20. The cliorda tympani joining it at an acute angle. 21. The submaxillary ganglion. 22. The inferior dental nerve. 23. Its mylo-hyoidcan branch. 24. The auricular nerve, dividing behind the articulation of the lower jaw, to reunite and form a single trunk. 25. Its branch of communication with the facial nerve. 26. Its temporal branch. t We now encounter a different mode of describing the nerves from that which has been so long in use; for whore it was customary to describe these branches as branches of the fifth pair running down to form Meckel's ganglion, wc now find them described as running up to join the fifth pair. This arises from the belief now general that these ganglia form a part of the great sympathetic, and the student will find their description under that head. — G. SUPERIOR AND INFERIOR MAXILLARY NERVES, 401 T -p ^ Lu 1 7 \ Middle dental, Infra-orbital canal, . j Anterior dental. On the face, . . . j ^^f c^^^' •^ ( Lutaneous. The Orbital branch* enters the orbit through the spheno-maxillary fissure, and divides into two branches : lachrymal.-f which ascends along the outer wall of the orbit to the lachr\Tnal gland, and com- municates with the lachr\Tnal nerve : temporo-malar'l which passes forwards and divides into two branches : one piercing the malar bone, is distributed to the integument of the cheek, communicating with the facial nen-e; the other escaping through the outer wall of the 01-bit supplies the temporal muscle and integument in the tempo- ral region, and communicates with the temporal, anterior auricular, and facial nerve. The Two branches from Meckel's ganglion ascend from that body- to join the nerve, as it crosses the spheno-maxillary fossa. The Posterior dental hranches pass through small foramina, in the posterior surface of the superior maxillaiy- bone, and supply the pos- terior teeth. The Middle and anterior denial branches descend to the teeth : the former beneath the lining membrane of the antrum, the latter through distinct canals in the walls of the bone. The Muscular and cutaneous branches are the terminating fila- ments of the nerve ; they supply the muscles and integument of the cheek, and form an intricate plexus with branches of the facial nerve. The LvFERioR Maxillary Nerve proceeds from the inferior angle of the Casserian ganglion ; it is the largest of the three divisions of the fifth nerve, and is augmented in size by the anterior or motor root, which passes behind the ganglion, and unites ^"ith the inferior maxillary as it escapes through the foramen ovale. Emerging at the foramen ovale the nerve diWdes into two trunks, external and in- ternal, which are separated from each other by the external pter}-- goid muscle. The External trunk, into which may be traced the whole of the motor root, immediately di\-ides into five branches which are dis- tributed to the muscles of the temporo-maxillary region ; they are — The Masseteric, which crosses the sigmoid notch with the mas- seteric artery to the masseter muscle. It sends a small branch to the temporal muscle, and a filament to the temporo-maxillary arti- culation. Temjporal ; two branches passing between the upper border of the external pterygoid muscle and the temporal bone to the tem- poral muscle. Two or three filaments from these nen^es pierce the * Nervus subcutaneus maUz of other anatomists. — G, + The malar branch. — G. X The temporal branch. — G. 51 402 GUSTATORY NERVE INFERIOR DENTAL NERVE. temporal fascia, and communicate with the lachrymal, temporo- malar, auricular and facial nerve. Buccal f" a large branch which pierces the fibres of the external pterygoid, to reach the buccinator muscle. This nerve sends fila- ments to the temporal and external pterygoid muscle, to the mucous membrane and integument of the cheek, and communicates with the facial nerve. Internal 'pterygoid ; a long and slender branch, which passes in- wards to the internal pterygoid muscle. This nerve is remarkable from its connexion with the otic ganglion, to which it is closely attached. The Internal trunk divides into three branches — Gustatory, Inferior dental, Anterior auricular. The Gustatory Nerve descends between the two pterygoid muscles to the side of the tongue, where it becomes flattened, and divides into numerous filaments, which are distributed to the papillag and mucous membrane. Relations. — It lies at first between the external pterygoid muscle and the pharynx, next between the two pterygoid muscles, then be- tween the internal pterygoid and ramus of the jaw, and between the stylo-glossus muscle and the submaxillary gland; lastly, it runs along the side of the tongue, resting upon the hyo-glossus muscle, and covered in by the mylo-hyoideus and mucous membrane. The gustatory nerve, while between the two pterygoid muscles, receives a branch from the inferior dental ; lower down it is joined at an acute angle by the chorda tympani which passes downwards in the sheath of the gustatory to the submaxillary gland, where it unites with the submaxillary ganglion. On the hyo-glossus muscle some branches of communication are sent to the hypoglossal, and in the course of the nerve several small branches to the mucous membrane of the fauces, and to the tonsils, and numerous filaments to the submaxillary gland. The Inferior Dental Nerve passes downwards with the inferior dental artery, at first between the two pterygoid muscles, and then between the internal lateral ligament and the ramus of the lower jaw, to the dental foramen. It then runs along the canal in the inferior maxillary bone, distributing branches to the teeth, and divides into two branches, incisive and mental. The incisive branch passes for- wards to supply the incisive teeth : and the mental branch escapes through the mental foramen, to be distributed to the muscles, and integument of the chin, and to communicate with the facial nerve. It gives off but one branch, the mylo-liyoidean, wliich leaves the * The name buceal is usually applied to the central branches from the pes anserinus of the facial nerve. — G. AURICULAR NERVE SPINAL NERVES. 403 nerve just as it is about to enter the dental foramen. Tliis branch pierces the insertion of the internal lateral ligament, and descends along a groove in the bone to the superior surface of the mylo-hyoid muscle, to which it is distributed. The ApfTERioR Auricular Nerve passes directly backwards be- hind the articulation of the lower jaw, against which it rests. In this situation it divides into two branches, which reunite, and form a kind of plexus. From the plexus two branches are given off — ascending and descending. The ascending or temporal branch* sends a considerable branch of communication to the facial nerve, and then ascends in front of the ear to the temporal region, upon which it is distributed in company with the branches of the temporal artery. In its course it sends filaments to the temporo-maxillary articulation, to the pinna and meatus of the ear, and to the integu- ment in the temporal region. It communicates on the temple with branches of the facial, supra-orbital, lachrymal, and temporo-malar nerve. The descending branch enters the parotid gland, to which it sends numerous branches ; it communicates with the inferior dental and auricularis magnus nerve, and supplies the external ear and the temporo-maxillary articulation. SPINAL NERVES. There are thirty-one pairs of spinal nerves, each arising by two roots, an anterior or motor root, and a posterior or sensitive root. The anterior roots arise from a narrow white line upon the ante- rior columns of the spinal cord, and gradually approach towards the anterior longitudinal sulcus as they descend. The posterior roots, more regular than the anterior, arise from a Fiarrow gray band formed by the internal gray substance of the cord. They are larger, and the filaments of the origin more nume- rous than those of the anterior roots. A ganglion is found upon each of the posterior roots in the intervertebral foramina. The first cervical nerve forms an exception to these characters. Its posterior root is smaller than the anterior; there is frequently no ganglion upon it, and it often joins in the whole or in part with the spinal accessory nerve. After the formation of the ganglion the two roots unite, and con- stitute a spinal nerve, which escapes through the intervertebral fora- men, and divides into an anterior branch, for the supply of the front half of the body, and a posterior branch, for the posterior half. The anterior branches, with the exception of the two first cervical nerves, are larger than the posterior; an arrangement which is proportioned to the larger extent of surface they are required to supply. * This is usually called the superficial temporal nerve. — G. 404 ANTERIOR CERVICAL NERVES. The Spinal nerves are divided into — Cervical . . . . 8 pairs Dorsal . . . .12 Lumbar .... 5 Sacral .... 6 The Cervical nerves pass off transversely from the spinal cord ; the dorsal are oblique in their direction ; and the lumbar vertical, and form the large assemblage of nerves at the termination of the cord called cauda equina. The Cervical Nerves increase in size from above downv^'^ards ; the first (sub-occipital) passes out of the spinal canal between the occipital bone and the atlas ; and the last, betw^een the last cervical and first dorsal vertebra. Each nerve, at its escape from the inter- vertebral foramen, divides into an anterior and a posterior branch. The anterior branches of the four upper cervical nerves form the cervical plexus ; the posterior branches, the posterior cervical plexus. The anterior branches of the four inferior cervical together with the first dorsal form the brachial plexus. Anterior cervical nerves. — The Anterior branch of the first cervical nerve escapes from the vertebral canal through the groove upon the posterior arch of the atlas which supports the vertebral artery, beneath which it lies. It then descends in front of the transverse process of the atlas, and forms a loop by communicating with an ascending branch of the second nerve. The Anterior branch of the second cervical nerve divides into three branches at its exit from the intervertebral foramen between the atlas and axis, viz. an ascending branch, which completes the arch of communication with the first nerve; and two descending branches, which communicate with the third nerve. The Anterior branch of the tliird cervical nerve, double the size of the preceding, divides at its exit from the intervertebral foramen into numerous branches, some of which communicate and form loops and anastomoses with the second, and others with the fourth nerve. The Anterior branch of the fourth cervical nerve, of the same size with the preceding, communicates by anastomosis with the third, and sends a small branch downwards to the fifth nerve. Its prin- cipal branches pass downwards and outwards across the posterior triangle of the neck, towards the clavicle and acromion. The Cervical Plexus is constituted by the loops of communica- tion, and by the anastomoses which take place between the anterior branches of the four first cervical nerves. The plexus rests upon the levator anguli scapulae, posterior scalenus, and splenius muscle, and is covered in by the sterno-mastoid and platysma. The branches of the cervical plexus may be arranged into three groups, superficial ascending, superficial descending; and deep — CERVICAL BKANCHES. 405 ( Superficialis colli, Ascending. < Auricularis magnus, a n ■ ii i Occipitalis minor. Superficial <^ \ A.rn.^i«w Deep. rx J- » Acromiales, Descending. | ciaviculares. Communicating branches, Muscular, Communicans noni. Phrenic. The Superficialis colli is formed by communicating branches from the second and third cervical nerves ; it curves around the posterior border of the sterno-mastoid and crosses obliquely behind the ex- ternal jugular vein to the anterior border of that muscle, where it divides into an ascending and a descending branch ; the descending branch is distributed to the integument on the side and front of the neck ; the ascending branch passes upwards to the submaxillary region, and divides into four or five filaments, some of which pierce the platysma myoides and supply the integument as high up as the chin and the lower part of the face, while others form a plexus with the descending branches of the facial nerve beneath the platysma. One or two filaments from this nerve accompany the external jugular vein. The Auricularis magnus also proceeds from the second and third cervical nerve ; it curves around the posterior border of the sterno- mastoid and ascends upon that muscle, lying parallel with the ex- ternal jugular vein to the parotid gland, where it divides into a superficial and deep branch. The superficial branch is distributed to the integument over the parotid gland, and to the anterior surface of the external ear. Therieep branch pierces the parotid gland and crosses the mastoid process, where it divides into branches which supply the posterior part of the pinna and the integument of the side of the head. Previously to its division the auricularis magnus nerve sends oflf several facial branches which are distributed to the cheek. The terminal branches of this nerve communicate with branches of the anterior auricular, the facial, and the occipitalis major nerve. The Occipitalis minor arises from the second cervical nerve ; it curves around the posterior border of the sterno-mastoid above the preceding and ascends upon that muscle, parallel with its posterior border, to the lateral and posterior side of the head. It is distributed to the integument in this region. The Acromiales and Ciaviculares are two or three large nerves which descend from the plexus and divide into numerous branches which pass downwards over the clavicle, and are distributed to the integument of the upper and anterior part of the chest from the sternum to the shoulder. The Communicating branches are filaments which arise from the loop between the first and second cervical nerve, and pass inwards 406 POSTERIOR CERVICAL PLEXUS. to communicate with the sympathetic, the pneumogastric, and the lingual nerve. The three first cervical nerves send branches to the first cervical ganglion ; the fourth sends a branch to the trunk of the sympathetic, or to the middle cervical ganglion. From the second cervical nerve a large branch is given off which goes to join the spinal accessory nerve. The JSluscular branches proceed from the third and fourth cervical nerves; they are distributed to the trapezius, levator anguli scapula;, and rhomboidei muscles. From the second cervical nerve a small muscular branch is sent to the rectus anticus major. The Communicans noni is a long slender branch formed by fila- ments from the first, second, and third cervical nerves : it descends upon the outer side of the internal jugular vein, and forms a loop with the descendens noni over the sheath of the carotid vessels. The Phrenic nerve is formed by filaments from the third, fourth, and fifth cervical nerves, receiving also a branch from the sympa- thetic. It descends to the root of the neclv, resting upon the scalenus anticus muscle, then crosses the first portion of the subclavian artery, and enters the chest between it and the subclavian vein. Within the chest it passes through the middle mediastinum, between the pleura and pericardium to the diaphragm to which it is distri- buted, and communicates in the abdomen with the phrenic and solar plexus, and on the right side with the hepatic plexus. The left phrenic nerve is rather longer than the right, from the inclina- tion of the heart to the left side. Posterior cervical nerves. — The posterior division of the first cer- vical nerve (sub-occipital), larger than the anterior, escapes from the vertebral canal through the opening for the vertebral artery, lying posteriorly to that vessel, and emerges into the triangular space formed by the rectus posticus major, obliquus superior, and obliquus inferior. It is distributed to the recti and obliqui muscles, and sends one or two filaments downwards to communicate with the second cervical nerve. The posterior branch of the second cer- vical nerve is three or four times greater than the anterior branch, and is larger than the other posterior cervical nerves. The poste- rior branch of the third cervical nerve is smaller than the preceding, but larger than the fourth ; and the other posterior cervical nerves go on progressively decreasing to the seventh. Posterior Cervical Plexus. — This plexus is constituted by the succession of anastomosing loops and communications which pass between the posterior branches of the first, second, and third cer- vical nerves. It is situated between the complexus and semispinaHs colli, and its branches are the — Musculo-c utaneous. Occipitalis major. The Musculo-cutaneous branches pass inwards between the com- plexus and semispinalis colli to the ligamenlum nuchse, distributing BRACHIAL PLEXUS. 407 muscular filaments in their course. They then pierce the aponeu- rosis of the trapezius and become subcut^aneous, sending branches outwards to supply the integument of the posterior aspect of the neck, and upwards to the posterior region of the scalp. The Occipitalis major is the direct continuation of the second cervical nerve ; it ascends obliquely inwards, between the obliquus inferior and complexus, pierces the complexus and trapezius, after passing for a short distance between them, and ascends upon the posterior aspect of the head between the integument and occipito- frontalis, in company with the occipital artery. The occipitalis major sends numerous branches to the muscles of the neck, and is distributed to the integument of the scalp, as far forwards as the middle of the vertex of the head. The Posterior branches of the fourth, fifth, sixth, seventh, and eighth nerves pass inwards between the muscles of the back in the cervical and upper part of the dorsal region, and reaching the sur- face near to the middle line are reflected outwards to be distributed to the integument. The fourth and fifth are nearly transverse in their course, and lie between the semispinalis colli and complexus. The sixth, seventh, and eighth are directed nearly vertically down- wards ; they pierce the aponeurosis of origin of the splenius and trapezius. BRACmAL PLEXUS. The Brachial OY axillary plexus of nerves is formed by communi- cations between the anterior branches of the four last cervical and first dorsal nerve. These nerves are all similar in size, and their mode of disposition in the formation of the plexus is the following: the fifth and sixth nerves unite to form a common trunk, which soon divides into two branches ; the last cervical and first dorsal also unite immediately upon their exit from the intervertebral fora- mina, and the common trunk resulting from their union after a short course also divides into two branches ; the seventh nerve passes outwards between the common trunks of the two preceding, and opposite the clavicle divides into a superior branch which unites with the inferior division of the superior trunk, and an inferior branch which communicates with the superior division of the inferior trunk ; from these divisions and communications the brachial plexus results. The brachial plexus communicates with the cervical plexus by means of a branch sent from the fourth to the fifth nerve, and by the inferior branch of origin of the phrenic nerve. The plexus is broad in the neck, narrow as it descends into the axilla, and again enlarges at its lower part where it divides into its six terminal branches. Relations. — The brachial plexus is in relation in the neck with the two scaleni muscles, between which its nerves issue; lower down it is placed between the clavicle and subclavius muscle above, and the first rib and first serration of the serratus magnus muscle below. 408 BRACHIAL PLEXUS BRANCHES. In the axilla, it is situated at first to the outer side and then behind the axillary artery, resting by its outer border against the tendon of the subscapularis muscle. At this point it completely surrounds the artery by means of the two cords which are sent oft' to form the median nerve. Its Branches may be arranged into two groups, humeral and de- scending, — Humeral Branches. Descending Branches. Superior muscular, External cutaneous, Short thoracic, Internal cutaneous, Long thoracic. Lesser internal cutaneous. Supra-scapular, Median, Subscapular, Ulnar, Inferior muscular. Musculo-spiral, Circumflex. The superior Muscular nerves are several large branches which are given off by the fifth cervical nerve above the clavicle ; they are — a subclavian branch to the subclavius muscle, which usually sends a communicating filament to the phrenic nerve ; — a rhomboid branch to the rhomboidei muscles; and frequently an angular branch to the levator anguli scapulffi. The Short thoracic nerves are two in number ; they arise from the brachial plexus at a point parallel with the clavicle, and are divisible into an anterior and a posterior branch. The anterior branch passes forwards between the subclavius muscle and the subclavian vein, and is distributed to the pectoralis major muscle, entering it by its costal surface. In its course it gives off a branch which forms a loop of communication with the posterior branch. The posterior branch passes forward beneath the axillary arteiy and unites with the communicating branch of the preceding to form a loop, from which numerous branches are given ofl' to the pectoraUs major and pectoralis minor. The Long thoracic nerve (external respiratory of Bell) is a long and remarkable branch arising from the fourth and fifth cervical nerves, immediately after their escape from the intervertebral fora- mina. It passes down behind the plexus and axillary vessels, resting on the scalenus posticus muscle ; it then descends along the side of the chest upon the serratus magnus muscle to its lowest serration. It sends numerous filaments to this muscle in its course. The Supra-scapular nerve arises above the clavicle from the fifth cervical nerve and descends obliquely outwards to the supra-scapu- lar notch ; it then passes through the notch, crosses the supra-spinous fossa beneath the supra-spinatus muscle, and passing in front of the concave margin of the spine of the scapula enters the infra-spinous fossa. It is '^distributed to the supra-spinatus and infra-spinatus muscle. The Subscapular nerves are three or four in number; of which one arises from the brachial plexus above the clavicle, and the EXTERNAL CUTANEOUS NEKVE. 409 the axilla. They are distributed to the subscapularis others in muscle. The terminal branches of the plexus are arranged in the following order : the external cutaneous, and one head of the median to the outer side of the artery ; the other head of the median, internal cutaneous, and ulnar, upon its inner side; and the circumflex and musculo- spiral behind. The External Cutaneous Nerve (mus- culo-cutaneous, perforans Casserii) arises from the brachial plexus in common with the ex- ternal head of the median; it pierces the coraco-brachialis muscle and passes between the biceps and brachialis anticus, to the outer side of the bend of the elbow, where it perfo- rates the fascia, and divides into an external and internal branch. These branches pass behind the median cephalic vein and are distributed to the integu- ment upon the outer side of the fore-arm as far as the wrist, communicating with the in- ternal cutaneous and radial nerves. From the internal division at the lower third of the fore- arm a branch is given off which accompanies the radial artery to the wrist and supplies several filaments to the synovial membranes of the wrist, both on its anterior and posterior aspect. The Branches of the external cutaneous nerve in the upper arm are distributed to the coraco-brachialis, biceps, and brachialis anti- cus muscle. The Internal Cutaneous Nerve is one of Fig. 132.* * The Brachial plexus of nerves with its branches and their distribution. 1. The brachial plexus. 2. The short thoracic nerves. 3. The long thoracic or external respiratory of Bell. 4. The phrenic nerve. 5. The supra-scapular nerve. 6. The subscapular nerves. 7. The external cutaneous nerve. 8. Tiie point at which it pierces the coraco-brachialis muscle. 9. The internal cutaneous nerve : the point at which it pierces the deep fascia. 10. The origin of the median nerve by two heads. 11. The bend of the elbow where the median passes between the two heads of the pronator radii teres, and of the flexor sublimis digitorum. 12. Its muscular branches. 13. Its anterior interosseous branch. 14. The point at which the nerve passes beneath the annular ligament and divides into six terminal branches. The branch which crosses the annular ligament is the superficial palmar. 15. The ulnar nerve giving off several muscular branches to the triceps. IG. Tlie point at which it passes between the two heads of the flexor carpi ulnaris. 17. Its dorsal branch, 18. The termination of tlic nerve, dividing into a superficial and deep palmar branch. 19. The nmsculo- spiral nerve. 20. IVLuscular branches. 21. Spiral cutaneous nerve. 22. The posterior interosseous nerve piercing the supinator brcvis muscle. 23. Tlic radial nerve. The two last nerves are the terminal branclics of the musculo-spiral. 24. The point at which the radial nerve pierces the deep fascia. 25. The circumflex nerve. 52 ' 410 MEDIAN ^•ERVE BRANCHES. the internal and smallest of the branches of the axillary plexus ; it arises from the plexus in common with the ulnar and internal head of the median, and passes down the inner side of the arm in com- pany with the basilic vein. At about the middle of the arm it pierces the deep fascia by the side of the basilic vein and divides into two branches, anterior and posterior. Each of these branches subdivides into several filaments, which are distributed to the integument upon the anterior and posterior aspect of the ulnar border of the fore-arm as far as the wrist. At the bend of the elbow the filaments of the anterior branch pass in front of the median basilic vein, and some- times behind that vessel. On the fore-arm the nervous filaments communicate with the external cutaneous and with the ulnar nerve. The Lesser Internal Cutaneous Nerve or nerve of Wrlsherg is very irregular in point of origin. It is a long and slender nerve, and usually arises from the common trunk of the last cervical and first dorsal nerve. Passing downwards into the axillary space it com- municates with the external branch of the first intercosto-humeral nerve, and descends upon the inner side of the internal cutaneous nerve, to the middle of the posterior aspect of the upper arm, where it pierces the fascia and is distributed to the integument of the elbow, communicating with the filaments of the internal cutaneous and spiral cutaneous. In its course it gives off two or three cutaneous filaments to the integument of the inner and anterior aspect of the upper arm. The Median Nerve has received its name from taking a course along the middle of the arm to the palm of the hand; it is, there- fore, intermediate in position, betw^een the radial and ulnar nerves. It commences by two heads, which embrace the axillary artery ; lies at first to the outer side of the brachial artery, which it crosses at its middle ; and descends on its inner side to the bend of the elbow. It then passes between the two heads of the pronator radii teres and flexor sublimis digitorum muscles, and runs down the fore-arm be- tween the flexor sublimis and profundus, and beneath the annular ligament into the palm of the hand. The branches of the median nerve are, — Muscular, Superficial palmar, Anterior interosseous, Digital. The Muscular branches are given off by the nerve at the bend of the elbow ; they are distributed to all the muscles on the anterior aspect of the fore-arm, with the exception of the flexor carpi ulnaris, and to the periosteum. The branch to the pronator radii teres sends off reflected branches to the elbow-joint. The Jlnterior interosseous is a large branch accompanying the anterior interosseous artery, and supplying the deep layer of muscles in the fore-arm. It passes beneath the pronator quadratus muscle, and ])icrccs flic interosseous membrane near to the wrist. On reaching the posterior aspect of the wrist it joins a large and ULNAR NERVE ERANCPIES. 411 remarkable ganglion, which gives off a number of branches for the supply of the joint. The Superficial falmar h-anc/i arises from the median nerve at about the lower fourth of the fore-arm ; it crosses the annular liga- ment, and is distributed to the integument over the ball of the thumb and in the palm of the hand. The median nerve at its termination in the palm of the ■ hand is very considerably spread out and flattened, and it divides into six branches, one muscular and five digital. The muscular branch is distributed to the muscles of the ball of the thumb. The digital branches are thus arranged : — two pass outwards to the thumb ; one to the radial side of the index finger ; one subdivides for the supply of the adjoining sides of the index and middle fingers ; and the re- maining one, for the supply of the adjoining sides of the middle and ring fingers. The digital nerves in their course along the fingers are situated to the inner side of the digital arteries. Opposite the base of the first phalanx each nerve gives off" a dorsal branch which runs along the border of the dorsum of the finger. Near the extremity of the finger the digital nerve divides into a 'palmar and a dorscd branch ; the former supplying the sentient extremity of the finger, and the latter the structures around and beneath the nail. The digital nerve maintains no communication with its fellow of the opposite side. The Ulnar Nerve is somewhat smaller than the median, behind which it lies, gradually diverging from it in its course. It arises from the brachial plexus in common with the internal head of the median and the internal cutaneous nerve, and runs down the inner side of the arm, to the groove between the internal condyle and olecranon, resting upon the internal head of the triceps, and accompanied by the inferior profunda artery. At the elbow it is superficial, and supported by the inner condyle, against which it is easily com- pressed, giving rise to the thrilling sensation along the inner side of the fore-arm and little finger, ascribed to striking the " funny bone." It then passes between the two heads of the flexor carpi ulnaris and descends along the inner side of the fore-arm, crosses the annular ligament, and divides into two branches, superficial and deep palmar. At the commencement of the middle third of the fore-arm, it becomes applied against the artery, and lies to its ulnar side, as far as the hand. The Branches of the ulnar nerve are, — Muscular in the upper arm, Dorsal branch. Articular, Superficial palmar, Muscular in the fore-arm. Deep palmar. Anastomotic, The Muscular branches in the upper arm arc a few filaments dis. tributed to the triceps. The Articular branches are several filaments to the elbow-joint. 412 3IUSCULO-SPIRAL NERVE. which are given off from the nerve as it lies in the groove betw^een the inner condyle and the olecranon. The Muscular branches in the fore-arm are distributed to the flexor carpi ulnaris and flexor profundus digitorum muscle. The jlnastomotic branch is a small nerve which arises from the ulnar at about the middle of the fore-arm, and divides into a deep and a superficial branch ; the former accompanies the ulnar artery, and the latter pierces the deep fascia and communicates with the internal cutaneous nerve. The Dorsal branch passes beneath the tendon of the flexor carpi ulnaris, at the lower third of the fore-arm, and divides into branches w^hich supply the integument and two fingers and a half on the pos- terior aspect of the hand, and communicate with the radial nerve. The Superficial palmar branch divides into three filaments, which are distributed, — one to the ulnar side of the little finger, one to the adjoining borders of the httle and ring fingers, and a communica- ting branch to join the median nerve. The Deep 'palmar branch passes between the abductor and flexor minimi digiti, to the deep palmar arch, supplying the muscles of the little finger, and the lumbricales and interossei in the palm of the hand. The MuscuLO-spiRAii Nerve, the largest branch of the brachial plexus, arises from the posterior part of the plexus by a common trunk with the circumflex nerve. It passes downwards from its origin in front of the tendons of the latissimus dor si and teres major muscle, and winds around the humerus in the spiral groove, accom- panied by the superior profunda artery, to the space between the brachialis anticus and supinator longus muscle, and thence onwards to the bend of the elbow, where it divides into two branches, the posterior interosseous and radial nerve. The Branches of the musculo-spiral nerve are, — Muscular, Spiral cutaneous. Radial, Posterior interosseous. The Muscular branches are distributed to the triceps, to the su- pinator longus, and to the extensor carpi radialis longior. The Spiral cutaneous nerve pierces the deep fascia immediately below the insertion of the deltoid muscle, and passes down the outer side of the fore-arm as far as the wrist. It is distributed to the integument. The Radial nerve runs along the radial side of the fore-arm to the commencement of its lower third ; it then passes beneath the tendon of the supinator longus, and at about two inches above the wrist-joint divides into an external and an internal branch. The external branch, the smaller of the two, is distributed to the outer border of the hand and of the thumb. The internal branch crosses CIRCUMFLEX NERVE DORSAL NERVES. 413 the direction of the extensor tendons of the thumb and divides into several filaments for the supply of the ulnar border of the thumb, the radial border of the index finger, and the adjoining borders of the index and middle fingers. It communicates on the back of the hand with the dorsal branch of the ulnar nerve. In the upper third of the fore-arm the radial nerve lies beneath the border of the supinator longus muscle. In the middle third it is in relation with the radial artery lying to its outer side. It then quits the artery, and passes beneath the tendon of the supinator longus, to reach the back of the hand. The Posterior interosseous nerve separates from the radial at the bend of the elbow, pierces the supinator brevis muscle, and emerges from its lower border on the posterior aspect of the fore-arm, where it divides into branches which supply the whole of the muscles on the posterior aspect of the fore-arm. One branch, longer than the rest, descends to the posterior part of the wrist, and forms a large gangliform swelling (the common character of nerves which supply joints), from which numerous branches are distributed to the wrist- joint. The Circumflex Nerve arises from the posterior part of the brachial plexus by a common trunk with the musculo-spiral nerve. It passes downwards over the border of the subscapularis muscle, winds around the neck of the humerus, with the posterior circumflex artery, and terminates by dividing into numerous branches which supply the deltoid muscle. The Branches of the circumflex nerve are muscular and cuta- neous. The Muscular branches are distributed to the subscapularis, teres minor, teres major, latissimus dorsi, and deltoid. The cuta- neous branches pierce the deltoid muscle and are distributed to the integument of the shoulder. One of these cutaneous branches, larger than the rest, winds around the posterior border of the del- toid, and divides into filaments which pass in a radiating direction across the shoulder and are distributed to the integument. DORSAL NERVES. The dorsal nerves are twelve in number on each side ; the first appears between the first and second dorsal vertebra, and the last between the twelfth dorsal and first lumbar. Each nerve, as soon as it has escaped from the intervertebral foramen, divides into two branches ; a dorsal branch and the true intercostal nerve. The Dorsal branches pass directly backwards between the trans- verse processes of the vertebrae, lying internally to the anterior costo-transverse ligament, where each nerve divides into a muscular and a musculo-cutaneous branch. The muscular branch enters the substance of the muscles in the direction of a line corresponding with the interval of separation between the longissimus dorsi and sacro-lumbalis, and is distributed to the muscles of the back. The musculo-cutaneous branch passes inwards, crossing the semispinalis 414 INTERCOSTAL NERVES. dorsi to the spinous processes of the dorsal vertebrae ; it then pierces the aponeurosis of origin of the trapezius and latissimus dorsi, and divides into branches which are inclined outwards beneath the in- tegument to which they are distributed. The posterior branch of the first dorsal nerve resembles in its mode of distribution the pos- terior branches of the last cervical. The posterior branches of the four last dorsal nerves pass obliquely downwards and outwards into the substance of the erector spinas in the situation of the interspace between the sacro-lumbalis and longissimus dorsi. After supplying the erector spinse and communicating freely with each other they approach the surface along the outer border of the sacro-lumbalis, where they pierce the aponeuroses of the transversalis, internal oblique, serratus posticus inferior, and latissimus dorsi muscle, and divide into internal branches which supply the integument upon the middle line in the lumbar region, and external branches which are distributed to the integument upon the side of the lumbar and in the gluteal region. The Intercostal nerves receive one or two filaments from the ad- joining ganglia of the sympathetic, and pass forwards in the inter- costal space with the intercostal vessels, lying below the veins and artery. At the termination of the intercostal spaces near to the sternum, the nerves pierce the intercostal and pectoral muscles, and incline downwards and outwards to be distributed to the integu- ment of the mamma and front of the chest. Those which are situ- ated between the false ribs pass behind the costal cartilages, and between the transversalis and obliquus internus muscles ; and sup- ply the rectus and the integument on the front of the abdomen. The first and last dorsal nerves are exceptions to this distribution. The anterior branch of the first dorsal nerve divides into two branches ; a smaller, which takes its course along the under surface of the first rib to the sternal extremity of the first intercostal space ; and a larger, which crosses obliquely the neck of the first rib, to join the brachial plexus. The last dorsal nerve, next in size to the first, sends a branch of communication to the first lumbar nerve, to assist in forming the lumbar plexus. The Branches of each intercostal nerve are a muscular twig to the intercostal and neighbouring muscles, and a cutaneous branch which is given off at about the middle of the arch of the rib. The first dorsal nerve has no cutaneous branch. The cutaneous branches of the second and third intercostal nerves are named, from their origin and distribution, intercosto-humeral. The First intercosto-humeral nerve is of large size ; it pierces the external intercostal muscle of the second intercostal space, and divides into an internal and an external branch. The internal branch is distributed to the integument of the inner side of the arm. The external branch communicates with the nerve of Wrisberg, and divides into filaments which supply the integument upon the inner and posterior aspect of the arm as far as fhe elbow. This nerve sometimes takes the place of the nerve of Wrisberg. LUMBAR NERVES. 415 The Second intercosto-humeral nerve is much smaller than the preceding ; it emerges from the external intercostal muscle of the third intercostal space between the serrations of the serratus magnus muscle, and divides into filaments which are distributed to the inte- gument of the shoulder. One of these filaments may be traced in- wards to the integument of the mamma. The cutaneous branches of the fourtli and fifth intercostal nerve send twigs to the integument of the mammary gland. The cuta- neous branches of the remaining intercostal nerves reach the surface between the serrations of the serratus magnus muscle above and the external oblique below, and each nerve divides into an anterior and a fosterior branch ; the former being distributed to the integu- ment of the antero-lateral, and the latter to that of the lateral part of the trunk. The cutaneous branch of the last dorsal nerve is remarkably large ; it pierces the internal and external oblique muscles, crosses the crest of the ilium, and is distributed to the integument of the gluteal region. LUMBAR NERVES. There are five pairs of lumbar nerves, of which the first makes its appearance between the first and second lumbar vertebra, and the last between the fifth lumbar and the base of the sacrum. The anterior branches increase in size from above downwards, and form the lumbar plexus. The posterior branches diminish in size from above downwards ; they form loops of communication with each other, and are distributed to the muscles of the lumbar region, and to the integument over the sacrum in the same manner with the posterior branches of the lower dorsal nerves. The lumbar -plexus is formed by the communications and anasto- moses which take place between the anterior branch of the last dorsal and of the five lumbar nerves. It is narrow above and in- creases in breadth inferiorly, is situated between the transverse processes of the lumbar vertebrse and the psoas magnus muscle, and receives filaments of communication from the lumbar ganglia of the sympathetic. The Branches of the lumbar plexus are the Musculo-cutaneous, External-cutaneous, Genito-crural, Crural, Obturator, Lumbo-sacral. The Musculo-cutaneous nerves, two in number, superior and infe- rior, proceed from the first lumbar nerve. The superior musculo- cutaneous nerve (ilio-scrotal) passes outwards between the posterior fibres of the psoas magnus, and crosses obliquely the quadratus lum- 416 BRANCHES OF THE LUMBAR PLEXUS. 133.* borum muscle to the crest of the iUiim. It then pierces the transversalis muscle, winds along the crest of the ilium between the trans- . versalis and internal oblique, and divides into ' two branches, abdominal and scrotal. The abdominal branch is continued forwards par- allel with the last intercostal muscle to the rectus muscle, to which it is distributed, send- L ing a branch forwards to the integument of the abdomen. The scrotal branch opposite the anterior superior spinous process of the ilium, communicates with the inferior mus- culo-cutaneous nerve, and escapes at the ex- ternal abdominal ring, with the spermatic cord in the male, and with the round liga- ment in the female. It is distributed to the integument of the front of the os pubis and of fairn I II the groin, to the scrotum in the male and to the greater labium in the female. The infe- rior musculo-cutaneous nerve also arises from the first lumbar nerve. It is much smaller than the preceding, crosses the quadratus lumborum below it, and takes the same course along the crest of the ilium. It terminates, either by communicating with the superior nerve, or by escaping with it through the ex- ternal abdominal ring and following the same distribution. The External cutaneous nerve (inguino-cu- taneous) proceeds from the second lumbar nerve. It pierces the posterior fibres of the psoas muscle ; and crossing the ihacus ob- liquely, lying beneath the iliac fascia to the anterior superior spinous process of the ihum, passes into the thigh beneath Poupart's liga- ment. It then pierces the fascia lata at about two inches below the anterior superior spine * A diagram showin;^ the lumbar and sacral plexuses, with the nerves of the lower extremity. ] . The five lumbar nerves ; whieh, with a branch from the last dorsal, constitute the lumbar plexus. 2. The four upper sacral nerves ; wliich, with the last lumbar, form the sacral plexus. 3. The two musculo-cutaneous nerves, branches of the first lumbar nerve. 4. The external-cutaneous nerve. 5. The gcnilo-crural nerve. 6. The crural or femoral nerve. 7. Its muscular branches. 8. Its cutaneous branches, middle cutaneous. 9. Its descending or saphenous branches. 10. The short saphenous nerve. 11. The long or internal saphenous. 12. The obturator nerve. 13. The gluteal nerve; a branch of the lumbo-sacral nerve. 14. The interntil pudic nerve. 15. The lesser ischiatic nerve. 10. The greater ischiatic nerve. 17. The popliteal nerve. 18. The peroneal nerve. 1!). The muscuhir Ijranchcs of the ])0|)]jtc!al. 20. Tlie posterior tibial nerve ; dividing at 21, into the two plantar nerves. 22. The external saphenous nerve, formed by the union of tlic communieans poplitci and connnunicans pcronei. 23. The anterior tibial nerve. 24. The musculo-cutaneous nerve, piercing the dcci» fascia, and dividing into two cutaneous branches, for the supply of the dorsum of the foot. CRURAL NERVE BRANCHES. 417 of the ilium, and divides into two branches, anterior and posterior. The 'posterior branch crosses the tensor vaginae femoris muscle to the outer and posterior side of the thigh, and supplies the integu- ment in that region. The anterior nerve divides into tv^^o branches which are distributed to the integument upon the outer border of the thigh, and to the articulation of the knee. The Genito-crural proceeds also from the second lumbar nerve. It traverses the psoas magnus from behind forwards, and runs down on the anterior surface of that muscle and beneath its fascia to near Poupart's ligament, where it divides into a genital and a crural branch. The genital branch crosses the external iliac artery to the internal abdominal ring and descends along the spermatic canal, lying behind the cord to the scrotum, where it divides into branches which supply the spermatic cord and cremaster in the male, and the round ligament in the female. At the internal abdominal ring this nerve sends some filaments to the lower border of the inter- nal oblique and transversalis muscle. The crural branch enters the sheath of the femoral vessels in front of the femoral artery. It pierces the sheath below Poupart's ligament, and is distributed to the integument of the anterior aspect of the thigh as far as its middle. This nerve often communicates with a cutaneous branch of the crural nerve in the thigh. The Crural, or Femoral Nerve, is the largest of the divisions of the lumbar plexus ; it is formed by the union of the branches from the second, third, and fourth lumbar nerves, and, emerging from beneath the psoas muscle, passes downwards in the groove between it and the iliacus, and beneath Poupart's ligament into the thigh, where it spreads out and divides into numerous branches. At Pou- part's ligament it is separated from the femoral artery by the breadth of the psoas muscle, which at this point is scarcely more than half an inch in diameter, and by the iliac fascia, beneath which it lies. Branches. — While situated within the pelvis the crural nerve gives off several muscular branches to the iliacus and psoas. On emerging from beneath Poupart's ligament the nerve becomes flat- tened and divides into numerous branches, which may be arranged into, — Cutaneous, Muscular, Branch to the femoral sheath, Short saphenous nerve, Long saphenous nerve. The Cutaneous branches are four or five in number ; they pierce the fascia lata at irregular distances below Poupart's ligament, and are distributed to the integument on the front and inner side of the thigh, constituting the middle and internal cutaneous nerves. Two of these nerves pass through the sartorius muscle before becoming cutaneous. 53 418 SAPHE^"OUS NERVE, The Muscular branches are several large twigs which are distri- buted to the muscles on the anterior aspect of the thigh. Two or three of these branches are sent to the sartorius ; one to the tensor vaginse femoris, one to the rectus, one to the vastus externus, and one of very large size to the vastus internus and crurseus. The latter sends off a cutaneous branch and several filaments to the periosteum of the lower part of the femur, and to the articulation of the knee. The Branch to the femoral sheath is a small nerve which passes inwards to the sheath of the femoral vessels at the upper part of the thigh, and divides into several filaments which surround the femoral and profunda vessels. Two of these filaments, one from the front, and the other from the posterior part of the sheath, unite to form a small nerve which escapes from the saphenous opening and passes downwards with the saphenous vein. Other filaments are distributed to the adductor muscles, and communicate with the internal saphe- nous nerve. The Short saphenous nerve inclines inwards to the sheath of the femoral vessels, and divides into a superficial and a deep branch. The superficial branch passes downwards along the inner border of the sartorius muscle to the lower third of the thigh, it then joins the internal saphenous vein and accompanies that vessel to the knee- joint, when it terminates by communicating with the long saphenous nerve. The deep branch descends upon the outer side of the sheath of the femoral vessels, and crosses the sheath at its lower part to a point opposite to the termination of the femoral artery, where it divides into several filaments which constitute a plexus by their communication with other nerves. One of these filaments commu- nicates with the descending branch of the obturator nerve, another with the long saphenous nerve, and two or three are distributed to the integument upon the internal and posterior aspect of the thigh. The Long saphenous nerve inclines inw^ards to the sheath of the femoral vessels, and entering the sheath accompanies the femoral artery to the tendinous canal formed by the adductor longus and vastus internus muscles. It then quits the artery, and, passing be- tween the tendons of the sartorius and gracilis, descends along the inner side of the leg with the internal saphenous vein, crosses in front of the inner ankle, and is distributed to the integument on the inner side of the foot as far as the great toe. The internal saphenous nerve receives at its upper part a large branch of communication from the obturator nerve, and another at the inner side of the knee-joint. In its course it gives off" an articu- lar branch for the supply of the synovial membrane of the knee- joint, and several cutaneous nerves ; one to the integument of the thigh ; one, of large size, which pierces the lower part of the sartorius and distributes filaments to the integument of the knee, and some to the intogiirnent of the leg, of the inner ankle, and of the inner side of the loot. The Obturator nerve is formed by a branch from the third, and SACRAL NERVES. 419 another from the fourth lumbar nerve. It passes downwards in the fibres of the psoas muscle through the angle of bifurcation of the common ihac vessels, and along the inner border of the brim of the pelvis, to the obturator foramen, where it joins the obturator artery. Having escaped from the pelvis it gives oft' two small branches to the obturator externus muscle and divides into four branches, — three anterior, which pass in front of the adductor brevis, supplying that muscle, the pectineus, the adductor longus, and the gracilis ; and a posterior branch which passes downwards behind the adductor brevis, and ramifies in the adductor magnus. From the branch which supplies the adductor brevis, a communi- cating filament passes outwards through the angle of bifurcation of the femoral vessels to unite with the long saphenous nerve. From the branch to the adductor longus a long cutaneous nerve proceeds, which issues from beneath the inferior border of that muscle, sends filaments of communication to the plexus of the short saphenous nerve, and descends to the inner side of the knee, where it pierces the fascia and communicates with the long saphenous nerve. It is distributed to the integument upon the inner side of the leg. From the posterior branch an articular branch is given off which pierces the adductor magnus muscle, accompanies the pophteal artery, and is distributed to the synovial membrane of the knee-joint on its pos- terior aspect. The Lumbosacral nerve. — The anterior division of the fifth lum- bar nerve, conjoined with a branch from the fourth, constitutes the lumbo-sacral nerve which descends over the base of the sacrum into the pelvis, and assists in forming the sacral plexus. SACRAL NERVES. There are six pairs of sacral nerves ; the first escapes from the vertebral canal through the first sacral foramina, and the two last between the sacrum and coccyx. The • posterior sacral nerves are very small and diminish in size from above downwards ; they communicate with each other immediately after their escape from the posterior sacral foramina, and divide into branches which are distributed to the muscles and integument in the sacral and gluteal region. The anterior sacral nerves diminish in size from above downwards ; the first is of large size and unites with the lumbo- sacral nerve ; the second, of equal size, unites with the preceding ; the third, which is scarcely one-fourth the size of the third, also joins with the preceding nerves in the formation of the sacral plexus ; the fourth is atjout one-third the size of the preceding sacral nerve, it divides into several branches, one of which is sent to the sacral plexus, a second to join the fifth sacral nerve, a third to the viscera of the pelvis, communicating with the hypogastric plexus, and a fourth to the coccygeus muscle, and to the integument around the anus. The fifih anterior sacral nerve presents about half the size of the fourth ; it divides into two branches, one of which communicates 420 SACRAL PLEXUS. with the Toiirth, the other M'ith the sixth. The sixth sacral nerve is exceedingly small ; it gives off an ascending filament which is con- tinuous with the communicating branch of the fifth ; and a descend- ino- filament which passes downwards by the side of the coccyx and traverses the fibres of the great sacro-ischiatic ligament to be distributed to the gluteus maximus and to the integument. All the anterior sacral nerves receive branches from the sacral ganglia of the sympathetic at their emergence from the sacral foramina. The Sacral plexus is formed by the lumbo-sacral, and by the anterior branches of the four upper sacral nerves. The plexus is triangular in form, the base corresponding with the whole length of the sacrum, and the apex with the lower part of the great ischiatic foramen. It is in relation behind with the pyriformis muscle, and in front with the pelvic fascia which separates it from the branches of the internal iliac artery, and from the viscera of the pelvis. The Branches of the sacral plexus are divisible into the internal and the external ; they may be thus arranged : Internal. External. Visceral, Muscular, Muscular. Gluteal, Internal pudic, Lesser ischiatic, Greater ischiatic. The Visceral nerves are three or four large branches which are derived from the fourth and fifth sacral nerves : they ascend upon the side of the rectum and bladder ; in the female upon the side of the rectum, the vagina and the bladder ; and interlace with the branches of the hypogastric plexus, sending in their course numerous filaments to those viscera. The Muscular branches given off within the pelvis are one or two twigs to the levator ani ; an obturator branch which curves around the spine of the ischium to reach the internal surface of the obturator internus muscle ; and an hoemorrhoidal nerve which descends to the termination of the rectum to supply the sphincter and the in- tegument. The Muscular branches supplied by the sacral plexus externally to the pelvis are, a branch to the pyramidalis ; a branch to the gemellus superior ; and a branch of moderate size which descends between the gemelli muscles and the ischium, and is distributed to the gemellus inferior, the quadratus fcmoris, and to the capsule of the hip-joint. The Gluteal nerve is a branch of the lumbo-sacral ; it passes out of the pelvis with the gluteal artery, through the great sacro-ischiatic foramen, and divides into a superior and an inferior brancii. The superior branch follows the direction of the su[)erior curved line of the ilium, accompanying the deep superior branch of the gluteal artery, and sending filaments to the gluteus medius and minimus. LESSER ISCHIATIC NERVE. 421 The inferior passes obliquely downwards and forwards between the gluteus medius and minimus, distributing numerous filaments to both, and terminates in the tensor vaginae femoris muscle. The Internal pudic nerve arises from the lower part of the sacral plexus, passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, and takes the course of the internal pudic artery. While situated beneath the obturator fascia it lies below that vessel and divides into a superior and an inferior branch. The superior nerve ascends upon the posterior surface of the ramus of the ischium, pierces the deep perineal fascia and ac- companies the arteria dorsalis penis to the glans to which it is dis- tributed. At the root of the penis this nerve gives off a cutaneous branch which runs along the side of the organ, and with its fellow of the opposite side supplies the integument of the upper two-thirds of the penis and of -the prepuce. The inferior or perineal nerve pursues the course of the internal pudic artery in the perineum and sends off three principal branches, — 1, an external perineal nerve which ascends upon the outer side of the crus penis, and supplies the scrotum ; 2, a superficial perineal nerve which accompanies the artery of that name and distributes filaments to the scrotum, to the integument of the under part of the penis and to the prepuce ; 3, the nerve of the bulb, which sends twigs to the sphincter ani, to the transversus perinei, and accelerator urinee, and terminates by ramify- ing in the corpus spongiosum. In the female the internal pudic nerve is distributed to the parts analogous to those of the male. The superior branch supplies the clitoris ; and the inferior the parts in the perineum and the vulva. The Lesser iscliiaiic nerve passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, and divides into muscular and cutaneous branches. The muscular branches — inferior gluteal — are distributed to the gluteus maximus ; some ascending in the substance of that muscle to its upper border, and others descending. The cutaneous branches are two in number, — the perineal cutaneous and the middle posterior cutaneous. The perineal cutaneous nerve (pudendalis longus inferior ; Soem.) curves around the tuberosity of the ischium and ascends in a direction parallel to the ramus of the ischium and os pubis to the scrotum, where it communicates with the superficial perineal nerve, and di- vides into an internal and an external branch. The internal branch passing down upon the inner side of the testis to the scrotum ; the external branch to its outer side, and both terminating in the integu- ment of the under border of the penis. The middle posterior cuta- neous nerve crosses the tuberosity of the ischium, and pierces the deep fascia at the lower border of the gluteus maximus. It then passes downwards along the middle of the posterior aspect of the thigh, and of the popliteal region, and is distributed to the integument as far as the middle of the calf of the leg. In its course the nerve gives off several cutaneous branches to the integument upon the inner and outer side of the thigh, and in the popliteal region a com- 422 GREAT ISCHIATIC NERVE. municating branch wliich pierces the fascia of the leg and unites with the external saphenous nerve. The Great Ischiatic Nerve is the largest nervous cord in the body ; it is formed by the sacral plexus, or rather it is a prolonga- tion of the plexus, and at its exit from the great sacro-ischiatic fora- men beneath the pyriformis muscle measures three quarters of an inch in breadth. It descends through the middle of the space between the trochanter major and tuberosity of the ischium, and along the posterior part of the thigh to about its lower third, where it divides into two large terminal branches, popliteal and peroneal. This division sometimes takes place at the plexus, and the two nerves descend together side by side ; occasionally they are sepa- rated at their commencement by a part or the whole of the pyri- formis muscle. The nerve in its course down the thigh rests upon the gemellus superior, tendon of the obturator internus, gemellus inferior, quadralus femoris, and adductor magnus muscle, and is covered in by the gluteus maximus, and by the biceps and semiten- dinosus muscle. The Branches of the great ischiatic nerve, previously to its divi- sion, are muscular and articular. The muscular branches are given off from the upper part of the nerve and supply the biceps, the semi- tendinosus, the semi-membranosus, and the adductor magnus. The articular branch descends to the upper part of the external condyle of the femur, and divides into filaments which are distributed to the fibrous capsule and to the synovial membrane of the knee-joint. The Popliteal Nerve passes through the middle of the popliteal space, from the division of the great ischiatic nerve to the lower border of the popliteus muscle, where it passes with the artery beneath the arch of the soleus, and becomes the posterior tibial nerve. It is superficial in the whole of its course, and lies exter- nally to the vein and artery. The Branches of the popliteal nerve are muscular or sural and articular, and a cutaneous branch the communicans poplitei. The Muscular branches, of considerable size, and four or five in number, are distributed to the two heads of the gastrocnemius, to the soleus, to the plantaris, and to the popliteus. The Jirticular nerve pierces the ligamentum posticum Winslowi, and supplies the interior of the knee-joint. It usually sends a twig to the popliteus muscle. The Communicans poplitei is a large nerve which arises from the popliteal at about the middle of its course, and descends between the two heads of the gastrocnemius, and along the groove formed by the two bellies of that muscle ; at a variable distance below the articulation of the knee it receives a large branch, the communicans peronci, from the peroneal nerve, and the two together constitute the external saphenous nerve. The External saphenous nerve pierces the deep fascia below the fleshy part of the gastrocnemius muscle, and continues its course down the leg, lying along the outer border of the tendo Achillis and POSTERIOR TIBIAL NERVE. 423 by the side of the external saphenous vein which it accompanies to the foot. At the lower part of the leg it winds around the outer malleolus, and is distributed to the outer side of the foot and of the little toe, communicating with the external peroneal cutaneous nerve, and sending numerous filaments to the integument of the heel and of the sole of the foot. The Posterior Tibial Nerve is" continued along the posterior aspect of the leg from the lower border of the popliteus muscle to the posterior part of the inner ankle, where it divides into the internal and external plantar nerve. In the upper part of its course it lies to the outer side of the posterior tibial artery; it then becomes placed superficially to that vessel, and at the ankle is again situated to its outer side ; in the lower third of the leg it lies parallel with the inner border of the tendo AchilUs. The Branches of the posterior tibial nerve are three or four mus- cular twigs to the deep muscles of the posterior aspect of the leg ; the branch to the flexor longus pollicis accompanies the fibular arteiy ; one or two filaments which entwine around the artery and then terminate in the integument :* and some cutaneous branches which pass downwards upon the inner side of the os calcis and are distributed to the integument of the heel. The Internal plantar nerve, larger than the external, crosses the posterior tibial vessels to enter the sole of the foot, where it lies in the interspace between the abductor poUicis and flexor brevis digi- torum; it then enters the sheath of the latter muscle, and divides opposite the bases of the metatarsal bones into three digital branches; one to supply the adjoining sides of the great and second toe ; the second to the adjoining sides of the second and third toe ; and the third to the third and fourth toes. The distribution is precisely similar to that of the digital branches of the median nerve. In its course the internal plantar nerve gives o^ cutaneous branches to the integument of the inner side and sole of the foot ; musczdar branches to the muscles forming the inner and middle group of the sole ; a digital branch, to the inner border of the great toe ; and articidar branches to the articulations of the tarsal and metatarsal bones. The External plantar nerve, the smaller of the two, follows the course of the external plantar artery to the outer border of the musculus accessorius, beneath which it sends several large mus- cular branches to supply the abductor pollicis and the articulations of the tarsal and metatarsal bones. It then gives branches to the integument of the outer border and sole of the foot, and sends for- ward two digital branches to supply the little toe and one half the next. * It is extremely interesting' in a physiological point of view, to observe the mode of distribution of these filaments. I have traced them in relation with several, and I iiave no doubt tliat they exist in connexion with all the superficial arteries. Tliey seem to be the direct monilors to the artery of the presence or approach of danger. 424 PERONEAL NERVE. The Peroneal Nerve is one half smaller than the popliteal ; it passes downwards by the side of the tendon of the biceps, crossing the inner head of the gastrocnemius and the origin of the soleus, to the neck of the fibula, where it pierces the origin of the peroneus longus muscle, and divides into two branches, the anterior tibial and musculo-cutaneous. The Branches of the peroneal nerve previously to its division are, the communicans peronei, cutaneous, and muscular. The comniu- nicans peronei , much, smaller than the communicans poplitei, crosses the external head of the gastrocnemius to the middle of the leg. It there sends a large branch to join the communicans poplitei and constitute the external saphenous nerve, and descends very much reduced in size by the side of the external saphenous vein to the side of the external ankle, to which and to the integument of the heel it distributes filaments. The cutaneous branch descends in the integument upon the outer side of the leg, in which it ramifies. The muscular branches proceed from near the termination of the peroneal nerve ; they are distributed to the upper part of the tibialis anticus. The Anterior tibial nerve commences at the bifurcation of the peroneal, upon the head of the fibula, and passes beneath the upper part of the extensor longus digitorum, to reach the outer side of the anterior tibial artery, just as that vessel has emerged through the opening in the interosseous membrane. It descends the anterior aspect of the leg with the artery; lying at first to its outer side, and then in front of it, and near the ankle becomes again placed to its outer side. Reaching the ankle it passes beneath the annular liga- ment ; it accompanies the dorsalis pedis artery, supplies the adjoin- ing sides of the great and second toes, and communicates .with the internal peroneal cutaneous nerve. The Branches given oflf by the anterior tibial nerve are, muscular to the muscles in its course, and on the foot a tarsal branch which passes beneath the extensor brevis digitorum, and distributes fila- ments to the interossei muscles and to the articulations of the tarsus and metatarsus. The Musculo-cutaneous nerve passes downwards in the direction of the fibula, in the substance of the peroneus longus ; it then passes forwards to get between the peroneus longus and brevis, and at the lower third of the leg pierces the deep fascia, and divides into two peroneal cutaneous branches. In its course it gives off several branches to the peronei muscles. The Peroneal cutaneous nerves pass in front of the ankle-joint, and are distributed to the integument of the foot and of the toes ; the external supplying three toes and a half, and the internal one and a half. They communicate with the saphenous and anterior tibial nerve. The external saphenous nerve frequently supplies the fifth toe and the adjoining side of the fourth. CRANIAL GANGLIA. 425 SYMPATHETIC SYSTEM. The Sympathetic system consists of a series of ganglia, extending along each side of the vertebral column from the head to the coccyx, communicating with all the other nerves of the body, and distribu- ting branches to all the internal organs and viscera. It communicates with the other nerves immediately at their exit from the cranium and vertebral canal. The fourth and sixth nerves, however, form an exception to this rule ; for with these it unites in the cavernous sinus ; and with the olfactory, optic, and auditory, at their ultimate expansions. The branches of distribution accompany the arteries which supply the different organs, and form communications around them, which are called plexuses, and take the name of the artery with which they are associated : thus we have the mesenteric plexus, hepatic, plexus, splenic plexus, &c. All the internal organs of the head, neck, and trunk are supplied with branches from the sympathetic, and some of them exclusively ; hence it is considered a nerve of organic life. It is called the ganglionic nerve from the circumstance of beino^ formed by a number of ganglia ; and from the constant disposition which it evinces in its distribution, to communicate and form small knots or gangha. There are six sympathetic ganglia in the head: viz., the ganglion of Ribes ; the ciliary or lenticular ; the naso-palatine, or Cloquet's ; the spheno-palatine, or Meckel's ; the submaxillary ; and the otic, or Arnold's : three in the neck ; superior, middle, and inferior : ticelve in the dorsal region ; four in the lumbar region ; and four or five in the sacral region. Each ganglion may be considered as a distinct centre giving off branches in four different directions, viz., superior or ascending to communicate with the ganglion above ; inferior or descending, to communicate with the ganglion below; external to communicate with the spinal nerves ; and internal, to communicate with the sym- pathetic filaments of the opposite side, and to be distributed to the viscera. CRANIAL GANGLIA. Ganglion of Ribes, Ciliary, or lenticular gangUon, Naso-palatine, or Cloquet's gangHon, Spheno-palatine, or Meckel's ganglion, Submaxillary ganglion. Otic, or Arnold's ganglion. 1. The Ganglion of Ribes is a smaU ganghon situated upon the anterior communicating artery, and formed by the union of the 54 426 CRANIAL GANGLIA. sympathetic filaments, which accompany the ramifications of the two anterior cerebral arteries. These filaments are derived from the carotid plexus at each side ; and through their intervention, the ganghon of Ribes is brought into connexion with the carotid plexus, and with the other ganglia of the sympathetic. This gan- ghon, though of very spall size, is interesting, as being the superior point of union between the sympathetic chains of opposite sides of the body. Fig. 134.* 2. The Ciliary Ganglion {lenticular) is a small quandrangular and flattened ganglion situated within the orbit, between the optic nerve and the external rectus muscle; it is in close contact with the optic nerve, and is surrounded by a quantity of fat, which renders its dis- section somewhat difficult. Its branches of distribution are the ciliary, which arise from its * The cranial gang-lia of the sympathetic nerve. 1. The ganglion of Ribes. 2, The filament by which it communicates with the carotid plexus (3). 4. The ciliary or len- ticular ganglion, giving off ciliary branches for the supply of the globe of the eye. 5. Part of the inferior division of the third nerve, receiving a short thick branch from the ganglion. 6. Part of the nasal nerve, receiving a longer branch from the ganglion. 7. A slender filament sent directly backwards from the ganglion to the sympathetic branches in the cavernous sinus. 8. Part of the sixth nerve in the cavernous sinus, receiving two branches from the carotid plexus. 9. Meckel's ganglion (spheno-pala- tine). 10. Its ascending branches, communicating with the superior maxillaiy nerve. 11. Its descending branches, the posterior palatine. 12. Its anterior branches, spheno- palatine or nasal. 19. The naso-palatine branch, one of the nasal branches. * The swelling which Cloquet imagines to be a ganglion. 14. The posterior branch of the ganglion, the Vidian nerve. 15. Its carotid branch communicating with the carotid plexus. 16. Its petrosal branch, joining the angular bend of the facial nerve. 17. The facial nerve. 18. The chorda tympani nerve, which descends to join the gustatory nerve. 13. The gustatory nerve. 20. The submaxillary ganglion, receiving the chorda tympani nerve from the gustatory. 21. The superior cervical ganglion of the sym- pathetic. CRANIAL GANGLIA. 427 anterior angles by two groups : tlie upper group, consisting of about four filaments ; and the lower, of five or six. They accompany the ciliary arteries in a waving course, and divide into a number of branches which pierce the sclerotic around the optic nerve, and supply the tunics of the eyeball. A small filament is said, by Tiedemann, to accompany the arteria centralis retinae into the centre of the globe of the eye. Its branches of communication are three : — 1. From the posterior superior angle of the nasal branch of the ophthalmic nerve._ 2. K short thick branch from the posterior inferior angle to the inferior division of the third nerve. 3. A long filament, which passes back- wards to the cavernous sinus, and communicates with the carotid plexus. 3. The Naso-palatine Ganglion (Cloquet's), is a small lengthened body, situated in the naso-palatine canal. There is no difficulty in finding it in that situation. But it is still a question whether it be actually a ganglion. Arnold refuses to admit it in his plates of the cranial nerves, and denies its existence : Cruveilhier agrees with him in opinion. Mr. Charles Guthrie, demonstrator of anatomy in the Charing-Cross School of Medicine, has recently satisfied himself of its existence and of its ganglionic nature.* Its branches of distribution are, two or three small filaments to the anterior part of the palate, — anterior palatine nerves. Its branches of communication are two long delicate filaments, which ascend upon the septum narium, beneath the mucous mem- brane, and pass across the posterior part of the roof of the nares, and through the spleno-palatine foramina, to terminate in the spheno- palatine ganglion at each side. 4. The Spheno-palatine Ganglion (Meckel's) the largest of the cranial ganglia of the sympathetic, is very variable in its dimensions. It is situated in the spheno-maxillary fossa. Its branches are divisible into four groups ; ascending, descending, anterior or internal, and posterior. The branches of distribution are, the internal or nasal, four or five in number, which enter the nose through the spheno-palatine foramen, and supply the mucous membrane of the nares ; and the descending or posterior palatine branches, three in number, which pass downwards through the posterior palatine canal^ and are dis- tributed to the mucous membrane of the nose and antrum maxillare, to the velum palati and to the palate. The branches of communication are the ascending,-\ two small branches which pass upwards to join the superior maxillary nerve ; and the posterior branch or Vidian nerve. The VidianX nerve passes directly backwards from the spheno- * I have several times dissected for this ganglion, and have as yet never failed to find it.— G. + Arnold figures, in his beautiful plates of the cranial nerves, two small ascending filaments which enter the orbit and join the optic nerve. t Guido Guidi, latinized into Vidus Vidius, was professor of anatomy and medicine in the College of France in 1542. His work is posthumo'is, and was published in 1611. 428 SUB-MAXILLARY GANGLION. palatine ganglion, through the pterygoid or Vidian canal, to the foramen lacerum basis cranii, where it divides into two branches, the carotid and petrosal* The carotid branch enters the carotid canal, and joins the carotid plexus. The petrosal branch enters the cranium through the foramen lacerum basis cranii, and passes backwards beneath the Casserian ganghon, and beneath the dura mater, lying in a groove upon the anterior surface of the petrous hone, to the hiatus Fallopii. Entering the hiatus Fallopii it imme- diately joins the facial nerve, just as that cord is making its angular bend, previously to winding back along the inner wall of the tympa- num.f The petrosal branch accompanies the facial nerve, along the aqueeductus Fallopii, enclosed in its sheath to within a few hnes of the stylo-mastoid foramen. It then quits the facial nerve, return- ing upon itself at an acute angle, and enters the tympanum near the base of the pyramid. It now takes the name of chorda tympani and crosses the tympanum enveloped in mucous membrane, between the handle of the malleus and long process of the incus to the fissura Glaseri; passing • through a particular opening in this fissure it descends upon the inner side of the cond3de of the lower jaw, and internally to the auricular and inferior dental nerves to the gusta- tory nerve, which it joins at an acute angle.J Accompanying the gustatory, enclosed in its sheath, to the submaxillary gland, it quits that nerve and communicates with the submaxillary ganglion. The petrosal branch of the Vidian nerve receives a branch from the tympanic nerve while in the hiatus Fallopii. The Vidian nerve thus becomes the medium of communication between the spheno-palatine ganglion and submaxillary ganglion ; and between both of these gangha and the carotid plexus ; and through the tympanic nerve with the glosso-pharyngeal and pneu- mogastric nerves : and if the fusion of nervous substance be admitted, between the whole of these and the facial, the auditory, and the gustatory nerves. 5. The Submaxillary Ganglion is of small size, but very distinct, and is situated in the submaxillary gland. Its branches of distribution are numerous, and ramify upon the ducts of the gland, and upon Wharton's duct. Its branches of communication are, — 1, one or two small branches which join the gustatory nerve ; and 2, several minute branches * Or the deep and superficial petrous. — G, t Here two rival opinions clash ; one set of anatomists, and with them Swan and Arnold, believe that the petrosal branch unites with tlie substance of the facial nerve ; the two latter writers even g^o so far as to describe a g-angiionie enlargement upon the facial nerve at this point, and Arnold would seem to intimate that the nerve is actually a branch of this ganglion; while another set maintain that tlic petrosal branch merely accompanies the facial nerve, being enclosed in its neurilemma. As the question is yet litigated, and as I am prepared vvitli no positive proof to decide for either party, I shall at present adopt the latter view as the more convenient for description, and for explaining the connexions between the different cranial ganglia. The latter opinion has for its supporters, Cloquet, Ribes, and liirzel. X Here, again, the question effusion of nervous substance, or mere contact, has been warmly agitated, but with no positive and unquestionable results. OTIC GANGLION CAROTID PLEXUS, 429 which communicate with the sympathetic filaments ramifying upon the facial artery. It is associated with the carotid plexus, and the other cranial ganglia, by means of the petrosal branch of the Vidian. 6. The Otic Ganglion (Arnold's)* is a small red body, resting against the inner surface of the inferior maxillary nerve, imme- diately below the foramen ovale; it is in relation extern aV y w\X\\ the trunk of the inferior maxillary nerve, just at the point of union of the motor root; internally it rests against the cartilage of the Eusta- chian tube and tensor palati muscle ; and posteriorly it is in con- tact with the arteria meningea magna. It is closely adherent to the internal pterygoid nerve, and appears like a swelling upon that branch. The branches of the otic ganglion are seven in number ; two of distribution, and five of communication. The branches of distribution are, — 1, a small filament to the tensor tympani muscle ; and, 2, one to the tensor palati muscle. The branches of communication are, — 1, two or three small branches to the motor root of the inferior maxillary nerve ; 2, two branches to the auricular nerve : 3, a filament to the facial nerve ; 4, a long filament, the nervous pelrosus superficialis minor to com- municate with the tympanic nerve (Jacobson's) in the tympanum ; and, 5, one or two small branches which join the sympathetic fila- ments of the arteria meningea media artery. Carotid Plexus. — The ascending branch of the superior cervical ganglion enters the carotid canal with the internal carotid artery, and divides into two branches, which form several loops of commu- nication with each other around the artery. This constitutes the carotid 'plexus. They also form frequently a small gangliform swell- ing upon the under part of the artery, which is called the carotid ganglion. The latter, however, is not constant ; and, as it performs no special function, we do not include it amongst the cranial gan- gUa of the sympathetic. The continuation of the carotid plexus onwards with the artery by the side of the sella turcica, is called the cavernous plexus. The carotid plexus is the centre of communication between all the cranial ganglia ; and being derived from the superior cervical ganglion, between the cranial gangUa and those of the trunk, it also communicates with the greater part of the cerebral nerves, and distributes filaments with each of the branches of the internal carotid, which accompany those branches in all their ramifications. Thus, the Ganglion of Ribes is formed by the union of the fila- ments which accompany the anterior cerebral arteries, and which meet on the anterior communicating artery. The ciliary ganglion communicates with the plexus by means of the long branch which is sent back to join it in the cavernous sinus. The spheno-palatine, * Frederick Arnold, " Dissertatio Inau;^uralis de Parte Ceplialica Nervi Sympa- thetici," Heidelberg, 1826 ; and "Ueber don Ohrknoten," 1828. 430 CERVICAL GANGLIA. and with it the naso-palatlne ganglion, joins the plexus by means of the carotid branch of the Vidian. The submaxillary ganglion is also connected with it through the Vidian. And the otic ganglion is brought in relation with it by means of the tympanic nerve and by the Vidian. It communicates with the third nerve in the cavernous sinus, and through the ciliary ganglion ; with the Casserian ganglion ; with the ophthalmic division of the fifth in the cavernous sinus, and by means of the ciliary ganglion ; with the superior maxillary, through the spheno-palatine ganglion ; and with the inferior maxillary, through the chorda tympani and Vidian. It sends two branches directly to the sixth nerve, which unite* with it as it crosses the cavernous sinus ; it communicates with the facial and auditory nerves, through the medium of the petrosal branch of the Vidian ; and with the glosso-pharyngeal and pneumogastric nerves, through the nervus petrosus supeijicialis minor, a branch from the otic ganglion to the tympanic nerve. CERVICAL GANGLIA. The Superior cervical ganglion is long and fusiform, of a grayish colour, smooth, and of considerable thickness, extending from within an inch of the carotid foramen in the petrous bone to opposite the lower border of the third cervical vertebra. It is in relation in front with the sheath of the internal carotid artery and internal jugular vein ; and behind with the rectus anticus major muscle. Its branches, like those of all the sympathetic ganglia in the trunk, are divisible into superior, inferior, external, and internal; to which may be added, as proper to this ganglion, anterior. The superior is a single branch which ascends by the side of the internal carotid, and divides into two branches ; one lying to the outer side, the other to the inner side of that vessel. The two branches enter the carotid canal, and communicate by means of several filaments sent from one to the other, to constitute the carotid plexus. The inferior or descending branch, sometimes two, is the cord of communication with the middle cervical ganglion. The external branches are numerous, and may be divided into two sets: 1, Those which communicate with the glosso-pharyngeal, pneumogastric, and hypoglossal nerves ; and, 2, those which com- municate with the three first cervical nerves. The internal branches are three in number: 1. Pharyngeal, to assist in forming the pharyngeal plexus ; 2. Laryngeal, to join the superior laryngeal nerve and its branches; and, 3. The superior cardiac nerve, or nervous superficialis cordis. * Panizza, in his " Experimental Researches on the Nerves," denies this communi- cation, and states very vaguely that " they are merely lost and entwined around it," — Edinburgh Medical and Surgical Journal, January 1836. CERVICAL GANGLIA — CARDIAC NERVES. 431 The anterior branches accompany the carotid artery with its branches, around which they form intricate plexuses; they are called, from the softness of their texture, nervi molles. The Middle cervical ganglion (thyroid ganglion) is of small size, and sometimes altogether wanting. It is situated opposite the fifth cervical vertebra, and rests upon the inferior thyroid artery. This relation is so constant, as to have induced Haller to name it the " thyroid ganglion." Its superior branch, or branches, ascend to communicate with the superior cervical ganglion. Its inferior branches descend to join the inferior cervical gan- glion. Its external branches communicate with the third, fourth, and fifth cervical nerves. Its internal branch is the middle cardiac nerve, nervus cardiacus magnus. The Inferior cervical ganglion (vertebral ganglion) is much larger than the preceding, and is constant in its existence. It is of a semi- lunar form, and is situated upon the base of the transverse process of the seventh cervical vertebra, immediately behind the vertebral artery : hence its title to the designation " vertebral ganglion.''^ Its superior branches communicate with the middle cervical gan- glion. The inferior branches pass some before and some behind the sub- clavian artery, to join the first thoracic gangHon. The external branches consist of two sets ; one which communi- cates with the sixth, seventh, and eighth cervical nerves ; and one which accompanies the vertebral artery along the vertebral canal, forming the vertebral plexus. This plexus sends filaments to all the branches given off by the artery, and communicates in the skull with the filaments of the carotid plexus accompanying the branches of the internal carotid artery. . The internal branch is the inferior cardiac nerve, nervus cardi- acus minor. Cardiac Nerves.* — The superior cardiac nerve {nervus super- ficialis cordis) arises from the lower part of the superior cervical ganglion; it then descends the neck behind the common carotid artery, and, parallel with the trachea, crosses the inferior thyroid artery, and accompanying the recurrent laryngeal nerve for a short distance, passes behind the arteria innominata to the concavity of the arch of the aorta, where it joins the cardiac ganglion. In its course it receives branches from the pneumogastric nerve, and sends filaments to the thyroid gland and trachea. The Middle cardiac nerve {nervus cardiacus magnus) proceeds from the middle cervical ganglion, or, in its absence, from the cord * There is no constancy with regard to the origin and course of these nerves; there- fore the student must not be disappointed in finding the description in discord with his dissection. 432 CARDIAC GANGLION — THORACIC GANGLIA. of communication between the superior and inferior. It is the largest of the three nerves, and hes nearly parallel with the recurrent laryn- geal. At the root of the neck it divides into several branches, which pass some before and some behind the subclavian artery ; it com- municates with the superior and inferior cardiac, and. with the pneumogastric and recurrent nerves, and descends to the bifurca- tion of the trachea, to the great cardiac plexus. The Inferior cardiac nerve {nerviis cardiacus minor) arises from the inferior cervical gangUon, communicates freely with the recur- rent laryngeal and middle cardiac nerves, and descends to the front of the bifurcation of the trachea, to join the great cardiac -plexus. The Cardiac ganglion is a ganglionic enlargement of variable size, situated beneath the arch of the aorta, to the right side of the hgament of the ductus arteriosus. It receives the superior cardiac nerves of opposite sides of the neck, and a branch from the pneu- moo-astric nerve, and gives off numerous branches to the cardiac plexuses. The Great cardiac plexus is situated upon the bifurcation of the trachea, above the right pulmonary artery, and behind the arch of the aorta. It is formed by the convergence of the middle and inferior cardiac nerves, and by branches from the pneumogastric nerve. The Anterior cardiac plexus is situated in front of the ascending aorta, near to its origin. It is formed by the communications of filaments that proceed from three different sources. 1st, from the superior cardiac nerves, crossing the arch of the aorta ; 2dly, from the cardiac ganglion beneath the arch ; and, 3dly, from the great cardiac plexus, — passing between the ascending aorta and the right auricle. The anterior cardiac plexus supplies the anterior aspect of the heart, distributing numerous filaments with the left coronary artery, which form the anterior coronary plexus. The Posterior cardiac plexus is formed by numerous branches from the great cardiac plexus, and is situated upon the posterior part of the ascending aorta, near to its origin. It divides into two sets of branches : one set accompanying the right coronary artery in the auriculo-ventricular sulcus ; the other set joining the artery on the posterior aspect of the heart. They both together constitute the posterior coronary plexus. The great cardiac plexus likewise gives branches to the auricles of the heart, and others, to assist in forming the anterior and poste- rior pulmonary plexuses. THORACIC GANGLIA. The Thoracic ganglia are twelve in number on each side. They are flattened and triangular, or irregular in form, and present the peculiar gray colour and pearly lustre of the other sympathetic ganglia ; they rest upon the heads of the ribs, and are covered in SEMILUNAR GANGLION SOLAR PLEXUS. 433 by the pleura costalis. The two first and the last ganglia are usually the largest. Their brandies are superior, inferior, external and internal. The superior and inferior are prolongations of the substance of the ganglia rather than branches ; the former to communicate with the o-ano;lion above, the latter wdth that below. The external branches, two or three in number, communicate witii each of the spinal nerves. The ijiternal branches of the five upper ganglia are aortic, and follow the course of the intercostal arteries to that trunk: the branches of the lower ganglia unite to form the two splanchnic nerves. The Great splanchnic nerve arises from the sixth dorsal ganglion, and receives branches from the seventh, eighth, ninth, and tenth, which increase it to a nerve of considerable size. It descends in front of the vertebral column, within the posterior mediastinum, pierces the diaphragm immediately to the outer side of each crus, and terminates in the semilunar ganglion. The Lesser splanchnic nerve {renal) is fornied by filaments from the tenth, eleventh, and sometimes from the twelfth dorsal ganglion. It pierces the diaphragm, and descends to join the renal plexus. The Semilunar ganglion is a large, irregular, gangliform body, pierced by numerous openings, and appearing like the aggregation of a number of smaller ganglia, having spaces between them. It is situated by the side of the cceliac axis, and communicates with the ganglion of the opposite side, both above and below that trunk, so as to form a gangliform circle, from which branches pass off in all directions, like rays from a centre. Hence the entire circle has been named the solar plexus. The Solar plexus receives the gi'eat splanchnic nerves ; part of the lesser splanchnic nerves ; the termination of the right pneumo- gastric nerve ; some branches from the right phrenic nerve ; and sometimes one or two filaments from the left. It gives oft" nume- rous filaments, which accompany, under the name of plexuses, all the branches given oft' by the abdominal aorta. Thus, we have derived from the solar plexus the — Phrenic plexuses, Gastric plexus, Hepatic plexus, Splenic plexus. Supra-renal plexuses, Renal plexuses, Supei'ior mesenteric plexus, Spermatic plexuses, Inferior mesenteric plexus. The Renal plexus is formed chiefty by the lesser splanchnic nerve, but receives many filaments from the solar plexus. 55 434 LUMBAK AND SACRAL GANGLIA. The- Spermatic plexus is formed principally by the renal plexus. The Inferioi' mesenteric plexus receives filaments from the aortic plexus. LUMBAR GANGLIA. The Lumhar ganglia are four in number on each side, of the peculiar pearly gray colour, fusiform, and situated upon the ante- rior part of the bodies of the lumbar vertebrae. The superior and inferior branches of the lumbar ganglia are branches of communication with the ganglion above and below, as in the dorsal region. The external branches, two or three in number, communicate with the lumbar nerves. The internal branches consist of two sets ; of which the upper pass inwards in front of the abdominal aorta, and form around that trunk a plexiform interlacement, which constitutes the aortic plexus ; the lower branches cross the common iliac arteries, and unite over the promontory of the sacrum, to form the hypogastric plexus. The Jiortic plexus is formed by branches from the lumbar ganglia, and receives filaments from the solar and superior mesenteric plexuses. It sends filaments to the inferior mesenteric plexus, and terminates in the hypogastric plexus. The Hypogastric plexus is formed by the termination of the aortic plexus, and by the union of branches from the lower lumbar gan- gha. It is situated over the promontory of the sacrum, between the two common iliac arteries, and bifurcates inferiorly into two lateral portions, which communicate with branches from the fourth and fifth sacral nerves. It distributes branches to all the viscera of the pelvis, and to the branches of the internal iliac artery. SACRAL GANGLIA. The Sacral ganglia are four or five in number on each side. They are situated upon the sacrum, close to the anterior sacral foramina, and resemble the lumbar ganglia in form and mode of connexion, although they are much smaller in size. The superior and inferior branches communicate with the gan- glia above and below. The external branches communicate with the sacral and coccygeal nerves. The internal branches communicate very freely with the lateral divisions of the hypogastric plexus, and arc distributed to the pelvic viscera. The last sacral ganglia of the opposite sides give off branches which join a small ganglion, situated on the first bone of the coccyx, called tlie ganglion impar, or axygos. This ganglion resem- bles in its position and function the ganglion of Ribcs, serving to connect the inferior extremity of the syn)pathetic system, as does the former ganglion its upper extremity. It gives ofll" a few small branches to the coccyx and rectum. CHAPTER IX. ORGANS OF SENSE. The organs of sense, the instruments by which the animal frame is brought into relation with surrounding nature, are five in number. Four of these organs are situated within the head, viz. the apparatus of smell, sight, hearing, and taste, and the remaining organ, of touch, is resident in the skin, and is distributed over the entire surface of the body. THE NOSE AND NASAL FOSS^. The organ of smell consists essentially of two parts : one exter- nal, the nose ; the other internal, the nasal fossce. The nose is the triangular pyramid projecting from the centre of the face, immediately above the upper lip. Superiorly, it is con- nected with the forehead, by means of a narrow bridge ; inferiorly, it presents two openings, the nostrils, which overhang the mouth, and are so constructed that the odour of all substances must be re- ceived by the nose before they can be introduced within the lips. The septum between the openings of the nostrils is called the columna. Their entrance is guarded by a number of stiff hairs {vibrissce), which project across the openings, and act as a filter in preventing the introduction of foreign substances, such as dust or insects, with- the current of air intended for respiration. The anatomical elements of which the nose is composed are, — 1. Integument. 2. Muscles. 3. Bones. 4. Fibro-cartilages. 5. Mu- cous membrane. 6. Vessels and nerves. 1. The Integument forming the tip (lobulus) and wings (alee) of the nose is extremely thick and dense, so as to be with difficulty separated from the fibro-cartilage. It is furnished with a number of sebaceous follicles, which by their oily secretion, protect the ex- tremity of the nose in excessive alternations of temperature. The sebaceous matter of these follicles becomes of a dark colour upon the surface, from the attraction of the carbonaceous matter floating in the atmosphere : hence the spotted appearance which the tip of the nose presents in large cities. When the integument is firmly compressed, the inspissated sebaceous secretion is squeezed out from the follicles, and taking the cylindrical form of their excretory ducts, has the appearance of small white maggots with black heads. 436 CAIfTILAGES OF THE NOSE. 2. The Muscles are brought into view by reflecting the integu- ment : they are the pyramidaUs nasi, compressor nasi, levator labii superioris alffique nasi, and depressor labii superioris alaeque nasi. They have been already described with the muscles of the face. 3. The Bones of the nose are the nasal, and nasal processes of the superior maxillary. 4. The Fibro-cartilages give form and stability to the outwork of the nose, providing at the same time, by their elasticity, against in- juries. They are five in number, the Fibro-cartilage of the septum, Two lateral fibro-cartilages. Two alar fibro-cartilages. The Fibro-cartilage of the septum, somewhat triangular in form, divides the nose into its two nostrils. It is connected above with the nasal bones and lateral fibro-cartilages ; behind, with the eth- moidal septum and vomer ; and, below, with the palate processes of the superior maxillary bones. The alar fibro-cartilages and columna move freely upon the fibro-cartilage of the septum, being but loosely connected with it by perichondrium. The Lateral fibro-cartilages are also trian- gular : they are connected, in front, with the fibro-cartilage of the septum ; above with the nasal bones ; behind with the nasal processes of the superior maxillary bones ; and belaiv with the alar fibro-cartilages. Alar fibro-cartilages. — Each of these carti- lages is curved in such a manner as to corre- spond with the opening of the nostril, to which it forms a kind of rim. The inner portion is loosely connected with the same part of the opposite cartilage, so as to form the columna. It is expanded and thickened at the point of the nose to constitute the lobe ; and, upon the side fe forms a curve corresponding with the form of the ala. This curve is prolonged downwards and forwards in the direction of the posterior border of the ala by three or four small fibro- cartilaginous plates, which are appendages to the alar fibro-carti- lage. The whole of these fibro-cartilages are connected with each other, and to the bones, by perichondrium, which, from its mem- branous structure, permits of the freedom of motion existing between them. Fig. 135* -Jry^^ * The fibro-cartilages of the nose. 1. The nasal bones. 2. The fibre cartilage of the septurn. 3. The lateral fibro-cartilages. 4. The alar fibro-cartilages. 5. The central portions of the alar fibro-cartilages which constitute the columna. G, The appendix of the alar fibro-cartilage. 7. The nostrils. NASAL FOSSiE. 437 5. The Mucous membrane, lining the interior of the nose, is con- tinuous with the sldn externally, and with the pituitary membrane of the nasal fossae within. Around the entrance of the nostrils it is provided with num.erous vibrisscs. 6. Vessels and Nerves. — The Arteries of the nose are the lateralis nasi from the facial, and the nasalis septi from the superior coro- nary. Its JVerves are the facial, infra-orbital, and nasal branch of the ophthalmic. NASAL FOSS^. To obtain a good view of the nasal fosses, the face must be di- vided through the nose by a vertical incision, a little to one side of the middle line. The JVasal fosscB are two irregular, compressed cavities, extend- ing backwards from the nose to the pharynx. They are bounded superiorhj by the sphenoid and ethmoid bones. Inferiorhj by the hard palate ; and in the middle line they are separated from each other by a bony and fibro-cartilaginous septum. A plan of the boundaries of the nasal fossse will be found at page 62. Upon the outer wall of each fossa, in the dried skull, are three projecting processes, termed spongy bones. The two superior belong to the ethmoid, the inferior is a separate bone. In the fresh fossse these are covered with mucous membrane, and serve to increase its surface by their projection and by their convoluted form. The space intervening between the superior and middle spongy bones is the superior meatus ; the space between the middle and inferior bones is the middle meatus ; and that between the inferior and the floor of the fossa is the inferior meatus. These meatuses are passages which extend from before backwards, and it is in rushing through and amongst these that the atmosphere deposits its odorant particles upon the mucous membrane. There are several openings into the nasal fossa : thus, in the superior meatus are the openings of the sphenoidal and posterior ethmoidal cells, in the middle the anterior ethmoidal cells, the frontal sinuses, and the antrum maxillare ; and, in the inferior meatus, the termina- tion of the nasal duct. In the dried bone there are two additional openings, the spheno-palatine and the anterior palatine foramen ; the former being situated in the superior, and the latter in the inferior meatus. The Mucous membrane of the nasal fossse is called pituitary, or Schneiderian.* The former name being derived from its secretion, the latter from Schneider, who was the first to show that the secre- tion of the nose proceeded from the mucous membrane, and not from the brain, as was formerly imagined. It is continuous with the general gastro-pulmonary mucous membrane, and may be traced * Conrad Victor Sclincider, Professor of Medicine at Wittenberg. His work,|_en- titled Dc Catarrhis, Slc. was published in 1661. 438 EYE SCLEROTIC COAT, through the openings in the meatuses, into the sphenoidal and eth- moidal cells ; into the antrum maxillare ; through the nasal duct to the surface of the eye, where it is continuous with the conjunctiva ; along the Eustachian tubes into the tympanum and mastoid cells, to which it forms the Uning membrane ; and through die posterior nares into the pharnyx and mouth, and thence through the lungs and ali- mentary canal. The surface of this membrane is furnished with a columnar epi- thelium supporting innumerable vibratile cilia. Vessels and Nerves. — The Arteries of the nasal fossee are the anterior and posterior ethmoidal, from the ophthalmic artery ; and spheno-palatine and pterygo-palatine from the internal maxillary. The JVerves are, the olfactory, the spheno-palatine branches from Meckel's ganglion, and the nasal branch of the ophthalmic. The ultimate filaments of the olfactory nerve terminate in minute papillae. THE EYE, WITH ITS APPENDAGES. The form of the eyeball is that of a sphere, of about one inch in diameter, having the segment of a smaller sphere ingrafted upon its anterior surface, which increases its antero-posterior diameter. The axes of the two eyeballs are parallel with each other, but do not cor- respond with the axes of the orbits, which are directed outwards. The optic nerves follow the direction of the orbits, and therefore enter the eyeballs to their nasal side. The Globe of the Eye is composed of tunics and of refracting media called humours. The tunics are three in number, the 1. Sclerotic and Cornea, 2. Choroid, Iris, and Ciliary processes, 3. Retina and Zonula ciliaris. The humours are also three — Aqueous, Crystalline (lens), Vitreous. 1. The Sclerotic and Cornea form the external tunic of the eye- ball, and give to it its peculiar form. Four-fifths of the globe are invested by the sclerotic, the remaining fifth by the cornea. The Sclerotic (tfxX7]^o^, hard) is a dense fibrous membrane, thicker behind than in front. It is continuous, posteriorly, with the sheath of the optic nerve, which is derived from the dura mater, and it is pierced by that nerve as well as by the ciliary nerves and arteries. Anteriorly it presents a bevelled edge which receives the cornea in the same way that a watch-glass is received by the groove in its CRYSTALLINE AND VITREOUS HUMOUR. 439 case. Its anterior surface is covered by a thin tendinous layer, the tunica albuginea, derived from the expansion of the tendons of the four recti muscles. By its posterior surface it gives attachment to the tw^o oblique muscles. The tunica albuginea is covered, for a pjart of its extent, by the mucous membrane of the front of the eye, the conjunctiva ; and, by reason of the brilliancy of its whiteness, gives occasion to the common expression, " the white of the eye." At the entrance of the optic nerve the sclerotic forms a thin cribriform lamella {lamina cribrosa), which is pierced by a number of minute openings for the passage of the nervous filaments. One of these openings, larger than the rest, and situated in the centre of the lamella, is the porus opticus, through which the arteria centralis retinae enters the eye. Fig-. 136.« The Cornea (corneus, horny) is the transparent projecting layer that forms the anterior fifth of the globe of the eye. In its form it is circular, concavo-convex, and resembles a watch-glass. It is received by its edge, which is sharp and thin, within the bevelled border of the sclerotic, to which it is very fii'mly attached, and it is somewhat thicker than the anterior portion of that tunic. When * A longitudinal section of the globe of the eye. 1. The sclerotic, thicker bcliind than in front. 2. The cornea, received within the anterior margin of the sclerotic, and con- nected with it by means of a bevelled edge. 3. The choroid, connected anteriorly with (4) the ciliary ligament, and (5) the ciliary processes. 6. The iris. 7. The pupil. 8. The third layer of the eye, the retina, terminating anteriorly by an abrupt border at the commencement of the ciliary processes. 9. The canal of Petit, which encircles the lens (12) ; the thin layer in front of this canal is tlie zonula ciliaris, a prolongation of the vascular layer of the retina to the lens. 10. The anterior chamber of the eye contain- ing the aqueous humour ; the lining membrane by which the humour is secreted is represented in the diagram. 11. The posterior chamber. 12. The lens, more conve.v behind than before, and enclosed in its proper capsule. 13. The vitreous humour enclosed in the hyaloid membrane, and in cells formed in its interior by that membrane. 14. A tubular sheath of the hyaloid membrane, which serves for the passage of the artery of the capsule of the lens. 15. The neurilemma of the optic nerve. 16. The arteria centralis retinas, embedded in its centre. 440 STRUCTURE OF THE CORNEA. examined from the exterior, its vertical diameter is seen to be about one-sixteenth shorter than the transverse, in consequence of the overlapping above and below, of the margin of the sclerotica ; on the interior, however, its outline is perfectly circular. The cornea is composed of four layers, 1, of the conjunctiva; 2, of the cornea proper, which consists of several thin lamelloe con- nected together by an extremely fine cellular tissue; 3, of the cornea elastica, a " fine, elastic, and exquisitely transparent membrane, exactly applied to the inner surface of the cornea proper ;" and 4, of the lining membrane of the anterior chamber of the eyeball. The cornea elastica is remarkable for its perfect transparency, even when submitted for many days to the action of water or alcohol ; while the cornea proper is rendered perfectly opaque by the same immersion. To expose this membrane, Dr. Jacob suggests that the eye should be placed in water for six or eight days, and then that all the opaque cornea should be removed layer after layer. Another character of the cornea elastica is its great elasticity, which causes it to roll up when divided or torn, in the same manner with the cap- sule of the lens. The use of this layer, according to Dr. Jacob, is to "preserve the requisite permanent correct curvature of the flaccid cornea proper." The opacity of the cornea, produced by pressure on the globe, results from the infiltration of fluid into the cellular tissue connect- ing its layers. This appearance cannot be produced in a sound living eye. Dissection. — The sclerotic and cornea are now to be dissected away from the second tunic ; this, with care, may be easily per- formed, the only connexions subsisting between them being at the circumference of the iris, the entrance of the optic nerve, and the perforation of the ciliary nerves and arteries. Pinch up a fold of the sclerotic near its anterior circumference, and make a small opening into it, then raise the edge of the tunic, and with a pair of fine scissors, having a probe point, divide the entire circumference of the sclerotic, and cut it away bit by bit. Then separate it from its attachment around the circumference of the iris by a gentle pressure with the edge of the knife. The dissection of the eye must be conducted under water. In the course of this dissection the ciUary nerves and long ciliary arteries will be seen passing forwards between the sclerotic and choroid, to be distributed to the iris. 2. Second tunic. — Tlie second tunic of the eyeball is formed by the choroid, ciliary ligament and ins, the ciliary processes being an appendage' developed from its inner surface. The choroid* is a vascular membrane of a rich chocolate-brown * Tho word choroid has been very much abused in anatomical lanj^uaa^e ; it was originally applied to tho membrane of the foetus called chorion from tho Greek word X^fiov, domicilium, that membrane being, as it were, the abode or recc])taelc of the foDtuf. Y^oftov comes from ^ceptce, to take or receive. Now it so happens that the cho- rion in the ovum is a vascular membrane of a peculiar structure. Hence the term CILIARY LIGAMENT. 441 colour upon its external surface, and of a deep black colour within. It is connected to the sclerotic, externally, by an extremely fine cel- lular tissue, and by the passage of nerves and vessels. Internally it is in simple contact with the third tunic of the eye, the retina. It is pierced posteriorly for the passage of the optic nerve, and is con- nected anteriorly with the iris, ciliary processes, and with the line of junction of the cornea and sclerotic, by a dense white structure, the ciliary ligament, which surrounds the circumference of the iris like a ring. The choroid membrane is composed of three layers : — 1. An external or venous, which consists principally of veins arranged in a peculiar manner : hence they have been named vencB vorticosce. The marking upon the surface of the membrane produced by these veins, resembles so many centres, to which a number of curved lines converge. It is this layer which is connected with the ciliary ligament. 2. The middle or arterial layer {tunica Ruyschiana*) is formed principally by the ramifications of minute arteries, and secretes upon its surface the pigmentum nigrum. It is reflected inwards at its junction with the ciliary ligament, so as to form the ciliary processes. 3. The internal layer is a delicate membrane (membrana figmenti) which presents a beautiful appearance beneath the microscope ; it is composed of several laminae of nucleated hexagonal cells, which contain the granules of pigmentum nigrum, and are arranged so as to resemble a tesselated pavement. In animals the pigmentum nigrum, upon the posterior wall of the eyeball, is replaced by a layer of considerable extent, and of metallic brilliancy, called the tapetum. The ciliary ligament, or circle, is the bond of union between the external and middle tunics of the eye, and serves to connect the cornea and sclerotic at their fine of junction with the iris and ex- ternal layer of the choroid. It is also the point to which the ciliary nerves and vessels proceed previously to their distribution, and it receives the anterior ciliary arteries through the anterior margin of the sclerotic. A minute vascular canal is situated within the ciliary ligament, called the ciliary canal, or the canal of Fontana,f from its discoverer. The Iris (iris, a rainbow) is so named from its variety of colour in different individuals : it forms a septum between the anterior and posterior chambers of the eye, and is pierced somewhat to the nasal side of its centre by a circular opening,^ which is called the pupil. choroid, ;^''/j/ov e/tfoc, like the chorion, has been used indiscriminately to signify vas- cular structures, as in the choroid membrane of the eye, the choroid plexus, ifcc. and we find Cruveilhier in his admirable work on Anatomy, vol. iii. p. 463, saying in a note, " Choroide est synonymc de vasculeuse." * Ruysch was born at the Hague in 1638, and was appointed professor of Anatomy at Amsterdam in 1665. His whole life was employed in making injected preparations, for wliich he is justly celebrated. He came to the conclusion that the body was en- tirely made up of vessels. He died at the advanced age of ninety-three years. t Felix Fontana, an anatomist of Tuscany. His " Description of a New Canal in the Eye," was published in 1778, in a letter to the Professor of Anatomy in Upsal. 56 442 IRIS CILIARY PROCESSES, By its periphery it is connected with the ciliary ligament, and by its inner circumference forms the margin of the pupil : its anterior sur- face looks towards the cornea, and the posterior towards the ciliary processes and lens. It is composed of two layers, an anterior or muscular, consisting of radiating fibres which converge from the circumference towards the centre, and have the power of dilating the pupil ; and circular, which surround the pupil like a Fig. 137.* sphincter, and by their action pro- ;/ duce contraction of its area. The posterior layer is of a deep purple tint, and is thence named uvea, from its resemblance in colour to a ripe grape. The Ciliary processes may be seen in two ways, either by re- moving the iris from its attachment to the ciliary ligament, when a front view of the processes will be ob- tained, or by making a transverse section through the globe of the eye, when they may be examined from behind, as in fig. 137. The ciHary processes consist of a number of triangular folds, formed apparently by the plaiting of the internal layer of the cho- roid. They are, according to Zinn, about sixty in number, and may be divided into large and small, the latter being situated in the spaces between the former. The periphery is connected with the ciliary ligament, and is continuous with the internal layer of the choroid. The central border is free, and rests against the circum- ference of the lens. The anterior surface corresponds with the uvea ; the posterior receives the folds of the zonula ciliaris between its processes, and thus establishes a connexion between the choroid and the third tunic of the eye. The ciliary processes are covered with a thick layer of pigmentum nigrum, which is more abundant upon them, and upon the anterior part of the choroid, than upon the posterior. When the pigment is washed off, the processes are of a whitish colour. 3. Third tunic. — The third tunic of the eye is the retina, which is prolonged forwards to the lens by the zonula ciliaris. Dissection. — If after the preceding dissection the choroid mem- brane be carefully raised and removed, the eye being kept under water, the retina may be seen very distinctly. The Retina is composed of three layers : — * The anterior segment, of a transverse section of the globe of the eye, seen from within. 1. The divided edge of the three tunics ; sclerotic, choroid (the dark layer,) and retina. 2. the pupil. 3. The iris, the surface presented to view in this section being the uvea. 4. The ciliary processes. .'3. Tiic scalloped anterior border of the retina. RETINA STRUCTURE. 443 External or Jacob's membrane, Middle, Nervous membrane, Internal, Vascular membrane. Jacob's memhrane is extremely thin, and is seen as a flocculent film when the eye is suspended in water. Examined by the micro- scope, it is seen to be composed of granules having a tesselated arrangement. Dr. Jacob considers it to be a serous membrane. The Nervous memhrane is the expansion of the optic nerve, and forms a thin semi-transparent bluish white layer, which envelopes the vitreous humour, and extends forwards to the commencement of the ciliary processes, where it terminates in an abrupt scalloped margin. This layer has been observed by Treviranus to be composed of cylindrical fibres, which proceed from the optic nerve and bend abruptly inwards, near their termination, to form the internal papil- lary layer, which lies in contact with the hyaloid membrane ; each fibre constituting by its extremity a distinct papilla. The Vascular memhrane consists of the ramifications of a minute artery, the arteria centralis retinae, and its accompanying vein ; the artery pierces the optic nerve, and enters the globe of the eye through the porus opticus in the centre of the lamina cribrosa. This artery may be seen very distinctly by making a transverse section of the eyeball. Its branches are continuous anteriorly with the zo- nula ciliaris. This vascular layer forms distinct sheaths for the nervous papillae, which constitute the inner surface of the retina. In the centre of the posterior part of the globe of the eye the retina presents a circular spot, which is called the foramen of Soemmering ;f it is surrounded by a yellow halo, the limhus luteus, and is frequently obscured by an elliptical fold of the retina, which, from its constancy of appearance, has been regarded as a normal condition of the mem- * The posterior segment of the transverse section of the globe of the eye, seen from \vithin. 1. The divided edge of the three tunics. Tlie membrane covering the whole internal surface is the retina. 2. The entrance of the optic nerve with the arteria cen- tralis retinae piercing its centre. 3, 3. The ramifications of the arteria centralis. 4. The foramen of Soemmering, in the centre of the axis of the eye; the shade from the sides of the section obscures the Jimbus luteus which surrounds it. 5. A fold of the retina, which generally obscures the foramen of Soemmering after the eye has been opened. t Samuel Thomas Soemmering is celebrated for the beautiful and accurate plates which accompany his works. The account " De Foramine Ccntrali Retina? Humanne, Limbo Luteo cincto," was published in 1779, in the Commcntaliones Soc. Rfiff. Scieiit. Goltincrcnsis. Fig. 138.* 444 HUMOURS OF THE EYE. brane. The term foramen is misapplied to this spot, for the vascu- lar layer and the membrani Jacobi are continued across it ; the ner- vous substance alone appearing to be deficient. It exists only in animals having the axis of the eyeballs parallel with each other, as man, quadrumana, and some saurian reptiles, and is said to give passage to a small lymphatic vessel. The zonula ciliaris (zonula of Zinn)* is a thin vascular layer which connects the anterior margin of the retina with the anterior surface of the lens near to its circumference. It presents upon its surface a number of small folds corresponding with the ciliary pro- cesses, between which they are received. These processes are arranged in the form of rays around the lens, and the spaces be- tween them are stained by the pigmentum nigrum of the cihary processes. They derive their vessels from the vascular layer of the retina. The under surface of the zonula is in contact with the hyaloid membrane, and around the lens forms the anterior fluted wall of the canal of Petit. The connexion between these folds and the ciliary processes may be very easily demonstrated by dividing an eye transversely into two portions, then raising the anterior half, and allowing the vitreous humour to separate from its attachment by its own weight. The folds of the zonula will then be seen to be drawn out from between the folds of the ciliary processes. Humours. — The Aqueous humour is situated in the anterior and posterior chambers of the eye ; it is a weakly albuminous fluid, hav- ing an alkaline reaction, and a specific gravity very little greater than distilled water. According to Petit, it scarcely exceeds four or five grains in weight. The anterior chamber is the space intervening between the cornea in front, and the iris and pupil behind. The 'posterior chamber is the narrow space, less than half a line in depth,f bounded by the posterior surface of the iris and pupil in front, and by the ciliary processes, zonula ciHaris, and lens behind. The two chambers are lined by a thin layer, the secreting mem- brane of the aqueous humour. The Vitreous humour forms the principal bulk of the globe of the eye. It is an albuminous fluid resembling the aqueous humour en- closed in a delicate membrane, the hyaloid, which sends processes into its interior, forming cells in which the humour is retained. A small artery may sometimes be traced through the centre of the vitreous humour to the capsule of the lens ; it is surrounded by a tubular sheath of the hyaloid membrane. This vessel is easily in- jected in the foetus. * John Gottfried Zinn, Professor of Anatomy in Gottingen ; his " Descriptio Anato- mica Oculi Hurnani," was published in 1755 ; with excellent plates. It was republished by WrisbcrjT in 1780. t Winslow and Licutaud thouglit tiie iris to be in contact with the lens; it frequent- ly adheres to the capsule of the latter in iritis. The depth of the posterior chamber is greater in old than in young persons. CRYSTALLINE HUMOTJE STRUCTURE. 445 The Crystalline humour or lens is situated immediately behind the pupil, and is surrounded by the ciliary processes, which slightly overlap its margin. It is more convex on the posterior than on the anterior surface, and is embedded in the anterior part of the vitreous humour, from which it is separated by the hyaloid membrane. It is invested by a peculiarly transparent and elastic membrane, the capsule of the lens, which contains a small quantity of fluid called liquor Morgagni* and is retained in its place by the attachment of the zonula ciliaris. Dr. Jacob is of opinion that the lens is connected to its capsule by means of cellular tissue, and that the liquor Mor- gagni is the result of a cadaveric change. The Lens consists of concentric layers, of which the external are soft, the next firmer, and the central form a hardened nucleus, These layers are best demonstrated by boiling, or by immersion in alcohol, when they separate easily from each other. Another divi- sion of the lens takes place at the same time ; it splits into three tri- angular segments, which have the sharp edge directed towards the centre, and the base towards the circumference. The concentric lamellae are composed of minute parallel fibres, which are united with each other by means of scalloped borders ; the convexity on the one border fitting accurately the concave scallop upon the other. Immediately around the circumference of the lens is a triangular canal, the canal of Petit,-f about a line and a half in breadth. It is bounded in front by the flutings of the zonula ciliaris ; behind by the hyaloid membrane ; and within by the border of the lens. The Vessels of the globe of the eye are the long, and short, and anterior ciliary arteries, and the arteria centralis retinae. The long ciliary arteries, two in number, pierce the posterior part of the scle- rotic, and pass forward on each side, between that membrane and the choroid, to the ciliary ligament, where they divide into two branches, which are distributed to the iris. The short ciliary arteries pierce the posterior part of the sclerotic coat, and are distributed to the internal layer of the choroid membrane. The anterior ciliary are branches of the muscular arteries. They enter the eye through the anterior part of the sclerotic, and are distributed to the iris. It is the increased number of these arteries in iritis that forms the peculiar red zone around the circumference of the cornea. The arteria centralis retince enters the optic nerve at about half an inch from the globe of the eye, and passing through the porus opticus is distributed upon the inner surface of the retina, forming its vascular layer ; one branch pierces the centre of the vitreous humour, and supphes the capsule of the lens. The JVerves of the eyeball are the optic, two ciliary nerves from * John Baptist Morgagni was born in 1682. He was appointed Professor of Medi- cine in Bologna, and published the first part ©f his "Adversaria Anatomica," in 1706. He died in 1771. t John Louis Petit, a celebrated French surgeon : he published several surgical and anatomical Essays, in the early part of the 18th century. He died in 1750. 446 APPE^CDAGES OF THE EYE. the nasal branch of the ophthalmic, and the ciliary nerves from the ciliary ganglion. Observations. — The sclerotic is a tunic of protection, and the cornea a medium for the transmission of light. The choroid sup- ports the vessels destined for the nourishment of the eye, and by its pigmentum nigrum absorbs all loose and scattered rays that might confuse the image impressed upon the retina. The iris, by means of its powers of expansion and contraction, regulates the quantity of light admitted through the pupil. If the iris be thin, and the rays of light pass through its substance, they are immediately absorbed by the uvea ; and if that layer be insufficient, they are taken up by the black pigment of the ciliary processes. In Albinoes, where there is an absence of pigmentum nigrum, the rays of light traverse the iris and even the sclerotic, and so over- whelm the eye with light, that sight is destroyed, except in the dimness of evening or at night. In the manufacture of optical instruments care is taken to colour their interior black, with the same object, the absorption of scattered rays. The transparent lamellated cornea and the humours of the eye have for their office the refraction of the rays in such proportion as to direct the image in the most favourable manner upon the retina. Where the refracting medium is too great, as in over convexity of the cornea and lens, the image falls short of the retina (myopia, near-sightedness) ; and where it is too little the image is thrown beyond the nervous membrane (presbyopia, far-sightedness). These conditions are rectified by the use of spectacles, which provide a differently refracting medium externally to the eye, and thereby correct the transmission of light. APPENDAGES OF THE EYE. The Appendages of the eye {tutamina oculi) are the eyebrows, eyelids, eyelashes, conjunctiva, caruncula lachrymalis, and the lachrymal apparatus. The Eyebrov:s {sitpercilia) are two projecting arches of integu- ment covered with short thick hairs, which form the upper boundary of the orbits. They are connected beneath with the orbiculares, occipito-frontales, and corrugatores superciliorum muscles; their use is to shade the eyes from a too vivid light, or protect them from particles of dust and moisture floating over the forehead. The Eyelids {palpehrcs) are two valvular layers placed in front of the eye, serving to defend it from injury by their closure. When drawn open they leave between them an elliptical space, the angles of which are called canthL The outer canthus is formed by the meeting of the two lids at an acute angle. The inner canthus is prolonged for a short distance inwards towards the nose, and a triangular space is left between the lids in this situation, which is called the lacus lachrymalis. At the commencement of the lacus TARSI MEIBOMIAN GLANDS. 447 lachrymalis upon each of the two hds is a small angular projection, the lachrymal papilla or tubercle ; and at the apex of each papilla is a small orifice (punctum lachrymale), the commencement of the lachrymal canal. The eyeUds have, entering into their structure, integument, orbicu- laris muscle, tarsal cartilages, Meibomian glands, and conjunctiva. The tegumeniary cellular tissue of the eyelids is remarkable for its looseness and for the entire absence of adipose substance. It is particularly hable to serous infiltration. The fibres of the orbicu- laris muscle covering the eyelids, are extremely thin and pale. The Tarsal cartilages are tw^o thin lamellas of fibro-cartilage about an inch in length, which give form and support to the eyelids. The superior is of a semilunar form, about one-third of an inch in breadth at its middle, and tapering to each extremity. Its lower border is broad and flat, its upper is thin, and gives attachment to the levator palpebrte and to the fibrous membrane of the lids. The Inferior fibro-cartilage is an elliptical band, narrower than the superior, and situated in the substance of the lower lid. Its upper border is flat, and corresponds with the flat edge of the upper car- tilage. The lower is held in its place by the fibrous membrane. At the inner canthus the tarsal cartilages terminate at the com- mencement of the lachrymalis, and are attached to the margin of the orbit by the tendo oculi. At their outer extremity they termi- nate at a short distance from the angle of the canthus, and are retained in their position by means of a decussation of the fibrous structure of the broad tarsal ligament, called the external palpebral ligament. The Fibrous membrane of the lids is firmly attached to the perios- teum, around the margin of the orbit, by its circumference, and to the tarsal cartilages by its central margin. It is thick and dense on the outer half of the orbit, but becomes thin to its inner side. Its use is to retain the tarsal cartilages in their place, and give support to the lids ; hence it has been named the broad tarsal ligament. The Meibomian glands* are embedded in the internal surface of the cartilages, and are very distinctly seen on examining the inner surface of the Uds. They have the appearance of parallel strings of pearls, about thirty in number in the upper cartilage, and some- what fewer in the lower ; they open by minute foramina upon the edges of the lids. They correspond in length with the breadth of the cartilage, and are consequently longer in the upper than in the lower lid. Each gland consists of a single lengthened follicle or tube, into which a number of small clustered follicles open ; the latter are so numerous as almost to conceal the tube by which the secretion is poured out upon the margin of the lids. They are figured, after a very careful examination, in Dr. Quain's " Elements of Anatomy." * Henry Meibomius, "de Vasis Palpebrarum Novis," 1666. ^. 448 LACHKYMAL APPARATUS. Occasionally an arch is formed between two of them, as is seen in that figure, and produces a very graceful appearance. The edges of the eyelids are furnished with a triple row of lono^ thick hairs, which curve upwards from the upper lid, and down- wards from the lower, so that they may not interlace with each other in the closure of the eyelids, and prove an impediment to the opening of the eyes. These are the eyelashes (cilia), important organs of defence to the sensitive surface of so deUcate an organ as the eye. The Conjunctiva is the mucous membrane of the eye. It covers the whole of its anterior surface, and is then reflected upon the lids so as to form their internal layer. The duplicatures formed between the globe of the eye and the lids are called the superior and inferior 'palpebral sinuses, of which the former is much deeper than the in- ferior. Where it covers the cornea the conjunctiva is very thin and closely adherent, and no vessels can be traced into it. Upon the sclerotica it is thicker and less adherent, and to the inner sur- face of the lids is very closely connected, and is exceedingly vas- cular. It is continuous with the general gastro-pulmonary mucous membrane, and sympathizes in its aflections, as may be observed in various diseases. From the surface of the eye it may be traced through the lachrymal gland ; along the edges of the lids it is con- tinuous with the mucous hning of the Meibomian glands, and at the inner angle of the eye may be followed through the lachrymal canals into the lachrymal sac, and thence downwards through the nasal duct into the inferior meatus of the nose. This membrane is coated with a lamellated epithelium composed of vesicles and flattened scales, with central nuclei. The Caruncula lachrymalis is the small reddish body which occu- pies the lacus lachrymalis at the inner canthus of the eye. In health it presents a bright pink tint ; in sickness it loses its colour and becomes pale. It consists of an assemblage of follicles similar to the Meibomian glands, embedded in a fibro-cartilaginous tissue, and is the source of the whitish secretion which so constantly forms at the inner angle of the eye. It is covered with minute hairs which are sometimes so long as to be distinctly visible to the naked eye. Immediately to the outer side of the caruncula is a slight dupli- cature of the conjunctiva, called plica semilunaris, which contains a minute plate of cartilage, and is the rudiment of the third lid of animals, the membrana nictitans of birds. Vessels and nerves. — The palpebral are supplied internally with arteries from the ophthalmic, and externally from the facial and transverse facial. Their nerves are branches of the fifth and of the facial. LACHRYMAL APPARATUS. The Lachrymal apparatus consists of the lachrymal gland with LACHRYMAL GLAND, CANALS AND SAC. 449 its excretory ducts ; the puncta lachrymalia, and lachrymal canals ; the lachrymal sac and nasal duct. The Lachrymal gland is situated at the upper and outer angle of the orbit, and consists of two portions, orbital and palpebral. The orbital fortiori, about three quarters of an inch in length, is flattened and oval in shape, and occupies the lachrymal fossa in the orbital plate of the frontal bone ; being in contact with the periosteum, to which it is closely connected by its upper and convex surface ; being in relation with the globe of the eye, and with the superior and ex- ternal rectus by its inferior or concave surface ; and Vv'ith the broad tarsal ligament by its anterior border. By its posterior border it receives its vessels and nerves. The 'palpebral portion, smaller than the preceding, is situated in the upper eyelid, extending downwards to the superior margin of the tarsal cartilage. It is continuous with the orbital portion above, and is enclosed in an investment of dense fibrous membrane. The secretion of the lachrymal gland is con- veyed away by ten or twelve small ducts which run for a short distance beneath the conjunctiva, and open upon its surface by a series of pores about one-twentieth of an inch apart, situated in a curved line a Uttle above the upper border of the tarsal cartilage. Lachrymal canals. — The lachrymal canals commence at the minute openings, puncta lachrymalia, seen upon the lachrymal papillas of the lids at the outer extremity of the lacus lachrymalis, and proceed inwards to the lachrymal sac, where ^they terminate beneath a valvular semilunar fold of the hning membrane of the sac. The superior duct at first ascends, and then turns suddenly inwards towards the sac, forming an abrupt angle. The inferior duct forms the same kind of angle, by descending at first, and then turning abruptly inwards. They are dense and elastic in structure, and remain constantly open, so that they act like capillary tubes in absorbing the tears from the surface of the eye. The two fasciculi of the tensor tarsi muscle are inserted into these ducts, and serve to draw them inwards. The Lachrymal sac is the upper extremity of the nasal duct, and is scarcely more dilated than the rest of the canal. It is lodged in the groove of the lachrymal bone, and is often distinguished inter- nally from the nasal duct by a semilunar or circular valve. It con- sists of mucous membrane, but is covered in and retained in its place by a fibrous expansion, derived from the tendon of the orbicularis, which is inserted into the ridge on the lachrymal bone : it is also covered by the tensor tarsi muscle, which arises from the same ridge, and in its action upon the lachrymal canals may serve to compress the lachrymal sac. The Nasal duct is a short canal about three quarters of an inch in length, directed downwards, backwards, and a little outwards to the inferior meatus of the nose, where it terminates by an expanded orifice. It is lined by mucous membrane, which is continuous with the conjunctiva above, and with the pituitary membrane of the nose 57 450 OEGAN OF HEARIXO. below. Obstruction from inflammation and suppuration of this duct constitutes the disease called fistula lachrymaHs. Vessels and nerves. — The lachrymal gland is supplied with blood by the lachrymal branch of the ophthalmic artery, and \Yith nerves by the lachrymal branch of the ophthalmic and orbital branch of the superior maxillary. THE ORGAN OF HEARING. The Ear is composed of three parts. 1. External ear. 2. Mid- dle ear, or tympanum. 3. Internal ear, or labyrinth. The External Ear consists of two portions, the pinna and meatus; the former representing a kind of funnel which collects the vibrations of the atmosphere, called sounds, and the latter a tube which conveys the vibrations to the tympanum. The Pinna presents a number of folds and hollows upon its sur- face, which have different names assigned to them. Thus the ex- ternal folded margin is called the helix (=>^'i, a fold). The eleva- tion parallel to and in front of the helix is called antihelix (avri, op- posite.) The pointed process, projecting like a valve over the open- ing of the ear from the. face, is called the tragus {r^ayog, a goat), probably from being sometimes covered with bristly hair Uke that of a goat ; and a tubercle opposite to this is the antitragus. The lower dependent and fleshy portion of the pinna is the lohulus. The space between the helix and antihelix is named \\\e fossa innominata. Another depression is observed at the upper extremity of the anti- helix, wliich bifurcates and leaves a triangular space between its branches called the scaphoid fossa ; and the large central space to which all the channels converge is the concha, which opens directly into the ?neatus. The pinna is composed of integument, fihro-cartilage, ligaments, and muscles. The Integument is thin, and closely connected with the fibro-car- lage. The Fihro-cartilage gives form to the pinna, and is folded so as to produce the various convexities and grooves which have been described upon its surface. The helix commences in the concha, and partially divides that cavity into two parts ; on its anterior bor- der is a tubercle for the attachment of the attraliens aurem muscle, and a little above this a small vertical fissure, the fissure of the helix. The termination of tlic helix and antihelix forms a length- ened process, the -processus caudatus, which is separated from the concha by an extensive fissure. Upon the anterior surface of the tragus is another fissure, the fissure of the tragus, and in the lobulus the fibro-cartilage is wholly deficient. The fibro-cartilage of the meatus, at the upper and anterior })art of the cylinder, is divided from the concha by a fissure which is closed in the entire ear by ligamentous fibres ; it is firmly attaclicd at its termination to the processus auditorius. MUSCLES, VESSELS, AND NERVES OF THE EAR. 451 The Ligaments of the external ear are those which attach the pinna to the side of the head, viz. the anterior, posterior, and liga- ment of the tragus ; and those of the fibro-cartilage, which serve to preserve its folds and connect the opposite margins of the fissures. The latter are two in number,— the ligament between the concha and the processus caudatus, and the broad ligament which extends from the upper margin of the fibro-cartilage of the tragus to the helix, and completes the meatus. The proper Muscles of the Pinna are the — Major helicis. Minor helicis, Tragicus, Antitragicus, • Transversus auriculae. The Major helicis is a narrow band of muscular fibres situated upon the anterior border of the helix, just above the tragus. The Minor helicis is placed upon the posterior border of the helix, at its commencement in the fossa of the concha. The Tragicus is a thin quadrilateral layer of muscular fibres, situated upon the tragus. The Antitragicus arises from the antitragus, and is inserted into the posterior extremity, or processes caudatus of the helix. The Transversiis auriculcB, partly tendinous and partly muscular, extends transversely from the convexity of the concha to that of the helix, on the posterior surface of the pinna. These muscles are rudimentary in the human ear, and deserve only the title of muscles in the ears of animals. Two other muscles are described by Mr. Tod,* the obliquus auris and contractor meatus, or trago-helicus. The Meatus auditorius is a canal, partly cartilaginous and partly osseous, about an inch in length, which extends inwards and a little forwards from the concha to the tympanum. It is narrower in the middle than at each extremity, forms an oval cyhnder, the long diameter being vertical, and is slightly curved upon itself, the con- cavity looking downwards. It is lined by an extremely thin pouch of cuticle, which, when withdrawn after maceration, preserves the form of the meatus. Some slift' short hairs are also found in its interior, which stretch across the tube, and prevent the ingress of insects and dust. Be- neath the cuticle are a number of small ceruminous follicles, which secrete the wax of the ear. Vessels and JVerves. — The pinna is plentifully supplied with arte- ries ; by the anterior auricular from the temporal, and by the pos- terior nmicular from the external carotid. Its Nerves are derived from the auricular branch of the fifth, and from the auricularis magnus of the cervical plexus. * "The Anatomy and Physiology of the Organ of Hearing," by David Tod, 1832. 452 TVMPANUM CONTENTS. Tympanum. — The tympanum is an irregular bony cavity, com- pressed from without inwards, and situated within the petrous bone. It is bounded externally by the meatus and membrana tympani ; zn- ierna/A/ by its inner wall ; and in its circumference by the petrous bone and mastoid cells. The Membrana tympani is a thin and semi-transparent membrane of an ov^al shape, the longer diameter being nearly vertical. It is inserted into a groove around the circumference of the meatus near to its termination, and is placed obliquely across the area of that tube, the direction of the obliquity being downwards and inwards. It is concave towards the meatus, and convex towards the tympa- num, and is composed of three layers, an external cuticular, middle fibrous and muscular, and internal mucous, derived from the mucous lining of the tympanum. The tympanum contains three small bones, ossicula auditus, viz. the— Malleus, Incus, Stapes. The Malleus {hammer) consists of a head, neck, handle {manu- brium), and two processes, long {processus gracilis), and short {pro- cessus brevis). The manubrium is connected to the membrana tympani by its whole length extending to below the central point of that membrane. It lies beneath its mucous layer, and serves as a point of attachment to which the radiating fibres of the fibrous layer converge. The long process descends to a groove near to the fissura Glaseri, and gives attachment to the laxator tympani muscle. Into the short process is inserted the tendon of the tensor tympani, and the head of the bone articulates with the incus. The Incus {anvil) is named from an imagined resemblance to an anvil. It has also been likened to a bicuspid tooth, having one root longer, and widely separated from the other. It consists of two processes, which unite nearly at right angles, and at their junction form a flattened body, to articulate with the head of the malleus. The short process is attached to the margin of the opening of the mastoid cells by means of a short ligament ; the long process descends nearly parallel with the handle of the malleus, and curves inwards, near to its termination. At its extremity is a small globular projection, the as orbiculare, which is a distinct bone in the foetus, but becomes anchylosed to the long process of the incus in the adult; this process articulates with the head of the stapes. The Stapes is shaped like a stirrup, to which it bears a close re- semblance. Its head articulates with the os orbiculare, and the two branches are connected by their extremities with a flat oval-shaped plate, representing the foot of the stirrup. The foot of the stirrup is received into the fenestra ovalis, to the margin of which it is con- nected by means of a circular ligament ; it is in contact, by its sur- LIGAMENTS OF THE TYMPANUM. 453 face, with the membrana vestibuli, and is covered in by the mucous hning of the tympanum. The neck of the stapes gives attachment to the stapedius muscle. Fig. 139.* The ossicula auditus are retained in their position and moved upon themselves by means of ligaments and muscles. The Ligaments are three in number; the Ugament of the head of the malleus, which is attached superiorly to the upper wall of the tympanum : the hgament of the incus, a short and thick band, which serves to attach the extremity of the short process of that bone to the margin of the opening of the mastoid cells ; and the circular ligament which connects the margin of the foot of the stapes with the circumference of the fenestra ovalis. These Hgaments have been described as muscles, by Mr. Tod, under the names of supe- rior capitis mallei, obliquus incudis externus posterior, and mus- culus, vel structura stapedius inferior. * A diagram of the ear. p. The pinna, t. The tympanum. I. The labyrinth. 1. The upper part of the helix. 2. The antihelix. 3. Tlie tragus. 4. The antitragus. 5. The lobulus. 6. The concha.'^ 7. The upper part of the fossa innominata. 8. The meatus. 9. The membrana tympani, divided by the section. 10. The three little bones, crossing the area of tlie tympanum, malleus, incus, and stapes ; the foot of the stapes blocks up the fenestra ovalis upon the inner wall of the tympanum. 11. The promontory. 12. The fenestra rotunda; the dark opening above the ossicula leads into the mastoid cells. 13. The Eustachian tube ; the little canal upon this tube contains the tensor tympani muscle in its passage to the tympanum. 14. The vesti- bule. 15. The three semicircular canals, horizontal, perpendicular, and oblique. 16. The ampullfe upon the perpendicular and horizontal canals. 17. The cochlea. 18. A depression between the convexities of the two tubuli which communicate witli the tympanum and vestibule ; the one is the scala tympani, termmating at 12 ; the other is the scala vestibuli. 454 MUSCLES OF THE TYMPANU3I. . The Muscles of the tympanum are four in number, the — Tensor tympani, Laxator tympani, Laxator tympani minor, Stapedius. The Tensor tympani (muscukis internus mallei) arises from the spinous process of the sphenoid, from the petrous portion of the temporal bone, and from the Eustachian tube, and passes forwards in a distinct canal, separated from the tube by the processus coch- leariformis, to be inserted into the handle of the malleus, imme- diately below the commencement of the processus gracilis. The Laxator tympani (musculus externus mallei) arises from the spinous process of the sphenoid bone, and passes through an opening in the fissura Glaseri, to be inserted into the long process of the malleus. The Laxator tympani minor arises from the upper margin of the meatus, and is inserted into the handle of the malleus, near to the processus brevis. This is regarded as a hgament by some anato- mists. The Stapedius arises from the interior of the pyramid, and escapes from its summit to be inserted into the neck of the stapes. The openings in the tympanum are ten in number, five large and five small; they are — Large Openings. Small Openings. Meatus auditorius. Entrance of the chorda tympani, Fenestra ovalis, Exit of the chorda tympani, Fenestra rotunda. For the laxator tympani, Mastoid cells, For the tensor tympani, Eustachian tube. For the stapedius. The opening of the meatus auditorius has been previously de- scribed. The Fenestra ovalis (fenestra vestibuli), is a reniform opening, situated at the bottom of a small oval fossa (the pelvis ovalis), in the upper part of the inner wall of the tympanum, directly opposite the meatus. The long diameter of the fenestra is directed horizon- tally, and its convex borders upwards. It is the opening of com- munication between the tympanum and the vestibule, and is closed by the foot of the stapes and by the lining membranes of both cavities. The Fenestra rotunda (fenestra cochlea?) is somewhat triangular in its form, and situated in the inner wall of the tympanum, below and rather posteriorly to the fenestra ovalis, from which it is sepa- rated by a bony elevation, called llic promontory. It serves to establish a communication between the tympanum and the cochlea. OPENINGS OF THE TYMPANUM. 455 In the fresh subject it is closed by a proper membrane, as well as by the lining of both cavities. The Mastoid cells are very numerous, and occupy the whole of the interior of the mastoid process, and part of the petrous bone. They communicate by a large irregular opening with the upper and posterior circumference of the tympanum. The Eustachian tube is a canal of communication extending obliquely between the pharynx and the anterior circumference of the tympanum. In structure it is partly fibro-cartilaginous and partly osseous, is broad and expanded at its pharyngeal extremity, and narrow and compressed at the tympanum. The smaller openings serve for the transmission of the chorda tym- pani nerve, and three of the muscles of the tympanum. The opening by which the chorda tympani e7iters the tympanum, is near the root of the pyramid, at about the middle of the posterior wall. The opening of exit for the chorda tympani is at the fissura Glaseri in the anterior wall of the tympanum. The opening for the laxator tympani muscle is also situated in the fissura Glaseri, in the anterior wall of the tympanum. The opening for the tensor tympani muscle is in the inner wall, immediately above the opening of the Eustachian tube. The opening for the stapedius muscle is at the apex of a conical bony eminence, called the pyramid, which is situated on the poste- rior wall of the tympanum, immediately behind the fenestra ovalis. Directly above the fenestra ovalis is a rounded ridge formed by the projection of the aquceductus Fallopii. Beneath the fenestra ovalis and separating it from the fenestra rotunda is the promontory, a rounded prominence formed by the pro- jection of the first turn of the cochlea. It is channeled upon its sur- face by three small grooves, which lodge the three tympanic branches of Jacobson's nerve. The Foramina and processes of the tympanum may be arranged, according to their sit nation, into four groups. 1. In the External ivall is the meatus auditorius, closed by the memhrani tympani. 2. In the Inner wall, from above downwards, are the — Opening for the tensor tympani. Ridge of the aqu^ductus Fallopii, Fenestra ovahs. Promontory, Grooves for Jacobson's nerve, Fenestra rotunda. 3. In the Posterior wall are the — Opening of the mastoid cells, Pyramid, Opening for the stapedius, Apertura chordce (entrance). 456 INTERNAL EAK. 4. In the Anterior wall are the — Eustachian tube, Fissura Glaseri, Opening for the laxator tympani, Apertura chordae (exit). The tympanum is Hned by a vascular mucous membrane, which invests the ossicula and chorda tympani, and forms the internal layer of the membrani tympani. From the tympanum it is reflected into the mastoid cells, which it lines throughout, and passes through the Eustachian tube to become continuous with the mucous mem- brane of the pharynx. Vessels and Nerves. — The Arteries of the tympanum are derived from the internal maxillary, internal carotid, and posterior auricular. Its Nerves are — 1. Minute branches from the facial, which are distributed to the stapedius muscle. 2. The chorda tympani, which leaves the facial nerve near to the stylo-mastoid foramen, and arches upwards to enter the tympanum at the root of the pyramid ; it then passes forwards between the handle of the malleus and long process of the incus, to its proper opening in the fissura Glaseri. 3. The tympanic branches of Jacobson's nerve, which are distributed to the membranes of the fenestra oval is and fenestra rotunda, and to the Eustachian tube, and form a plexus by communicating with the carotid plexus and otic ganglion. 4. A filament from the otic gan- glion to the tensor tympani muscle. INTERNAL EAR. The Internal ear is called labyrinth, from the complexity of its communications : it consists of a membranous and an osseous por- tion. The osseous labyrinth presents a series of cavities which are channeled through the substance of the petrous bone, and is situated between the cavity of the tympanum and the meatus auditorius in- ternus. It is divisible into the — Vestibule, Semicircular canals, Cochlea. The Vestibule is a small three-cornered cavity, compressed from without inwards, and situated immediately within the inner wall of the tympanum. The three corners which are named ventricles or cornua arc placed, one anteriorly, one superiorly, and one poste- riorly. The Anterior ventricle receives the oval aperture of the scala vestibuli ; the superior, the ampullary o])enings of the superior and horizontal semicircular canals ; the posterior ventricle receives the ampullary opening of the oblique semicircular canal, the common aperture of the ol)lique and pcrpendiculnr canals, the termination of OPENINGS OF THE VESTIBULE. 457 the horizontal canal, and the aperture of the aquaeductiis vestibuli. In the anterior ventricle is a small depression, which corresponds with the posterior segment of the cnl de sac of the meatus audi- torius internus ; it is called the fovea hemispherica, and is pierced by a cluster of small openings, the macula cribrosa. In the sujyerior ventricle of the vestibule is another small depression, the fovea eUiptica, which is separated from the fovea hemispherica by a pro- jecting crest, the eminentia pyramid alis. The latter is pierced by numerous minute openings for the passage of nervous filaments. The posterior ventricle presents a third small depression, the fovea sulciformis, which leads upwards to the ostium aquseductus vestibuli. The internal wall of the vestibule corresponds with the bottom of the cul de sac of the meatus auditorius internus, and is pierced by numerous small openings for the transmission of nervous filaments. In the external or tymfanic wall is the reniform opening of the fenestra ovalis (fenestra vestibuli), the margin of which presents a projecting rim towards the cavity of the vestibule. The openings of the vestibule may be arranged, like those of the tympanum, into large and small. The Large openings are seven in number, viz. the — Fenestra ovalis, Scala vestibuli. Five openings of the three semicircular canals. The Small openings are the — Aqua3ductus vestibuli, Openings for small arteries, Openings for branches of the auditory nerve. The Fenestra ovalis has already been described ; it is the opening into the tympanum. The opening of the scala vestibuli is the oval termination of the vestibular canal of the cochlea. The Jlquceductus vestibuli (canal of Cotunnius) is the conmience- ment of the small canal which opens under the osseous scale upon the posterior surface of the petrous bone. It gives a passage to a process of membrane which is continuous internally with the lining membrane of the vestibule, and externally with the dura mater, and to a small vein. The Openings for the arteries and nerves are situated in the in- ternal wall of the vestibule, and correspond with the termination of the meatus auditorius internus. The Semicircular Canals are three bony passages which com- municate with the vestibule, into wiiich they open by both extre- mities. Near one extremity of each of the canals is a remarkable dilatation of its cavity, which is called the ampulla (sinus ampullaceus). The iwjjcy/or or perpendicular canals (canalis scmicircularis verticahs 458 COCHLEA MODIOLUS, superior), is directed transversely across tlie petrous portion of the temporal hone, forming a projection upon the anterior face of the .petrous bone. It commences by means of an ampulla in the superior ventricle of the vestibule, and terminates posteriorly by joining with the oblique, and forming a common canal, which opens into the upper part of the posterior ventricle. The ?niddle or oblique canal (canalis semicircularis verticalis posterior), corresponds w^ith the posterior part of the petrous portion of the temporal bone ; it com- mences by an ampullary dilatation in the posterior ventricle, and curves nearly perpendicularly upwards to terminate in the common canal. In the ampulla of this canal are numerous minute openings for nervous filaments. The inferior or /lorizontal canal (canalis semicircularis horizontalis), is directed outwards towards the base of the petrous bone, and is shorter than the two preceding. It commences by an ampullary dilatation in the superior ventricle, and terminates in the posterior ventricle. The Cochlea {snail shell), forms the anterior portion of the laby- rinth, corresponding by its apex with the anterior wall of the petrous bone, and by its base with the anterior depression at the bottom of the cul de sac of the meatus auditorius in- ternus. It consists of an osseous and gradually tapering canal, about one inch and a half in length, which makes two turns and a half spirally around a central axis called the modiolus. The central axis or modiolus is large near its base where it corre- sponds with the first turn of the cochlea, and diminishes in diameter towards its extremity. At its base it is pierced by numerous minute openings which transmit the filaments of the cochlear nerve. These openings are disposed in a spiral manner, hence they have received from Cotunniusf the name of tractus spirahs foraminu- * The cochlea divided parallel with its axis, through the centre of the modiolus. After Breschet. I. The modiolus. 2. The infundibulum in which the modiolus ter- minates. 3, 3. The cochlear nerve, sending its filaments through the centre of the modiolus. 4, 4. The scala tympani of the first turn of the cochlea. 5, 5. The scala vestibuli of the first turn. 6. Section of the lamina spiralis, its zonula ossea ; one of the filaments of the cochlear nerve is seen passing between the two layers of the lamina spiralis to be distributed upon the membrane which invests the lamina. 7. The mem- branous portion of the lamina spiralis. 8. Loops formed by the filaments of the cochlear nerve. 'J, 9. Scala tympani of tlic second turn of the cochlea. 10, 10, Scala vestibuli of tlio second turn; the septum between the two is the lamina spiralis. 11. The scala tympani of the remaining half turn. 12. The remaining half turn of the scala vestibuli ; tlic dome placed over this half turn is the cupola. 13. The lamina of bone which forms the floor of the scala vestibuli curving spirally round to constitute the infundibulum (2). 14. The helicotrema through which a bristle is passed ; its lower extremity issues from the scala tyrnpani of the middle turn of the cochlea. t Dominico Cotunnius, an Italian physician; his dissertation " De Aqucfiduclibus Auris Humanae Interna;," was published in Naples in 1761. SCALA TVMPANI ET VESTIBULI. 459 lentus. The modiolus is every where traversed in the direction of its length by minute canals, which proceed from the tractus spiralis foraminulentus, and terminate upon the sides of the modiolus, by opening into the canal of the cochlea or upon the surface of its lamina spiralis. The central canal of the tractus spiralis foraminu- lentus is larger than the rest, and is named the tubulus centralis modioU ; it is continued onwards to the extremity of the modiolus, and transmits a nerve and a small artery, the arteria centralis modioU. The interior of the canal of the cochlea is partially divided into two passages (scalse) by means of a thin and porous lamina of bone (zonula ossea laminae spiralis), which is wound spirally around the modiolus in the direction of the canal. This bony septum extends for about two-thirds across the diameter of the canal, and in the fresh subject is prolonged to the opposite wall by means of a mem- branous layer, so as to constitute a complete partition — the lamina spiralis. The osseous lamina spiralis consists of two thin lamellas of bone, between which, and through the perforations on their sur- faces, the filaments of the cochlear nerve reach the membrane of the cochlea. At the apex of the cochlea the lamina spiralis termi- nates in a pointed, hook-shaped process, the hamulus laminae spiralis. The two scales of the cochlea which are completely separated throughout their length in the living ear, communicate superiorly over the hamulus laminae spiralis by means of an opening common to both, which has been termed by Breschet helico-trema (sXi^, sXIgcrc) volvere — T-^>5fia). Inferiorly, one of the two scalse, the scala vestibuli, terminates by means of an oval aperture in the anterior ventricle of the vestibule ; while the other, the scala tympani, becomes some- what expanded, and opens into the tympanum through the fenestra rotunda (fenestra cochleae). Near to the termination of the scala tympani is the small opening of the aquaeductus cochlese. The internal surface of the osseous labyrinth is lined by a f^bro- serous membrane, which is analogous to the dura mater in perform- ing the office of a periosteum by its exterior, whilst it fulfils the purpose of a serous membrane by its internal layer, secreting a limpid fluid, the aqua labyrinthi (liquor Cotunnii), and sending a reflection inwards upon the nerves distributed to the membranous labyrinth. In the cochlea the membrane of the labyrinth invests the two surfaces of the bony lamina spiralis, and being continued from its border across the diameter of the canal to its outer wall, forms the membranous lamina spiralis and completes the separation between the scala tympani and scala vestibuh. The fenestra ovahs and fenestra rotunda are closed by an extension of this membrane across them, assisted by the membrane of the tympanum and a proper intermediate layer. Besides lining the interior of the osseous cavity the membrane of the labyrinth sends two delicate processes along the aqueducts of the vestibule and cochlea to the internal sur- face of the dura mater of the petrous portion of the temporal bone, with which they are continuous. These processes are the remains 460 MEMBRAXOUS LABYRIX'TH. Fiff. 141 .t of a communication originally subsisting between the dura mater and the cavity of the labyrinth.* The Membranous LxVbykinth is smaller in size, but a perfect counterpart, with respect to form, of the vestibule and semicircular canals. It consists of a small elongated sac, sacculus communis (utriculus communis) ; of three semicircular membranous canals, which correspond with the osseous canals, and communicate with the sacculus com- munis ; and of a small round sac (saccu- lus proprius), which occupies the anterior ventricle of the vestibule, and lies in close contact with the external surface of the sacculus communis. The membranous semicircular canals are two-thirds smaller in diameter than the osseous canals. The membranous labyrinth is retained in its position by * Cotunnius regarded these processes as tubular caTials, through which the supera- bundant aqua labyrintlii might be expelled into the cavity of the cranium. Mr. Whar- ton Jones, in the article " Organ of Hearing" in the Cyclopa-dia of Anatomy and Physiology, also describes them as tubular canals which terminate beneath the dura mater of the petrous bone in a small dilated pouch. In tlie ear of a man deaf and dumb from birth, he found the termination of the aqueduct of the vestibule of unusu- ally large size in consequence of irregular dcvelopement. t The labyrinth of the lelt ear, laid open in order to show its cavities and the mem- branous labyrinth. After Breschct, I. The cavity of the vestibule, opened from its anterior aspect in order to show the three-cornered form of its interior, and the mem- branous labyrinth wliich it contains. The figure rests upon the common saccule of the membranous labyrinth, — the sacculus communis. 2. The ampulla of the superior or perpendicular semicircular canal, receiving a nervous fasciculus from the superior i)ranch of the vestibular nerve. 3, 4. Tiie superior or perpendicular canal with its con- tained membranous canal. 5. The ampulla of the inferior or horizontal semicircular canal, receiving a nervous fasciculus from the superior branch of the vestibular nerve, 6. The termination of the membranous canal of the horizontal semicircular canal in the sacculus communis. 7. The ampulla of the middle or oblique semicircular canal, receiving a nervous fasciculus from the inferior brancli of the vestibular nerve. 8. TJic oblique semicircular canal witli its membranous canal. 9. The common canal, result- ing from the union of the pcrpcudicular with tlie oblique semicircular canal. 10. The membranous common canal terminating in tiic sacculus communis. 11. The otoconite of tlic sacculus communis seen through the membranous parietcs of that sac. A nervous fasciculus from the inferior branch of the vestibular nerve is seen to be distributed to the sacculus communis near to the otoconite. The extremity of the sacculus above the otoconite is lodged in tlie sujwrior ventricle of the vestibule, and that below in tlic inferior ventricle. 12. The sacculus proprius situated in the anterior ventiicle ; its otoconite is seen through its membranous parietcs, and a nervous fasciculus derived from the middle branch of the vestibular nerve is distributed to it. The spaces around the membranous labyrinth are occupied by the aqua labyrinthi. 13. 1'hc first turn of the cochlea; the figure is situated in the scala tym])ani. 14. The extremity of the scala, tympani corresponding with the fenestra rotunda. 15. The lamina spiralis; the figure is situated in tlie scala vestibuli. 1 (i. The opening of the scala vestibuli into the vestibule. 17. The second turn of the cocldca ; the figure is jjlaced upon the lamina spiralis, and tliereforc in the scala vestibuli, the scala tympani being beneath the laniina. 18. The remaining half turn of the cochlea; the figure is jjlaccd in the scala tym])ani. 19, The lamina spiralis terminating in a falciform extremity. The dark sjiace in- cluded within the fiilciform ciu've of the extremity of the lamina spiralis is tlie heli- cotrcma. 20, The iufundibuhim. DISTEIBUTION OF THE AUDITORY NEKVE. 461 means of the numerous nervous filaments which are distributed to it from the openings in the inner wall of the vestibule, and is separated from the lining membrane of the labyrinth b}' the aqua labyrinthi. The structure of the membranous labyrinth is composed of four layers : an external or serous layer, derived from the lining mem- brane of the labyrinth ; a vascular layer, in which an abundance of minute vessels are distributed ; a nervous layer formed by the ex- pansion of the filaments of the vestibular nerve and of an internal and serous membrane, by which the limpid fluid which fills the membranous labyrinth is secreted. Some small patches of pigment have been observed by Mr. Wharton Jones in the tissue of the mem- branous labyrinth of man. Among animals such spots are constant. The membranous labyrinth is filled in the interior with a limpid fluid, first well described by Scarpa, and thence named liquor Scarpas* (endolymph, vitreous humour of the ear,) and contains two small calcareous masses called otoconites. The otoconites {ovs, u7og Mvtg, the ear-dust), consist of an assemblage of minute, crystalline particles of carbonate and phosphate of lime, held together by animal substance, and probably retained in form by a reflection of the lining membrane of the membranous labyrinth. They are found suspended in the liquor Scarpa, one in the sacculus communis, and the other in the sacculus proprius, from that part of each sac with which the nerves are connected. The Auditory Nerve divides into two branches at the bottom of the cul de sac of the meatus auditorius internus ; a vestibular nerve, and a cochlear nerve. The vestibular nerve, the most posterior of the two, divides into three branches, superior, middle, and inferior. The superior vestibular branch gives off a number of filaments which pass through the minute openings of the eminentia pyramidahs, and of the superior ventricle of the vestibule, and are distributed to the sacculus communis, and to the ampulte of the perpendicular and horizontal semicircular canals. The middle vestibular branch sends off" numerous filaments which pass through the openings of the macula cribrosa in the anterior ventricle of the vestibule, and are distributed to the sacculus proprius. The inferior and smallest branch takes its course backwards to the posterior wall of the vesti- bule, and gives oft^ filaments which pierce the wall of the ampullary dilatation of the oblique canal to be distributed upon its ampulla. According to Stiefensand there is in the situation of the point of entrance of the nervous filaments into the ampullre a deep depression upon the exterior of the membrane, and upon the interior a corre- sponding projection, which forms a kind of transverse septum, par- tially dividing the cavity of the ampulla into two chambers. Upon entering the structure of the sacculi and ampullae, the ner- vous filaments radiate in all directions, anastomosing with each * Antonio Scarpa is celebrated for several beautiful sarjrical and anatomical mono- graphs; as, for example, his work on "Aneurism," "Do Audita ct Olfactu," «.Vc. An account of the aqua labyrinthi will be found in iiis anatomical observations "De Struc- ture Fcnestrar' Rotunda', ct de Tympano Secundnrio." 462 ORGAN OF TASTE. Other, and forming interlacements and loops, and they terminate upon the inner surface of the membrane in minute papillae, resem- bling those of the retina. The Cochlear nerve divides into numerous filaments M'hich enter the foramina of the tractus spiralis foraminulentus in the base of the cochlea, and passing upwards in the canals of the modiolus bend outwards at right angles, to be distributed in the tissue of the lamina spiralis. The central portion of the nerve passes through the tubulus centralis of the modiolus, and supphes the apicial portion of the lamina spiralis. In the lamina spiralis the nervous filaments lying side by side on a smooth plane form numerous anastomosing loops, and spread out ultimately into a nervous membrane. According to Treviranus and Gottsche the ultimate terminations of the filaments assuine the form of papillse. The Arteries of the labyrinth are derived principally from the auditory branch of the superior cerebellar artery. ORGAN OF TASTE. The Tongue is composed of muscular fibres, which are distributed in layers arranged in various directions : thus, some are disposed hnghudinally; others transversely; others, again, ohJiquehj and vertically. Between the muscular fibres is a considerable quantity of adipose substance. The tongue is connected posteriorly with the os hyoides by mus- cular attachment, and to the epiglottis by mucous membrane, form- ing the three folds which are called frcena epiglottidis. On either side it is held in connexion with the lower jaw by mucous mem- brane, and in front a fold of that membrane is formed beneath its under surface, which is named /rcc7z?/77i lingua. The surface of the tongue is covered by a dense layer analogous to the corium of the skin, which gives support to the papilla!. A raphe marks the middle line of the organ, and divides it into sym- metrical halves. The Papilloi of the tongue are the — Papilla3 circumvallatse. Papillae conicoe, Papillce filiformcs, Papillae fungiformes. The PapillcB circumvallata; are of large size, and from fifteen to twenty in number.* They are situated on the dorsum of the tongue, near to its root, and form a row upon each side, which meets its fellow at the middle line, like the two branches of the letter V. Each papillcc resembles a cone, attached by its apex to the bottom of a cup-shaped depression: hence they are also named papillae * I think it rare to sc;r more than nino, four on each side of tlie middle one, wliioh is always the lar;fcpt. — (>. PAP1LL.E OF TONGUE. 463 calycifarmes. This cup-shaped cavity forms a kind of fossa around the papilla, whence their name circumvaUaUe. At the meeting of the two rows of these papillae upon the middle of the root of the tongue, is a deep mucous follicle called foramen ccEcum. The Papillce coniccB and filiformes cover the whole surface of the tongue in front of the circumvallatse, but are most abundant near its apex. They are conical and filiform in shape, and have their points directed backwards. The PajjillcE fungi formes are irregularly dispersed over the dorsum of the tongue, and are easily recognised amongst the other papillse by their rounded heads and larger size. A number of these papillse will generally be observed at the tip of the tongue. Behind the papillse circumvallatee, at the root of the tongue, are a number of mucous glands, which open upon the surface. They have been improperly described as papillse by some authors. Vessels and JVerves. — The tongue is abundantly supplied with blood by the lingual arteries. The JVerves are three in number, and of large size: — 1. The gustatory branch of the fifth, which is distributed to the papillee, and is the nerve of common sensation and of taste. 2. The glosso-pha- ryngeal, which is distributed to the mucous membrane, follicles, and glands of the tongue, is a nerve of sensation and motion ; it also serves to associate the tongue with the pharynx and larynx. Pa- nizza's experiments, tending to prove that this is the true nerve of taste, are rendered questionable by recent experiments. 3. The lingual, which is the motor nerve of the tongue, and is distributed to the muscles. The Mucous membrane which invests the tongue, is continous with the cutis along the margins of the lips. On either side of the frsenum linguae it may be traced through the sublingual ducts into the sub- lingual glands, and along Wharton's* ducts into the sub-maxillary glands ; from the sides of the cheeks it passes through the openings of Stenon'sj ducts to the parotid gland ; in the fauces, it forms the assemblage of folUcles called tonsils, and may be thence traced downwards into the larynx and pharynx, where it is continuous with the general gastro-pulmonary mucous membrane. Beneath the mucous membrane of the mouth are a number of small glandular granules, which pour forth their secretion upon the surface. A considerable number of them are situated within the lips, in the palate, and in the floor of the mouth. They are named from the position which they may chance to occupy, labial, pala- tine glands, &C.J * Thomas Wharton, an English physician, devoted considerable attention to the ana- tomy of the various glands : his work, entitled " Adenographia," ttc^ was publislied in 1656. t Nicholas Stenon, a Danish anatomist: he was made professor in Copenhnffen in 1672. ' ^ t These glands are salivary, having the same structure as the parotid and secreting tlie same fluid. — G. 464 OKGAN OF TOUCH. ORGAN OF TOUCH. Th&. Skin is composed of three layers, viz. the Cutis, Rete mucosum. Cuticle. The Cutis (dermis), or true skin, covers the entire surface of the body, and is continuous with the mucous membrane which lines its cavities. It consists of two layers, a deep one called corium, and a superficial or •papillary layer. The Corium is the base of support to the skin, and owes its den- sity of structure to an interlacement of fibrous bands which form a firm and elastic web. By its under surface it is connected with the common superficial fascia of the body, and presents a number of areolae, in which are lodged small masses of adipose tissue. On the upper surface the fibres are more closely aggregated, and form a smooth plane for the support of the papillary layer. The corium differs very much Yig. 142* in thickness in different parts of the body; thus, on the lips, eye- lids, and scrotum it is extremely thin. On the head, back, soles of the feet, and palms of the hand it is very thick ; and on the more exposed parts of the body it is much thicker than on those which are protected. The Papillary layer is soft, and formed by minute papillae which cover every part of its surface. On the body generally, the papillae are very small and irregular in their distribution; they are best seen in the palm of the hand or sole of the foot, where they are disposed in hncar ridges, as indi- cated by the markings on the cuticle. The ridges of papillae in M-. * Tlio anatomy of tlic skin. 1. The culiclo, sliowinjr tlio oblique lamina; of wliich it Ih c;oiii|)oscd and tliu imbricated disponition of tbo ridircs upon its surface. 3, The retc irmcosum. 3. Two of the (pi.idrilateral pa])illary masses, such as arc seen in the palm of the hand or sole of the foot; tlioy are composed of minute conical papillrc. 4. The deeper Inyer of the cutis, the corium. 5. Adipose vesicles; showinnf their appear- ance beneath tlie microscope. 6. A perspiratory fjland with its spiral duet, such as is seen in tlie palm of the hand or sole of the foot. 7. Another perspiratory tfland with a straighter duct, such as is seen in the scalp. 8. Two hairs from the sculp, enclosed in their follicles; their relative depth in the skin is preserved. 9. A pair of sebaceous glands, opening by short ducts into tiie Ibllicle ol'tlie hair. RETE MUCOSUM, 465 these situations are separated from each other by longitudinal fur- rows, and are divided by transverse furrows into small quadrilateral rounded masses. These quadrilateral masses are each composed of a considerable number of minute papillas, which are conical in form and variable in length, one or two of the papillse in each mass being generally longer than the rest. In the middle of the trans- verse furrow, between the papillse, is the opening for the perspira- tory duct. The papillae beneath the nail have a peculiar form and arrange- ment. At the root of the nail they are numerous, but small and very vascular ; opposite to the part of the nail called lunula, they are scarcely raised above the surface, and less vascular ; but beyond this point they form lengthened vascular plicae, which afford a large surface of secretion. These lengthened papilla deposit the horny secretion in longitudinal lamellae, which give to the nail the ribbed appearance which it presents upon its surface. Vessels and JVerves. — The papillae are abundantly supplied with vessels and nerves ; the former to enable them to perform the office of secretion in the pro- Fig. 143.* duction of the cuticle, the latter to give them the sensibility necessary to an organ of touch. The Rete mucosum is the soft medium which is situated between the papillary surface of the cutis and cuticle ; after a careful macera- tion it may be separated as a distinct layer, particularly in the negro, where it is firmer than in the European, and contains the colour- ing matter of the skin. The name rete mucosum, given to it by Malpighi, conveys a very inaccurate notion of its structure ; for it is neither a network, nor is it mucous. It is thin upon the general surface of the body ; but is thicker in the palm of the hand and sole of the foot, and pre- sents a close correspondence with the thickness of the cuticle. Examined with the microscope, it is seen to be moulded accurately upon the papillae, being thick in the spaces between these, and thin * Anatomy of a portion of skin taken from the palm of the hand. 1, 1. The papil- lary layer, in which the longitudinal furrows (2) marking the arrangements of the papillee into ridges is shown. Each ridge is moreover divided by transverse furrows (.3) into small quadrangular masses. The quadrangular masses consist of a tuft of minute conical papillae, of which one or two are frequently longer and larger than the rest. In this figure the long papillas are alone seen, the rest being too numerous to introduce into a wood-engraving. 4, 4. The rete mucosum raised from the papillary layer and turned back; the under surface of this stratum presents an accurate impres- sion of the papillary layer ; on which are seen longitudinal ridges corresponding with the longitudinal furrows, transverse ridges corresponding with the transverse furrows, and quadrangular depressions corresponding with the quadrangular masses of papilla?. Moreover, wherever one of the long papillse exists, a distinct conical sheath will be found in the rete mucosum. 5, 5. Perspiratory ducts drawn out straight by the sepa- ration of the rete mucosum from the papillary layer ; the point at which each perspi- ratory duct issues from the papillary layer, and pierces the rete mucosum, is the middle of the transverse furrow between the quadrangular masses. 59 466 STHUCTURE OF THE CUTICLE. over their convexities ; hence arises the appearance of a network. In the rete mucosum from the hand, these depressions are arranged in a Unear series, as are the papillas ; in other situations they are more irregular, but correspond aWays with the distribution of the papillte. The rete mucosum is the freshly secreted layer of cuticle, and gradually hardens as it approaches the surface. It has been shown by Henle to be composed of minute oval vesicular cells, which be- come converted in the hardened cuticle into flattened scales, each containing a central nucleus. The dark pigment of the negro exists in the form of small granules of colouring matter. The cuticle (epidermis, scarf-skin) is the horny unorganized lamella which covers and protects the entire surface of the more dehcate layers of the skin. In situations exposed to pressure, as the palm of the hand and sole of the foot, it is very thick ; on other parts it forms only a thin layer. The cuticle is marked on the sur- face by a net-work of hnes : these are more numerous and larger near to joints, where they form deep wrinkles on account of the inelastic nature of its structure. Their appearance differs in different regions of the body ; but every where depends upon the same cause, the inelasticity of the cuticle. At the entrance to the cavities of the body it is continuous with the epithelium or cuticular covering of the mucous membrane. The cuticle, in minute structure, consists of several successions of laminaj which are secreted by the cutis ; the last secreted layer being the rete mucosum. The rete mucosum is composed of small round masses or nuclei, connected together by a glutinous fluid containing a number of pigment granules. Each nucleus contains in its interior a minute central point, the nucleus-corpuscule, and around the exterior of the nucleus a vesicle is by degrees produced. The middle laminae of the cuticle are composed of these nucleated vesicles, which are more and more compressed and flattened as they are observed nearer to the surface. In the superficial laminee the vesicles are converted into thin scales, in the centre of which the nucleus with the nucleus-corpuscule is still apparent. The laminae of the cuticle arc disposed on the same plane with the surface of the skin in many situations, in others they are placed obliquely so as to project by their free extremities upon the surface ; in the palm of the hand and sole of the foot these layers correspond with the elevations of the papillae, and present an imbricated linear surface. This is particularly seen on the points of the fingers where the rows of papillas have a circular arrangement. The superficial laminae of the cuticle are being continually thrown off by exfoliation or removed by abrasion, to give place to the deep and more newly formed layers. Upon the inner surface of the cuticle a number of depressions and linear furrows are seen, corresponding with the projections of the papillae. A number of conical processes are also observed on NAILS HAIRS GLANDS. 467 this surface, which correspond with the passage of hairs through the cuticle, and with the openings of the perspiratory ducts. The Openings in the cuticle are the pores or openings for the per- spiratory ducts, the openings for the passage of the hairs, and those of the sebaceous follicles. APPENDAGES TO THE SKIN. The appendages to the skin are the nails, hairs, sebaceous glands, and perspiratory glands and ducts. The Kails are parts of the cuticle secreted in the same manner, composed of the same material, but disposed in a peculiar way to serve an especial purpose — the protection of the tactile extremities of the fingers. They are inserted by their root into a deep groove (matrix) of the skin, and are firmly attached to the papillary surface by the close connexion of the papillse with the longitudinal laminas. The white semilunar segment near the root of the nail is called the lunula. The cuticle is closely connected with it all round, and in maceration the nail comes off with that layer. The Hairs have a very different structure and arrangement from that of the nails : they are inserted for a considerable depth within the integument, and terminate in conical or somewhat bulbous roots. Each hair is enclosed beneath the surface by a vascular secretory follicle, which regulates its form during growth. Hairs are very rarely completely cylindrical ; they are generally more or less compressed, and somewhat prismoid in form. The transverse section is reniform ; in texture it is dense and homoge- neous towards the circumference, and porous and cellular in the centre like the pith of a plant. The Sebaceous glands are abundant in some parts of the skin, as in the armpits, the nose, &c., and vary in complexity of structure from a simple pouch-like follicle to a lobulated gland. At the ex- tremity of the nose they have several lobes ; and in the scalp they are lobulated like a bunch of grapes, and terminate in the follicles of the hairs near to the surface of the skin. They secrete an oily fluid which is poured out upon the surface of the skin, and tends to preserve the flexibility of the cuticle. The Perspiratory ducts are minute spiral tubes which commence in small lobulated glands, situated deeply in the integument beneath the corium and among the adipose vesicles. They are easily seen by examining a thin perpendicular section of the skin from the palm of the hand, with a lens of moderate power. Proceeding from the glands, the ducts ascend through the transverse furrow, between the quadrilateral masses of papilla and through the rete mucosum to terminate by open pores upon the surface of the cuticle. That portion of the tube which is situated in the cuticle, is pretty equally spiral ; but that below the level of the papillary surface is very irre- gularly twisted, and is often nearly straight. In the scalp the tubes are serpentine, or but slightly curved. 468 PORES OF THE SKIN. A good view of the perspiratory ducts passing between the cutis and cuticle, may be obtained by peeling off the cuticle from the palm of the hand in a decomposing limb ; or by scalding a small portion- of integument and then separating the cuticle. The Po7-es are best observed during perspiration, when the fluid is seen oozing through their minute openings. In the hand and sole of the foot they are easily seen by the naked eye without this assis- tance. They are disposed at regular distances along the ridges of the cuticle, and give rise to the appearance of lines cutting the ridges transversely. CHAPTER X. OF THE VISCERA. That part of the science of anatomy which treats of the viscera is named splanchnology, from the Greek words d'^fXay'/yov, viscus, and Xdyo?. The viscera of the human body are situated in the three great internal cavities, — the cranio-vertebral, thorax, and abdomen. The viscera of the cranio-vertebral cavity — the brain and spinal cord, with the principal organs of sense — have been already de- scribed, in conjunction with the nervous system. The viscera of the chest are — the central organ of circulation, the heart ; the organs of respiration, the lungs ; and the thymus gland. The abdominal viscera admit of a subdivision into those which properly belong to that cavity, viz. the alimentary canal, liver, pancreas, spleen, kid- neys, and supra-renal capsules, and those of the pelvis — the bladder and internal organs of generation. THORAX. The thorax is the conical cavity, situated at the upper part of the trunk of the body; it is narrow above and broad below, and is bounded in front by the sternum, six superior costal cartilages, ribs, and intercostal muscles ; laterally, by the ribs and intercostal mus- cles ; and, behind, by the same structures, and by the vertebral column, as low down as the upper border of the last rib and the first lumbar vertebra ; superiorly, by the thoracic fascia and first ribs ; and, inferiorly, by the diaphragm. . It is much deeper on the posterior than on the anterior wall, in consequence of the obliquity of the diaphragm, and contains the heart, enclosed in its pericardium, with the great vessels ; the lungs, with their serous covering^, the pleurae ; the cesophagus; some important nerves ; and, in the foetus, the thymus gland. THE HEART. The central organ of circulation, the heart, is situated between the two layers of pleura, which constitute the mediastinum, and is enclosed in a proper membrane, the pericardium. 470 PERICARDIUM. Pericardium. — The pericardium is a fibro-serous membrane like the dm'a mater, and resembles Fig. 144.* that membrane in deriving its serous layer from the reflected serous membrane of the viscus which it encloses. It consists, therefore, of two layers, an ex- ternal fibrous and an internal serous. The fibrous layer is attached above, to the great vessels at the root of the heart, where it is continuous with the thoracic fascia ; and below to the tendinous portion of the dia- phragm. The serous membrane invests the heart with the com- mencement of its great vessels, and is then reflected upon the in- ternal surface of the fibrous layer. The heart is placed obliquely in the chest, the base being directed upwards and backwards towards the right shoulder ; the apex for- wards, and, to the left, points to the space between the fifth and sixth ribs, at about two or three inches from the sternum. Its under side is flattened, and rests upon the tendinous portion of the dia- phragm ; its upper side is rounded and convex, and formed princi- pally by the right ventricle, and partly by the left. Surmounting the ventricles are the corresponding auricles, whose auricular appendages are directed forwards, and sUghtly overlap the root of the pulmonary artery. The pulmonary artery is the large anterior * The anatomy of the heart. 1. The right auricle. 2. The entrance of the supe- rior vena cava. 3. The entrance of the inferior cava. 4. The opening of the coronary vein, half closed by the coronary valve. 5, The Eustachian valve. 6. The fossa ovalis, surrounded by the annulus ovalis. 7. The tuberculum Loweri. 8. The musculi pec- tinati in the appendix auriculae. 9. The aurieulo-ventricular opening. 10. Thecavity of the right ventricle. 11. The tricuspid valve, attached by the chordoB tcndinaB to the carnefE columnae (12). 13. The pulmonary artery, guarded at its commencement by three semilunar valves. 14. The right pulmonary artery, passing beneath the arch and behind the ascending aorta. 15. The left pulmonary artery, crossing in front of the descending aorta. * The remains of the ductus arteriosus, acting as a ligament betw^cen the pulmonary artery and arch of the aorta. The arrows mark the course of the venous blood through the right side of the heart. Entering the auricle by the superior and inferior cav£e, it passes through the aurieulo-ventricular opening into the ventricle, and thence through the pulmonary artery to the lungs. 16. The left auricle. 17. The openings of the four pulmonnry veins. 18. The auriculo-venti'icular opening, 19. The left ventricle. 20. The mitral valve, attached by its chordae tendineaa to two large columnae carnete, which project from the walls of the ventricle. 21. The com- mencement and course of the ascending aorta behind the pulmonary artery, marked by an arrow. The entrance of the vessel is guarded by three semilunar valves. 22. The arch of the aorta. The comparative thickness of the two ventricles is shown in the diagram. The course of tlio pure blood through the left side of the heart is marked by arrows. The blood is brought from the lungs by the four pulmonary veins into the left auricle, and passes through the aurieulo-ventricular opening into the left ventricle, whence it is conveyed by the aorta to every part of the body. OPENINGS OF THE HEART. 471 vessel at the root of the heart ; it crosses obliquely the commence- ment of the aorta. The heart consists of two auricles and two ventricles, which are respectively named, from their position, right and left. The right is the venous side of the heart ; it receives into its auricle venous blood from every part of the body, by the superior and inferior cava and coronary vein. From the auricle the blood passes into the ventricle, and from the ventricle through the pul- monary artery, to the capillaries of the lungs. From these it is returned as arterial blood to the left auricle ; from the left auricle it passes into the left ventricle ; and from the left ventricle is carried through the aorta, to be distributed to every part of the body, and again returned to the heart by the veins. This constitutes the course of the adult circulation. The heart is best studied in situ. If, however, it be removed from the body, it should be placed in the position indicated in the above description of its situation. A transverse incision should then be made along the ventricular margin of the right auricle, from the appendix to its right border, and crossed by a perpendicular incision, carried from the side of the superior to the inferior cava. The blood must then be removed. Some fine specimens of white fibrin are frequently found with the coagula ; occasionally they are yellow and gelatinous. This appearance deceived the. older anato- mists, who called these substances " polypus of the heart :" they are also frequently found in the right ventricle, and sometimes in the left cavities. The Right Auricle is larger than the left, and is divided into a principal cavity or sinus, and an appendix auriculae. The interior of the sinus presents for examination five openings ; two valves ; two relics of foetal structure ; and two peculiarities in the proper structure of the auricle. They may be thus arranged : — Superior cava, Inferior cava, Openings <( Coronary vein. Foramina Thebesii, Valves Auriculo- ventricular opening. Eustachian valve. Coronary valve. n 7- J- ^ ^ 1 . s \ Annulus ovaUs, Relics of fcetal structure j ^^^^^ ^^^j.^^ c,, ^ r si n • 1 \ Tuberculum Loweri, Structure of the Auricle | j^^^^^^j- p^ctinati. The Superior cava returns the blood from the upper half of the body, and opens into the upper and front part of the auricle. The Inferior cava returns the blood from the lower half of the body, and opens into the lower and posterior wall, close to the par- tition between the auricles (septum auriculorum). The direction of 472 VALVES OPENINGS. these two vessels is such, that a stream forced through the superior cava vi'-ould be directed towards the auriculo-ventricular opening. In hke manner, a stream rushing upwards by the inferior cava would force its current against the septum auriculorum ; this is the proper direction of the two currents during foetal life. The Coronary vein returns the venous blood from the substance of the heart ; it opens into the auricle between the inferior cava and the auriculo-ventricular opening, under cover of the coronary valve. The Foramina Tkebesii* are minute pore-like openings, by which the venous blood exhales directly from the muscular structure of the heart into the auricle, without entering the venous current. These openings are also found in the left auricle, and in the right and left ventricles. The Auriculo-ventricular opening is the large opening of com- munication between the auricle and ventricle. The Eustac/iian-\ valve is a part of the apparatus of foetal cir- culation, and serves to direct the placental blood from the inferior cava, through the foramen ovale into the left auricle. In the adult it is a mere vestige and imperfect, though sometimes it remains of large size. It is formed by a fold of the lining membrane of the auricle, containing some muscular fibres, is situated between the opening of the inferior cava and the auriculo-ventricular opening, and is generally connected with the coronary valve. The Coronary valve is a semilunar fold of the lining membrane, stretching across the mouth of the coronary vein, and preventing the reflux of the blood in the vein during the contraction of the auricle. The Annulis ovalis is situated on the septum auriculorum, oppo- site the termination of the inferior cava. It is the rounded margin of the septum, which occupies the place of the foramen ovale of the foetus. The Fossa ovalis is an oval depression corresponding with the foramen ovale in the foetus. This opening is closed at birth by a thin valvular layer, which is continuous with the left margin of the annulis and is frequently imperfect at its upper part. The depres- sion or fossa in the right auricle results from this arrangement. There is no fossa ovalis in the left auricle. The Tuberculem Loweri^ is the portion of auricle intervening be- tween the openings of the superior and inferior cava. Being thicker than the walls of the veins it forms a projection, which was supposed by Lower to direct the blood from the superior cava into the auri- culo-ventricular opening. * Adam Christian Thebesius. His discovery of the openings now known by his name, is contained in his " Disscrtatio Medica de Cireulo Sanguinis in Corde," ]708. t Bartholomew Eustachius, born at San Severino, in Naples, was Professor of Medi- cine in Rome, where he died in 1570. He was one of the founders of modern anatomy, and the first who illustrated his works with good engravings on copper. t Richard Lower, M.D. " Tractatus de Corde ; item de Motu et Colore Sanguinis," 1669. His dissections were made upon quadrupeds, and his observations relate rather to animals than to man. EIGHT VENTRICLE. 473 The Musculi pecthiaii are small muscular columns situated in the appendix auriculae. They are very numerous, and are arrancred parallel w^ith each other; hence their cognomen, " peciinati,^^ like the teeth of a comb. The RIGHT VENTRICLE is triangular and three-sided in its form. Its anterior side is convex, and forms the larger proportion of the front of the heart. The inferior side is flat, and rests upon the dia- phragm : and the inner side corresponds with the partition between the two ventricles, septum ventriculorum. The right ventricle is to be laid open by making an incision par- allel with, and a Httle to the right of, the middle line, from the pul- monary artery in front, to the apex of the heart, and thence by the side of the middle line behind, to the auriculo-ventricular opening. It contains, to be examined, two openings, the auriculo-ventricular and that of the pulmonary artery; two apparatus of valves, the tricuspid and semilunar ; and a muscular and tendinous apparatus belonging to the tricuspid valves. They may be thus arranged : — Auriculo-ventricular opening, Opening of the pulmonary artery. Tricuspid valves, Semilunar valves. ChordsB tendiness, Carnese columnse. The Auricido-ventricular opening is surrounded by a fibrous ring, covered by the lining membrane of the heart. It is the opening of communication between the right auricle and ventricle. The Opening of the pulmonary artery is situated close to the sep- tum ventriculorum, on the left side of the right ventricle, and upon the anterior aspect of the heart. The Tricuspid valves are three triangular folds of the lining mem- brane, strengthened by a thin layer of fibrous tissue. They are connected by their base around the auriculo-ventricular opening ; and by their sides and apices, which are thickened, they give at- tachment to a number of slender tendinous cords, called chordae tendinese. The chordce. tendineas. are the tendons of the thick mus- cular columns {columnce carnecB) which stand out from the walls of the ventricle, and serve as muscles to the valves. A number of these tendinous cords converge to a single muscular attachment. The tricuspid valves prevent the regurgitation of blood into the auricle during the contraction of the ventricle, and they are prevented from being themselves driven back, by the chordae tendinae and their muscular attachments. This connexion of the muscular columns of the heart to the valves has caused their division into active and passive. The active valves are the tricuspid and mitral ; the passive the mere folds of lining membrane, viz. the semilunar. Eustachian, and coronaiy- Mr. T. W. King, of Guy's Hospital, has made the tricuspid 60 474 COLUMN-E CARNEY. valves a subject of special investigation, and has recorded his obser- vations in a very interesting paper* in the Guy's Hospital Reports. The valves consist, according to Mr. King, of curtains, cords, and columns. The anterior valve or curtain is the largest, and is so placed as to prevent the filling of the pulmonary artery during the distention of the ventricle. The 7'ig/it valve or curtain is of smaller size, and is situated upon the right side of the auriculo-ventricular opening. The third valve, or "fixed curtain" is connected by its cords to the septum ventriculorum. The cords (chordae tendinese) of the anterior curtain are attached, principally, to a long column (columna carnea), which is connected with the " right or thin and yielding ivall of the ventricle." From the lower part of this column a transverse muscular band, the " loJig moderator hand^'' is stretched to the septum ventriculorum or " solid walV of the ventricle. The right curtain is connected, by means of its cords, partly with the long column, and partly with its own proper column, the second column, which is also attached to the " yielding wall" of the ven- tricle. A third and smaller column is generally' connected with the right curtain. The " fixed curtain" is named from its attachment to the " solid wall" of the ventricle, by means of cords only, without fleshy columns. From this remarkable arrangement of the valves it follows, that if the right ventricle be over distended, the thin or " yielding icall" will give way, and carry with it the columns of the anterior and right valves. The cords connected with these columns will draw down the edges of the corresponding valves, and produce an open- ing between the curtains, through which the superabundant blood may escape into the auricle, and the ventricle be relieved from over-pressure. This beautiful mechanism is therefore adapted, to fulfil the " function of a safety valve" The ColumncB carneae (fleshy columns) is a name expressive of the appearance of the internal walls of the ventricles, which seem formed of muscular columns interlacing in almost every direction. They are divided into three sets, according to the manner of their connexion. 1. The greater number are attached by the whole of one side, and merely form convexities into the cavity of the ven- tricle. 2. Others are connected by both extremities, being free in the middle. 3. A few (columnar papillares) are attached by one extremity to the walls of the heart, and by the other give insertion to the chordae tendinese. The Semilunar valves, three in number, are situated around the commencement of the pulmonary artery, being formed by a folding of its lining membrane, strengthened by a thin layer of fibrous tissue. They are attached by their convex borders, and free by the con- cave which are directed upwards in the course of the vessel, so that, during the current of the blood along the artery they are pressed against the sides of the cylinder; but if any attempt at regurgitation * "Essay on the Safety Valve Function in the Right Ventricle of the Human Heart," by T. W. King. Guy's Hospital Reports, vol. ii. LEFT AURICLE AA'D VENTRICLE. 475 ensue they are immediately expanded, and effectually close the entrance of the tube. The margins of the valves are thicker than the rest of their extent, and each valve presents in the centre of this margin a small fibro-cartilaginous tubercle, called corpus Arantii,* which locks in with the two others during the closure of the valves, and secures the triangular space that would otherwise be left by the approximation of three semilunar folds. Between the semilunar valves and the cylinder of the artery are three pouches, called the pulmonary sinuses. Similar sinuses are situated behind the valves at the commencement of the aorta, and are much larger and more capacious than those of the pulmonary artery. The Pulmonary artery commences by a scalloped border, corre- sponding with the three valves which are attached along its edge. It is connected to the ventricle by muscular fibres, and by the lining membrane of the heart. The Left Auricle is somewhat smaller than the right; of a cuboid form, and situated more posteriorly. The appendix auriculce is constricted at its junction with the auricle, and has an arborescent appearance ; it is directed forwards towards the root of the pul- monary artery, to which the auriculae of both sides appear to con- verge. The left auricle is to be laid open by a -J- shaped incision, the horizontal section being made along the border which is attached to the base of the ventricle. It presents for examination five openings, and the muscular struc- ture of the appendix ; these are, — Four pulmonary veins. Auric ulo-ventricular opening, Musculi pectinati. The Pulmonary veins, two from the right and two from the left lung, open into the corresponding sides of the auricle. The two left pulmonary veins terminate frequently by a common opening. The Auricula-ventricular opening is the aperture of communica- tion between the auricle and ventricle. The Musculi pectinati are fewer in number than in the right auricle, and are situated only in the appendix auriculas. Left Ventricle. — The left ventricle is to be opened, by making an incision a little to the left of the septum ventriculorum, and con- tinuing it around the apex of the heart, to the auriculo-ventricular opening behind. The left ventricle is conical, both in external figure and in the form of its internal cavity. It forms the apex of the heart, by pre- jecting beyond the right ventricle, while the latter has the advantage * Julius Caesar Arantius, Professor of Medicine in Bologna. He was a disciple of Vesalius, one of tlie founders of modern anatum)'. His treatise " De Humani Fcetu," was published at Rome, in 1564. 476 STRUCTURE OF THE HEART, in length towards the base. Its walls are about seven lines in thick- ness, those of the right ventricle being about two lines and a half. It presents for examination, in its interior, two openings, two valves, and the tendinous cords and muscular columns ; they may be thus arranged : — Auriculo- ventricular opening, Aortic opening. Mitral valves, Semilunar valves. Chordse tendineae, Columnse carnecs. The Auriculo-ventricular opening is a dense fibrous ring, covered by the Uning membrane of the heart, but smaller in size than that of the right side. The Mitral valves are attached around the auriculo-ventricular opening, as are the tricuspid in the right ventricle. They are thicker than the tricuspid, and consist of only two segments, of which the larger is placed between the auriculo-ventricular opening and the commencement of the aorta, and acts the part of a valve to that foramen, during the filling of the ventricle. The difference in size of the two valves, both being triangular, and the space between them, has given rise to the idea of a " bishop's mitre" after which they are named. These valves, like the tricuspid, are furnished with an apparatus of tendinous cords, chordcB tendinecE, which are attached to two very large columnce carnece. The ColumncB carnece, admit of the same arrangement into three kinds, as on the right side. Those which are free by one extremity, the columnse papillares, are only two in number, and much larger than those on the opposite side. The Semilunar valves are placed around the commencement of the aorta, like those of the pulmonary artery ; they are similar in structure, and are attached to the scalloped border by which the aorta is connected with the ventricle. The tubercle in the centre of each fold is larger than those in the pulmonary valves, and it was these that Arantius particularly described ; but the term " corpora Arantii" is now applied indiscriminately to both. The fossae between the semilunar valves and the cylinder of the artery are much larger than those of the pulmonary artery; they are called the "sinus aorticiJ'* STRUCTURE OF THE HEART. The arrangement of the fibres of the heart has been made the subject of careful and accurate investigation by Mr. Searle, to whose excellent article, " Fibres of the Heart," in the Cyclopaedia of Anatomy and Physiology, I am indebted for the following sum- mary of their distribution : — FIBRES OF THE VENTRICLES. 477 For the sake of clearness of description the fibres of the ventri- cles have been divided into three layers, — superficial, middle, and internal — all of which are disposed in a spiral direction around the cavities of the ventricles. The mode of formation of these three layers w^ill be best understood by adopting the plan pursued by Mr. Searle in tracing the course of the fibres from the centre of the heart towards its periphery. The left surface of the septum ventriculorum is formed by a broad and thick layer of fibres, which proceed backwards in a spiral direction around the posterior aspect of the left ventricle, and become augmented on the left side of that ventricle, by other fibres derived from the bases of the two columnse papillares. The bi'oad and thick band formed by the fibres from these two sources, curves around the apex and lower third of the left ventricle, to the anterior border of the septum, where it divides into two bands, — a short or apicial band, and a long or basial band. The Short or apicial band is increased in thickness at this point by receiving a layer of fibres (derived from the root of the aorta and carnese columnae) upon its internal surface, from the right sur- face of the septum ventriculorum ; it is then continued onwards in a spiral direction from left to right, around the lower third of the anterior surface, and the middle third of the posterior surface of the right ventricle to the posterior border of the septum. From the latter point the short band is prolonged around the posterior and outer border of the left ventricle to the anterior surface of the base of that ventricle, and is inserted into the anterior border of the left auriculo-ventricular ring, and the anterior part of the root of the aorta and pulmonary artery. The Long or basial band, at the anterior border of the septum, passes directly backwards through the septum, forming its middle layer, to the posterior ventricular groove, where it becomes joined by fibres derived from the root of the pulmonary artery. It then winds spirally around the middle and upper third of the left ven- tricle to the anterior border of the septum, where it is connected by means of its internal surface with the superior fibres derived from the aorta, which form part of the right wall of the septum. From this point it is continued around the upper third of the anterior and posterior surface of the right ventricle to the posterior border of the septum, where it is connected with the fibres constituting the right surface of the septum ventriculorum. At the latter point the fibres of this band begin to be twisted upon themselves, like the strands of a rope, the direction of the twist being from below up- wards. This arrangement of fibres is called, by Mr. Searle, " the rope ;" it is continued spirally upwards, forming the brim of the left ventricle, to the anterior surface of the base of that ventricle, where the twisting of the fibres ceases. The long band then curves inwards towards the septum, and spreads out upon the left surface of the septum into the broad and thick layer of fibres with which this description commenced. 478 FIBRES OF THE AURICLES. The most inferior of the fibres of the left surface of the septum ventriculorum, after winding spirally around the internal surface of the apex of the left ventricle, so as to close its extremity, form a srnall fasciculus, which is excluded from the interior of the ventricle, and expands in a radiated manner over the surface of the heart, constituting its superficial layer of fibres. The direction of these fibres is, for the most part, oblique, passing from left to right on the anterior, and from right to left on the posterior surface of the heart, becoming more longitudinal near its base, and terminating by being inserted into the fibrous rings of the auriculo-ventricular openings, and of the pulmonary artery and aorta. Over the right ventricle the superficial fibres are increased in number by the addition of accessory fibres from the right surface of the septum, which pierce the middle layer, and take the same direction with the superficial fibres from the apex of the left ventricle, and of other accessory fibres from the surface of both ventricles. From this description it will be perceived, that the superficial layer of fibres is very scanty, and is pretty equally distributed over the surface of both ventricles. The middle layer of both ventricles is formed by the two bands, short and long. But the internal layer of the two ventricles is very differently constituted : that of the left is formed by the spiral expansion of the fibres of the rope, and of the two columnas papillares; that of the right remains to be described. The septum ventriculorum also consists of three layers, a left layer, the radiated expansion of the rope and carnese columnae ; a middle layer, the long band ; and a right /a?/e?% belonging to the proper wall of the right ventricle, and continuous both in front and behind with the long band, and in front also with the short band, and with the superficial layer of the right ventricle. The Internal layer of the right ventricle is formed by fasciculi of fibres which arise from the right segment of the root of the aorta, from the entire circumference of the root of the pulmonary artery, and from the bases of the columnae papillares. The fibres from the root of the aorta, associated with some from the carnese columnse, constitute a layer which passes obliquely forwards upon the right side of the septum. The superior fibres coming directly from the aorta join the internal surface of the long band at the anterior bor- der of the septum, while the lower two-thirds of the layer are con- tinuous with the internal surface of the short band, some of its fibres piercing that band to augment the number of superficial fibres. The fibres derived from the root of the pulmonary artery, conjoined with those from the base of one of the columnse papillares, curve forwards from their origin, and wind obliquely downwards and backwards around the internal surface of the wall of the ven- tricle to the posterior border of the septum, where they'^become continuous with the long band, directly that it has passed backwards through the septum. Fibres of the Auricles. — The fibres of the auricles are disposed in two layers, external and internal. The internal layer is formed of ORGANS OF RESPIRATION AND VOICE. 479 fasciculi which arise from the fibrous rings of the auriculo-ventri- cular openings, and proceed upwards to enlace with each other, and constitute the appendices auriculorum. These fascicuU are parallel in their arrangement, and in the appendices form projec- tions and give rise to the appearance which is denominated mus- culi pectinati. In their course they give off branches which con- nect adjoining fasciculi, and form a columnar interlacement between them. External Layer. — The fibres of the right auricle having completed the appendix, wind from left to right around the right border of this auricle, and along its anterior aspect, beneath the appendix, to the anterior surface of the septum. From the septum they are con- tinued to the anterior surface of the left auricle, where they separate into three bands, — superior, anterior, and posterior. The superior hand proceeds onwards to the appendix, and encircles the apex of the auricle. The anterior hand passes to the left, beneath the appendix, and winds a broad layer completely around the base of the auricle, and through the septum to the root of the aorta, to which it is partly attached, and from this point is continued onwards to the appendix, where its fibres terminate by interlacing with the musculi pectinati. The posterior hand crosses the left auricle obliquely to its posterior part, and winds from left to right around its base, encircUng the openings of the pulmonary veins ; some of its fibres are lost upon the surface of the auricle, others are con- tinued onwards to the base of the aorta ; and a third set, forming a small band, is prolonged along the anterior edge of the appendix to its apex, where it is continuous with the superior band. The septum auriculorum has four sets of fibres entering into its formation ; 1 . The fibres arising from the auriculo- ventricular rings at each side ; 2. Fibres arising from the root of the aorta, which pass upwards to the transverse band, and to the root of the superior cava; 3. Those fibres of the anterior band that pass through the lower part of the septum in their course around the left auricle ; and 4. A slender fasciculus, which crosses through the septum from the posterior part of the right auriculo-ventricular ring to the left auricle. It will be remarked from this description, that the left auricle is considerably thicker and more muscular than the right. Vessels and Nerves. — The Arteries supplying the heart are the anterior and posterior coronary. The Veins accompany the arteries, and empty themselves by the common coronary vein into the right auricle. The lymphatics terminate in the glands about the root of the heart. The nerves of the heart are derived from the cardiac plexuses, which are formed by communicating filaments from the sympathetic and pneumogastric. ORGANS OF RESPIRATION AND VOICE. The organs of respiration are the two lungs, with their air-tube, 480 THE LARYNX. the trachea, to the upper part of which is adapted an apparatus of cartilages, constituting the organ of voice, or larynx. THE LARYNX. The Larynx is situated at the forepart of the neck, between the trachea, and the base of the tongue. It is composed of cartilages, ligaments, muscles, vessels, and nerves, and mucous membrane. The Cartilages are the — Thyroid, Cricoid, Two Arytenoid, Epiglottis. The Thyroid (^v^sos — s't^Sog, like a shield) is the largest cartilage of the larynx : it consists of Iwo lateral portions, or alee, which meet at an acute angle in front, and form the projection which is known by the name of pomum Adami. Where the pomum Adami is promi- nent, a bursa mucosa is often found between it and the skin. Each ala is quadrilateral, and forms a rounded border poste- riorly, which terminates above, in the superior carnu, and below, in the inferior cornu. Upon the side of the ala is an oblique line, into which the sterno-thyroid muscle is inserted, and from which the thyro-hyoid takes its origin. Behind this is a vertical line which gives origin to the inferior constrictor muscle. In the receding angle, formed by the meeting of the two alee upon the inner side of the cartilage, and near to its lower border, are attached the epi- glottis, the chordae vocales, the thyro-arytenoid, and thyro-epiglot- tidean muscles. The Cricoid (z^i'xoj — d8os, like a ring) is a ring of cartilage, narrow in front and broad behind, where it is surmounted by tivo rounded surfaces, which articulate with the arytenoid cartilages. Upon the middle line, posteriorly, is a vertical ridge which gives attachment to the oesophagus, and on each side of the ridge are the depressions which lodge the crico-arytenoidei postici muscles. On either side of the ring is a glenoid cavity, which articulates with the inferior cornu of the thyroid cartilage. The Arytenoid cartilages (d^urai'va, a pitcher,)* two in number, are triangular in form. They are broad below, where they articulate with the upper border of the cricoid, and give attachment to the crico-arytenoidei postici, crico-arytenoidei laterales, and thyro- arytcnoidei muscles, and chordas vocales ; and pointed above, where * This derivation has reference to tlic appearance of both eartilag^es taken together and covered by mucous membrrine. In animals, vvhicli were the principal subjects of dissection amon^r the ancients, the openini"' of the larynx with the arytenoid cartilages bears a striking resemblance to the mouth of a pitcher having a large spout. LIGAMENTS OF THE LARYNX. 481 they articulate with two Httle curved cartilages, called cornicula laryngis (capitula laryngis). On the posterior surface they are concave, and lodge the arytenoideus muscle. The Epiglottis {iitiyXc^TTis, upon the tongue) is a fibro-cartilage of a yellowish colour, studded with a number of small mucous glands, which are lodged in shallow pits upon its surface. It is shaped like a cordate leaf, and is placed immediately in front of the opening of the larynx, which it closes completely when the larynx is drawn up beneath the base of the tongue. It is attached by its point to the receding angle, betvv^een the two alse of the thyroid cartilage. Two small cartilaginous tubercles (cuneiform) are often found in the folds of the mucous membrane which bound the opening of the larynx laterally. Ligaments. — The Ligaments of the larynx are numerous, and may be arranged into four groups: 1. Those which articulate the thyroid with the os hyoides. 2. Those which connect it with the cricoid. 3. Ligaments of the arytenoid cartilages. 4. Ligaments of the epiglottis. 1. The ligaments which connect the thyroid cartilage with the OS hyoides are three in number : — The two Tliyro-liyoidean ligaments pass between the superior cornua of the thyroid and the extremities of the greater cornua of the OS hyoides : a sesamoid bone is found in each. The Thyro-hyoid ean membrane is a broad membranous layer, occupying the entire space between the thyroid cartilage and os hyoides. It is pierced by the superior laryngeal nerve and artery. 2. The ligaments connecting the thyroid to the cricoid cartilage are also three in number : — Two Capsular ligaments, with their synovial membranes, which form the articulation between the inferior cornua of the thyroid and the sides of the cricoid, and the crico-thyroidean membrane, through which the operation of laryngotomy is performed. The latter is generally crossed by a small artery, the inferior laryngeal. 3. The ligaments of the arytenoid cartilages are four in number : — Two Capsular ligaments, and synovial membranes, which arti- culate the arytenoid cartilages with the cricoid; and the thyro- arytenoid ligaments, or chordce vocales, which pass backwards from the receding angle of the thyroid cartilage, near to its lower border, to be inserted into the bases of the arytenoid cartilages. The space between these two ligaments is the glottis, or rima glottidis. 4. The hgaments of the epiglottis are five in number : — 1. Three folds of mucous membrane, one at the middle, and one at each side, called frcena e-pi glottidis, which hold the epiglottis back to the tongue. 2. Epiglotto-fnjoidean ligainent, which connects the epiglottis to the posterior surface of the os hyoides. 3. The ligament which attaches the epiglottis to the receding angle of the thyroid cartilage. The Muscles of the larynx are eight in number : the five larger 61 482 LARYNX. are the muscles of the chordae vocales and rima glottidis ; the three smaller are muscles of the epiglottis. , The five muscles of the chordae vocales and rima glottidis are the— . Crico-thyroid, Crico-arytenoideus posticus, Crico-arytenoideus lateralis, Thyro-arytenoideus, Arytenoideus. Fig. 145* Fig. 146.f The Crico-thyroid muscle arises from the anterior surface of th,e cricoid cartilage, and is inserted into the lower and inner border of the thyroid. The Crico-arytenoideus posticus arises from the depression on the posterior surface of the cricoid cartilage, and is inserted into the outer angle of the base of the arytenoid. The Crico-arytenoideus lateralis arises from the upper border of the side of the cricoid, and is inserted into the outer angle of the base of the arytenoid cartilage. The Thyro-arytenoideus arises from the receding angle of the thy- roid cartilage, close to the outer side of the chorda vocalis, and passes backwards parallel with the chord, to be inserted into the base of the arytenoid cartilage. The Arytenoideus muscle occupies the posterior concave surface of the arytenoid cartilages, between which it is stretched. It con- * A posterior view of the larynx. 1. The tiiyroid cartilage. 2. One of its aseend- ing cornua. 3. One of the descending cornua. 4. 7. Tlie cricoid cartilage. 5, 5. The arytenoid cartilages. 6. The arytenoideus muscle, consisting of oblique and trans- verse fasciculi. 7. The crico-arytenoidci poslici muscles. 8. The epiglottis. + A side view of the larynx, one ala of the thyroid cartilage has been removed, 1. The remaining ala of the thyroid cartilage. 2. One of the arytenoid cartilages. 3. One of the cornicula laryngis. 4. The cricoid cartilage. 5. The crico-arytenoideus posticus muscle. 6. The crico-arytenoideus lateralis. 7. The thyro-arytenoideus. 8. The crico-thyroidean membrane. 9. One half of the epiglottis. 10. The upper part of the trachea. MUSCLES OF THE LARYNX, 483 sists of three planes of transverse and oblique fibres ; hence it was formerly considered as several muscles, under the names of trans- versi and obliqui. The three muscles of the epiglottis are the — Thyro-epiglottideus, Aryteno-epiglottideus superior, Aryteno-epiglottideus inferior ( 2i.ryit;no-t;pigiouiut;us supei lui, Aryteno-epiglottideus inferior (Hilton's muscle). The Thyro-epiglottideus appears to be formed by the upper fibres of the thyro-ary tenoideus muscle : they spread out upon the external surface of the sacculas laryngis, on which they are lost ; a few of the anterior fibres being continued onwards to the side of the epi- glottis. The Aryteno-epighttideus superior consists of a few scattered fibres, which pass forwards in the fold of mucous membrane form- ing the lateral boundary of the entrance into the larynx, from the apex of the arytenoid cartilage to the side of the epiglottis. The Aryteno-epiglottideus inferior. — This muscle was discovered by Mr. Hilton, and is very important in relation to the sacculus laryngis, with which it is closely connected. It may be found by raising the mucous membrane immediately above the ventricle of the larynx. It arises by a narrow and fibrous origin from the ary- tenoid cartilage, just above the attachment of the chorda vocalis ; and passing forwards, and a little upwards, expands over the upper half, or two-thirds of the sacculus laryngis, and is inserted by a broad attachment into the side of the epiglottis. Actions. — The crico-thyroid and arytenoid muscles are contractors of the rima glottidis ; the crico-arytenoideus posticus and lateralis, and the thyro-arytenoideus, are dilators. The crico-thyi'oid muscles elongate, and thereby bring together the chordas vocales, by drawing the thyroid cartilage downwards and forwards ; their posterior attachment at the arytenoid cartilages being fixed. The arytenoid muscle approximates the arytenoid cartilages, and consequently the chordae vocajes, directly. The crico-thyroidei postici being attached to the outer angles of the bases of the arytenoid cartilages, draw them from each other, and stretch the chordae vocales. The crico-arytenoidei laterales draw the arytenoid cartilages from each other, but relax the chordae vo- cales ; and the thyro-arytenoidei increase the width of the glottis, by directly relaxing the chords vocales. The thyro-epiglottideus acts principally by compressing the glands of the sacculus laryngis and the sac itself: by its attachment to the epiglottis it would act feebly upon that valve. The aryteno-epiglot- tideus superior serves to keep the mucous membrane of the sides of the opening of the glottis tense, when the larynx is drawn upwards, and the opening closed by the epiglottis. Of the aryteno-epiglotti- deus, the " functions appear to be," writes Mr. Hilton, " to compress the subjacent glands which open into the pouch ; to diminish the 484 MUCOUS MEMBRANE OF THE LARYNX. capacity of that cavity, and change its form ; and to approximate the epiglottis and the arytenoid cartilage." ■ Mucous JMembrane. — The larynx is lined by the mucous mem- brane, which is continued from the mouth and pharynx, and pro- longed onwards through the trachea and bronchi to the bronchial cells. The chordse vocales form two horizontal projections of the mucous membrane, and constitute the lateral boundaries of the glottis, or rima glottidis. Immediately above the horizontal projec- tion of the chorda vocalis, at each side, is a depressed fossa, the ventricle of the larynx. The superior boundary of the ventricle is an arched border of mucous membrane, which is very incorrectly termed the superior chorda vocalis. If the rounded extremity of a probe be introduced into the ventricle of the larynx, and then directed upwards, it will enter a considerable pouch, which has been recently described by Mr. Hilton as the sacculus laryngis.* From the ven- tricle of the larynx the sacculus is continued upwards, nearly as high as the upper border of the thyroid cartilage, and sometimes beyond it. When dissected from the interior of the larynx it is found covered by the aryteno-epiglottideus muscle and a fibrous membrane, which is attached to the superior chorda vocalis below ; to the epiglottis in front ; and to the upper border of the thyroid cartilage above. If examined from the exterior of the larynx, it will be seen to be covered by the thyro-epiglottideus muscle. On the surface of its mucous membrane are the openings of sixty or seventy small follicular glands, which are situated in the sub-mucous tissue, and give to its external surface a rough and ill-dissected ap- pearance. This mucous secretion is intended for the lubrication of the chordse vocales, and is directed upon them by two small valvular folds of mucous membrane, which are situated at the entrance of • the sacculus. The Entrance of the larynx is formed by two folds of mucous membrane, stretched between the apices of the arytenoid cartilages and the sides of the epiglottis. The arytenoid glands and superior aryteno-epiglottidean muscles are situated within these folds. * This sac was discovered and described by Mr. Hilton before he was aware that it had already been pointed out by the older anatomists. I myself made a dissection, which I still possess, of the same sac in an enlarged state during the month of August, 1837, without any knowledge either of Mr. Hilton's labours, or Morgagni's account. The sac projected considerably above the upper border of the thyroid cartilage, and the extremity had been snipped off on one side in the removal of the muscles. The larynx was presented to me by Dr. George Moore of Camberwell : he had obtained it from a child who died of bronchial disease ; and he conceived that this peculiar disposition of the mucous membrane might possibly explain some of the symptoms by which the case was accompanied. Cruveilhier made the same discovery in equal ignorance of Mor- gagni's description, for we read in a note at page 677, vol. ii. of his Anatomic Descrip- li'ce, — ".I'ai vu pour la premiere fois cette arri6re cavit6 chez un individu affects de phthisic laryngc'ic, oil elle 6tait trds-devcloppt'C. Je fis dcs recherches sur le larynx d'autres inciividus, et jc trouvai que cette disposition 6tait constantc. Je nc savais pas alors que Morgagni avait indique et fait repr^sentcr la m6mc disposition." Cruveilhier compares its form very aptly to a." Phrijgian casque " and Morgagni's figure, Advers. 1, Epist. Anat. '.i, plate 9, fig. 4, has the same appearance. But neither of these anato- mists notice the follicular glands described by Mr. Hilton. TRACHEA. 485 The Glands of the larynx are, 1. The epiglottic — most impro- perly named — for it consists merely of a mass of fat, situated be- tween the convexity of the epiglottis and the thyro-hyoid membrane. 2. The arytenoid glands, some small granules found in the folds of mucous membrane near the apex of the arytenoid cartilage. Vessels and Nerves. — The Arteries of the larynx are derived from the superior and inferior thyroid. The nerves are the superior laryngeal and recurrent laryngeal ; both branches of the pneumo- gastric. The two nerves communicate with each other freely ; but the superior laryngeal is distributed principally to the mucous mem- brane at the entrance of the larynx ; the recurrent, to the muscles. In children, and in the female, the larynx is less developed than in the adult male ; the thyroid cartilage forms a more obtuse angle, and is less firm : in the male the angle is acute, and the cartilages often converted into bone. THE TRACHEA. The Trachea extends from opposite the fifth cervical vertebra to opposite the third dorsal, where it divides into the two bronchi. The right bronchus larger than the left, passes off nearly at right angles to the upper part of the corresponding lung. The left descends obliquely and passes beneath the arch of the aorta, to reach the left lung. The Trachea is composed of — Fibro-cartilaginous rings, Fibrous membrane, Mucous membrane. Longitudinal elastic fibres. Muscular fibres, Glands. The Fibro-cartilaginous rings are from fifteen to twenty in num- ber, and extend for two-thirds around the cylinder of the trachea. They are deficient at the posterior part, where the tube is completed by fibrous membrane. The last ring has usually a triangular form in front. The rings are connected to each other by a membrane of yellow elastic fibrous tissue, which in the space between the ex- tremities of the cartilages, posteriorly, forms a distinct layer. The Longitudinal elastic fibres are situated immediately beneath the mucous membrane on the posterior part of the trachea, and enclose the entire cylinder of the bronchial tubes to their ultimate terminations. The Muscular fibres form a thin layer, extending transversely be- tween the extremities of the cartilages.* On the posterior surface * I have several times seen a layer of longitudinal museular fibres superadded to the transverse. — G. 486 THYROID GLAND LUNGS. they are covered in by a cellulo-fibrous lamella, in which are lodged the tracheal glands. These are small flattened ovoid bodies, situated in great number between the fibrous and muscular layers of the membranous portion of the trachea, and also between the two layers of elastic fibrous tissue connecting the rings. They pour their secretion upon the mucous membrane. Thyroid Gland. The thyroid gland is one of those organs which it is found ex- tremely difficult to classify from the absence of any positive know- ledge with regard to its function. It is situated upon the trachea, and in an anatomical arrangement should therefore be considered in this place, although bearing no part in the function of respiration. This gland consists of two lobes, which are placed one on each side of the trachea, and are connected with each other by means of an isthmus, which crosses its upper rings. There is considerable variety in the situation and breadth of this isthmus ; which should be recollected in the performance of operations upon the trachea. In structure it appears to be composed of a dense cellular paren- chyma, enclosing a great number of vessels. The gland is larger in young subjects and in females, than in the adult and males. It is the seat of an enlargement called bronchocele, goitre, or the Der- byshire neck. A muscle is occasionally found connected with its upper border or with its isthmus ; and attached, superiorly, to the body of the os hyoides, or to the thyroid cartilage. It was named by Soemmering the " levator glandules thyroidecB.^^ Vessels and Nerves. — It is abundantly supplied with blood by the superior and inferior thyroid arteries. Sometimes an additional artery is derived from the arteria innominata, and ascends upon the front of the trachea to be distributed to the gland. The wounding of this vessel, in tracheotomy, might be fatal to the patient. The nerves are derived from the superior laryngeal and sympathetic. THE LUNGS. The lungs are two conical organs, situated one on each side of the chest, embracing the heart, and separated from each other by a membranous partition, the mediastinum. On the external or thoracic side they are convex, and correspond with the form of the cavity of the chest ; internally they are concave, to receive the convexity of the heart. Superiorly they terminate in a tapering cone which extends above the level of the first rib, and inferiorly they are broad and concave, and rest upon the convex surface of the diaphragm. Their posterior border is rounded and broad, the anterior sharp and marked by one or two deep fissures, and the inferior which sur- rounds the base is also sharp. The colour of the lungs is pinkish gray, mottled, and variously STRUCTURE OF LUNG. 487' marked with black. The surface is figured with irregularly polygo- nal outlines which represent the lobules of the organ, and the area of each of these polygonal spaces is crossed by lighter lines. Fig. 147.* Each lung is divided into two lobes, by a long and deep fissure which extends from the posterior surface of the upper part of the organ, downwards and forwards to near the anterior angle of its base. In the right lung the upper lobe is subdivided by a second fissui'e, which extends obliquely forwards from the middle of the preceding to the anterior border of the organ, and marks off a small triangular lobe. The Right lung is larger than the leTt, in consequence of the in- clination of the heart to the left side. It is also shorter, from the great convexity of the liver, which presses the diaphragm upwards upon the right side of the chest considerably above the level of the left. It has three lobes. The left lung is smaller, has but two lobes, but is longer than the rig-ht. * Anatomy of the heart and lungs. 1. The right ventricle ; tlie vessels to the right of the figure are the middle coronary artery and veins ; and those to its left, the ante- rior coronary artery and veins. 2. The left ventricle. 3. The right auricle. 4. The left auricle. 5. The pulmonary artery. 6, 6. The right pulmonary artery. 7. The left pulmonary artery. 8. The remains of tlie ductus arteriosus. 9. The arch of the aorta. 10. The superior vena cava. 11. Tlie right vena innominata, and the artcria innominata. 12. The right subclavian artery and vein. 13. Tiic right common carotid artery and vein. 14. The left vena innominata. 15. The left carotid artery and vein. 16. The left subclavian artery and vein. 17. The trachea. 18. The right bronchus. 19. The left bronchus. 20, 20. The pulmonary veins; 18, 6, 20, form the root of the right lung; and 7, 19, 20, the root of the left. 21. The superior lobe of the right lung. 22. Its middle lobe. 23. Its inferior lobe. 24. The superior lobe of the left lung. 25. Its inferior lobe. 488 KOOT OF LUNG, Each lung is retained in its place by its root, which is formed by the pulmonary artery, pulmonary veins and bronchial tubes, together with the bronchial vessels and pulmonary plexuses of nerves The large vessels of the root of each lung are arranged in a similar order from before, backwards, on both sides, viz. Pulmonary veins. Pulmonary artery, Bronchus. From above, downwards, on the right side this order is exactly reversed ; but on the left side the bronchus has to stoop beneath the arch of the aorta, which alters its position to the vessels. They are thus disposed on the two sides : — Right. Left. Bronchus, Artery, Artery, Bronchus, Veins. Veins. Structure. — The lungs are composed of the ramifications of the bronchial tubes which terminate in bronchial cells (air cells), of the ramifications of the pulmonary artery and veins, bronchial arteries and veins, lymphatics and nerves ; the whole of these structures being held together by cellular tissue, which constitutes the "paren- chyma. The parenchyma of the lungs, when examined on the sur- face or by means of a section, is seen to consist of small polygonal divisions, or lobules which are connected to each other by an inter- lobular cellular tissue. These lobules again consist of smaller lobules, and the latter are formed by a cluster of air cells, in the parietes of which the capillaries of the pulmonary artery and pul- monary veins are distributed.* Bronchial tubes. — The two bronchi proceed from the bifurcation of the trachea to their corresponding lungs. The right takes its course nearly at right angles with the trachea, and enters the upper part of the right lung, while the left, longer and smaller than the right, passes obliquely beneath the arch of the aorta, and enters the lung at about the middle of its root. Upon entering the lungs they divide into two branches, and each of these divides and subdivides dichotomously to their ultimate termination in small dilated sacs, the bronchial or pulmonary cells. The fibro-cartilaginous rings which are observed in the trachea become incomplete and irregular in shape in the bronchi, and in the smaller bronchial tubes are lost altogether. At the termination of these tubes the fibrous and muscular coats become extremely thin, * The walls of the air cells are so imperfect that all the cells of any lobule commu- nicate freely with each other, whilst the contiguous lobules, are separated by the paren- chyma. Dr. Horner's dissections exhibit this in a beautiful manner. See Horner's Special Anatomy, 3d edition. — G. PLEURA MEDIASTINUM. 489 and are probably continued upon the lining mucous membrane of the air cells. The Pulmonary artery, conveying the dark and impure venous blood to the lungs, terminates in capillary vessels, which form a minute network upon the parietes of the bronchial cells, and then converge to form the pulmonary veins, by which the arterial blood, purified in its passage through the capillaries, is returned to the left auricle of the heart. The Bronchial arteries, branches of the thoracic aorta, ramify upon the bronchial tubes and in the tissue of the lungs, and supply them with nutrition, while the venous blood is returned by the bronchial veins to the vena azygos. The Lymphatics, commencing upon the surface and in the sub- stance of the lungs, terminate in the bronchial glands. These glands, very numerous and often of large size, are placed at the roots of the lungs, around the bronchi, and at the bifurcation of the trachea. In early life they resemble lymphatic glands in other situations ; but in old age, and often in the adult, they are quite black, and filled with carbonaceous matter, and occasionally with calcareous deposits. The JVerves are derived from the pneumogastric and sympathetic. They form two plexuses, — anterior pulmonary plexus, situated upon the front of the root of the lungs, and composed chiefly of filaments from the great cardiac plexus ; and posterior pulmonary plexus on the posterior aspect of the root of the lungs, composed principally of branches from the pneumogastric. The branches from these plexuses follow the course of the bronchial tubes, and are distributed to the bronchial cells. PLEURiE. Each lung is enclosed, and its structure maintained, by a serous membrane — the pleura, which invests it as far as the root, and is thence reflected upon the parietes of the chest. That portion of the membrane which is in relation with the lung is called pleura pulmo- nalis, and that in contact with the parietes, pleura costalis. The reflected portion, besides forming the internal lining to the ribs and intercostal muscles, also covers the diaphragm and the thoracic surface of the vessels at the root of the neck. The pleura must be dissected from oflf the root of the lung, to see the vessels by which it is formed and the pulmonary plexuses. MEDIASTINUM. The approximation of the two reflected pleuras in the middle line of the thorax forms a septum which divides the chest into the two pulmonary cavities. This is the mediastinum. The two pleurae are not, however, in contact with each other at the middle line in the formation of the mediastinum, but leave a space between them which contains all the viscera of the chest with the exception of the lungs. The mediastinum is divided into the anterior, middle, and postet^ior. 62 490 ABDOMEN. The Anterior mediastinum is a triangular space, bounded in front by the sternum, and on each side by the pleura. It contains a quan- tity of loose cellular tissue, in which are found some lymphatic glands and vessels passing upwards from the liver ; the remains of the thymus gland, the origins of the sterno-hyoid, sterno-thyroid, and triangularis sterni muscles, and the internal mammary vessels of the left side. The Middle mediastinum contains the heart enclosed in its peri- cardium ; the ascending aorta ; the superior vena cava ; the bifurca- tion of the trachea ; the pulmonary arteries and veins ; and the phrenic nerves. The Posterior mediastinum is bounded behind by the vertebral column, in front by the pericardium, and on each side by the pleura. It contains the descending aorta; the greater and lesser azygos veins, and superior intercostal vein ; the thoracic duct ; the oeso- phagus and pneumogastric nerves ; and the great splanchnic nerves. ABDOMEN. The abdomen is the inferior cavity of the trunk of the body ; it is bounded in front and at the sides by the lower ribs and abdominal muscles ; behind, by the vertebral column and abdominal muscles ; above, by the diaphragm ; and, below, by the pelvis : and contains the alimentary canal, the organs subservient to digestion, viz. the liver, pancreas, and spleen, and the organs of excretion, the kidneys, with the supra-renal capsules. Regions. — For convenience of description of the viscera, and for reference to the morbid affections of this cavity, the abdomen is divided into certain districts or regions. Thus, if two transverse lines be carried around the body, the one parallel with the convexi- ties of the ribs, the other with the highest points of the crests of the ilia, the abdomen will be divided into three zones. Again, if a per- pendicular line be drawn at each side, from the cartilage of the eighth rib to the middle of Poupart's ligament, the three primary zones will each be subdivided into three compartments or regions, a middle and two lateral. The middle region of the upper zone being immediately over the small end of the stomach, is called epigastric {^id — /atfT^, over the stomach). The two lateral regions being under the cartilages of the ribs are called hypochondriac (vifo — xov^^oi, under the cartilages). The middle region of the middle zone is the umbilical; the two lateral, the lumbar. The middle region of the inferior zone is the hypogastric {M — yadrrj^, below the stomach) ; and the two lateral, the iliac. In addition to these divisions, we constantly use the term inguinal region, in reference to the vicinity of Poupart's ligament. Position of the Viscera. — In the upper zone will be seen the liver, extending across from the right to the left side ; the stomach and spleen on the left, and the pancreas and duodenum behind. In the middle zone is the transverse portion of the colon, with the upper part of the ascending and descending colon, omentum, small intes- tines, mesentery, and, behind, the kidneys and supra-renal capsules. PERITONEUM ^REFLECTIONS. 491 In the inferior zone is the lower part of the omentum and small in- testines, the caecum, ascending and descending colon with the sigmoid flexure, and ureters. The smooth and polished surface, which the viscera and parietes of the abdomen present, is due to the peritoneum which should in the next place be studied. Fig. 148.* PERITONEUM. The Peritoneum (■n-s^irstveiv to extend around) is a serous membrane, and therefore a shut sac : a single exception exists in the human subject to this character^ viz. in the female, where the peritoneum is perforated by the open extremities of the Fallo- pian tubes, and is continuous with their mucous lining. The simplest idea that can be given of a serous membrane, which may apply equally to all, is, that it invests the viscus or viscera, and is then reflected upon the parietes of the contain- ing cavity. If the cavity con- tain only a single viscus, the consideration of the serous membrane is extremely simple. But in the abdomen, where there are a number of viscera, the serous membrane passes from one to the other until it has invested the whole, before it is reflected on the parietes. Hence its reflections are a little more complicated. In tracing the reflections of the peritoneum in the middle * The reflections of the peritoneum. D. The diaphragm. L. The liver. S. The stomach. C. The transverse colon. D. The transverse duodenum, P. The pancreas. I. The small intestines. R. The rectum. B. The urinary bladder. 1. The anterior layer of the peritoneum, lining the under surface of the diaphragm. 2. The posterior layer. 3. The two layers passing to the posterior border of the liver, and fjrming the coronary ligament. 4. The lesser omentum : the two layers passing from the under surface of the liver to the lesser curve of the stoma(th. 5. The two layers meeting at the greater curve, then passing downwards and returning upon themselves, forming (6) the greater omentum. 7. The transverse meso-colon. 8. The posterior layer traced upwards in front of D, the transverse duodenum, and P, the pancreas, to become continuous with the posterior layer (2). 9. The foramen of Winslow ; tlie dotted line bounding this foramen infcriorly, marks the course of the hepatic artery forwards, to enter between the layers of the lesser omentum. 10. The mesentery encircling the small intestine. 11. The reeto-vesical fold, formed by the descending anterior layer. 12. The anterior layer traced upwards upon the internal surface of the abdominal parietes to the layer (1), with which the examination commenced. 492 PERITONEUM DUPLICATUEES. line, we commence with the diaphragm, which is hned by two layers, one from the parietes in front, anterior, and one from the parietes behind, posterior. These two layers of the same membrane, at the posterior part of the diaphragm, descend to the upper surface of the liver, forming the coronary and lateral ligaments of the liver. They then surround the liver, one going in front, the other behind that viscus, and, meeting at its under surface, pass to the stomach, forming the lesser omentum. They then, in the same manner, sur- round the stomach, and meeting at its lower border descend for some distance in front of the intestines, and return to the transverse colon, forming the great omentum; they then surround the transverse colon, and pass directly backwards to the vertebral column, forming the transverse meso-colon. Here the two layers separate ; the posterior ascends in front of the pancreas and aorta, and returns to the pos- terior part of the diaphragm, where it forms the posterior layer with which we commenced. The anterior descends, invests all the small intestines, and returning to the vertebral column forms the mesentery. It then descends into the pelvis in front of the rectum, which it holds in its place by means of a fold called meso-rectum, forms a pouch, the recto-vesical fold, between it and the bladder, ascends upon the posterior surface of the bladder, forming its false ligaments, and returns upon the anterior parietes of the abdomen to the dia- phragm, whence we first traced it. In the female, after descending into the pelvis in front of the rectum, it is reflected upon the posterior surface of the vagina and uterus. It then descends on the anterior surface of the uterus, and forms at either side the broad hgaments of that organ. From the uterus it ascends upon the posterior surface of the bladder and ante- rior parietes of the abdomen, and is continued, as in the male, to the diaphragm. In this way the continuity of the peritoneum, as a whole, is dis- tinctly shown, and it matters not where the examination commence or where it terminate, still the same continuity of surface will be discernible throughout. If we trace it from side to side of the abdomen, we may commence at the umbilicus ; we then follow it outwards lining the inner side of the parietes to the ascending colon; it surrounds that intestine; it then surrounds the small intestine, and returning on itself forms the mesentery. It then invests the descending colon, and reaches the parietes on the opposite side of the abdomen, whence it may be traced to the exact point from which we started. The viscera, which are thus shown to be invested by the perito- neum in its course downwards, are the — Liver, Stomach, Transverse colon, Small intestines. Pelvic viscera. PERITONEUM OMENTA. 493 The folds, formed between these and between the diaphragm and the Hver, are (Diaphragm.) Broad, coronary, and lateral Hgaments. (Liver.) Lesser omentum. (Stomach.) Greater omentum. (Transverse colon.) Transverse meso-colon, Mesentery, Meso-rectum, Recto-vesical fold. False ligaments of the bladder. And in the female, the Broad ligaments of the uterus. The ligaments of the liver will be examined with that organ. The Lesser omentum is the dupUcature passing between the liver and the upper border of the stomach. It is extremely thin, except- ing at its right border, where it is free, and contains between its layers, the Hepatic artery, Ductus communis choledochus, Portal vein. Hepatic plexus of nerves. Lymphatics. These structures are enclosed in a loose cellular tissue, called Glisson's capsule.* The relative position of the three vessels is, — the artery to the left, the duct to the right, and the vein between and behind. If the finger be introduced behind this right border of the lesser omentum, it will be situated in an opening called the foramen of Winslow.-\ In front of the finger will lie the right border of the lesser omentum ; behind it the diaphragm, covered by the ascending * Francis Glisson, Professor of Medicine in the University of Cambridge, His work, " De An'atomia Hepatis," was published in 1654, + Jacob Benignus Winslow : his " Exposition Anatomique de la Structure du Corps Humain," was publislied in Paris in 1732, 494 OMENTA MESENTERY. or posterior layer of the peritoneum ; helow, the hepatic artery, curving forwards from the ccehac axis ; and above, the lobus SpigeUi. These, therefore, are the boundaries of the foramen of Winslow, which is nothing more than a constriction of the general cavity of the peritoneum at this point, arising out of the necessity for the hepatic and gastric arteries to pass forwards from the coeliac axis to reach their respective viscera. If air be blown through the foramen of Winslow, it will descend behind the lesser omentum and stomach to the space between the descending and ascending pair of layers, forming the great omen- tum. This is sometimes called the lesser cavity of the peritoneum, and that external to the foramen the greater cavity ; in which case the foramen is considered as the means of communication between the two. There is a great objection to this division, as it might lead the inexperienced to believe that there M^ere really two cavi- ties. There is but one only, the foramen of Winslow being merely a constriction of that one, to facilitate the communication between the nutrient arteries and the viscera of the upper part of the abdo- men. The Great omentum consists of four layers of peritoneum, the two which descend from the stomach, and the same two, returning upon themselves to the transverse colon. A quantity of adipose substance is deposited around the vessels which ramify through its structure. It would appear to perform a double function in the economy. 1st. Protecting the intestines from cold; and, 2dly. Facilitating the move- ment of the intestines upon each other during their vermicular action. The Transverse meso-colon {iJ^s(fog, middle, being attached to the middle of the cyhnder of the intestine) is the medium of connexion between the transverse colon and the posterior wall of the abdomen. It also affords to the nutrient arteries a passage to reach the intes- tine ; and encloses between its layers, at the posterior part, the trans- verse portion of the duodenum. The Mesentery (f^stfov sWs^ov, being connected to the middle of the cylinder of the small intestine) is the medium of connexion between the small intestines and the posterior wall of the abdomen. It is oblique in its direction, being attached to the posterior wall, from the left side of the second lumbar vertebra to the right iUac fossa. It retains the small intestines in their places, and gives passage to the mesenteric arteries, veins, nerves, and lymphatics. The Meso-rectum, in like manner, retains the rectum in connexion with the front of the sacrum. Besides this, there are some minor folds in the pelvis, as the recto-vesical fold, the false ligaments of the bladder, and broad ligaments of the uterus. The Jlppendices epi/phiccB are small irregular pouches of perito- neum, filled with fat. and situated like fringes upon the large intes- tine. Three other duplicatures of peritoneum are situated in the sides of the abdomen ; they are the gastro-phrenic ligamen , the gastro- ALIMENTARY CANAL. 495 splenic omentum, the ascending and descending meso-colon. The gastro-'phrenic ligament is a small duplicature of the peritoneum, which descends from the diaphragm to the extremity of the oeso- phagus, and to the lesser curve of the stomach. The g astro-splenic omentum is the dupHcature which connects the spleen to the sto- mach. The ascending meso-colon is the fold which connects the upper part of the ascending colon with the posterior wall of the abdomen ; and the descending meso-colon, that which retains the sigmoid flexure, in connexion with the abdominal wall. Structure of serous membrane. — Serous membrane consists of two layers, an external or cellular layer, and an internal layer or epithe- lium. The cellular layer upon its outer surface is rough and vascu- lar, and adherent to surrounding structures ; but on its inner surface is dense and smooth, and wholly deficient of vessels carrying red blood. The smooth and brilliant surface of serous membrane is due to a distinct epithelium, which has been shown by the excellent re- searches of Henle, to be composed of laminae of vesicles, and of flattened polygonal scales with central nuclei, hke the epithelium of mucous membrane. Dr. Henle has observed this structure, which may be easily demonstrated with a good microscope upon the sur- face of all the serous membranes of the body, upon the surface of the lining membrane of arteries and veins, and upon synovial mem- branes. The general characters of a serous membrane are its resemblance to a shut sac, and its secretion of a peculiar fluid, resembUng the serum of the blood ; but the former of these characters is not abso- lutely essential to the identity of a serous membrane; for, as we have shown above, the peritoneum in the female is perforated by the extremities of the Fallopian tubes ; while in aquatic reptiles there is a direct communication between its cavity and the medium in which they live. From the variable nature of the secretion of these membranes, they have been divided into two classes — the true serous membranes, viz. the arachnoid, pericardium, pleurae, peritoneum, and tunicae va- ginales, which pour out a secretion containing but a small propor- tion of albumen ; and the synovial membranes and bursae which secrete a fluid containing a larger quantity of albumen. ALIMERTTARY CANAL. The Alimentary canal is a musculo-membranous tube, extending from the mouth to the anus. It is variously named in the different parts of its course ; hence it is divided into the Mouth, Pharynx, (Esophagus, Stomach, 496 ALIMENTARY CANAL. { Duodenum, Small intestine } Jejunum, (lie um. ( Caecum, Large intestine } Colon, ( Rectum. ^ The Mouth is the irregular cavity which contains the organs of taste and the principal instruments of mastication. It is bounded in front by the lips ; on either side by the internal surface of the cheeks ; above by the hard palate and teeth of the upper jaw ; below by the tongue, by the mucous membrane stretched between the arch of the lower jaw and the under surface of the tongue, and by the teeth of the inferior maxilla; and behind by the soft palate and fauces. The Lips are two fleshy folds, formed externally by common in- tegument, and internally by mucous membrane, and containing between these two layers the muscles of the lips, a quantity of fat, and numerous small labial glands. They are attached to the sur- face of the upper and lower jaw, and each lip is connected to the gum in the middle hne by a fold of mucous membrane, the frsenum labii superioris and frsenum labii inferioris, the former being the larger. The Cheeks (buccas) are continuous on either hand with the lips, and form the sides of the face ; they are composed of integument, a large quantity of fat, muscles, mucous membrane, and buccal glands. The mucous membrane lining the cheeks is reflected above and below upon the sides of the jaws, and is attached posteriorly to the anterior margin of the ramus of the lower jaw. At about its mid- dle, opposite to the second molar tooth of the upper jaw, is a papilla, upon which may be observed a small opening, the entrance of the duct of the parotid gland. The Hard palate is a dense structure, composed of mucous mem- brane, palatal glands, fibrous tissue, vessels and nerves, and firmly connected to the palate processes of the superior maxillary and palate bones. It is bounded in front and on each side by the alveolar processes and gums, and is continuous behind with the soft palate. It is marked along the middle line by an elevated raph^, and pre- sents upon each side of the raphe a number of transverse ridges and grooves. Near the anterior extremity, and immediately behind the middle incisor teeth, is a papilla which corresponds with the termination of the naso-palatine canal, and has been supposed to be endoM'ed with a peculiar sensibility. The Gums are composed of a thick and dense mucous membrane, which is closely adherent to the periosteum of the alveolar pro- cesses, and embraces the necks of the teeth. They are remarkable for their hardness and insensibility, and for their close contact, without adhesion, to the surface of the tooth. From the neck of SALIVARY GLANDS. 497 the tooth they are reflected into the alveolus, and become continuous with the periosteal membrane of that cavity. The Tongue has been already described as an organ of sense ; it is invested by mucous membrane, which is reflected from its under part upon the inner surface of the lower jaw, and constitutes, with the muscles beneath, the floor of the mouth. Upon the under sur- face of the tongue, near to its anterior part, the mucous membrane forms a considerable fold, which is called the frsenum linguas ; and on each side of the frajnum is a large papilla, tiie commencement of the duct of the submaxillary gland, and several smaller openings, the ducts of the sublingual gland. The Soft 'palate (velum pendulum palati) is a fold of mucous mem- brane situated at the posterior part of the mouth. It is continuous, superiorly with the hard palate, and is composed of mucous mem- brane, palatal glands, and muscles. Hanging from the middle of its inferior border is a small rounded process, the uvula ; and passing outwards from the uvula on each side are two curved folds of the mucous membrane, the arches, or pillars of the palate. The anterior pillar is continued downwards to the side of the base of the tongue, and is formed by the projection of the palato-glossus muscle. The posterior pillar is prolonged downwards and backwards into the pharynx, and is formed by the convexity of the palato-pharyngeus muscle. These two pillars, closely united above, are separated below by a triangular interval or niche, in which the tonsil is lodged. The Tonsils (amygdate) are two glandular organs, shaped like almonds, and situated between the anterior and posterior pillar of the soft palate, on each side of the fauces. They are cellular in texture, and composed of an assemblage of mucous folhcles, which open upon the surface of the gland. Externally, they are invested by the pharyngeal fascia, which separates them from the superior constrictor muscle and internal carotid artery, and prevents an ab- scess from opening in that direction. In relation to surrounding parts, they correspond with the angle of the lower jaw. The space included between the soft palate and the root of the tongue is the isthmus of the fauces. It is bounded above by the soft palate : on each side by the pillars of the soft palate and tonsils ; and below by the root of the tongue. It is the opening between the mouth and pharynx. SALIVARY GLANDS. Communicating with the mouth are the excretory ducts of three pairs of salivary glands, the parotid, submaxillary, and sublingual. The Parotid gland {ifa^a, near, oZg, cjto?, the ear), the largest of the three, is situated immediately in front of the external ear, and extends superficially for a short distance over the masseter muscle, and deeply behind the ramus of the lower jaw. It reaches infe- riorly to below the level of the angle of the lower jaw, and poste- riorly to the mastoid process, slightly overlapping tlie insertion. of 63 498 SUBMAXILLARY SUBLINGUAL GLAND. the sterno-mastoid muscle. Embedded in its substance are the external carotid artery, temporo-maxillary vein, and facial nerve ; and, emera;incr from its anterior border, the tranverse facial artery and branches of the pes anserinus ; and above, the temporal artery. The duct of the parotid gland (Stenon's* duct) commences at the papilla upon the internal surface of the cheek, opposite the second molar tooth of the upper jaw ; and, piercing the buccinator muscle, crosses the masseter to the anterior border of the gland, where it divides into several branches, which subdivide and ramify through its structure, to terminate in the small cascal pouches of which the gland is composed. A small branch is generally given off from the duct while crossing the masseter muscle, which forms, by its rami- fications and terminal dilatations, a small glandular appendage, the socia parotidis. Stenon's duct is remarkably dense and of con- siderable thickness, while the area of its canal is extremely small. The Submaxillary gland is situated in the posterior angle of the submaxillary triangle of the neck. It rests upon the hyo-glossus and mylo-hyoideus muscles, and is covered in by the body of the lower jaw and by the deep cervical fascia. It is separated from the parotid gland by the stylo-maxillary ligament, and from the subbn^Tual by the mylo-hyoideus muscle. Embedded among its lobules is the facial artery and the submaxillary ganglion. The Excreiorxj duct (Wharton's) of the submaxillary gland com- mences upon the papilla, by the side of the frjEnum lingua, and passes backwards beneath the mylo-hyoideus and resting upon the hyo-glossus muscle, to the middle of the gland, where it divides into numerous branches, which ramify through the structure of the gland to its ccecal terminations. It lies in its course against the mucous membrane forming the floor of the mouth, and causes a projecting rido;e upon its surface. The Subungual is an elongated and flattened gland, situated be- neath the mucous membrane of the floor of the mouth, on each side of the frcenum linguas. It is in relation above with the mucous membrane ; in front with the depression by the side of the symphy- sis of the lower jaw ; externalhj with the mylo-hyoideus muscle ; and internally w^ith the lingual nerve and genio-hyo-glossus muscle. It pours its secretion into the mouth by seven or eight small ducts, which commence by small openings on each side of the frasnum lingua). Structure.— "IhQ salivary are conglomerate glands, consisting of lobes, which are made up of angular lobules, and these of still smaller lobules. The smallest lobule is apparently composed of granules, which are minute cacal pouches, formed by the dilatation of the extreme ramifications of the ducts. These minute ducts unite to form lobu- * Nicholas Stenon, an anatomist of great research. He discovered the parotid duct while in Paris. He was appointed professor of medicine in Copenhagen in 1673. His work, " De MuscuUh et Ghuidulis Oi)scrvationc9," was published in IGGd. PHARYNX ITS OPENINGS. 499 lar ducts, and the lobular ducts constitute by their union a single excretory duct. The cascal pouches are connected by cellular tissue, so as to form a minute lobule ; the lobules are held together by a more con- densed cellular layer ; and the larger lobes are enveloped by a dense cellulo-fibrous capsule, which is firmly attached to the deep cervical fascia. Vessels and Nerves. — The parotid gland is abundantly supplied with arteries by the external carotid ; the submaxillary by the facial ; and the sublingual by the sublingual branch of the hngual artery. The JVerves of the parotid gland are derived from the auricular branch of the inferior maxillary nerve, from the auricularis mag- nus, and from the nervi molles of the external carotid artery. The submaxillary gland is supplied by the branches of the submaxillary ganglion, and by filaments from the mylo-hyoidean nerve ; and the sublingual by filaments from the submaxillary ganglion and gusta- tory nerve, PHARYNX. The pharynx (c Glandulis Intostinoriirn," waa published in K)77. MUSCULAR COAT. 509 The (Esophagus is very muscular ; its longitudinal fibres are con- tinuous above with the pharynx, and are attached in front to the vertical ridge on the posterior surface of the cricoid cartilage ; the uppermost circular fibres are also attached on each side to the cricoid cartilage. Below, both sets of fibres are continued upon the stomach. On the stomach the longitudinal fibres are most appa- rent along the lesser curve, and the circular at the smaller end. At the pylorus the latter are aggregated into a thick circular ring, which, with the spiral fold of mucous membrane, constitutes the pyloric valve. At the great end of the stomach a new order of fibres is introduced, having for their object to strengthen and com-, press that extremity of the organ. They are directed more or less horizontally from the great end towards the lesser end, and are generally lost upon the sides of the stomach at about its middle ; these are the oblique fibres. The Small intestine is provided with both layers, equally distri- buted over the entire surface. At the termination of the ileum the circular fibres are continued into the two folds of the ilio-CEBcal valve, while the longitudinal fibres pass onwards to the large intes- tine. In the large intestine the longitudinal fibres commence at the appendix vermiformis and are collected into three bands, an anterior, broad; and two posterior and narrower bands. These bands are nearly one half shorter than the intestine, and give to it the sacculated appearance which is characteristic of the cfficum and colon. In the descending colon the posterior bands usually unite and form a single band. From this point the two bands are con- tinued downwards upon the sigmoid flexure to the rectum, around which they spread out and form a thick and very muscular lon- gitudinal layer. The circular fibres in the csecum and colon are exceedingly thin ; in the rectum they are thicker, and at its lower extremity they are aggregated into the thick muscular ring which is called the internal sphincter ani.* Serous Coat. — The pharynx and oesophagus have no covering of serous membrane. The alimentary canal within the abdomen has a serous layer, derived from the peritoneum. The Stomach is completely surrounded by the peritoneum ex- cepting along the line of junction of the great and lesser omentum. T\\Q first or oblique portion of the duodenum is also completely in- * Mr. Wilson does not seem to have paid the same close attention !o the anatomy of the anus as to other parts of the body, and we here find a deficiency in the description which we shall endeavour to supply. The Muscular coat of the rectum consists of much stronger fasciculi than that of the colon ; the transverse fibres terminate at the anus by agfgrcgating^ into a ring wliicii is called the internal sphincter muscle, as in c fig-. 152. The longitudinal fibres being outside of the transverse, when they reach the internal sphincter wind around it and are inserted into the submucous coat from one to four inches above the anus. They tlius Ibrm a pulley-like arrangement which everts the mucous membrane in defecation and is the active agent in j)rodueing prolapsus ani. I have observed that wlicn hwmor- rhoids exist many of the fibres run to be inserted into them, hence their ready extru- sion when the patient is directed to force them down. The following cut exhibits this arrangement. See Horner's Special Anatomy, 1836. — G, 510 VESSELS OF INTESTINES. eluded by the serous membrane with the exception of the points of attachment of the omenta. Fig. 152.* The descending fortion has mere- ly a partial covering on its an- terior surface. The transverse portion is also behind the perito- neum, being situated between the two layers of the transverse me- so-colon, and has but a partial coverinsr. The rest of the small intestine is completely invested by it, excepting along the con- cave border to which the mesen- tery is attached. The ccecum is more or less invested by the peri- toneum, the more frequent dispo- sition being that in which the in- testine is surrounded for three- fourths only of its circumference. The ascending and the descend- ing colon are covered by the se- rous membrane only in front. The transverse colon is invested completely, with the exception of the lines of attachment of the greater omentum and transverse meso-colon. And the sigmoid Jlexure is entirely surrounded, with the exception of the part cor- responding with the junction of the left meso-colon. The upper third of the rectum is completely enclosed by the peritoneum; the middle third has an anterior covering only, and the inferior third none whatsoever. Vessels and JVerves. — The Arteries of the alimentary canal, as they supply the tube from above downwards, are the pterygo-pala- tine, ascending pharyngeal, superior thyroid, and inferior thyroid in the neck; oesophageal in the thorax ; gastric, hepatic, splenic, superior and inferior mesenteric in the abdomen ; and inferior mesenteric, iliac, and internal pudic in the pelvis. The veins from the abdomi- nal alimentary canal unite to form the vena portae. The lymphatics and lacteals open into the thoracic duct. * A vertical section of the parietcs of the anus, passing through the middle line of one of the cohiinns of tlic rectum, and tiic neiglibouring parts, c. The internal spliinctcr, with its arched fibres transversely divided, n, d. The jjlane of arclicd fibres of the muscular coat, similarly divided, e. Tlie point of greatest contraction of the in- ternal sphincter, f. The external sphincter, a. The point of grcntcst contraction of the same muscle, ir. The plane of longitudinal fibres of tlie muscular coat, longitudi- nally divided, i. Some of those fibres terminating in tlie internal sphincter, k. Others, terminating in the external sphincter. 1. The remaining longitudinal fibres, collected into a scrnitcri(hrious fasciculus, passing over tiie lovirer margin of the internal spliineter, to be reverted upward within tlie duplicature of the column, m. These reverted fibres again becoming muscular, and terminating in the mucous coat. l. The mucous coat, w. A bristle in oncof tiic sacs. — G. THE LIVER. 511 The Nerves of the pharynx and oBsophagus are derived from'the glosso-pharyngeal, pneumogastric, and sympathetic. The nerves of the stomach are the pneumogastric and sympathetic branches from the solar plexus ; and those of the intestinal canal are the superior and inferior mesenteric and hypogastric plexuses. The extremity of the rectum is supplied by the coccygeal nerves from the spinal cord. THE LIVER. The liver is a conglomerate gland of large size, appended to the alimentary canal, and performing the double office of separating impurities from the venous blood of the chylo-poietic viscera pre- viously to its return into the general venous circulation, and of secreting a fluid necessaiy to chylification, the bile. It is the largest Fig. 153.* organ in the body, weighing about four pounds, and measuring through its longest diameter about twelve inches. It is situated in the right hypochondriac region, and extends across the epigastrium into the left hypochondriac, frequently reaching by its left extremity to the upper end of the spleen. It is placed obliquely in the abdo- men ; its convex surface looking upwards and forwards, and the concave downwards and backwards. The anterior border is sharp, free, and marked by a deep notch, the posterior rounded and broad. It is in relation, superiorly and posteriorly with the diaphragm, and inferiorly with the stomach, ascending portion of the duodenum, transverse colon, right supra-renal capsule and right kidney, and corresponds by its free border with the lower margin of the ribs. * The upper surface of the liver. 1. The right lobe. 2. The left lobe. 3. The an- terior or free border. 4. The posterior or rounded border. 5. The broad ligament. 6. The round ligament. 7, 7. The two lateral ligaments. 8, 8. The spnce loft un- covered by the peritoneum, and surrounded by the coronary ligament. 9. Tlie inferior vena cava. 10. The point of the lobus Spigclii. 3. The fundus of the gall-bladder seen projecting beyond the anterior border of the right lobe. 512 ' LIGAMENTS OF THE LIVER. The liver is retained in its place by five ligaments ; four of which are formed by duplicatures of the peritoneum, and are situated upon the convex surface of the organ; the fifth being a fibrous cord which passes through a fissure in its under surface, from the umbilicus to the inferior vena cava. They are the — Longitudinal, Two lateral. Coronary, Round. The Longitudinal ligament (broad, ligamentum suspensorium hepatis) is an antero-posterior fold of peritoneum, extending from the notch on the anterior margin of the liver to its posterior border. Between its two layers in the anterior and free margin is the round ligament. The two Lateral ligaments are formed by the two layers of peri- toneum, which pass from the under surface of the diaphragm to the posterior border of the liver ; they correspond with its lateral lobes. The Coronary ligament is formed by the separation of the two layers forming the lateral ligaments near their point of convergence. The posterior layer is continued unbroken from one lateral Hgament into the other ; but the anterior quits the posterior at each side, and is continuous with the corresponding layer of the longitudinal liga- ment. In this way a large oval surface on the posterior border of the liver is left uncovered by peritoneum, and is connected to the diaphragm by a dense cellular tissue. This space is formed prin- cipally by the right lateral ligament, and is pierced near its left extremity by the inferior vena cava, previously to the passage of that vessel through the tendinous opening in the diaphragm. The Round ligament is a fibrous cord resulting from the oblitera- tion of the umbilical vein, and situated between the two layers of peritoneum in the anterior border of the longitudinal ligament. It may be traced from the umbilicus, along the longitudinal fissure upon the under surface of the liver to the inferior vena cava to which it is connected. The under surface of the liver is marked by five fissures which divide its surface into five compartments or lobes, two principal and three minor lobes ; they are the — Fissures. Lobes. Longitudinal fissure. Right lobe. Fissure of the ductus vcnosus. Left lobe. Transverse fissure, Lobus quadratus, Fissure for the gall-bladder, Lobus Spigelii, Fissure for the vena cava. Lobus caudatus. FISSURES OP THE LIVER. 513 The Longitudinal fissure is a deep groove running from the notch upon the anterior margin of the liver, to the posterior border of the organ. At about one third from its posterior extremity it is joined by a short but deep fissure, the transverse, which meets it trans- versely from the under part of the right lobe. Fig. 154.* The longitudinal fissure in front of this junction lodges the fibrous cord of the umbilical vein, and is generally crossed by a band of hepatic substance called the pons hepatis. The Fissure for the ductus venosus is the shorter portion of the longitudinal fissure, extending from the junctional termination of the transverse fissure to the posterior border of the liver, and con- taining a small fibrous cord, the remains of the ductus venosus. This fissure is therefore but a part of the longitudinal fissure. The Transverse fissure is the short and deep fissure, about two inches in length, through which the hepatic ducts, hepatic artery, and portal vein enter the liver. Hence this fissure was considered by the older anatomists as the gate (porta) of the liver ; and the large vein entering the organ at this point, the portal vein. At their entrance into the transverse fissure the branches of the hepatic duct are the most anterior, next those of the artery, and most posteriorly the portal vein. * The under surface of the liver. 1. The rig-ht lobe. 2. The left lobe. 3. The lobus quadratus. 4. The lobus Spigelii. 5. Tlio lobus caudatus. 6. The longitudinal fis- sure, in which is seen the rounded cord ; the remains of the umbilical vein. 7. The pons hepatis. 8. The fissure for the ductus venosus ; the obliterated cord of the ductus is seen passing backwards to be attached to the coats of tlie inferior vena cava 9. 10. The gall-bladder lodged in its fossa. 11. The transverse fissure, containing from before backwards, the hepatic duct, hepatic artery, and portal vein. 12. The vena cava. 13. A depression corresponding with the curve of the colon. 14. A double depression pro- duced by the right kidney and its supra-renal capsule. 15. The rough surface on the posterior border of the liver left uncovered by peritoneum ; the cut edge of peritoneum surrounding this surface forms part of the coronary ligament. 16. The notch on the anterior border, separating the two lobes. 17. The notch on the posterior border, cor- responding with the vertebral column. G5 514 LOBES OF THE LIVER. The Fissure for the gall-bladder is a shallow fossa extending for- wards, parallel with the longitudinal fissure, from the right extre- mity of the transverse fissure to the free border of the liver, where it frequently forms a notch. The Fissure for the vena cava is a deep and short fissure occa- sionally a rounded tunnel, which proceeds from a little behind the right extremity of the transverse fissure to the posterior border of the liver, and lodges the inferior vena cava. These five fissures taken collectively resemble an inverted y, the base corresponding with the free margin of the liver, and the apex with its posterior border. Viewing them in this way, the two anterior branches represent the longitudinal fissure on the left, and the fissure for the gall-bladder on the right side ; the two posterior, the fissure for the ductus venosus on the left, and the fissure for the vena cava on the right side, and the connecting bar the transverse fissure. Lobes. — The Right lobe is four or six times larger than the left, from which it is separated on the concave surface by the longitu- dinal fissure, and on the convex by the longitudinal ligament. It is marked upon its under surface by the transverse fissure, and by the fissures for the gall-bladder and vena cava, and presents three depressions, one in front for the curve of the ascending colon, and two behind for the right supra-renal capsule, and kidney. The Left lobe is small and flattened, convex upon its upper sur- face, and concave below, where it lies in contact with the anterior surface of the stomach. It is sometimes in contact by its extre- mity with the upper end of the spleen, and is in relation by its pos- terior border with the cardiac orifice of the stomach, and left pneu- mogastric nerve. The lobus quadratus is a quadrilateral lobe situated upon the under surface of the right lobe : it is bounded in front by the free border of the liver ; behind by the transverse fissure ; to the right by the gall-bladder ; and to the left by the longitudinal fissure. The Lobus Spigelii* is a small triangular lobe, also situated upon the under surface of the right lobe : it is bounded in front by the transverse fissure ; and on the sides by the fissures for the ductus venosus and vena cava. The Lobus caudatus is a small tail-like appendage to the lobus Spigelii, from which it runs outwards like a crest into the right lobe, and serves to separate the right extremity of the transverse fissure from the commencement of the fissure for the vena cava. In some livers this lobe is extremely well-marked, in others it is small and ill-defined. Reverting to the comparison of the fissures with an inverted y, it * Adrian Spijrcl, a I3c]gian physician, professor at Padua after Casscrius in 1616. IT(! assi;[rn(;d considerable importance to tliis little lobe, but it had been described by Sylvius full sixty yours before his time. STRUCTURE OF THE LIVER, 515 will be observed that the quadrilateral interval, in front of the trans- verse bar, represents the lobus quadratus; the triangular space behind the bar, represents the Spigelii ; and the apex of the letter, the point of union between the inferior vena cava, and the remains of the ductus venosus. The Vessels entering into the structure of the liver are also Jive in number'; they are, the Hepatic artery, Portal vein. Hepatic veins. Hepatic ducts. Lymphatics. The Hepatic artery, portal vein, and hepatic duct enter the liver at the transverse fissure, and ramify through portal canals to every part of the organ ; so that their general direction is from below upwards, and from the centre towards the circumference. The Hepatic veins commence at the circumference and proceed from before backwards, to open into the vena cava, on the posterior border of the hver. Hence the branches of the two veins cross each other in their course. The portal vein, hepatic artery, and duct are moreover enveloped in a loose cellular tissue, the capsule of Glisson, which permits them to contract upon themselves when emptied of their contents ; the hepatic veins, on the contrary, are closely adherent by their parietes to the surface of the canals in which they run, and are unable to contract. By these characters the anatomist is enabled, in any sec- tion of the liver, to distinguish at once the most minute branch of the portal vein from the hepatic vein; the former will be found more or less collapsed, and always accompanied by an artery and duct, and the latter widely open and solitary. The Lymphatics are described in the Chapter dedicated to those vessels. The JVerves of the liver are derived from the systems both of animal and of organic hfe; the former proceed from the right phrenic and pneumogastric nerves, and the latter from the hepatic plexus. Structure and Minute Anatomy of the Liver, according to Mr. Kiernan. The Liver is composed of lobules, of a connecting medium, called Glisson' s capsule, of the ramifications of the portal vein, hepatic duct, hepatic artery, hepatic veins, lymphatics, and nerves, and is enclosed and retained in its proper situation by the peritoneum. I shall describe each of these structures singly, following rigidly the dis- coveries of Mr. Kiernan. 516 LOBULES OF THE LIVER. 1. The Lobules are small granular bodies, of about the size of a millet seed, of an irregular form, and presenting a number of rounded projecting processes upon their surface. When divided longitudinally, they have a foliated appearance;, and transversely, a polygonal outline, with sharp or rounded angles, according to the smaller or greater quantity of Glisson's capsule contained in the liver. Each lobule is divided upon its exterior into a base and a capsular surface. The base corresponds with one extremity of the lobule, is flattened, and rests upon an • hepatic vein, which is thence named sublobular. The capsular surface includes the rest of the periphery of the lobule, and has received its designation from being enclosed in a cellular capsule derived from the capsule of Glisson. In the centre of each lobule is a small vein, the intralobular, which is formed by the convergence of six or eight minute venules from the rounded processes situated upon the surface. The intralobular vein thus constituted takes its course through the centre of the lon- gitudinal axis of the lobule, pierces the middle of its base, and opens into the sublobular vein. The circumference of the lobule, with the exception of its base, which is always closely attached to a sublobular vein, is connected by means of its cellular capsule with the capsular surface of surrounding lobules. The cellular interval between the lobules is the interlobular fissure, and the angular inter- stices formed by the apposition of several lobules are the interlobular spaces. Fiff. 155.* The lobules of the centre of the liver are angular, and somewhat smaller than those of the surface, from the greater compression to which they arc submitted. The superficial lobules are incomplete, and give to the surface of the organ the appearance, and all the advantages resulting from an examination of a transverse section. * The lobules of the liver. A. The lobules as they arc seen upon the surface of the liver, or whnn divided transversely. ] . The intralobular vein in the eentre of each lobule. 2. The interlobular fissure. 3. Tlie interlobular si)aeo. B. A longitudinal section of two lol)u]es. 1. A superficial lobule, tci iniiiating- abruptly, and resembling a section at its exiremity. 9. A deep lobule, showing the foliated appearance of its section. 3. The intralobular vein, with its converging venules ; the vein terminates in a sublobular vein. 4. The external, or capsular surface of the lobule. GLISSOn's capsule PORTAL VEIN. 517 " Each lobule is composed of a plexus of biliary ducts, of a venous plexus formed by branches of the portal vein, of a branch (intra- lobular), of an hepatic vein, and of minute arteries ; nerves and absorbents, it is to be presumed, also enter into their formation, but cannot be traced into them." " Examined with the microscope, a lobule is apparently composed of numerous minute bodies of a yel- lowish colour, and of various forms, connected with each other by vessels. These minute bodies are the acini of Malpighi." " If an uninjected lobule be examined and contrasted with an injected lobule, it will be found that the acini of Malpighi in the former are identical with the injected lobular biliary plexus in the latter, and the blood-vessels in both will be easily distinguished from the ducts." Glisson's capsule is the cellular tissue which envelopes the hepatic artery, portal vein, and hepatic duct, during their passage through the right border of the lesser omentum, and which continues to surround them to their ultimate distribution in the substance of the lobules. It forms for each lobule a distinct capsule, which invests it on all sides with the exception of its base, connects all the lobules together, and constitutes the proper capsule of the entire organ. But " Glisson's capsule," observes Mr. Kaernan, " is not mere cellular tissue ; it is to the liver what the pia mater is to the brain ; it is a cellulo-vascular membrane in which the vessels divide and subdivide to an extreme degree of minuteness ; which Imes the portal canals, forming sheaths for the larger vessels contained in them, and a web in which the smaller vessels ramify ; which enters the interlobular fissures, and with the vessels forms the capsules of the lobules ; and which finally enters the lobules, and with the blood-vessels expands itself over the secreting biliaiy ducts." Hence arises a natural division of the capsule into three portions, a vaginal, an interlobula?; and a lobular portion. The vaginal portion is that which invests the hepatic artery, hepatic duct, and portal vein, in the portal canals ; in the larger canals it completely surrounds these vessels, but in the smaller is situated only on that side which is occupied by the artery and duct. The interlobular portion occupies the interlobular fissures and spaces, and the lobular portion forms the supporting tissue to the substance of the lobules. The Portal vein, entering the liver at the transverse fissure, rami- fies through its structure in canals which resemble, by their surfaces, the external superficies of the liver, and are formed by the capsular surfaces of the lobules, — " all their canals being," as it were, " tubu- lar inflections inwards of the superficies of the liver." These are the portal canals, and contain, besides the portal vein with its rami- fications, the artery and duct with their branches. In the larger canals, the vessels are separated from the parietes of the cavity by a web of Glisson's capsule ; but, in the smaller, the portal vein is in contact with the surface of the canal for about two- 518 STRUCTURAL ANATOHY OF THE LIVER. thirds of its cylinder, the opposite third being in relation with the artery and duct and their investing capsule. If, therefore, the portal v.ein were laid open by a longitudinal incision in one of these smaller canals,, the coats being transparent, the outline of the lobules, bounded by their interlobular fissures, would be as distinctly seen as upon the external surface of the liver, and the smaller venous branches would be observed entering the interlobular spaces. The branches of the portal vein are, the vaginal, interlobular, and lobular. The vaginal branches are those which, being given off in the portal canals, have to pass through the sheath (vagina) of GUs- son's capsule, previously to entering the interlobular spaces. In this course they form an intricate plexus, the vaginal plexus, which, depending for its existence on the capsule of Glisson, necessarily surrounds the vessels, as does that capsule in the larger canals, and occupies the capsular side only in the smaller canals. The interlo- bular branches are given off from the vaginal portal plexus where it exists, and directly from the portal veins, in that part of the smaller canals where the coats of the vein are in contact with the walls of the canal. They then enter the interlobular spaces and divide into branches, which cover with their ramifications every part of the surface of the lobules with the exception of their bases, and those extremities of the superficial lobules which appear upon the surfaces of the liver. The interlobular veins communicate freely with each other, and with the corresponding veins of adjoin- ing fissures, and establish a general portal anastomosis throughout the entire liver. The lobular branches are derived from the interlo- bular veins ; they form a plexus within each lobule, and converge from the circumference towards the centre, where they terminate in the minute radicles of the intralobular portal vein. This plexus, interposed between the interlobular portal veins and the intralobular hepatic vein, constitutes the venous part of the lobule, and may be called the lobular venous plexus. The irregular islets of the substance of the lobules, seen between the meshes of this plexus by means of the microscope, are the acini of Malpighi, and are shown by Mr. Kiernan to be portions of the lobular biliary plexus. The portal vein returns the venous blood from the chylopoietic viscera, to be circulated through the lobules ; it also receives the venous blood which results from the distribution of the hepatic artery. The Hepatic duct, entering the liver at the transverse fissure, divides into branches, which ramify through the portal canals, with the portal vein and hepatic artery, to terminate in the substance of the lobules. Its branches, like those of the portal vein, are vaginal, interlobular, and lobular. The Vaginal branches ramify through the capsule of Glisson, and form a vaginal biliary plexus, which, like the vaginal portal plexus, surrounds the vessels in the large canals, but is deficient on that side of the smaller canals near which the duct is placed. The branches given off by the vaginal biliary plexus are interlobular and lobular. KIERNAN S RESEARCHES. 519 The interlobular branches proceed from the vaginal bUiary plexus where it exists, and directly from the hepatic duct on that side of the smaller canals against which the duct is placed. They enter the interlobular spaces, and ramify upon the capsular surface of the lobules, in the interlobular fissures, where they communicate freely Avith each other. The lobular ducts are derived chiefly from the interlobular; but to those lobules forming the walls of the portal canals, they pass directly from the vaginal plexus. They enter the lobule and form a plexus in its interior, the lobular biliary plexus, which constitutes the principal part of the substance of the lobule. The ducts terminate either in loops or in cjecal extremities. The coats of the ducts are very vascular, and supplied with a number of mucous follicles, which are distributed irregularly in the larger, but are arranged in two parallel longitudinal rows in the smaller ducts. The Hepatic artery enters the liver with the portal vein and hepatic duct, and ramifies with those vessels through the portal canals. Its branches are the vaginal, interlobular, and lobular. The vaginal branches, like those of the portal vein and hepatic duct, form a vaginal plexus, which exists throughout the whole extent of the portal canals, with the exception of that side of the smaller canals which corresponds with the artery. The interlobular branches, arising from the vaginal plexus and from the parietal side of the artery in the smaller canals, ramify through the interlobular fis- sures, and are principally distributed to the coats of the interlobular ducts. " From the superficial interlobular fissures small arteries emerge, and ramify in the proper capsule, on the convex and concave surface of the liver, and in the hgaments. These are the capsular arteries" Where the capsule is well developed, " these vessels cover the sur- faces of the liver with a beautiful plexus," and " anastomose with branches of the phrenic, internal mammary, and supra-renal arte- ries," and with the epigastric. The Lobular branches, extremely minute and few in number, are the nutrient vessels of the lobules, and terminate in the lobular venous plexus. All the venous blood resulting from the distribution of the hepatic artery, even that from the vasa vasorum of the hepatic veins, is returned into the portal vein. The Hepatic veins commence in the substance of each lobule by minute venules, which receive the blood from the lobular venous plexus, and converge to form the intralobular vein. The intralobular vein passes through the central axis of the lobule, and through the middle of its base, to terminate in a sublobular vein ; and the union of the sublobular veins constitutes the hepatic trunks, which termi- nate in the inferior vena cava. The hepatic venous system consists, therefore, of three sets of vessels ; intralobular veins, sublobular veins, and hepatic trunks. 520 STRUCTUEAL ANATOMY OF THE LIVER, The SuhlohuJar veins are contained in canals formed solely by the bases of the lobules, with which, from the absence of Ghsson's cap- sule, they are in immediate contact. Their coats are thin and trans- parent ; and, if they be laid open by a longitudinal incision, the bases of the lobules will be distinctly seen, separated by interlobular fissures, and perforated through the centre by the opening of the intralobular vein. The Hepatic trunks are formed by the union of the sublobular veins; they are contained in canals (hepatic venous) similar in structure to the portal canals, and lined by a prolongation of the proper capsule. They proceed from before backwards, and termi- nate by two large openings, corresponding to the right and left lobe of the liver in the inferior vena cava. It is to Kiernan that anatomical science is indebted for the clear, distinct, and intelligible idea of the structure of this most compli- cated organ, which has been furnished by the researches of that anatomist. To value this knowledge as it deserves, we have but to reflect upon the unsuccessful, though not fruitless, labours of those great discoverers in structural anatomy, Malpighi and Ruysch, upon the same subject, and the strange misconceptions of modern authors, among whom Miiller and Cruveilhier occupy so conspicuous a place. It is not, however, in an anatomical, or even a physiological point of view merely, that we have to admii^e these discoveries ; for in their practical application to the elucidation of pathological appear- ances, and the explanation of the phenomena of disease, they are still more interesting. Summary. — The liver has been shown to be composed of lobules ; the lobules (excepting at their bases) are invested and connected together, the vessels supported, and the whole organ enclosed by Glisson's capsule ; and they are so arranged, that the base of every lobule in the liver is in contact with an hepatic vein (sublobular). The Portal vein distributes its numberless branches through portal canals, which are channeled through every part of the organ ; it brings the returning blood from the chylopoietic viscera ; it collects also the venous blood from the ultimate ramifications of the hepatic artery in the liver itself. It gives oft" branches in the canals, which are called vaginal, and form a venous vaginal plexus; these give off' interlobular branches, and the latter enter the lobules and form lobular venous plexuses, from the blood circulating in which the bile is secreted. The Bile in the lobule is received by a network of minute ducts, the lobular biliary plexus ; it is conveyed from the lobule into the interlobular ducts ; it is thence poured into the biliary vaginal plexus of the portal canals, and thence into the excreting ducts, by which it is carried to the duodenum and gall-bladder, after being mingled in its course with the mucous secretion from the numberless muci- parous follicles in the walls of the ducts. The Hepatic artery distributes branches through every portal canal; gives cM vaginal branches wliicli form a vaginal hepatic STRUCTURAL ANATOMY OF THE LIVER. 521 plexus, from which the interlobular branches arise, and these latter terminate ultimately in the lobular venous plexuses of the portal vein. The artery ramifies abundantly in the coats of the hepatic ducts, enabhng them to provide their mucous secretion ; and sup- plies the vasa vasorum of the portal and hepatic veins, and the nu- trient vessels of the entire organ. The Hepatic veins commence in the centre of each lobule by minute radicles, which collect the impure blood from the lobular venous plexus and convey it into the intralobular veins ; these open into the sublohular veins, and the sublobular veins unite to form the large hepatic trunks by which the blood is conveyed into the vena cava. The physiological deduction arising out of this anatomical ar- rangement is, that the bile is loholly secreted from venous blood, and not from a mixed venous and arterial blood, as is believed by MiJller ; for although the portal vein receives its blood from two sources, viz. from the chylopoietic viscera and from the capillaries of the hepatic artery, yet the very fact of the blood of the latter ves- sel having passed through its capillaries into the portal vein, or in extremely small quantity into the capillary network of the lobular venous plexus, is sufficient to establish its venous character.* The pathological deductions depend upon the following facts : — Each lobule is a perfect gland ; of uniform structure, of uniform colour, and possessing the same degree of vascularity throughout. It is the seat of a double venous circulation, the vessels of the one {hepatic) being situated in the centre of the lobule, and those of the other {portal) in the circumference. Now the colour of the lobule, as of the entire hver, depends chiefly upon the proportion of blood contained within these two sets of vessels ; and so long as the cir- culation is natural the colour will be uniform. But the instant that any cause is developed which shall interfere with the free circula- tion of either, there will be an immediate diversity in the colour of the lobule. Thus, if there be any impediment to the free circulation of the venous blood through the heart or lungs, the circulation in the hepatic veins will be retarded, and the sublobular and the intra- lobular veins will become congested, giving rise to a more or less extensive redness in the centre of each of the lobules, while the mar- ginal or non-congested portion presents a distinct border of a yel- lowish white, yellow, or green colour, according to the quantity and quality of the bile it may contain. *' This is 'passive congestion' of the liver, the usual and natural state of the organ after death ;" and, as it commences with the hepatic vein, it may be called the first stage of hepatic-venous congestion. But if the causes which produced this state of congestion con- tinue, or be from the beginning of a more active kind, the conges- * For argumenis upon this contested question, see the article " Liver," in the " Cyclo- paedia of Anatomy and Physiology," edited by Dr. Todd. 6l> 522 GALL-RLADDEU. tion will extend through the lobular venous plexuses "into those branches of the portal vein situated in the interlohidar -fissures, but not to those in the spaces, which, being larger, and giving origin to those in the fissures, are the last to be congested." In this second stage the liver has a mottled appearance, the non-congested sub- stance is arranged in isolated, circular, and ramose patches, in the centres of which the spaces and part of the fissures are seen. This is an extended degree of hepatic-venous congestion ; it is " active congestion^' of the liver, and very commonly attends diseases of the heart and lungs. There is another form of partial venous congestion which com- mences in the portal vein; this is, therefore, portal venous congestion. It is of very rare occurrence, and Mr. Kiernan has observed it in children only. " In this form the congested substance never assumes the deep red colour which characterizes hepatic venous conges- tion; the interlobular fissures and spaces, and the marginal portions of the lobules are of a deeper colour than usual ; the congested substance is continuous and cortical, the non-congested substance being medullary, and occupying the centres of the lobules. The second stage of hepatic- venous congestion, in which the congested substance appears, but is not cortical, may be easily confounded with portal venous congestion. These are instances of partial congestion, but there is sometimes general congestion of the organ. " In general congestion the whole liver is of a red colour, but the central portions of the lobules are usually of a deeper hue than the marginal portions." GALL-BLADDER. The gall-bladder is the reservoir for the bile ; it is a pyriform sac situated in a fossa, upon the under surface of the right lobe of the liver, and extending from the right extremity of the transverse fis- sure to its free margin. It is divided into a body, fundus, and neck ; the fundus or broad extremity in the natural position of the fiver is placed downwards, and frequently projects beyond the free margin of the fiver, while the neck, small and constricted, is directed upwards. This sac is composed of three coats, serous, fibrous, and mucous. The serous coat is partial, is derived from the peritoneum, and covers that side only which is unattached to the liver. The middle oy fibrous coat is a thin but strong cellulo-fibrous layer, inter- mingled with tendinous fibres. It is connected on one side to the liver, and on the other to the peritoneum. The internal or mucous coat is but loosely connected with the fibrous layer; it is every where raised into minute ruga3 which give it a beautifully reticu- lated appearance, and forms at the neck of the sac a spiral valve. It is continuous through the hepatic duct with the mucous mem- brane lining all the ducts of the liver, and through the ductus com- munis choledochus, with the mucous membrane of the alimentary canal. THE PANCREAS. . 523 The Biliary ducts are, — the ductus communis choledochus, the cystic and the hepatic duct. The Ductus communis choledochus (xoX^i bihs, Six^i^at recipio) is the common excretory duct of the Kver and gall-bladder; it is about three inches in length, and commences upon the papilla, situated on the inner side of the cylinder of the perpendicular portion of the duodenum. Passing obliquely between the mucous and muscular coats, it ascends behind the duodenum, and through the right border of the lesser omentum ; and divides into two branches, the cystic duct and the hepatic duct. It is constricted at its commencement in the duodenum, and becomes dilated in its progress upwards. The Cystic duct, about an inch in length, passes outwards to the neck of the gall-bladder, with which it is continuous. The Hepatic duct continues onwards to the transverse fissure of the liver, and divides into two branches, which ramify through the portal canals to every part of the liver. The coats of the hepatic ducts are an external or fibrous, and an internal or mucous. The external coat is composed of a contractile fibrous tissue, which is probably muscular ; but its muscularity has not yet been demonstrated in the human subject. The mucous coat is continuous on the one hand with the lining membrane of the hepatic ducts and gall-bladder, and on the other with that of the duodenum. Vessels and JVerves. — The gall-bladder is supplied with blood by the cystic artery, a branch of the hepatic. Its veins return their blood into the portal vein. The nerves are derived from the hepatic plexus. THE PANCREAS. The Pancreas is a long, flattened, conglomerate gland, analogous to the salivary glands. It is about six inches in length, and between three or four ounces in weight, and is situated transversely across the posterior wall of the abdomen, behind the stomach, and resting upon the aorta, vena portee, inferior vena cava, the origin of the superior mesenteric artery, and the left kidney and supra-renal capsule ; opposite to the first and second lumbar vertebras. It is divided into a body, a greater, and a smaller extremity ; the great end or head is placed towards the right, and is surrounded by the curve of the duodenum ; the lesser end extends to the left as far as the spleen. The anterior surface of the body of the pancreas is covered by the ascending posterior layer of the peritoneum and is in relation with the stomach, the first portion of the duodenum and the commencement of the transverse arch of the colon. The pos- terior surface is grooved for the splenic vein, and tunneled by a complete canal for the superior mesenteric and portal vein, and for the superior mesenteric artery. The upper border presents a deep groove, sometimes a canal for the splenic artery and vein, and is in relation with the oblique portion of the duodenum, the 524 THE SPLEEN. lobus Spigelii, and the coeliac axis. And the lower border is sepa- rated from the transverse portion of the duodenum by the superior roesenteric artery and vein. Upon the posterior part of the head of the .pancreas is a lobular fold of the gland which completes the canal of the superior mesenteric vessels, and is called the lesser pan- creas. In structure it is composed of reddish-yellow angular lobules ; these consist of smaller lobules, and the latter are made up of the arborescent ramifications of minute ducts, terminating in csecal pouches. The pancreatic duct commences at the papilla upon the inner and posterior surface of the perpendicular portion of the duodenum by a small dilatation which is common to it and to the ductus communis choledochus, and passing obliquely between the mucous and muscu- lar coats runs from right to left through the middle of the gland, lying nearer to its anterior than to its posterior surface. At about the commencement of the apicial third of its course it divides into two parallel terminal branches. It gives off numerous small branches, which are distributed through the lobules, and constitute with the latter the substances of the gland. The duct which re- ceives the secretion from the lesser pancreas is called the ductus pancreaticus minor ; it opens into the principal duct near to the duo- denum, and sometimes passes separately into that intestine. As a variety, two pancreatic ducts are occasionally met with. Vessels and Nerves. — The arteries of the pancreas are branches of the splenic, hepatic, and superior mesenteric ; the veins open into the splenic vein ; the lymphatics terminate in the lumbar glands. The nerves are filaments of the splenic plexus. THE SPLEEN. The spleen is an oblong flattened organ of a dark bluish-red co- lour, situated in the left hypochondriac region. It is very variable in size and weight, spongy and vascular in texture and exceedingly friable. The external surface is convex, the internal slightly con- cave, indented along the middle fine, and pierced by several large and irregular openings for the entrance and exit of vessels ; this is the hilus llenis. The upper extremity is somewhat larger than the lower, and rounded ; the inferior is flattened ; the posterior border is obtuse ; the anterior is sharp and marked by several notches. The spleen is in relation by its external or convex surface with the diaphragm, which separates it from the ninth, tenth, and eleventh ribs ; by its concave surface with the great end of the stomach, the extremity of the pancreas, the gastro-splenic omentum with its ves- sels, the left kidney and supra-renal capsule, and with the left crus of the diapliragm ; by its upper end with the diaphragm, and some- times with the extremity of the left lobe of the liver, and by its lower end with the left extremity of the transverse arch of the colon. It is connected to the stomach by the gastro-splenic omentum and by capsuLjE renales. 525 the vessels contained in that duplicature. A second spleen (lien succenturiatus) is sometimes found appended to one of the branches of the splenic artery, near to the great end of the stomach ; when it exists, it is round and of very small size, rarely larger than a hazel- nut. I have seen two and even three of these bodies. The spleen is invested by the peritoneum and by a tunica propria of yellow elastic tissue, which enables it to yield to the greater or less disten- sion of its vessels. The elastic tunic forms sheaths for the vessels in their ramifications through the organ, and from these sheaths small fibrous bands are given off in all directions, which become at- tached to the internal surface of the elastic tunic, and constitute the cellular framework of the spleen. The substance occupying the interspaces of this tissue is soft and granular, and of a bright red colour ; in animals it is interspersed with small, white, soft corpus- cules. Vessels and Nerves. — The Splenic artery is of a very large size in proportion to the bulk of the spleen ; it is a division of the cceliac axis. The branches which enter the spleen are distributed to dis- tinct sections of the organ, and anastomose very sparingly with each other. The veins by thin numerous dilatations constitute the principal part of the bulk of the spleen ; they pour their blood into the splenic vein, which is one of the two great formative trunks of the portal vein. The lymphatics are remarkable for their number and large size, they terminate in the lumbar glands. The nerves are the splenic plexus, derived from the solar plexus. THE SUPRA-RENAL CAPSULES. The supra-renal capsules are two small yellowish and flattened bodies surmounting the kidneys, and inclining inwards towards the vertebral column. The right is somewhat three-cornered in shape, the left more semilunar ; they are connected to the kidneys by the common investing cellular tissue, and each capsule is marked upon its anterior surface by a fissure which appears to divide it into two lobes. The right supra-renal capsule is closely adherent to the pos- terior and under surface of the liver, and the left lies in contact with the pancreas. Both capsules rest upon the crura of the diaphragm on a level with the tenth dorsal vertebra, while by their inner border they are in relation with the great splanchnic nerve, and with the semilunar ganglion. They are larger in the foetus than in the adult, and appear to perform some office connected wdth embryonic life. The anatomy of these organs in the fa3tus will be found in the suc- ceeding chapter. In structure they are composed of two substances, cortical and medullary. The cortical substance is of a yellowish colour, and consists of straight parallel fibres placed perpendicularly side by side. The medullary substance is generally of a dark brown colour, double the quantity of the yellow substance, soft in texture, and contains within its centre the trunk of a large vein — the vena supra- 526 THE KIDNEYS. renalis. It is the large size of this vein that gives to the fresh supra- renal capsule the appearance of a central cavity ; the dark-coloured pulpy or fluid contents of the capsule, at a certain period after death, are produced by softening of the medullary substance. Dr. Nagel* has shown, by his injections and microscopic examinations, that the appearance of straight fibres in the cortical substance is caused by the direction of a plexus of capillary vessels. Of the numerous minute arteries, supplying the supra-renal capsule, he says, the greater number enter the cortical substance at every point of its surface, and, after proceeding for scarcely half a line in its substance, divide into a plexus of straight capillary vessels. Some few of the small arteries pierce the cortical layer and give off several branches in the medullary substance, which proceed in different directions, and re-enter the cortical layer to divide into a capillary plexus in a similar manner with the preceding. From the capillary plexus, composing the cortical layer, the blood is received by numerous small veins which form a venous plexus in the medullary substance, and terminate at acute angles in the large central vein. Vessels and JVerves. — The supra-renal arteries are derived from the aorta, from the renal, and from the phrenic arteries ; they are remarkable for the innumerable minute arteries into which they divide previously to entering the capsule. The supra-renal vein collecting the blood from the medullary v^enous plexus and receiving the several branches which pierce the cortical layer, opens directly into the vena cava on the right side, and into the renal vein on the left. The Lymphatics are large and very numerous ; they terminate in the lumbar glands. The nerves are derived from the renal and from the phrenic plexus. THE KIDNEYS. The kidneys, the secreting organs of the urine, are situated in the lumbar regions behind the peritoneum, and on each side of the ver- tebral column, which they approach by their upper extremities. Each kidney is between four and five inches in length, about two inches and a half in breadth, and somewhat more than one inch in thickness ; and weighs between three and five ounces. The kidneys are usually enclosed in a quantity of fat, they rest upon the dia- phragm, upon the anterior lamella of the transversalis muscle, M'hich separates them from the quadratus lumborum, and upon the psoas magnus. The 7v'ght Iddneij is somewhat lower than the left, from the position of the liver ; it is in relation by its anterior surface with the liver and descending portion of the duodenum, which rest upon it, and is covered in by the ascending colon and by its flexure. The left kidney, higher than the right, is covered in front by the great end of the stomach, by the spleen, descending colon with its flexure, * Mailer's Archiv. 1836. STRUCTURE OF KIDNEYS. 52T Fig. 156.* and by a portion of the small intestines. The anterior surface of the kidney is convex, while the posterior is flat ; the superior ex- tremity is in relation with the supra-renal capsule ; the convex border is turned outwards towards the parietes of the abdomen; and the concave border looks inwards towards the vertebral column, and is excavated by a deep fissure — the hilus renalis — in which are situated the vessels and nerves and pelvis of the kidney ; the renal vein being the most anterior, next the renal artery, and lastly the pelvis. The kidney is dense and fragile in tex- ture, and is invested by a proper fibrous capsule, which is easily torn from its sur- face. When divided by a longitudinal in- cision carried from the convex to the con- cave border, it presents in its interior two structures, an external or vascular (corti- cal), and an internal or tubular (medullary) substance. The tubular 'portion is formed of pale reddish-coloured conical bodies cor- responding by their bases with the vascular structure, and by their apices with the hilus of the organ ; these bodies are named cones, and are from eight to fifteen in number. The vascular 'portion is composed of blood- vessels, and of the plexiform convolutions of uriniferous tubuli, and not only forms the surface of the kidney, but dips between the cones and surrounds them nearly to their apices. The tubuli uriniferi communicate fre- quently with each other in the vascular structure of the kidney, and terminate in anastomosing loops and csecal extremities. They are each surrounded by a fine network of capillary vessels. When examined with a lens of low power, a muhitude of small globular bodies, glomeruli (corpora Malpighiana) are seen to be interspersed through the vascular structure of the organ, and to be connected to the minute twigs of the arteries. They are about xroth of an inch in diameter, are composed of an aggregated plexus of capillary vessels, and enclose a small central cavity, the use of which is as yet unknown. The Cones are composed of minute straight tubuli uriniferi of about the diameter of a fine hair ; they divide into parallel branches in their course, and commence by minute openings upon the apex or papilla of each cone. The papillte are invested by mucous mem- * A section of the kidney, surmounted by the supra-renal capsule ; the swellings upon the surface mark tlic original constitution of the organ by distinct lobes. 1. The supra-renal capsule. 2. The vascular portion of the kidney. 3,3, Its tubular portion, consisting of cones. 4, 4. Two of the pnpillns projecting into thin corresponding calices. 5, 5, 5. The three infundibuli ; the middle 5 is situated in tlic moutli of a caly-x. 6. The pelvis. 7. The ureter. 528 3IALE PELVIS CONTEIVTS. brane, which is continuous with the hning membrane of the tubuh, and forms a cup-hke pouch, the cahjx, around each papilla. ■ The cahces communicate with a common cavity of larger size, situated at each extremity, and in the middle of the organ ; and these three cavities — the inf^indibula — constitute by their union the large membranous sac, which occupies the hilus renalis, the ■pelvis of the kidney. The kidney in the embryo and fcetus consists of lobules. See the anatomy of the foetus in the succeeding chapter. The Ureter (o6^ov, urine, t%siv, to keep), the excretory duct of the kidney, is a membranous tube of about the diameter of a goose-quill, and nearly eighteen inches in length ; it is continuous superiorly with the pelvis of the kidney, and is constricted inferiorly, where it lies in an oblique direction between the muscalar and mucous coats Fig. 157.* * A side view of the viscera of the male pelvis in situ. The riafht side of the pelvis has been removed by a vertical section made througli the os pubis near to the sym- physis ; and another through the middle of the sacrum. 1. The divided surface of tlie OS pubis. 2. The divided surface of the sacrum. 3. The body of the bladder. A. Its fundus; from tlie apex is seen passing upwards the urachus. 5. Tlic base of the blad- der. 6. The ureter. 7. Tlie neck of the bladder. 8, 8. The pelvic fascia ; the fibres immediately above 7 are given off from the pelvic fascia and represent the anterior ligaments of the bladder. 9. The prostate gland. 10. ''I'he membranous portion of tlio urethra, between tlie two layers of the deep perineal fascia. II. Tlie deep perineal fascia formed of two layers. 12. One of Cowper's glands between the two layers of deep perineal fascia, and bcneatli the membranous ])ortion of tlie urethra. 13. Tiic bulb of the corpus sponjriosum. 14. The body of the corpus spongiosum. 1.5. The right erus penis. 16. I'he upper part of tlie first portion of tlio rectum. 17. The recto- vesical fold of peritoneum. 18. The second portion of llio rectum. 19. The riglit vesicula scminalis. 20. The vas deferens. 21. The rectum covered with tlie descend- ing layer of the pelvic fascia, just as it is making its bend backwards to constitute the third portion. 22. A part of the levator ani muscle investing the lower part of the rec- tum. 23. The external sphincter ani. 24. The interval between the deep and super- ficial perineal fuscia; they arc seen to be continuous beneath the figure. THE PELVIS AND BLADDER. 529 of the base of the bladder, and opens upon its mucous surface. Lying along the posterior wall of the abdomen, it is situated behind the peritoneum and is crossed by the spermatic vessels ; in its course downwards it rests upon the anterior surface of the psoas, and crosses the common iliac artery and vein, and then the external iliac vessels. Within the pelvis it crosses the umbilical artery and the vas deferens in the male, and the upper part of the vagina in the female. There are sometimes two ureters to one kidney. The ureter, the pelvis, the infundibula, and the calices are com- posed of two coats, an external or fibrous coat, the tunica propria; and an internal mucous coat which is continuous with the mucous membrane of the bladder inferiorly, and with the lining of the tubuli uriniferi above. Vessels and JVerves. — The renal artery is derived from the aorta ; it divides into several large branches before entering the hilus. There are frequently two renal arteries and sometimes three. The Veins terminate in the vena cava by a single large trunk on each side ; the left renal vein receiving the left spermatic vein. In- jections thrown into the renal artery and returning by the vein, generally make their way into those vessels by rupture ; and when the injection returns by the tubuli uriniferi, it always occurs from the bursting of the capillary vessels of the ducts into their cavities. The lymphatic vessels terminate in the lumbar glands. The JVej^ves are derived from the renal plexus, which is formed partly by the solar plexus, and partly by the lesser splanchnic nerve. The renal plexus gives branches to the spermatic plexus, and branches which accompany the ureters : hence the morbid sympa- thies which exist between the kidney, the ureter, and the testicle ; and by the communications with the solar plexus, with the stomach and diaphragm, and indeed with the whole system. THE PELVIS. The cavity of the pelvis is that portion of the great abdominal cavity which is included within the bones of the pelvis, below the level of the linea-ilio-pectinea and the promontory of the sacrum. It is bounded by the cavity of the abdomen above, and by the peri- neum below ; its internal parietes are formed in front, below, and at the sides, by the peritoneum, pelvic fascia, levatores ani muscles, obturator fascias and muscles ; and behind, by the sacrum, and sacral plexus of nerves. The Viscera of the pelvis in the male are the urinary bladder, the prostate gland, vesiculas seminales, and the rectum. BLADDER. The Bladder is an oblong membranous viscus of an ovoid shape, situated behind the os pubis and in front of the rectum. It is larger in its vertical diameter than from side to side ; and its long axis is 67 530 LIGAMENTS OP THE BLADDER. directed from above, obliquely downwards and backwards. It is divided into body, fundus, base, and neck. The hodij comprehends the middle zone of the organ • the fundus, its upper segment ; the base, the lower broad extremity, which rests upon the rectum ; and the neck the narrow constricted portion which is applied against the prostate gland. This organ is retained in its place by ligaments which are divided into true and false ; the true ligaments are seven in number, two anterior, two lateral, two umbiUcal, and the urachus ; the false liga- ments are folds of the peritoneum, and are four in number, tw"o an- terior and two posterior. The Anterior ligaments are formed by the pelvic fascia, which passes from the inner surface of the os pubis, on each side of the symphysis, to the front of the bladder. The Lateral ligaments are formed by the reflection of the pelvic fascia from the levatores ani muscles, upon the sides of the base of the bladder. The Umbilical ligaments are the fibrous cords which result from the obliteration of the umbilical arteries of the foetus ; they pass for- wards on each side of the fundus of the bladder, and ascend beneath the peritoneum to the umbilicus. The Urachus is a small fibrous cord formed by the obliteration of a tubular canal existing in the embryo ; it is attached to the apex of the bladder, and thence ascends to the umbilicus. The False ligaments are folds of peritoneum, the two lateral cor- respond with the passage of the vasa deferentia, from the sides of the bladder to the internal abdominal rings, and the two posterior with the course of the umbilical arteries, to the fundus of the organ. The bladder is composed of three coats, an external or serous coat, a muscular and a mucous coat. The serous coat is partial, and derived from the peritoneum, which invests the posterior sur- face and sides of the bladder, from about opposite the point of termi- nation of the two ureters to its summit, whence it is guided to the anterior wall of the abdomen by the umbilical ligaments and urachus. The muscular coat consists of two layers, an external layer com- posed of longitudinal fibres, the detrusor urinse ; and an internal layer of oblique and transverse fibres irregularly distributed. The anterior longitudinal fibres commence by four branches (the tendons of the bladder, or of the detrusor urinaj), two superior from the os pubis, and two inferior from the ramus of the ischium on each side, and spread out as they ascend upon the anterior surface of the blad- der to its fundus ; they then converge upon the posteiior surface of the organ, and descend to its neck where they arc inserted into the isthmus of the prostate gland, and into a ring of elastic tissue, which surrounds the commencement of the prostatic portion of the urethra. Some of the anterior fibres are also attached to this ring. The lateral fibres commence at the prostate gland and the elastic ring of the urethra on one side, and spread out as they ascend upon tlic side of the bladder to descend upon the opposite side, and l)e in- serted into the prostate and opposite segment of the same ring. Two BLADDER. 531 bands of oblique fibres are described by Sir Charles Bell, as origi- ginating at the terminations of the ureters, and converging to the neck of the bladder; the existence of these muscles is not well es- tablished. It has been well shown by Mr. Guthrie,* that there are no fibres at the neck of the bladder capable of forming a sphincter vesicas. The fibres corresponding with the trigonum vesicas are transverse. Sir Astley Cooper has demonstrated around the neck of the bladder within the prostate gland, a ring of elastic tissue, which has for its object the mechanical closure of the urethra against the involuntary passage of the urine. It is into this elastic ring that the longitudinal fibres of the detrusor urinas are inserted, so that this muscle taking a fixed point at the os pubis will not only compress the bladder, and thereby tend to force its contents along the urethra ; but will at the same time, by means of its attachment to this ring dilate the en- trance of the urethra, and afford a free egress to the contents of the bladder.f * "On the Anatomy and Diseases of the Neck of the Bladder and of the Urethra." t In Horner's Special Anatomy, vol. ii. p. 82, we find a different account of the sphincter apparatus at the neck of the bladder, which I subjoin because I have found it correct in every case wliich I have examined. On one point I beg leave to differ from Prof. Horner's description, viz. : in place of considering' the transverse band con- necting the two lobes of the prostate, and the triangular lamina underlying the vesical triangle as muscular, I believe them to belong to the proper elastic tissue such as forms the ligamentum nuchas in the mammiferaj and the middle coat of the arterial system. I annex a cat to the description of Horner, taken by his permission from a drawing by Peale. — G. Fig. 158.t " The internal orifice of the neck of the bladder resembles strongly that of a Florence flask, modified, however, by the projection of the uvula vesicte, which makes it somewhat crescentic below. The neck of the bladder penetrates the prostate gland, but, at its commence- ment, is surrounded by loose cellular tissue containing a very large and abun- dant plexus of veins. The internal layer of muscular fibres is here transverse ; and they cross and intermix with each other in different directions, forming a close compact tissue, which has the effect of a particular apparatus for re- taining the urine, and is called muscu- lus sphincter vesicce urinariae. Gene- rally, anatomists have not considered this structure as distinct from the mus- cular coat at large ; but Sir Charles Bell, now a professor in the University of Edinburgh, whose reputation as an ana. tomist is well established, gives the fol- lowing account of it : — " ' Begin the dissection by taking off the inner membrane of the bladder from around the orifice of the urethra. A set of fibres will be discovered, on the lower t Represents the neck of the bladder with the sphincter apparatus as described by Horner. 1, 1. Orifice of the neck of the bladder. 2, 2, 2, 2. Orifices of the ureters. 3, 3. Tiie triangular tissue, supposed to be muscular under the mucous membrane of the vesical triangle. 4, 4. Part of the detrusor urina muscle. 5. The elastic band which acts as a constant sphincter to the neck of the bladder. — G. 532 PROSTATE GLAND. The Mucous coat is thin and smooth and exactly moulded upon the muscular coat, to wliich it is connected by a somewhat thick layer of submucous tissue, called by some anatomists, the nervous coat ; its papillce are very minute, and there is scarcely a trace of mucous" follicles. This mucous membrane is continuous through the ureters with the lining membrane of the uriniferous ducts and through the urethra, with that of the prostatic ducts, tubuli semi- niferi, and Cowper's glands. Upon the internal surface of the base of the bladder is a triangu- lar smooth plane of a paler colour than the rest of the mucous mem- brane ; the trigonum vesicae, or trigone vesicale. This is the most sensitive part of the bladder, and the pressure of calculi upon it gives rise to great saflering. It is bounded on each side by the raised ridge, corresponding with the muscles of the ureters, at each pos- terior angle by the openings of the ureters, and in front by a slight elevation of the mucous membrane at the entrance of the urethra, called the uvula vesicce. The external surface of the base of the bladder corresponding with the trigonum, is also triangular, and is separated from the rectum merely by a thin layer of fibrous membrane, the recto-vesical fascia. It is bounded behind by the recto-vesical fold of peritoneum ; and on each side by the vas deferens, and vesicula seminalis, which converge almost to a point at the base of the prostate gland. It is through this space that the opening is made in the recto-vesical operation for puncture of the bladder. PROSTATE GLAND. The prostate gland {•n'^oldrfiit.i proeponere) is situated in front of the neck of the bladder behind the deep perineal fascia and upon the half of the orifice, which, being carefully dissected, will be found to run in a semi- circular form round llie urethra. These fibres make a band of about half an inch in breadth, particularly strong on the lower part of the opening, and, having mounted a little above the orifice, on each side, they dispose of a portion of their fibres in the substance of the bladder. A smaller and somewhat weaker set of fibres will be seen to complete their course, surrounding the orifice on the upper part ; to these sphincter fibres a bridle is joined, which comes from the union of the muscles of the ureters.' " After repeated observations on this point, I have come to the conclusion that Mr. Bell has indicated a real structure ; but my own dissections have resulted as follows : The inferior semicircumferencc of the neck of the bladder is surrounded by a thick fasciculus of muscular fibre, half an inch wide, running in a transverse direction, and having its ends attached to the lateral lobes of the prostate gland, being above the third lobe of the latter. This fasciculus is perfectly distinct from the ordinary muscular fibre of the bladder, and resembles in its texture the musculo-fibrous coat of the arte- ries. The superior semicircumferencc is also surrounded by a thin layer of muscular fibres of an ordinary kind, forming a broad, thin band of a crcsccntic shape, the lower ends of which arc insensibly lost in the adjacent muscular coat of the bladder by being spread out. And, lastly, beneath the mucous membrane of tlie vesical triangle there is a triangular muscle of the same size as the vesical triangle. Having elongated angles, the anterior angle may be traced to the posterior part of the caput gallinaginis, and the posterior angles to the orifices of the ureters and the adjacent part of the l)laddcr. The texture of this muscle- is also like that of tlie musculo-fibrous coat of the arteries. When a bladder is recent, this detail of structure is made out with diffi- culty : it recpiires to be ])reviously hnrdened in spirits of wine. That a power exists in the neck of the bladder of retaining completely the urine, has been satisfactorily demonstrated to me in a case of fistula in pcrinco, which was presented to the notice' of the late Dr. Fhyeick and myself, a few years ago." VESICUL^ SEMINALES. 533 rectum, through which it may be distinctly felt. It surrounds the commencement of the urethra for a little more than an inch of its extent, and resembles a Spanish chestnut both in size and form ; the base being directed backwards towards the neck of the bladder, the apex forwards, and the convex side towards the rectum. It is re- tained firmly in its position by the two superior, and the two inferior tendons of the bladder, by the attachments of the pelvic fascia, and by a process of the internal layer of the deep perineal fascia, which forms a sheath around the membranous urethra, and is inserted into the apex of the gland. It consists of three lobes, two lateral and a middle lobe or isthmus ; the lateral lobes are distinguished by an in- dentation upon the base of the gland, and by a slight furrow upon its upper and lower surface. The third lobe or isthmus is a small transverse band which passes between the two lateral lobes at the base of the organ. In structure the prostate gland is composed of ramified ducts, terminating in lobules of follicular pouches which are so closely compressed as to give to a thin section of the gland a cellular appearance beneath the microscope. It is pale in colour and hard in texture, splits easily in the course of its ducts, and is surrounded by a plexus of veins which are' enclosed by the strong fibrous membrane with which it is invested. Its secretion is poured into the prostatic portion of the urethra by fifteen or twenty excre- tory ducts. The urethra in passing through the prostate lies one third nearer to its upper than to its lower surface. VESICULiE SEMINALES. Upon the under surface of the base of the bladder, and converging towards the base of the prostate gland, are two lobulated and somewhat pyriform Fig. 159* bodies, about two inches in length, the vesi- cuIjb seminales. Their upper surface is in contact with the base of the bladder; the under side rests upon the rectum, separated only by the recto-vesical fascia ; the larger extremities are directed backwards and outwards, and the smaller ends almost meet at the base of the prostate. They enclose between them a triangular space, which is bounded posteriorly by the recto-vesical fold of peritoneum, and which corresponds with the trigonum vesicas on the interior of the bladder. Each vesicula is formed by the convolutions of a single tube, which gives off several irregular cajcal branches. It is * The posterior aspect of the male bladder ; the serous covering is removed in order to show the muscular coat. 1. The body of the bladder. 2. Its fundus. 3. Its inferior fundus or base. 4. The urachus. 5, 5, The ureters. 6, 6. The vasa defcrcntia. 7, 7. The vcsiculce seminales. The triangular area, corresponding with tJie trigonum vesicfB tlu-ough which tlic bladder would" be pierced, in puncttiring the bladder tln-ough the rectum. The dotted line forming the base of this triangular area, marks the ex- tent of the recto-vesical fold of the peritoneum. 534 MALE ORGANS OF GENERATION. enclosed in a dense fibrous membrane, derived from the pelvic fascia, and is constricted beneatli the isthmus of the prostate gland into a small excretory duct. The vas deferens, somewhat enlarged and convoluted, lies along the inner border of each vesicula, and is in- cluded in its fibrous investment. It communicates with the duct of the vesicula, beneath the isthmus of the prostate, and forms* the ejaculatory duct. The ejaculatory duct is about three quarters of an inch in length, and running forwards, first between the base of the prostate and the isthmus and then through the elastic tissue of the veru montanum, opens upon the mucous membrane of the urethra, near to its fellow of the opposite side, at the anterior ex- tremity of that process. MALE ORGANS OF GENERATION. The organs of generation in the male are, the penis and the testes, with their appendages. The Penis is divided into a body, root, and extremity. The body is surrounded by a thin integument, which is remarkable for the looseness of its cellular connexion with the deeper parts of the organ, and for containing no adipose tissue. The root is broad, and firmly adherent to the rami of the os pubis and ischium by means of two strong processes, the crura, and is connected to the sym- physis pubis by a fibrous membrane, the ligamentum suspensorium. The extremity, or glans penis resembles an obtuse cone, somewhat compressed from above downwards, and of a deeper red colour than the surrounding skin. At its apex is a small vertical slit, the meatus urinarius, which is bounded by two more or less protuberant labia : and, extending backwards from the meatus, is a depressed raphe, to which is attached a loose fold of mucous membrane, the fraenum prceputii. The base of the glans is marked by a projecting collar, the corona glandis, upon which are seen a number of small papillary elevations, formed by the aggregation of minute sebaceous glands, the glandulas Tysoni (odorifera?). Behind the corona is a deep fossa, bounded by a circular fold of integument, the prcBpuVntm, which, in the quiescent state of the organ, may be drawn over the glans, but, in its distended state, is obliterated, and serves to facili- tate its enlargement. The internal surface of the prepuce is lined by mucous membrane, covered by a thin cuticle ; this membrane, upon reaching the base of the glans, is reflected over the glans penis, and, at the meatus urinarius, becomes continuous with the mucous lining of the urethra. * It has bocn customary hitherto, in works on anatomy, to describe the course of excretory ducts as proceeding from the jrland, and passing- tlicncc to tlic point at wiiich tlie secretion is jiourcd out. In the description of tiie vas deferens, with its connexion with tiie duct of the vesicula seminalis, I liavc adopted this plan, that I might not too far depart from cstaljlislied habit. But as it is more correct and consistent with tlie present state of science to consider the gland as a dev(;lopement of tlie duet, I have pursued the latter principle in the description of most of the other glandular organs of the body. CORPUS SPONGIOSUM ERECTILE TISSUE. 535 The penis is composed of the corpus cavernosum and corpus spongiosum, and contains in its interior the longest portion of the urethra. The Corpus cavernosum is distinguished into two lateral portions (corpora cavernosa), by an imperfect septum and by a superior and inferior groove, and is divided posteriorly into iwvo crura. It is firmly adherent, by means of its crura, with the ramus of the os pubis and ischium. It forms, anteriorly, a single rounded extremity, which is received into a fossa in the base of the glans penis ; the superior groove lodges the dorsal vessels of the organ, and the infe- rior receives the corpus spongiosum. Its fibrous tunic is thick, elastic, and extremely firm, and sends a number of fibrous bands and cords (trabeculse) inwards from its inferior groove, which cross its interior in a radiating direction, and are inserted into the inner walls of the tunic. These trabeculse are most abundant on the middle line, where they are ranged vertically, side by side, some- what like the teeth of a comb, and constitute the imperfect partition of the corpus cavernosum, called the septum pectiniforme. This septum is more complete at its posterior than towards its anterior part. The tunic of the corpus cavernosum consists of strong longitu- dinal fibrous fasciculi, closely interwoven with each other. Its internal structure is com^posed of erectile tissue. The Corpus spongiosum is situated along the under surface of the corpus cavernosum, in its inferior groove. It commences by its posterior extremity between and beneath the crura penis, where it forms a considerable enlargement, the bulb, and terminates an- teriorly by another expansion, the glans penis. Its middle portion, or body, is nearly cylindrical, and tapers gradually from its pos- terior towards its anterior extremity. The bulb is adherent to the deep perineal fascia by means of the tubular prolongation of the an- terior layer, which surrounds the membranous portion of the urethra; in the rest of its extent the corpus spongiosum is attached to the corpus cavernosum by cellular tissue, and by veins which wind around that body to reach the dorsal vein. It is composed of erec- tile tissue, enclosed by a dense fibrous tissue, much thinner than that of the corpus cavernosum, and contains in its interior the spongy portion of the urethra, which lies nearer to its upper than to its lower wall. Erectile tissue is a peculiar cellulo-vascular structure, entering in considerable proportion into the composition of the organs of gene- ration. It consists essentially of a plexus of veins so closely con- voluted and interwoven with each other, as to give rise to a cellular appearance when examined upon the surface of a section. The veins forming this plexus are smaller in the glans penis, coquis spon- giosum, and circumference of the corpus cavernosum, than in the central part of the latter, where they are large and dilated. They have no other coat than the internal lining prolonged from the neighbouring veins ; and the interstices of the plexus are occupied 536 URETHRA. by a peculiar reddish fibrous substance. They receive their blood from the capillaries of the arteries in the same manner with veins generally, and not by means of vessels having a peculiar form and distribution, as described by Miiller. The helicine arteries of that physiologist have no existence.* Vessels and Nerves. — The arteries of the penis are derived from the internal pudic ; they are, the arteries of the bulb, arteries of the corpus cavernosum, and dorsalis penis. Its veins are superficial and deep. The deep veins run by the side of the deep arteries, and ter- minate in the internal pudic veins. The superficial veins emerge in considerable number from the base of the glans, and converge on the dorsum penis, to form a large dorsal vein, which receives othei: veins from the corpus cavernosum and spongiosum in its course, and passes backwards between two layers of the ligamentum suspen- sorium, and through the deep fascia beneath the arch of the os pubis, to terminate in the prostatic and vesical plexuses. The Lymphatics terminate in the inguinal glands. The nerves are derived from the internal pudic nerve, from the sacral plexus, and, as shown by Professor Miiller in his beautiful monograph, from the hypogastric plexus. URETHRA. The urethra is the membranous canal extending from the neck of the bladder to the meatus urinarius. It is sigmoid in its course, and is composed of two layers, a mucous coat and an elastic fibrous coat. The mucous coat is thin and smooth ; it is continuous, inter- nally, with the mucous membrane of the bladder ; externally, with the investing membrane of the glans ; and, in certain points of its extent, with the lining membrane of the numerous ducts of mucous glands, — of those of Cowper's glands, the prostate gland, vasa deferentia, and vesicula; seminales. The elastic fibrous coat varies in thickness in the different parts of the course of the urethra : it is thick in the prostate gland, forms a firm investment for the mem- branous portion of the canal, and is thin in the spongy portion, where it serves as a bond of connexion between the mucous mem- brane and the corpus spongiosum. The urethra is about nine inches in length, and is divided into a prostatic, membranous, and spongy portion. The Prostatic portion, a little more than an inch in length, is situated in the prostate gland, about one-third nearer to its upper than to its lower surface, and extending from its base to its apex. Upon its lower circumference or floor is a longitudinal fold of mucous membrane — the verumontanum, or caput gallinaginis, — and on each side of the veru, a depressed fossa — the prostatic sinus — in which are seen the numerous openings of the prostatic ducts. At the an- terior extremity of the verumontanum are the openings of the two * Soc my investigation upon this structure in the " Cyclopaedia of Anatomy and Pliysiology." Article, " Penis." URETHRA AND BLADDER. 537 ejaculatory ducts, and between them a third opening, which leads backwards into a small dilated sac — the sinus pocularis. The pro- static portion of the urethra, when distended, is the most dilated part of the canal ; but, excepting during the passage of urine, is com- pletely closed by means of a ring of elastic tissue which encircles the urethra as far as the anterior extremity of the verumontanum. In the contracted state of the urethra, the verumontanum acts as a valve, being pressed upwards against the upper wall of the canal; but, during the action of the detrusor muscle of the bladder, the whole elastic ring is expanded by the muscular fibres which are inserted into it ; and the veru is especially drawn downwards by two delicate tendons, which have been traced by Mr. Tyrrell, from the posterior fibres of the detrusor into the tissue of this process. Fiff. 160* * A longitudinal section of the bladder, prostate gland, and penis, showin'r the urethra. 1. The urachiis attached to the upper part of the fundus of tlie bladder. 2. The recto-vesical fold of peritoneum, at its point of reflection from the base of the bladder, upon the anterior surface of the rectum. 3. The opening of the right ureter. 4. A slight ridge, formed by the muscle of the ureter, and extending from the termi- nation of the ureter to tlie commencement of the urethra. This ridge forms the lateral boundary of the trigonum vesicEE. 5. The commencement of tlie urethra ; the eleva- tion of mucous membrane immediately behind the figure is the uvula vesica. The constriction of the bladder at this point is the necli of the bladder. 6. The prostatic portion of the uretlira. 7. The prostate gland ; the diiference of tliickness of the gland, above and below the urethra, is shown. 8. The isthmus, or third lobe of the prostate ; immediately beneath which the ejaculatory duct is seen passing. 9. The right vesicula seminalis ; the vas deferens is seen to be cut short off, close to its junc- tion with the ejaculatory duct. 10. The membranous portion of the urethra. 11. Cowper's gland of the right side, with its duct. 12. The bulbous portion of the urethra ; throughout the whole length of the urethra of the corpus spongiosum, nu- merous lacunas are seen. 13. The fossa navicularis. 14. The corpus cavernosum, cut somewhat obliquely to the right side, near its lower part. Tlie character of the venous- cellulnr texture is well shown. 15. The right cms penis. 16. Near the upper part of the corpus cavernosum, the section has fallen a little to tlie left of tiie middle line; a portion of the septum pcctiniforme is consequently seen. Tliis figure also indicates the thickness of the fibrous investment of the corpus cavernosum, and its abrupt ter- mination at the base of (17) the glans penis. \b. The lower segment of the glans. 19. The meatus urinarius. 20. The corpus spongiosum. 21. The bulb of the corpus spongiosum. G8 533 MEMBRANOUS URETHRA. The discovery ojf this beautiful structure is due to our distin- guished countryman, Sir Astley Cooper, and is one other instance of the marvellous indications of design evinced in the structure of the animal frame. Instead of a muscular apparatus, liable to fatigue, Nature has employed, for the purpose of retaining the ui'ine, an elastic substance, which closes the urethra constantly by an unweary- ing physical property. Expulsion, on the contrary, occurring only at intervals, demands the exercise of muscular action, that action being immediately applied to the elastic agent and drawing it aside. It is by means of this interesting provision that the semen and the last drops of urine are expelled from the urethra without a chance of reflux into the bladder, and that the urine is enabled to pass freely along its canal without danger of entering the prostatic or ejacula- tory ducts. The Membranous portion, the narrowest part of the canal, is somewhat less than an inch in length. It is situated between the two layers of the deep perineal fascia, and is surrounded by the fan-like expansions of the upper and lower segments of the com- pressor urethrce muscle which meet at the raphe along its upper and lower surface. It is continuous posteriorly with the prostatic urethra, and anteriorly with the spongy portion of the canal. Its coverings are the mucous membrane, elastic fibrous layer, com- pressor urethras muscle, and a partial sheath from the deep perineal fascia. The Spongy portion forms the rest of the extent of the canal, and is lodged in the corpus spongiosum from its commencement at the deep perineal fascia to the meatus urinarius. It is narrowest in the body, and becomes dilated at cither extremity, posteriorly in the bulb, where it is named the bulbous portion, and anteriorly in the glans penis, where it forms the fossa navicularis. The meatus urinarius is the most constricted part of the canal; so that a cathe- ter, which will enter that opening, maybe passed freely through the" whole extent of a healthy urethra. Opening into the bulbous portion are two small excretory ducts about three quarters of an inch in length, which may be traced backwards, between the coats of the urethra and the bulb, to the interval between the two layers of tlie deep perineal fascia, where they ramify in two small lobulatcd and somewhat compressed glands of about the size of peas. These are Cowper's glands ; they are situated immediately beneath the mem- branous portion of the urethra, and are enclosed by the lower seg- ment of the compressor urethroe muscle so as to bo subject to mus- cular compression. Upon the whole of the internal surface of the spongy portion of the urethra, particularly along its upper wall, are numerous small openings or lacuna; which arc the entrances of mucous glands situated in the submucous cellular tissue. The openings of these lacuna; are directed forwards, and arc liable occa- sionally to intercept the \)dmi of a small catheter in its passage into the bladder. At about an inch and a half from the opening of the meatus one of these lacuna; is generally found much larger than the TESTES. 539 rest, and is named the lacuna magna. In a beautiful preparation of this lacuna, made by Sir Astley Cooper, the extremity of the canal presents several large primary ramifications. TESTES. The testes are two small glandular organs suspended from the abdomen by the spermatic cords, and enclosed in an external tegu- mentary covering, the scrotum. The Scrotum is distinguished into two lateral halves or hemi- spheres by a raphe, which is continued anteriorly along the under surface of the penis, and posteriorly along the middle line of the perineum to the anus. Of these two lateral portions the left is some- what longer than the right, and corresponds with the greater length of the spermatic cord on the left side. The scrotum is composed of two layers, the integument and a proper covering, the dartos ; the integument is extremely thin, transparent, and abundant, and beset by a number of hairs which issue obliquely fi'om the skin, and have prominent roots. The dartos is a thin layer of a peculiar contractile fibrous tissue, intermediate in properties between muscular fibre and elastic tissue ; it forms the proper tunic of the scrotum, and sends inwards a distinct septum (septum scroti) which divides it into two cavities for the two testes. The dartos is continuous around the base of the scrotum with the common superficial fascia of the abdomen and perineum. The Spermatic cord is the medium of communication between the testes and the interior of the abdomen ; it is composed of arteries, veins, lymphatics, nerves, the excretory duct of the testicle and its proper coverings. It commences at the internal abdominal ring, where the vessels of which it is composed converge, and passes obliquely along the spermatic canal ; the cord then escapes at the external abdominal ring and descends through the scrotum to the posterior border of the testicle. The left cord is somewhat longer than the right, and permits the left testicle to reach a lower level than the risrht. The Arteries of the spermatic cord are the spermatic artery from the aorta ; the deferential artery, accompanying the vas deferens, from the superior vesical; and the cremasteric branch from the epigastric artery. The spermatic veins form a plexus which con- stitutes the chief bulk of the cord ; they are provided with valves at short intervals, and the smaller veins have a peculiar tendril-like arrangement which has obtained for them the name of vasa pampi- niformia. The lymphatics are of large size, and terminate in the lumbar glands. The nerves are the spermatic plexus, which is derived from the aortic and renal plexus, the genital branch of the genito-crural nerve, and the scrotal branch of the ilio-scrotal. The Vas deferens, the excretory duct of the testicle, it situated along the posterior border of the cord, where it may be easily dis- tinguished by the hard and cordy sensation which it communicates 540 COVEKINGS OF COED TESTIS. Fiff. 161.* to the fingers. Its parietes are very thick and tough, and its canal extremely small and lined by the mucous membrane continued from the urethra. The Coverings of the spermatic cord are the spermatic fascia, cremaster muscle, and fascia propria. The spermatic fascia is a prolongation of the intercolumnar fascia, derived from the borders of the external abdominal ring during the descent of the testicle in the foetus. The cremasteric covering (erythroid) is the thin mus- cular expansion formed by the spreading out of the fibres of the cremaster, which is likewise carried down by the testis during its descent. The fascia propria is a continuation of the intundibiliform process from the transversalis fascia which immediately invests the vessels of the cord, and is also obtained during the descent of the testis. The Testis (testicle) is a small oblong and rounded gland, some- what compressed upon the sides and behind, and suspended in the cavity of the scrotum by the spermatic cord. Its position in the scrotum is oblique ; so that the upper extremity is directed upwards and forwards, and a little outwards; the lower, downwards and back- wards, and a little inwards ; the convex sur- face looks forwards and downwards, and the flattened surface to which the cord is attached, backwards and upwards. Lying against its outer and posterior border is a flattened body which follows the course of the testicle, and extends from its upper to its lower extremity ; this body is named, from its relation to the testis, epididymis {s'fi upon, SiSufj^os the testicle) ; it is divided into a central part or body, an upper extremity or globus major, and a lower extremity, globus minor (cauda) epididymis. The globus major is situated upon the upper end of the testicle, to which it is closely adherent ; the globus minor is placed at its lower end, is attached to the testis by cellular tissue, and curves upwards, to become continuous with the vas deferens. The testis is invested by three tunics — tunica vaginalis, tunica albuginea, and tunica vasculosa ; and is connected to the inner sur- face'of the dartos by a large quantity of extremely loose cellular tissue, in which fat is never deposited, but which is very susceptible of serous infiltration. ■* A transverse section of the testicle. 1. The cavity of the tunica vaginalis; the most external layer is the tunica vaginalis reflcxa ; and that in contact with the organ, the tunica vaginalis propria. 2. The tunica albuginea. 3. The mediastinum testis, giving off numarous fibrous cords in a radiated direction to the internal surface of the tunica albuginea. The cut extremities of tlic vessels belowr the number belong to the rete testis ; and tliose above to tiie artei'ies and veins of the organ. 4. The tunica vas- culosii, or pia mater testis. .5. One of the lobules, consisting of the convolutions of the tubuli'seminiferi, and terminating by a single duct — the vas rectum. Corresponding lobules arc seen between the other fibrous cords of the mediastinum. 6. Section of the epididymis. STRUCTURE OF THE TESTIS. 541 The Tunica vaginalis is a pouch of serous membrane derived* from the peritoneum in the descent of the testis, and afterwards obliterated from the abdomen to within a short distance of the gland. Like other serous coverings it is a shut sac, investing the organ and thence reflected so as to form a bag around its circumference ; hence it is divided into the tunica vaginalis propria, and tunica vaginalis rejlexa. The tunica vaginalis propria covers the surface of the tunica albuginea, and surrounds the epididymis, connecting it to the testis by means of a distinct duplicature. The tunica vaginaUs re- flexa is attached by its external surface, through the medium of a quantity of loose cellular tissue, to the inner surface of the dartos. Between the two layers is the smooth surface of the shut sac, moist- ened by its proper secretion. The Tunica albuginea (dura mater testis) is a thick fibrous mem- brane of a bluish white colour, and the proper tunic of the testicle. It is adherent externally to the tunica vaginaHs propria, and from the union of a serous with a fibrous membrane is considered a fibro- serous membrane, like the dura mater and pericardium. After sur- rounding the testicle, the tunica albuginea is refllected from its pos- terior border into the interior of the gland, and forms a projecting longitudinal ridge, which is called the mediastinum testis (corpus Highmorianum*) from which numerous fibrous cords (trabeculas, septula) are given off", to be inserted into the inner surface of the tunic. The mediastinum serves to contain the vessels and ducts of the testicle in their passage into the substance of the organ, and the fibrous cords are admirably fitted, as has been shown by Sir Astley Cooper, to prevent compression of the gland. If a transverse section be made of the testis, and the surface of the mediastinum examined, it will be observed that the blood-vessels of the substance of the organ are situated near the posterior border of the mediastinum, while the divided ducts of the rete testis, occupy a place nearer to the free margin. The Tunica vasculosa (pia mater testis) is the nutrient membrane of the testis ; it is situated immediately within the tunica albuginea and encloses the substance of the gland, sending processes inwards between the lobules, in the same manner that the pia mater is re- flected between the convolutions of the brain. The substance of the testis consists of numerous conical flattened lobules (lobuli testis), the bases being directed towards the surface of the organ, and the apices towards the mediastinum. Krause found between four and five hundred of these lobules in a single testis. Each lobule is invested by a distinct sheath formed by two layers, one being derived from the tunica vasculosa, the other from the tunica albuginea. The lobule is composed of one or several minute tubuli, iubuli seminiferi,-\ exceedingly convoluted, anasto- * Nathaniel Higflimore, a physician of Oxford, in his "Corporis Humani Disquisitio Anatomica," publislied in 1051 : he considers the corpus Hifrhnioiianum as a duct formed by the converg;ence of the fibrous cords, which he mistakes for smaller ducts. t Lauth estimates the wliolc number of tubuli seminiteri in each testis, at 840, and their average lengtli at 2 feet 3 inches. According to this calculation, the whole length of the tubuli seniinifcri would be 1890 feet. 542 EPIDIDYMIS. • mosing frequently with each other near to their extremities, termi- nating in loops or in free c^cal ends, and of the same diameter (_|_ Lauth) throughout. The tubuli seminiferi are of a bright yel- low colour ; they become less convoluted in the apices of the lobules, and terminate by forming between twenty and thirty small straight ducts of about twice the diameter of the tubuli seminiferi, — the vasa recta. The vasa recta enter the substance of the mediastinum, and terminate in from seven to thirteen ducts, smaller in diameter than the vasa recta. These ducts pursue a waving course from below upwards through the fibrous tissue of the mediastinum ; they com- municate freely with each other, and constitute the 7'ete testis. At the upper extremity of the mediastinum, the ducts of the rete testis terminate in from nine to thirty small ducts, the vasa ejferentia,* which form by their convolutions a series of conical masses, the coni vasculosi ; from the bases of these cones tubes of larger size proceed, which constitute by their complex convolutions the body of the epididymis. The tubes become gradually larger towards the lower end of the epididymis, and terminate in a single large and convoluted duct, the vas deferens. The Epididytnis is formed by the convolutions of the excretory seminal ducts, externally to the testis, pre- viously to their termination in the vas deferens. The more numerous convolutions and the ag- gregation of the coni vasculosi at the upper end of the organ constitute the globus major ; the continuation of the convolutions downwards is the body ; and the smaller number of con- volutions of the single tube at the lower ex- tremity, the globus minor. The tubuli are connected together by a very delicate cel- lular tissue, and are enclosed by the tunica vaginalis. A small convoluted duct, of variable length, is generally connected with the duct of the epi- didymis immediately before the commencement of the vas deferens. This is the vasculum aberrans of Haller ; it is attached to the epi- didymis by the cellular tissue in which that body is enveloped. Sometimes it becomes dilated towards its extremity, but more fre- quently retains the same diameter throughout. Fiff. I62.t * Each vas deferens witli its cone measures, according' to Lautli, about 8 inches. The entire Icnjrth of tlic tubes composing the epidid)'mis, according to the same authority, is about 21 feet. t Anatomy of tin; testis. 1,1. The tunica albupfinca. 9,2. The mediastinum testis. 3, .3. The lobuli testis. 4, 4. Tiic vasa recta. r>, 5. The rete testis. 6. The vasa cfTcrentia, of which five only are lepresented in tliis dingrain. 7. TIjc coni vasculosi, constituting the globiis ma jor of tiie epididymis. 8. Tlie body of the epididymis. 9. The globus minor of the epididymis. 10, The vas deferens. 11. The vasculum aberrans. FEMALE PELVIS. 543 The Fas deferens may be traced upwards in the course of the seminal fluid, from the globus minor of the epididymis along the pos- terior part of the spermatic cord, and along the spermatic canal to the internal abdominal ring. From the ring it is reflected inwards to the side of the fundus of the bladder, and descends along its posterior surface, crossing the direction of the ureter, to the inner border of the vesicula seminalis. In this situation it becomes somewhat larger in size and convoluted, and terminates at the base of the prostate gland, by uniting with the duct of the vesicula seminalis and constituting the ejaculatory duct. The ejaculatory duct, which is thus formed by the junction of the duct of the vesicula seminaUs with the vas deferens, passes forwards to the anterior extremity of the veru- montanum, where it terminates by opening into the prostatic urethra. FEMALE PELVIS. The peculiarities of the form of the female pelvis have already been examined with the anatomy of the bones. Its lining bounda- ries are the same with those of the male. The contents are, the bladder, vagina, uterus with its appendages, and the rectum. Some portion of the small intestines also occupy the upper part of its cavity. The Bladder is in relation with the os pubis in front, with the uterus behind, from which it is usually separated by a convolution of small intestine, and with the neck of the uterus, and with the vagina beneath. The form of the female bladder corresponds with that of the pelvis, being broad from side to side, and often bulging more on one side than on the other. This is particularly evident after frequent parturition. The coats of the bladder are the same as those of the male. The Urethra is about an inch and a half in length, and is lodged m the upper wall of the vagina, in its course downwards and for- wards, beneath the arch of the os pubis, to the meatus urinarius. It is lined by mucous membrane, which is disposed in longitudinal folds, and is continuous internally with that of the bladder, and ex- ternally with the vulva ; the mucous membrane is surrounded by a proper coat of elastic tissue, to which the muscular fibres of the detrusor urinae are attached. It is to this tissue that is due the re- markable dilatability of the female urethra, and its speedy return to its original diameter. The meatus is encircled by a ring of fibrous tissue, which pi'events it from distending with the same facility as the rest of the canal ; hence it is sometimes advantageous in per- forming this operation to divide its margin slightly with the knife. Vagina. — The Vagina is a membranous canal, leading from the vulva to the uterus, and corresponding in direction with the axis of the outlet of the pelvis. It is constricted at its commencement, but near the uterus becomes considerably dilated ; and is closed by the contact of the anterior with the posterior wall. Its length is very 544 VAGINA UTERUS. variable ; but it is always longer upon the posterior than upon the anterior wall, the former being usually about five or six inches in length, and the latter four or five. It is inserted into the cervix of the uterus, which projects into the upper extremity of the canal. In Structure the vagina is composed of a mucous lining, a layer of erectile tissue, and an external tunic of a cellulo-jibrous structure, resembling the dartos of the scrotum. The upper fourth of the posterior wall of the vagina is covered, on its pelvic surface, by the peritoneum; while in front the peritoneum is reflected from the upper part of the cervix of the uterus to the posterior surface of the bladder. On each side it gives attachment superiorly to the broad ligaments of the uterus ; and inferiorly to the pelvic fascia, and to the levatores ani. The Mucous membrane presents a number of transverse papill(B or rugcB upon its upper and lower surfaces, which extend outwards on each side from a middle rafhe. The transverse papillae and raphe, are more apparent upon the upper than upon the lower sur- face, and the two raphe are called the columns of the vagina. The mucous membrane is covered by a thin cuticular epithelium, which is continued from the labia, and terminates by a fringed border at about the middle of the cervix uteri. The Middle or erectile laijer consists of erectile tissue enclosed between two layers of fibrous membrane ; this layer is thickest near the commencement of the vagina, and becomes gradually thinner as it approaches the uterus. The External, or dartoid layer of the vagina, serves to connect it to the surrounding viscera. Thus, it is very closely adherent to the under surface of the bladder, and drags that organ down with it in prolapsus uteri. To the rectum it is less closely connected, and that intestine is therefore less frequently affected in prolapsus. UTERUS. The Uterus is a flattened organ of a pyriform shape, having the base directed upwards and forwards, and the apex downwards and backwards in the line of the axis of the inlet of the pelvis, and forming a considerable angle with the course of the vagina. It is convex on its posterior surface, and somewhat flattened upon its anterior aspect. In the unimpregnated state it is about three inches in length, two in breadth across its broadest part, and one in thick- ness, and is divided into fundus, body, cervix, and os uteri. At the period of puberty the uterus weighs about one ounce and a half; after parturition from two to three ounces ; and at the ninth month of utcro-gcstation from two to four pounds. The Fundus and bodij arc enclosed in a duplicature of peritoneum, which is connected with the two sides of the pelvis, and forms a transverse septum between the bladder and rectum. The folds formed by this duplicature of peritoneum on either side of the organ arc the broad ligaments of the ulonis. The cervix is the CONTENTS OF FEMALE PELVIS, 545 lower portion of the organ; it is distinguished from the body by a well-marked constriction ; to its upper part is attached the upper extremity of the vagina, and at its extremity is an opening which is nearly round in the virgin, and transverse after parturition — the OS 2<^erf— bounded before and behind by two labia; the anterior labium being the most thick, and the posterior somewhat the longest. Fig. 163 * The opening of the os uteri is of considerable size, and is named the orificium uteri externum; the canal then becomes narrowed, and at the upper end of the cervix is constricted into a smaller opening — the orificium intemum.f At this point the canal of the cervix expands into the shallow triangular cavity of the uterus, the inferior angle corresponding with the orificium internum, and the two superior angles, which are funnel-shaped and represent the * A side view of the viscera of the female pelvis. 1. The symphysis pubis ; to the upper part of which the tendon of the rectus muscle is attached. 2. The abdominal parietes. 3. The collection of fat, forming- the projection of the mons Veneris. 4. The urinary bladder. 5. The entrance of the left ureter. 6. The canal of the urethra, converted into a mere fissure by the contraction of its walls. 7. The meatus urinarius. 8. The clitoris, with its prEeputium, divided through the middle. 9. The left nympha. 10. The left labium majus. 11. The meatus of the vagina, narrowed by the contrac- tion of its sphincter. 12. The canal of the vagina, upon which the transverse rugse are apparent, 13. The thick wall of separation between the base of the bladder and the vagina. 14, The wall of separation between the vagina and the rectum. 15. The perineum. 1 6. The os uteri. 17. Its cervix. 18. The fundus uteri. The cavitas uteri is seen along the centre of the organ. 10, The rectum, sliowing the disposition of its mucous membrane, 20. The anus, 21, The upper part of the rectum, invested by the peritoneum. 22. Tlie recto-uterine fold of the peritoneum. Just above the figure. 23. The utcro-vesical fold. 24, The reflection of the peritoneum, from the apex of the bladder, upon the trachus to the internal surface of the abdominal parietes, 25. The last lumbar vertebra. 26. The sacrum. 27, Tlio coccyx. t The orificium internum is not unfrequcntly obliterated in old persons. Indeed, this obliteration is so common, as to have induced Mayer to regard it as normal. 69 546 STKUCTURE OF UTERUS. original bicornute condition of the organ, with the commencement of the Fallopian tubes. In the canal of the cervix uteri are two or three longitudinal folds to which numerous oblique folds converge so as to give the idea of branches from the stem of a tree ; hence this appearance has been denominated the arhor vitce uterina. Be- tween these folds, and around the os uteri, are numerous mucous follicles. It is the closure of the mouth of one of these follicles, and the subsequent distension of the follicle with its proper secre- tion, that occasions those vesicular appearances so often noticed within the mouth and cervix of the uterus, called the ovula of JVahoth. Structure. — The uterus is composed of three tunics ; of an external or serous coat derived from the peritoneum, which constitutes the duplicatures on each side of the organ called the broad ligaments ; of a middle or muscular coat, which gives thickness and bulk to the uterus ; and of an internal or mucous membrane, which lines its in- terior, and is continuous on the one hand with the mucous lining of the Fallopian tubes, and on the other with that of the vagina. In the unimpregnated state the muscular coat is exceedingly condensed in texture, offers considerable resistance to section with the scalpel, and appears to be composed of white fibres inextricably interlaced and mingled with blood-vessels. In the impregnated uterus the fibres are of large size and distinct, and are disposed in two layers, superficial and deep. The suferjicial layer consists of fibres which pursue a vertical direction, some being longitudinal and others oblique. The longitudinal fibres are found principally upon the middle line, forming a thin plane upon the anterior and posterior face of the organ and upon its fundus. The oblique fibres occupy chiefly the sides and fundus. At the angles of the uterus the fibres of the superficial layer are continued outwards upon the Fallopian tubes, and into the round ligaments and the ligaments of the ovaries. The deej) layer consists of two hollow cones of circular fibres having their apex at the openings of the Fallopian tubes, and by their bases intermingling with each other on the body of the organ. These fibres are continuous with the deep muscular layer of the Fallopiaii tubes, and indicate the primitive formation of the uterus by the blending of these two canals. Around the cervix uteri the muscular fibres assume a circular form interlacing with and crossing each other at acute angles. The mucous membrane is provided with a columnar ciliated epithelium, which extends from the middle of the cervix uteri to the extremities of the Fallopian tubes. Vessels and Nerves. — The Arteries of the uterus are the uterine from the internal iliac, and the spermatic from the aorta. The veins are very large and remarkable ; in the impregnated uterus they are called sinuses, and consist of canals channeled through the substance of the organ, being merely lined by the internal membrane of the veins. They terminate on each side of the uterus in the uterine plexuses. The lymphatics terminate in the lumbar glands. FALLOPIAN TUBES OVARIES. 547 The Nerves are derived from the hypogastric and spermatic plexuses, and from the sacral plexus. The Jlppendages of the uterus are enclosed by the lateral dupli- catures of peritoneum, called the broad ligaments. They are the Fallopian tubes and ovaries. FALLOPIAJf TUBES. The Fallopian* tubes or oviducts, the uterine trumpets of the French writers, are situated in the upper border of the broad liga- ments, and are connected with the superior angles of the uterus. They are somewhat trumpet-shaped, being much smaller at the uterine than at the free extremity, and narrower in the middle than at either end. Each tube is about four or five inches in length, and more or less flexuous in its course. The canal of the Fallopian tube is exceedingly minute, its inner extremity opens by means of the ostium uterinum into the upper angle of the cavity of the uterus, and the opposite end into the cavity of the peritoneum. The free or expanded extremity of the Fallopian tube presents a double and sometimes a triple series of small processes or fringes which sur- round the margin of the trumpet or funnel-shaped opening, the ostium abdominale. This fringe-like appendage to the end of the tube has gained for it the appellation of the fimbriated extremity ; and the remarkable manner in which this circular fringe applies itself to the surface of the ovary during sexual excitement, the additional title of morsus diaboli. One of these processes longer than the rest, or, according to Cruveilhier a distinct ligamentous cord, is attached to the distal end of the ovary, and serves to guide the tube in its seizure of that organ. The Fallopian tube is composed of three tunics, an external and loose investment derived from the peritoneum ; a middle or muscular coat consisting of circular [internal] and longitudinal [external] fibres, continuous with those of the uterus ; and an internal or lining mucous membrane which is continuous on the one hand with the mucous membrane of the uterus, and at the opposite extremity with the peritoneum. In the minute canal of the tube the mucous membrane is thrown into longitudinal folds or rugas, which indicate the adaptation of the tube to dilatation. OVARIES. The Ovaries are two oblong flattened and oval bodies of a whitish colour, situated in the posterior layer of peritoneum of the broad ligaments. They are connected to the upper angles of the uterus * Gabriel Fallopius, a nobleman of Modcna, was one of the founders of modern anatomy. He was Professor at Ferrara, then at Pisa, and afterwards succeeded Vesa- lius at Padua. His principal observations are collected in a work, " Observationes Anatomicoe," which he published in 1561. 548 ♦ EXTERNAL OEGANS. at each side by means of a rounded cord, consisting chiefly of mus- cular fibres derived from the uterus, — the ligament of the ovary. In structure the ovary is composed of a cellulo-fibrous parenchyma or stroma, traversed by blood-vessels, and enclosed in a capsule consistincr of three layers ; a vascular layer, which is situated most internally and sends processes inwards towards the interior of the oro-an; a middle or fibrous layer of considerable density and an external investment of peritoneum. In the cells of the stroma of the ovary the small vesicles or ovisacs of the future ova, the Graafian vesicles, as they have been termed, are developed. They are usu- ally about fifteen fully formed Graafian vesicles in each ovary ; but Dr. Martin Barry has shown that countless numbers of microscopic ovisacs exist in the parenchyma of the organ, and that very few out of these are perfected so as to produce ova. After conception a yellow spot, the corpus luteum, is found in one or both ovaries- The corpus luteum is a globular mass of yellow, spongy tissue, traversed by white cellular bands, and containing in its centre a small cavity, more or less obUterated, which was origi- nally occupied by the ovum. The interior of the cavity is lined by a puckered membrane, the remains of the ovisac. In recent corpora lutea the opening by which the ovum escaped from the ovisac through the capsule of the ovary is distinctly visible ; when closed, a small cicatrix may be seen upon the surface of the ovary in the situation of the opening. A similar appearance to the preceding, but of smaller size, and without a central cavity, is sometimes met with in the ovaries of the virgin, — this is ^ false coripus luteum. Vessels and Nerves. — The Arteries of the ovaries are the sper- matic. Its nerves are derived from the spermatic plexus. The Round ligaments are two muscular and fibrous cords situated between the layers of the broad ligaments, and extending from the upper angles of the uterus, and along the spermatic canals to the labia majora, in which they are lost. They are accompanied by a small artery, by several filaments of the spermatic plexus of nerves, and by a plexus of veins. The latter occasionally become varicose, and form a small tumour at the external abdominal ring which has been mistaken for inguinal hernia. The round ligaments serve to retain the uterus in its proper position in the pelvis, and during utero- gestation to draw the anterior surface of the organ against the abdominal parietes. EXTERNAL ORGANS OF GENERATION. The female organs of generation arc divided into the internal and external; the internal arc contained within the pelvis, and have been already dcscriljcd, — they arc the vagina, uterus, ovaries, and Fallo- pian tubes. The external organs are the mons Veneris, labia ma- jora, labia minora, clitoris, meatus urinarius, and the opening of the vagina. The Mons Veneris is the eminence of integument, situated upon LABIA CLITORIS. 549 the front of the os pubis. Its cellular tissue is loaded with adipose substance, and the surface covered with hairs. The Labia majora axe two large longitudinal folds of integument, consisting of fat and loose cellular tissue. They enclose an elliptical fissure, the common urino-sexual opening or vulca. The vulva re- ceives the inferior opening of the urethra and vagina, and is bounded anteriorly by the commissura superior, and posteriorly by the com- missura inferior. Stretching across the posterior commissure is a small transverse fold, the frcenulum labior'um or fourchette, which is ruptured during parturition, and immediately within this fold is a small cavity, the fossa navicular'is. The breadth of the perineum is measured from the posterior commissure to the margin of the anus, and is usually not more than an inch across. The external surface of the labia is covered with hairs ; the inner surface is smooth, and lined by mucous membrane, which contains a number of sebaceous foUicles, and is covered by a thin cuticular epithelium. The use of the labia majora is to favour the extension of the vulva during par- turition ; for, in the passage of the head of the fcetus the labia are completely unfolded and effaced. The Labia minora, or nymphcE are two smaller folds situated within the labia majora. Superiorly they are divided into two pro- cesses, which surrounds the glans clitoridis, the superior fold form- ing the prseputium clitoridis, and the inferior its frgenulum. Infe- riorly, they diminish gradually in size, and are lost on the sides of the opening of the vagina. The nymphce consist of mucous mem- brane, covered by a thin cuticular epithelium. They are provided with a number of sebaceous folhcles, and contain, in their interior, a layer of erectile tissue. The Clitoris is a small elongated organ situated in front of the os pubis, and supported by a suspensory ligament. It is formed by a small body, which is analogous to the corpus cavernosum of the penis, and, like it, arises from the ramus of the os pubis and ischium on each side, by two crura. The extremity of the clitoris is called its glans. It is composed of erectile tissue, enclosed in a dense layer of fibrous membrane, and is susceptible of erection. Like the penis, it is provided with two small muscles, the erectores clitoridis. At about an inch beneath the clitoris is the entrance of the vagina, an elliptical opening, marked by a projecting margin. The entrance to the vagina is closed in the virgin by a membrane of a semilunar form, which is stretched across the opening ; this is the hymen. Sometimes the membraiie forms a complete septum, and gives rise to great inconvenience by preventing the escape of the menstrual effusion. It is then called an impejforate hymen. The hymen must not be considered a necessary accompaniment to virginity, for its existence is very uncertain. When present it assumes a variety of appearances : it may be a membranous fringe, with a round open- ing in the centre, or a semilunar fold, leaving an opening in front ; or a transverse septum, having an opening both in front and behind ; or a vertical band with an opening at either side. 550 MAJIMARY GLAN^DS. The rupture of the hymen or its rudimentary existence, gives rise to the appearance of a fringe of papillae around the opening of the vagina : these are called cai-uncu/ce myrtiformes. "The triangular smooth surface between the clitoris and the en- trance of the vagina, which is bounded on each side by the upper portions of the nymphae, is the vestibule. At the upper angle of the vagina is an elevation formed by the projection of the upper wall of the canal, and analogous to the bulb of the urethra of the male : and immediately in front of this tubercle, and surrounded by it, is the opening of the urethra, the meatus urinarius. MAMMARY GLANDS. The MammcB are situated in the pectoral region ; and are separated from the pectoralis major muscle by a thin layer of superficial fascia. They exist in the male as well as in the female, but in a rudimentaiy state, unless excited into growth by some peculiar action, such as the loss or atrophy of the testes. Their base is somewhat elliptical, the long diameter correspond- ing with the direction of the fibres of the pectoralis major muscle. The left mamma is generally a little larger than the right. Near the centre of the convexity of each mamma is a small pro- jection of the integument, called the ?iipple, which is surrounded by an areola having a coloured tint. In the female before impregna- tion, the colour of the areola is a delicate pink ; after impregnation it assumes a brownish hue which deepens in colour as pregnancy advances; and after the birth of a child, the brownish tint continues through life. The areola is furnished with a considerable number of sehaceous follicles, which secrete a peculiar fatty substance for the protection of the delicate integument around the nipple. During suckling these follicles are very much increased in size, and have the appearance of small pimples projecting from the skin. At this period they serve by their increased secretion to defend the nipple and areola from the excoriating action of the saliva of the infant. In Structure, the mamma is a conglomerate gland, and consists of lobes, which are held together by a dense and firm cellular tissue; the lobes are composed of lobules; and the lobules, of minute cascal vesicles, the ultimate terminations of the excretory ducts. The excretory ducts (tubuli lactiferi), from ten to fifteen in number, commence by small openings at the apex of the nipple, and pass inwards, parallel with each other, towards the central part of the gland, where they form dilatations (ampulla) and give off numerous branches to ramify through the gland to their ultimate terminations in the minute lobules. The ducts and cmcal vesicles are lined throughout by a mucous membrane, which is continuous at the apex of the nipple with the integument. NERVES OF MAMM^. 551 In the nipple the excretory ducts are surrounded by a tissue ana- logous to the dartos of the scrotum, to which the power of erectility of the nipple seems due. There is no appearance of any structure resembhng erectile tissue. Vessels and Nerves. — The mammce are supplied with arteries from the thoracic branches of the axillary, from the intercostals, and from the internal mammary. The Lymphatics follow the border of the pectoralis major to the axillary glands. The Nerves are derived from the thoracic and intercostals. CHAPTER XL ANATOMY OF THE FCETUS. The medium weight of a child of the full period, at birth, is seven pounds ; and its length nineteen inches. The head is of large size, and lengthened from before backwards ; the face small. The upper extremities are greatly developed, and the thorax expanded and full. The upper part of the abdomen is large, from the great size of the liver; the lower part is small and conical. And the lower extremi- ties are very small in proportion to the rest of the body. The external genital organs are very large, and fully developed. Osseous System. — The developement of the osseous system has been treated of in the first Chapter. The ligamentous system pre- sents no peculiarity deserving of remark. Muscular System. — The muscles of the foetus at birth are large and fully formed. They are of a lighter colour than those of the adult, and of a softer texture. The transverse strise upon the fibres of animal life are not distinguishable until the sixth month of foetal life. Vascular System. — The circulating system presents several pecuUarites; Istly, In the heart; there is a communication between the two auricles by means of the foramen ovale. 2dly, In the arte- rial system ; there is a communication between the pulmonary artery and descending aorta, by means of a large trunk — the ductus arteriosus. 3dly, Also in the arterial system ; the internal iliac arteries, under the name of hypogastric and umbilical, are continued from the foetus to the placenta, to which they return the blood which has circulated in the system of the foetus. 4thly, In the venous system; there is a communication between the umbilical vein and the inferior vena cava, called the ductus venosus. F(ETAL CIRCULATION. The pure blood is brought from the placenta by the umbilical vein. The umbilical vein passes through the umbilicus and enters the liver, where it divides into several branches, which may be arranged under three heads : — Istly, two or three of which are dis- tributed to the left lobe. 2d]y, A single branch which communicates with the ])ortal vein in the transverse fissure, and supplies the right lobe. 3dly, A large branch, the ductus venosus, which passes FffiTAL CIRCULATIOX, 553 Fiff. 1G'1.« o o directly backwards and joins the inferior cava. In the inferior cava the pure blood becomes mixed with that which is return- ing from the lower extremities, and is carried through the right auricle, guided by the Eustachian valve, and through the foramen ovale into the left auricle. From the left auricle it passes into the left ventricle, and from the left ventricle into the aorta, whence it is distributed, by means of the carotid and subclavian arteries, principally to the head and upper extremities. From the head and upper extremities, the impure blood is returned by the superior vena cava to the right auricle. From the right auricle, it is propelled into the right ventricle; and from the right ventricle into the pulmonary artery. In the adult, the blood would now be circulated through the lungs, and oxygenated ; but in the foetus the lungs are solid, and almost imper- vious. Only a small quantity of the blood passes therefore into the lungs; the greater part rushes through the ductus arteriosus, into the commencement of the descend- ing aorta. * The fetal circulation. 1. The umbilical cord, consisting of the umbilical vein and two umbilical arteries ; proceeding from the placenta (2). 3. The umbilical vein dividing into three branches ; two (4, 4) to be distributed to the liver ; and one (5), the ductus venosus, which enters the inferior vena cava (6). 7. The portal vein return- ing the blood from the intestines, and uniting with the right hepatic branch. 8. The right auricle ; the course of the blood is denoted by the arrow, proceeding from 8 to 9, the left auricle. 10. The left ventricle ; the blood following the arrow to the arch of the aorta (11), to be distributed through the branches given off by the arch to the head and upper extremities. The arrows 12 and 1.3, represent the return of the blood from the head and upper extremities through the jugular and subclavian veins, to the superior vena cava (14), to the right auricle (8), and in the course of the arrow through the right ventricle (15), to the pulmonary artery (16). 17. The ductus arteriosus, which appears to be a proper continuation of the pulmonary artery, the offsets at each side are the right and left pulmonary artery cut off; these are of extremely small size as compared with the ductus arteriosus. Tiie ductus arteriosus joins the descending aorta (18, 18), which divides into the common iliacs, and these into tlic internal iliacs, which become the umbilical arteries (19), and return the blood along the umbilical cord to the placenta; while the other divisions, the external iliacs (20), are continued into the lower extremities. The arrows at the termination of these vessels mark the return of the venous blood by the veins to the inferior cava. 70 \J u 554 FCKTAL CIRCULATION. Passing along the aorta, a small quantity of the impure blood is distributed by the external iliac arteries to the lower extremities ; the greater portion enters the internal iliacs, and is carried on- wards by the side of the bladder, and upwards along the anterior wall of the abdomen, and through the umbilicus, under the name of umhUical arteries, to the placenta, to which they return the blood that has been circulated through the system of the foetus. From a careful consideration of this circulation, we shall per- ceive — 1st. That the pure blood from the placenta is distributed in considerable quantity to the liver, before entering the general circu- lation. Hence arises the abundant nutrition of that organ, and its enormous size in comparison with the other viscera. 2dly. That the right auricle is the scene of meeting of a double current ; the one coming from the inferior cava, the other from the superior, and that they must cross each other in their respective course. How this crossing is effected the theorist will wonder; not so the practical anatomist ; for a cursory examination of the foetal heart will show, 1. That the direction of entrance of the two vessels is so opposite, that they may discharge their currents through the same cavity without admixture. 2. That the inferior cava opens almost directly into the left auricle. 3. That by the aid of the Eustachian valve, the current in the inferior cava will be almost entirely excluded from the right ventricle. 3dly. That the blood which circulates through the arch of the aorta comes directly from the placenta ; and, although mixed with impure blood of the inferior cava, yet is propelled in so great abundance to the head and upper extremities, as to provide for the increased nutrition of those important parts, and prepare them, by their greater size and developement, for the functions which they are required to perform at the instant of birth. 4thly. That the blood circulating in the descending aorta is very impure, being obtained principally from the returning current in the superior cava ; a small quantity only being derived from the left ventricle. Yet is it from this impure blood that the nutrition of the lower extremities is provided. Hence we are not surprised at their insignificant developement at birth, while we admire the providence of nature, that directs the nutrient current in abundance to the organs of sense, of prehension, and of deglutition, so necessary even at the instant of birth to the safety and welfare of the crea- ture. After birth, the foramen ovale becomes gradually closed by a membranous layer, which is developed from the margins of the opening from below upwards, and completely separates the two auricles. The situation of the foramen is seen in the adult heart, upon the septum auriculorum, and is called the fossa ovalis ; the projecting margin of the opening forms the annulus ovalis. As soon as the lungs have become inflated by the first spasmodic act of inspiration, the blood of the pulmonary artery rushes through its right and loft branches into the lungs, to be returned to the left ORGANS OF SENSE — TIIYKOID GLAND. 555 auricle by the palmonary veins. Thus the pulmonary circulation is established. Then the ductus arteriosus contracts, and degene- rates into an impervious fibrous cord, serving in after life merely as a bond of union between the left pulmonary artery and the con- cavity of the arch of the aorta. The current through the umbilical cord being arrested, the umbilical arteries likewise contract and become impervious, and degenerate into the umbilical ligaments of the bladder. The Umbilical vein and ductus venosus, also deprived of their circulating current, become reduced to fibrous cords, the former forming the round ligament of the liver, and the latter a fibrous band which may be traced along the fissure for the ductus venosus to the inferior vena cava. Nervous System. — The brain is very soft, almost pulpy, and has a reddish tint throughout: the difference between the white and gray substance is not well marked. The nerves are firm and well developed. ORGANS OF SENSE. Eye. — The eyeballs are of large size and well developed at birth. The pupil is closed by a vascular membrane called the memhrana pupillaris, which disappears at about the seventh month. Some- times it remains permanently, and produces blindness. It consists of two thin membranous layers, between which the ciliary arteries are prolonged from the edge of the iris, and form arches by re- turning to it again, without anastomosing with those of the opposite side. The removal of the membrane takes place by the contraction of their loops towards the edge of the pupil. The capsule of the lens is extremely vascular. Ear. — The ear is remarkable for its early developement ; the labyrinth and ossicula auditus are ossified at an early period, and the latter are completely formed before birth. The only parts re- maining incomplete are the mastoid cells, and the meatus auditorius. The membrani tympani in the foetal head is very obhqae, occupying almost the basilar surface of the skull ; hence probably arises a de- ficient acuteness in the perception of sound. It is also extremely vascular. JVose. — The sense of smell is very imperfect in the infant, as may be inferred from the small capacity of the nasal fossss, and the non-developement of the ethmoid, sphenoid, frontal, and maxillary sinuses. THYROID GLAND. The Thyroid gland is of a large size in the foetus, and is developed by two lateral halves, which approach and become connected at 556 THYMUS GLAND. the middle line so as to constitute a single gland. It is doubtful whether it performs any especial function in fcetal life. THYMUS GLAND. The Thymus gland* consists " of a thoracic and a cervical por- tion on each side. The former is situated in the anterior mediasti- num, and the latter is placed in the neck just above the first bone of the sternum, and behind the sterno-hyoidei and sterno-thyroidei muscles." It extends upwards from the fourth rib as high as the thyroid gland, resting upon the pericardium, and separated from the arch of the aorta and great vessels by the thoracic fascia in the chest, and lying on each side of the trachea in the neck. Although described usually as a single gland, it consists actually of two lateral, almost symmetrical glands, connected with each other by cellular tissue only, and having no structural communica- tion ; they may therefore be ^'?- 1^^''' "properly called a right and left thymus gland." Between the second and third months of embryo exist- ence, the thymus is so small as to be only " just perceptible ;" and continues gradually in- creasing with the growth of the foetus until the seventh. At the eighth month it is large ; but, during the ninth, it under- goes a sudden change, assumes a greatly increased size, and at birth weighs 240 grains. After birth it continues to en- large until the expiration of the first year, when it ceases to grow, and gradually diminishes, until at puberty it has almost disappeared. The thymus is a conglomerate gland, being composed of lobules disposed in a spiral form round a central cavity. The lobules are held together by a firm cellular tissue (" reticulated"), and the entire gland is enclosed in a coarse cellular capsule. The Lobules are very numerous, and vary in size from that of the * In the description of this gland I Iiave adliered closely to the history of it given by our great authority on this subject, Sir Astlcy Cooper, in his beautiful monograph "On the Anatomy of the Tiiymus Gland," 1832, t A section of the tliymus gland at the eiglith montii, showing its anatomy. This figure, and tiio succeeding, were drawn from two of Sir Astley Cooper's beautiful pre- parations, with the kind permission of their possessor. The references were made by Sir Astlcy's own hand. 1. The cervical portions of the gland ; the independence of the two lateral glands is well marked. 2. Secretory cells seen u])on the cut surface of the section ; these are observed in all parts of the secti(jn. 3, 3. The pores or openings of the secretory cells and pouches, they are seen covering the whole internal surface of the great central cavity or reservoir. The continuity of the reservoir in the lower or thoracic portion of tlie gland, with the cervical portion, is seen in the figure. STRUCTURE OF THYMUS. 557 Fig. 166.' head of a pin to a moderate-sized pea. Each lobule contains in its interior a small cavity, or " secretory cell,''' and several of these cells open into a small " pouch" which is situated at their base, and leads to the central cavity, the " reservoir of the thymus." The Reservoir is lined in its interior by a vascular mucous mem- brane, which is raised into ridges by a layer of ligamentous bands situated beneath it. The ligamentous bands proceed in various directions, and encircle the open mouths (pores) of the secretory cells and pouches. This ligamentous layer serves to keep the lobules together, and prevent the injurious distension of the cavity. When either gland is carefully unravelled by removing the cellular capsule and vessels, and dissecting away the reticulated cellular tissue, which retains the lobules in contact, the reservoir, from being folded in a serpentine manner upon itself, admits of being drawn out into a length- ened tubular cord,-\ around which the lobules are clustered in a spiral manner, and resemble knots upon a cord, or a string of beads. The reservoir, pouches, and cells, contain a white fluid "like chyle," or "like cream, but with a small admixture of red globules." In an examination of the thymic fluid which I lately made, with a Powell microscope magnify- ing 500 times linear measure, I observed that the corpuscles were very numerous, smaller than the blood corpuscles, globular and oval in form, irregular in outline, variable in size, and pro- vided with a small central nucleus. In the human fcetus this fluid has been found by Sir Astley in too small proportion to be sub- mitted to chemical analysis. But the thymic fluid of the fcetal calf, which exists in great abundance, gave the following analytical results: — one hundred parts of the fluid contained sixteen parts of solid matter, which consisted of, Incipient fibrine, Albumen, Mucus, and muco-extractive matter, Muriate and phosphate of potass, Phosphate of soda, Phosphoric acid, a trace. J * The course and termination of the " absorbent ducts" of the thymus of the calf; from one of Sir Astley Cooper's preparations. 1. The two internal jugular veins. 2. The superior vena cava. 3. The thoracic duct, dividing into two branches, which re- unite previously to tlicir termination in the root of the left jugular vein. 4. The two thymic ducts; that on the left side opens into the thoracic duct, and that on the right into the root of the right jugular vein. t See the beautiful plates in Sir Astley Cooper's work. \ This analysis was conducted by Dr. Dowler of Richmond. 558 FCETAL LUXGS A>-D HEART. The Arteries of the thymus gland are derived from the internal mammary, and from the superior and inferior thyroid. The Veins terminate in the left vena innominata, and some small branches in the thyroid veins. The Ae?'ue5 are very minute, and are derived chiefly through the internal mammary plexus, from the superior thoracic ganglion of the sympathetic. Sir Astley Cooper has also seen a branch from the junction of the pneumogastric and sympathetic pass to the side of the gland. The Lynrphatics terminate in the general union of the lymphatic vessels at the junction of the internal jugular and subclavian veins. Sir Astley Cooper has injected them only once in the human foetus, but in the calf he finds two large lymphatic ducts, which commence in the upper extremities of the glands, and pass downwards, to ter- minate at the junction of the jugular and subclavian vein at each side. These vessels he considers the " absorbent duds of the glands ; ' thymic ducts ;' they are the carriers of the fluid from the thymus into the veins." Sir Astley Cooper concludes his anatomical description of this gland with the following interesting physiological observations : — "As the thymus secretes all the parts of the blood, viz. albumen, fibrine, and particles, is it not probable that the gland is designed to prepare a fluid well fitted for the foetal growth and nourishment from the blood of the mother, before the birth of the foetus, and, consequently, before chyle is formed from food ? — and this process continues for a short time after birth, the quantity of fluid secreted from the thymus gradually declining as that of chyhfication becomes perfectly established." FffiTAL LUNGS. The Lungs previously to the act of inspiration, are dense and solid in structure, and of a deep red colour ; their specific gravity greater than water, in which they sink to the bottom, whereas lung which has respired will float upon that fluid. The specific gravity is, however, no test of the real weight of the lung ; the respired lung being actually heavier than the foetal. Thus the weight of the foetal lung, at about the middle period of uterine life, is to the weight of the body as 1 to 60.* But, after respiration, the relative weight of the lung to the entire body as 1 to 30. FCETAL HEART. The Heart of the foetus is large in proportion to the size of the body ; it is also developed very early, representing at first a simple vessel, and undergoing various degrees of complication until it ar- rives at the compound character which it presents after birth. The * Cruvclhicr. yVnatoiuio Descriptive, vol. ii. p. 021. VISCERA OP THE AEDOME?f. 559 two ventricles form, at one period, a single cavity, which is after- wards divided into two by the septum ventriculorum. The two auricles communicate up to the moment of birth, the septum being incomplete, and leaving a large opening between them, \\iq foramen ovale (foramen of Botal.)* The Ductus arteriosus is another peculiarity of the foetus con- nected with the heart ; it is a communication between the pulmo- nary artery and the aorta. It degenerates into a fibrous cord after birth, from the double cause of a diversion in the current of the blood towards the lungs, and from the pressure of the left bronchus, caused by its distension with air. VISCERA OF THE ABDOMEIV. At an early period of uterine life, and sometimes at the period of birth, as I have twice observed, in the imperfectly developed foetus two minute fibrous threads may be seen, passing from the umbilicus to the mesentery. These are the remains of the omphalo-mesen- teric vessels. The Omplialo-mesenteric are the first developed vessels of the germ : they ramify upon the vesicula umbilicalis, or yolk-bag, and supply the newly formed alimentary canal of the embryo. From them, as from a centre, the general circulating system is produced. After the establishment of the placental circulation they cease to carry blood, and dwindle to the size of mere threads, which may be easily demonstrated in the early periods of uterine life; but are completely removed, except under peculiar circumstances, at a later period. The Stomach is of small size, and the great extremity but little developed. It is also more vertical in direction the earlier it may be examined, a position that would seem due to the enormous mag- nitude of the liver, and particularly of its left lobe. The Appendix vermiformis cceci is long and of large size, and is continued directly from the central part of the cul-de-sac of the caecum, of which it appears to be a constricted continuation. This is the character of the appendix cseci in the higher qaadrumana. The large intestines are filled with a dark green viscous secre- tion called meconiuyn ((j/^xwv, poppy), from its resemblance to the in- spissated juice of the poppy. The Pancreas is comparatively larger in the fcetus than in the adult. The Spleen is comparatively smaller in the fcetus than in the adult. * Leonard Botal, of Piedmont, was tlie first of the moderns who Cfave an account of this opcnino^, in a worlv publislied in 15G5. His description is very imperfect. The foramen was well known to Galen, 560 FCETAL LIVEK AKi) KIDNEYS. FCETAL LIVER. "The Liver is the first formed organ in the embryo. It is deve- loped from the alimentary canal, and, at about the third week, fills the whole abdomen, and is one half the weight of the entire embryo. At the fourth month the liver is of immense size in proportion to the bulk of the foetus. At birth it is of very large size and occupies the whole upper part of the abdomen. The left lobe is as large as the right, and the falciform ligament corresponds with the middle line of the body. The liver diminishes rapidly after birth, probably from the obliteration of the umbilical vein. KIDNEYS AND SUPRA-RENAL CAPSULES. The Kidneys present a lobulated appearance in the foetus, which is the permanent type amongst some animals, as in the bear, the otter, and cetacea. The Supra-renal capsules are organs which appear, from their early and considerable developement, to belong especially to the economy of the foetus. They are distinctly formed at the second month of embryonic life, and are greater in size and weight than the kidneys. At the fourth month they are equalled in bulk by the kidneys, and at birth they are about one-third less than those organs. VISCERA OF THE PELVIS. The Bladder in the foetus is long and conical, and is situated alto- gether above the upper border of the os pubis, which is as yet small and undeveloped. It is, indeed, an abdominal viscus, and is con- nected superiorly with a fibrous cord, called the urachus, of which it appears to be an expansion. The Urachus is continued upwards to the umbilicus, and becomes connected with the umbiUcal cord. In animals it is a pervious duct, and is continuous with one of the membranes of the embryo — the allantois. It has been found pervious in the human foetus, and the urine has been passed through the umbilicus. Calculous concretions have also been found in its course. The Uterus, in the early periods of embryonic existence, appears to be bifid, from the large size of the Fallopian tubes, and the small developement of the body of the organ. At the end of the fourth month the body assumes a larger bulk, and the bifid appearance is lost. The cervix uteri in the foetus is larger than the body of the organ. The Ovaries are situated, like the testicles, in the lumbar region, near to the kidneys, and descend from thence gradually into the pelvis. 561 TESTES. The Testicles in the embryo are situated in the lumbar regions, immediately in front of and somewhat below the kidneys. They have connected with them inferiorly a peculiar structure which assists in their descent, and is called the gubernaculum testis. The Gubernaculum is a soft and conical cord composed of cellular tissue containing in its cells a gelatiniform fluid. In the abdomen it lies in front of the psoas muscle, and passes along the spermatic canal which it serves to distend for the passage of the testis. It is attached by its superior and larger extremity to the lower end of the testis and epididymis, and by the inferior extremity to the bottom of the scrotum. The gubernaculum is surrounded by a thin layer of muscular fibres, the cremaster, which pass upwards upon this body to be attached to the testis. Inferiorly the muscular fibres divide into three processes which, according to Mr. Curling,* are thus attached : — " The external and broadest is connected to Pou- part's ligament in the inguinal canal ; the middle forms a lengthened band, which escapes at the external abdominal ring, and descends to the bottom of the scrotum, where it joins the dartos ; the internal passes in the direction inwards, and has a firm attachment to the OS pubis and sheath of the rectus muscle. Besides these a number of muscular fibres are reflected from the internal oblique on the front of the gubernaculum." Fig. 167.+ Fig. 168.t * See an excellent paper " On the Structure of the Gubernaculum," ifcc. by Mr. Cur- ling, Lecturer on Morbid Anatomy in the London Hospital, in the Lancet, vol. ii. 1840-41, p. 70. t A diagram illustrating the descent of the testis. 1. The testis. 2. The epididy- mis. 3,3. The peritoneum. 4. The pouch formed around the testis by the peritoneum. 5. The pubic portion of the cremaster attached to tiie lower part of the testis. 6. The portion of the cremaster attaclied to Pou part's ligament. The mode of eversion of the cremaster is shown by these lines. 7. The gubernaculum, attached to the bottom of the scrotum, and becoming shortened by the contraction of the muscular fibres which surround it. 8, 8. The cavity of the scroluin. 9. The peritoneal cavity. X In this figure the testis has completed its descent. The gubernaculum is shortened to its utmost, and the cremaster is completely everted. The pouch of peritoneum above the testis is compressed so as to form a tubular canal. 1. A dotted line marks the point at which the tunica vaginalis will terminate superiorly ; and the figure 2 its cavity.- 3. The peritoneal cavity. 71 562 DESCENT OF THE TESTICLE. The Descent of the testicle is very gradual and progressive. Between the fifth and sixth month it has reached the lower part of the psoas muscle, and during the seventh it makes its way through the spermatic canal, and descends into the scrotum. While situated in the lumbar region, the testis and gubernaculum are placed behind the peritoneum, by which they are invested upon their anterior surface and sides. As they descend, the investing peritoneum is carried downwards with the testis into the scrotum, forming a lengthened pouch which by its upper extremity opens into the cavity of the peritoneum. The upper part of this pouch being compressed by the spermatic canal is gradually obliterated, the obhteration extending downwards along the spermatic cord nearly to the testis. That portion of the peritoneum which imme- diately surrounds the testis is, by the above process, cut off from its continuity with the peritoneum, and is termed the tunica vaginalis ; and as this membrane must be obviously a shut sac, one portion of it investing the testis, and the other being reflected so as to form a loose bag around it, its two portions have received the appellations of tunica vaginalis propria, and tunica vaginalis reflexa. The descent of the testis is effected by means of the traction of the muscle of the gubernaculum (cremaster). " The fibres," writes Mr. Curling,* " proceeding from Poupart's ligament and the obliquus internus, tend to guide the gland into the inguinal canal ; those attached to the os pubis, to draw it below the abdominal ring ; and the process descending to the scrotum, to direct it to its final des- tination." During the descent " the muscle of the testis is gra- dually everted, until, when the transition is completed, it forms a muscular envelope external to the process of peritoneum, which surrounds the gland and the front of the cord." " The mass com- posing the central part of the gubernaculum, which is so soft, lax, and yielding as in every way to facilitate these changes, becomes gradually diffused, and, after the arrival of the testicle in the scrotum, contributes to form the loose cellular tissue which after- wards exists so abundantly in this part." The attachment of the gubernaculum to the bottom of the scrotum is indicated throughout life by distinct traces. * Loc. cit. INDEX. Abdomen, 490 Abdominal regions, 490 Abdominal ring, 189, 249 Abductor oculi, 149 Acetabulum, 87 Acini, 516 Adductor oculi, 149 Air-cells, 488 Albino, 446 Alcock, Dr., researches of, 398 Alimentary canal, 495 Allantois, 559 Amphi-arthrosis, 100 Ampulla, 458 AmygdalsB, 497 Andersch, notice of, 393 Annulus ovalis, 472 Antihelix, 450 Antitragus, 450 Antrum of Highmore, 46 pylori, 500 Anus, 506, 510 Aorta, abdominal, 263 arch, 262 ascending, 261 thoracic, 263 Aortic sinuses, 260 Aponeurosis, 129 Apophysis, 21 Apparatus ligamentosus colli, 96 Appendices epiploicae, 494 Appendix vermiformis, 502, 559 Aqua labyrinthi, 461 Aquseductus cochlese, 459 vestibuli, 457 Aqueduct of Sylvius, 373 Aqueous humour, 444 Arachnoid membrane, 365, 383 Arantius, notice of, 475 Arbor vitae, 376 uterina, 546 Arch, femoral, 257 palmar, superficial, 297 Arcifovm fibres, 381 Areola, 550 Arnold, Frederick, researches, 427 Arteries. General anatomy, 261 structure, 262 Arteries — continued. anastomotica femor, 317 magna, 292 aorta, 263 articularcs genti, 318 auricular anterior, 275 posterior, 274 axillary, 288 basilar, 284 brachial, 291 bronchial, 297 bulbosi, 310 calcanean, 323 carotid common, 268 external, 269 internal, 278 carpal ulnar, 296 radial, 294 cavernosi, 310 centralis retince, 281 cerebellar inferior, 284 superior, 285 cerebral, 281 cervicalis anterior, 287 posterior, 287 choroidean, 281 ciliary, 280 circumflex anterior, 290 external, 316 circumflex ilii, 312, 315 internal, 316 posterior, 289 coccygeal, 308 coeliac, 298 colic, 303 comes nervi ischiat., 309 comes phrenici, 287 communicans cerebri, 281 pedis, 322 coronaria dextra, 267 labii, 273 sinistra, 267 ventriculi, 298 corporis bulbosi, 310 cavernosi, 310 cremasteric, 312 cystic, 300 dental, 276 digitales manus, 297 564 Arteries — continued. pedis, 324 dorsales poUicis, 291 dorsalis linguGe, 272 carpi, 294 hallucis, 322 nasi, 270 pedis, 320 penis, 310 scapulse, 285 emulgent, 305 epigastric, 312 superficial, 318 ethmoidal, 280 facial, 272 femoral, 313 frontal, 280 gastric, 298 gastro-duodenalis, 300 . epiploica dextra, 300 sinistra, 301 ' gluteal, 311 inferior, 309 hsemorrhoidal ext., 309 middle, 307 superior, 305 inferior, 309, hepatic, 299 ileo-colic, 303 iliac, common, 306 external, 312 internal, 306 ilio-lumbar, 310 infra-orbital, 277 innominata, 267 intercostal, 297 anterior, 287 superior, 287 inter-osseous, 296 intestini tenuis, 304 ischiatic, 308 labial, 273 lachrymal, 279 laryngeal, 270 lateralis nasi, 273 lingual, 271 lumbar, 305 malleolar, 319 mammary internal, 287 masseteric, 273 mastoid, 273 maxillary internal, 275 mediastinal, 287, meningea, anterior, 279 inferior, 274 media, 276 parva, 277 posterior, 284 mesenteric, 301 inferior, 304 metacarpal, 296 metatarsal, 320 musculo-plircnic, 287 nasal, 280 obturator, 310 Arteries — continued. occipital, 273 oesophageal, 297 ophthalmic, 279 orbitar, 275 palatine inferior, 273 posterior, 277 palpebral, 280 pancreatica magna, 301 pancreaticas parvos, 300 pancreatico-duoden., 300 parotidean, 274 perforantes, femoral, 316 palmares, 295 plantares, 323 pericardiac, 297 perineal superficial, 309 peroneal, 322 pharyngea ascendens, 274 phrenic, 298 plantar external, 324 internal, 323 popliteal, 317 princeps cervicis, 274 pollicis, 294 profunda cervicis, 287 femoris, 315 inferior, 292, superior, 292 pterygoid, 273 pterygo-palatine, 277 pudic external, 315 internal, 309 pulmonary, 325, 475 pyloric, 300 radial, 292 radialis indicis, 295 ranine, 271 recurrens inteross., 223 radialis, 293 tibialis, 319 ulnaris, 296 renal, 305 sacra media, 305 lateralis, 311 scapular posterior, 285 sigmoid, 305, spermatic, 303 spheno-palatine, 277 spinal, 284 splenic, 300 stylo-mastoid, 274 subclavian, 281 sublingual, 272 submaxillary, 273 submental, 273 subscapular, 285 supcrficialis cervicis, 287 volsB, 293 supra-orbital, 280 renal, 305, scapular, 285 sural, 318 tarsoa, 320 temporal, 274 565 Arteries — continued. temporales profundsE, 275 thoracic, 289 thyroidea inferior, 285 superior, 270 tibialis antica, 318 postica, 322 transversalis colli, 285 faciei, 274 humeri, 285 perinei, 309 tympanic, 276, 279 ulnar, 295 umbilical, 307 uterine, 310 vaginal, 310 vasa brevia, 301 intestini tenuis, 303, vertebral, 283 vesical, 307 Vidian, 278 Arthrodia, 101 Articulations, 104 Arytenoid cartilages, 480 Arytenoid glands, 485 Auricles of the heart, 471 Auriculo-ventricular openings, 472 Barry, Dr., researches of, 548 Base of the brain, 376 Bauhini, valvula, 505 Bell, Sir C, researches of, 360 Berzelius, analysis of bone, 17 Biliary ducts, 523 Bladder, 529 Bones, chemical composition, 17 developement, 21 general anatomy, 17 structure, 18 astragalus, 94 atlas, 24, axis, 25 calcis, 94 carpus, 79 clavieula, 73 coccyx, 30 costce, 71 cuboides, 96 cuneiforme carpi, 80 externum tarsi, 96 internum, 95 medium, 96 ethmoides, 44 femur, 89 fibula, 93 frontale, 34 humerus, 75 hyoides, 70 ilium, 84 innominatum, 84 ischium, 86 lachrymale, 48 magnum, 81 malare, 48 majcillare superius, 45 Bones — continued. maxillare inferius, 51 metacarpus, 82 metatarsus, 97 nasi, 45 naviculare, 95 occipitale, 30 palati, 49 parietale 33 patella, 91 phalanges manus, 84 pedis, 98 pisiforme, 80 pubis, 86 radius, 77 sacrum, 29 scaphoid es carpi, 79 tarsi, 95 scapula, 73 semilunare, 80 sesamoidea manus, 99 pedis, 99 sphenoides, 40 sternunx, 70 tarsus, 94 temporal, 36 tibia, 91 trapezoides, 81 trapezium, 81 triquetra, 54 turbinatum inferius, 51 superius, 44 ulna, 76 unciforme, 82 unguis, 48 vertebra prominens, 26 vertebrae cervical, 24 dorsal, 26 lumbar, 27 vomer, 51 Wormiana, 54 Botal, foramen of, 559 notice of, 559 Bowman, Mr., researches of, 1 41 Brain, 362 Bronchi, 485 Bronchial cells, 487 tubes, 488 Bronchocele, 486 Brunn, Von, notice of, 508 Brunner's glands, 508 Bulb, corpus spongiosum, 535 Bulbous part of the urethra, 538 Bulbus olfactorius, 387 Bursae mucosae, 103 Caecum, 502 Calamus scriptorius, 374 Calyces, 528 Camper's ligament, 254 Canal of Fontana, 442 Petit, 445 Sylvius, 372 Canals of Havers, 14 Canthi, 446 566 INDEX. Capillaries, 264 Capitula laryngis, 481 Capsule of Glisson, 517 Capsules supra-renal, 525 Caput gallinaginis, 536 Cardia, 500 Carpus, 79 Cartilag-e, 72 Cartilages. inter-articular of the clavicle, 119 inter-articular of the jaw. 111 inter-articular of the wrist,123 semilunar, 131 Cartilaginification, 21 Caruncula lachrymalis, 448 Carunculae myrtiformes, 550 Casserian ganglion, 398 Cauda equina, 384 Cementum, 65 Centrum ovale majus, 367 minus, 367 Cerebellum, 375 Cerebro-spinal axis, 359 Cerebrum, 366 Ceruminous follicles, 451 Cervical ganglia, 430 Chambers of the eye, 444 Cheeks, 496 Chorda3 tendineaj, 473, 475 vocales, 481 Willisii, 363 Choroid membrane, 440 plexus, 369, 372, 374 Cilia, 448 Ciliary canal, 442 ligament, 441 processes, 442 Circle of Willis, 285 Circulation, adult, 473 foetal, 553 Clitoris, 549 Cochlea, 458 Cock, Mr., researches of, 396 CcEliac axis, 298 Colon, 503 Columna nasi, 435 ColumnsB carnse, 474, 476 papillares, 474 Commissures, 373, 381 great, 367 Conarium, 373 Concha, 450 Congestion of the liver, 521 Coni rcnales, 527 vasculosi, 542 Conjunctiva, 448 Cooper, Sir Astlcy, researches of, 556 Coriuin, 464 Cornea, 'J39 Cornicula laryngis, 481 Cornu Ammonis, 370 Cornua of the ventricles, 367 Corona glandis, 534 Coronary valve, 472 Corpora albicantia, 378 Arantii, 475 cavernosa, 535 Malpighiana, 527 olivaria, 381 pisiformia, 378 pyramidalia, 378 quadrigemina, 373 restiformia, 376 striata, 369 Corpus callosum, 367 cavernosum, 535 fimbriatum, 370 geniculatum, externum, 373 internum, 373 Highmorianum, 541 luteum, 548 rhomboideum, 376 spongiosum, 535 striatum, 369 Costal cartilages, 72 Cotunnius, notice of, 458 Covvper's glands, 538 Cranial nerves, 389 Cribriform fascia, 257 Cricoid cartilage, 480 Crico-thyroid membrane, 481 Crura cerebelli, 376 cerebri, 378 penis, 535 Crural canal, 300 ring, 258 Crystalline lens, 445 Cuneiform cartilages, 481 Cupola, 459 Curling, Mr., researches of, 561 Cuticle, 466 Cutis, 464 Cystic duct, 523 Dartos, 539 Davy, Dr., researches of, 283 Derbyshire neck, 486 Dermis, 464 Detrusor urinffi, 532 Dcutsch, researches of, 19 Diaphragm, 193 Diaphysis, 21 Diarthrosis, 101 Digital cavity, 370 Diverging fibres, 380 Dorsi-spinal veins, 343 Ductus ad nasum, 450 arteriosus, 559 comm. choledochus, 523 cysticus, 523 cjaculatorius, 537 hepaticus, 523 lymphaticus dexter, 356 pancreaticus, 524 prostaticus, 5.32 thoracicus, 354 vcnosus, 552 Duodenum, 50 1 Dura mater, 363, 383 INDEX. 567 Ear, 450 Ejaculatory duct, 536 Elastic tissue, 105 Enamel, 65 Enarthrosis, 101 Encephalon, 3G0 Endolymph, 461 Ensiform cartilage, 71 Epidermis, 466 Epididymis, 540 Epigastric region, 490 Epiglottic gland, 486 Epiglottis, 481 Epiglotto-hyoidean ligament, 481 Epiphysis, 21 Epithelium, 505 Erectile tissue, 535 Eustachian tube, 455 valve, 472 Eustachius, notice of, 472 Eye, 438 brows, 446 globe, 438 lashes, 447 lids, 446 Falciform process, 257 Fallopian tubes, 547 Fallopius, notice of, 547 Falx cerebelli, 364 cerebri, 364 Fascia. general anatomy of, 246 cervical, deep, 247 superficial, 247 cribriform, 257 dentata, 384 iliaca, 251 inter-columnar, 189 lata, 257 lumbar, 191 obturator, 253 palmar, 255 pelvica, 252 perineal, 253 plantar, 259 propria, 258 recto-vesical, 253 spermatica, 189 temporal, 247 thoracic, 248 transversalis, 249 Fauces, 497 Femoral arch, 249 canal, 315 hernia, 258 ring, 257 Fenestra ovalis, 454 rotunda, 454 Fibres of the heart, 479 Fibro-cartilage, 72 inter-articular of the clavicle, 119 jaw. 111 knee, 131 wrist, 123 Fimbrioe, Fallopian, 558 Fissure of Bichat, 367 Sylvius, 377 Fissures of the liver, 513 Flocculus, 376 FcEtal circulation, 255 Foetus, anatomy of, 552 P'ollicles of Liebcrkuhn, 508 Fontana, notice of, 441 Foramen caecum, 463 commune anterius, 373 posterius, 373 Munro, of, 369 ovale, 552 saphenum, 256 Soemmering, of, 443 Winslow, of, 493 Foramina Thebesii, 472 Fornix, 371 Fossa innominata, 450 navicularis urethra?, 539 pudendi, 549 ovalis, 472 scaphoides, 450 Fourchette, 549 Frasna epiglottidis, 462 Fraenum labii, 549 lingutE, 462 preputii, 534 Galea capitis, 145 Galen, 260 Gall-bladder, 522 Ganglia, cervical, 430 increase of, 378, 381 lumbar, 434 sacral, 434 semilunar, 433 structure, of, 361 thoracic, 432 Ganglion of Andersch, 393 Arnold's, 429 azygos, 434 cardiac, 432 carotid, 429 Casserian, 398 ciliary, 426 Cloquet's, 427 impar, 434 jugular, 393 lenticular, 426 Meckel's, 427 naso-palatine, 427 otic, 429 petrous, 393 plcxiform, 395 Ribes, of, 425 spheno-palatine, 427 submaxillary, 428 thyroid, 431 vertebral, 431 Gimbernat's ligament, 189 Ginglymus, 101 Gland, epiglottic, 485 lachrymal, 449 568 INDEX. Gland, epiglottic, — continued. parotid, 497 pineal, 373 pituitary, 377 prostate, 532 tliyinup, 556 tliyroid, 48G Glands, ag-grcgate, 508 ar^'tenoid, 485 Brunner's, 508 Cowper's, 538 duodena], 508 gastric, 508 inguinal, 350 Lieberkuhn's, 508 lymphatic, 347 mammary, 550 mesenteric, 354 Meibomian, 447 oesophageal, 508 Pacchionian, 363 Peyer's, 508 pharyngeal, 507 salivary, 498 solitary, 508 sublingual, 498 submaxillary, 498 tracheal, 486 GlanduloB oderifertE, 534 Pacchioni, 383 Tysoni, 534 Glans clitoridis, 549 penis, 534 Glisson, notice of, 493 Glisson's capsule, 517 Globus major epididymis, 540 minor epididymis, 540 Glomeruli, 529 Glottis, 484 Goodsir, Mr,, researches of, 65 Goitre, 486 Gomphosis, 100 Graafian vesicles, 548 Grainger, Mr., researches of, 360 Gubernaculum testis, 561 Gums, 496 Guthrie, Mr., researches of, 532 Guthrie's muscle, 197 Hair, 467 Hall, Dr. Marshall, researches, 360 Harmonia, 100 Haversian canals, 20 Heart, 469 Helicinc arteries, 536 Helico-trcma, 459 Helix, 450 Hepatic duct, 518 Hernia, congenital, 251 diaphragmatic, 188 direct, 251 encysted, 251 femoral, 259 inguinal, 250 Highmore, notice olj 541 Hilton's muscle, 484 Hilus lienis, 524 renalis, 527 Hippocampus major, 370 minor, 370 Horner's muscle, 147 Houston, Mr., researches of, 505 Humours of the eye, 444 Hyaloid membrane, 444 Hymen, 549 Hypochondriac regions, 490 Hypogastric region, 490 Ileo-CBBcal valve, 505 Ileum, 502 Iliac regions, 490 Incus, 452 Infundibula, 528 Infundibulum, 377 Inguinal region, 493 Inter-articular cartilages, of the clavicle, 119 javir. 111 wrist, 123 Inter-columnar fibres, 187 Inter-vertebral substance, 101 Intestinal canal, 501 Iris, 441 Isthmus of the fauces, 497 Iter ad infundibulum, 373 a tertio ad quartum ventriculuni, 373 Jacob's membrane, 442 Jejunum, 502 Joint, ankle, 135 elbow, 121 hip, 128 lower jaw, 110 knee, 129 shoulder; 120 wrist, 125 Jones, Mr., researches of, 461 Kidneys, 526 Kicrnan, Mr., researches of, 516 King, Mr. T. W., researches of, 474 Krause, researches of, 197 Labia majora, 549 minora, 549 Labyrinth, 460 Lachrymal canals, 449 gland, 449 papillffi, 447 puncta, 447 sac, 449 tubercles, 447 Lacteals, 354 LacunfD, 539 Lacus lachrymalis, 446 Lamina cribrosa, 439 spiralis, 459 Laryngotomy, 481 Larynx, 480 Lateral ventricles, 367 ii-- i 569 Lauth, researches of, 541 Lens, 445 Lenticular ganglion, 426 Lieberkuhn's follicles, 508 Lien succenturiatus, 525 Ligament, 103 Ligaments, 100 acromio-clavicular, 119 alar, 133 ankle, of the, 135 annular, of tiic ankle, 259 radius, 123 wrist, anterior, 125 posterior, 255 arcuatum externum, 193 internum, 193 atlo-axoid, 109 breve plantse, 138 calcaneo-astragaloid, 137 cuboid, 137 scaphoid, 137 capsular of the hip, 128 jaw, 110 rib, 112 shoulder, 120 thumb, 125 carpal, 126 carpo-metacarpal, 126 common anterior, 104 posterior, 104 conoid, 119 coracoid, 120 coraco-acromial, 120 clavicular, 119 humeral, 120 coronary, 123 of the knee, 131 costo-clavicular, 118 sternal, 113 transverse, 112 vertebral, 112 xyphoid, 114 cotyloid, 128 crico-thyroidean, 481 crucial, 131 cruciform, 108 deltoid, 135 elbow, of the, 121 epiglotto-hyoidean, 481 glenoid, 120 hip-joint, of the, 128 ilio-femoral, 128 inter-articular of ribs, 112 inter-clavicular, 118 inter-osseous, calcaneo-astragal. 137 peroneo-tibial, 134 radio ulnar, 123 inter-spinons, 106 inter-transverse, 106 inter-vertebral, 105 knee, of the, 129 lateral of the ankle, 135 elbow, 121 jaw, 110 knee, 130 phalanges, foot, 139 phalanges, hand, 127 s — continuf^i^ 3ral of the \mst. 72 Ligaments- lateral of the Mst, 125 liver, of the, 512 longum plantae, 138 lumbo-iliac,:114 lumbo-sacral, 114 metacarpo-phalangeal, 127 metatarso-phalangeal, 139 mucosum, 133 nuchcB, 173 oblique, 123 obturator, 117 occipito-atloid, 107 axoid, 108 odontoid, 108 orbicular, 123 palpebral, 447 patellcB, 130 peroneo-tibial, 134 phalanges of the foot, 133 of the hand, 127 plantar, long, 138 plantar, short, 138 posticum Winslowii, 13!) ptery go-maxillary, 110 pubic, 117 radio-ulnar, 123 rhomboid, 118 rotund um, hepatis, 512 sacro-coccygean, 116 sacro-iliac, 115 sacro-ischiatic anterior, 1 1 6 posterior, 116 stellate, 112 sterno-clavicular, 118 stylo-maxillary. 111 sub-flava, 105 sub-pubic, 117 supra-spinous, 106 suspensorium hepatis, 512 penis, 534 tarsal, 136 tarso-metatarsal, 137 teres, 128 thyro-arytenoid, 481 thyro-hyoidean, 481 tibio-fibular, 134 transverse of the acetabulum, 129 of the ankle, 135 of the atlas, 109 of the knee, 131 of the metacarpus, 126 of the metatarsus, 139 of the scapula, 120 of the semilunar cartilages, 131 trapezoid, 119 tympanum, of the, 45 i wrist, of the, 125 Zinn, of, 14S Ligamentura nuchce, 173 Limbus luteus, 443 Linea alba, 188 Lineae semi-lunares, 1 "JS transversse, 307, 374 Linguctta laminosa, 376 Lips, 496 570 Liquor Cotuiinii, 459 Morgagni, 445 Scarpa, of, 4C1 Liver, 511 Lobules of the liver, 516 Lobuli testis, 541 Lobulus auris, 450 pneumogastricus, 376 Lobus caudalus, 514 quadratus, 514 Spigelii, 514 Locus niger, 378 perforatus, 378 Lower, notice of, 472 Lumbar fascia, 191 regions, 490 Lungs, 486 Lunula, 467 Lymphatic glands and vessels, 347 axillary, 349 bronchial, 352 cardiac, 353 cervical, 348 head and neck, 348 heart, 353 iliac, 351 inguinal, 350 intestines, 354 kidney, 354 lacteals, 354 liver, 353 lovs^er extremity, 350 lungs, 351 mediastinal, 351 mesenteric, 354 pelvic viscera, 354 popliteal, 350 spleen, 353 stomach, 353 testicle, 354 trunk, 351 upper extremity, 349 viscera, 352 Lyra, 371 Malleus, 452 Mammae, 550 Manmiary gland, 550 Mastoid cells, 455 Matrix, 467 Maxillo-pharyngeal space, 160 Mayo, Mr., researches of, 398 Meatus auditorius, 451 urinarius, female, 550 male, 496 Meatuses of the nares, 437 Meckel's ganglion, 427 Meconium, 559 Mediastinum, 489 testis, 541 Medulla of bones, 21 oblongata, 378 Meibomian glands, 447 Meibomius, notice of, 447 Membrana dentata, 384 nictitans, 448 pigmenti, 441 Membrana papillaris, 555 saccilbrmis, 123 tympani, 452 Membrane, choroid, 440 hyaloid, 444 Jacob's, 443 of the ventricles, 375 Membranous urethra, 53b Meniscus, 99 Mesenteric glands, 354 Mesentery, 494 Meso-colon, 494 Mcso-rectam, 494 Metacarpus, 82 Metatarsus, 97 Miescher, researches of, 19 Mitral valves, 476 Modiolus, 458 Mons Veneris, 548 Morgagni, notice of, 445 Morsus Diaboli, 547 Motor tract, 385 Mouth, 496 Mucous membrane, structure, 508 Miiller, researches of, 19 Muscles general anatomy of, 140 developement, 143 structure, 141 abductor min. digiti, 22D abduc. min. dig. pedis, 213 indicis, 221 pollicis, 218 pedis, 242 accelerator urinse, 197 accessorius, 243 abductor brevis, 231 longus, 231 magnus, 232 min. digiti, 220 pollicis, 219 pedis, 244 anconeus, 216 anti-tragicus, 451 arytenoideus, 482 aryteno-epiglot. inf , 483 superior, 483 attollens aurem, 156 oculum, 148 attrahens aurem, 156 auricularus, 216 azygos uvulae, 169 basio-glossus, 160 biceps flexor cruris, 233 cubiti, 207 biventer cervicis, 179 brachialis anticus, 208 buccinator, 155 ccrato-glossus, 160 cervicalis ascendens, 178 circumflcxus palati, 169 coccygeus, 200 complcxus, 179 compressor nasi, 151 urethra;, 198 constrictor inferior, 166 isth. faucium, 165 mediuB, 166 571 Muscles — continued. constrictor superior, 166 vaginsB, 200 coraco-brachialis, 207 corrugator supercilii, 147 cremaster, 190 crico-arytoenoid lat., 482 posticus, 482 thyroideus, 482 crureus, 229 cucullaris, 173 deltoid, 206 depressor ang. oris, 153 labii inferioris, 153 labii sup. alseque nasi, 152 depressor oculi, 148 detrusor urina?, 542 diapiiragm, 193 digastricus, 162 erector clitoridis, 201 penis, 197 spinae, 177 extensor carpi rad. brev., 214 carpi rad. long., 214 carpi ulnaris, 216 digiti minimi, 216 digitor. brevis, 241 digitor. com,, 214 digitor. longus, 235 indicis, 217, ossis metacarpi, 217 pollicis proprius, 235 primi internodii, 217 sec. internodii, 217 flexor accessorius, 243 brevis digiti minimi, 220 digiti minimi pedis, 244 carpi radialis, 210 ulnaris, 212 digitorum brevis, 243 profundus, 212 sublimis, 211 . longus digit, pedis, 238 longus pollicis manus, 213 pedis, 238 ossis metacarpi, 218, 220 pollicis brevis, 219 pedis, 244, longus, 238 gastrocnemius, 236 gemellus inferior, 226 superior, 225 genio-hyo-glossus, 163 hyoideus, 163 gluteus maximus, 224 medius, 224 minimus, 224 gracilis, 232 helicis major, 451 minor, 451 hyo-glossus, 164 iliacus, 230 indicator, 217 infra-spinatus, 205 uiter-costales externi, 186 interni, 186 Muscles — continued. inter-ossei manus, 221 pedis, 241, 245 inter-spinales, 181 inter-transversalcs, 181 intra- costales, 186 larynx, of the, 482 latissimus dorsi, 174 laxator tympani, 454 levator anguli oris, 152 scapulae, 174 ani, 199 gland ula3 thyroid., 486 labii inferioris, 153 superioris, 152 sup. alcEq. nasi, 151 menti, 153 palati, 168 palpebrae, 148 levatores costarum, 181 lingualis, 164 longissimus dorsi, 177 longus colli, 171 lumbricales maniis, 220 pedis, 243 mallei externus, 454 internus, 454 masseter, 154 multifidus spinas, 181 mylo-hyoideus, 162 myrtiformis, 152 obliquus abdom. ext., 188 abdom. int., 189 capitis inferior, 180 superior, 180 oculi inferior, 150 obliquus superior, 149 obturator externus, 226 obturator internus, 225 occipito-frontalis, 145 omo-hyoidcus, 161 opponens digit, min., 220 pollicis, 218 orbicularis oris, 151 palpebrarum, 146 palato-glossus, 165, 169 pharyngeus, 169 palmaris brevis, 220 longus, 210 pectineus, 231 pectoralis major, 203 minor, 203 peroneus brevis, 240 longus, 240 tertius, 235 plantaris, 236 platysma myoides, 158 popliteus, 238 pronator quadratus, 213 radii teres, 210 psoas magnus, 230 parvus, 193 pterygoideus ext., 155 int., 155 pyramidalis abdom., 192 nasi, 150 pyriformis, 225 quadratus femoris, 226 572 INDEX. Muscles — continued. quadratus lumborum, 193 menti, 153 rectus abdominis, 192 capitis ant. maj., 170 min., 170 lateralis, 180 post, maj., 180 min., 180 femoris, 228 oculi externus, 149 inferior, 148 internus, 149 superior, 148 retrahens aurem, 157 rhomboideus major, 176 minor, 174 risorius Santorini, 158 sacro-lumbalis, 177 sartorius, 228 scalenus anticus, 170 posticus, 171 semi-spinalis colli, 180 dorsi, 180 semi-membranosus, 233 semi-tendinosus, 233 serratus magnus, 204 posticus inf., 176 sup., 176 soleus, 236 sphincter ani, 199 internus, 199 • spinalis dorsi, 177 splenius capitis, 176 colli, 177 stapedius, 454 sterno-hyoideus, 160 mastoideus, 158 thyroideus, 160 stylo-glossus, 165 hyoideus, 162 pharyngcus, 167 subclavius, 2U4 subcrureus, 229 subscapularis, 204 supinator brevis, 216 longus, 214 Eupra-spinalcs, 181 supra-spinatus, 205 temporal, 154 tensor palati, 1 68 tarsi, 147 tympani, 454 vagina? fem., 227 teres major, 206 minor, 205 thyro-arytcnoidcus, 482 cpiglottidcus, 483 hyoideus, 160 tibialis anticus, 234 posticus, 239 trachelo-inastoideus, 179 tragicus, 451' transversalis abdom., 191 colli, 179 transversus auriw, 451 pedis, 244 perinei, 197, 200 Muscles — continued. trapezius, 173 triangularis oris, 153 sterni, 188 triceps extens. cruris, 236 cubiti, 208 ureters, of the, 532 vastus exteriuis, 229 internus, 229 zygomaticus major, 152 minor, 152 Muscular fibre, 141 Musculi pectinati, 473 Myolemma, 141 Myopia, 446 Naboth, ovula of, 546 Nagel, Mr., researches of, 526 Nails, 467 Nares, 499 Nasal duct, 449 fossffi, 62, 437 Nasmyth, Mr., researches of, 69 Nates cerebri, 373 Nerves. general anatomy, 357 abducentes, 389 accessorius, 398 acromiales, 405 auditory, 387, 461 auricularis anterior, 403 magnus, 405 posterior, 392 buccal, 402 cardiac, 397 cardiacus inferior, 431 magnus, 431 medius, 431 minor, 431 superior, 430 cervical, 404 cervico-facial, 392 chorda tympani, 391, 428 ciliary, 399 circumflex, 413 claviculares, 405 cochlear, 461 communicans noni, 406 peronei, 421 poplitei, 422 cranial, 389 crural, 417 cutaneous ext. branch., 409 ext. femoralis, 416 int. brachialis, 409 minor, 410 post, femoralis, 421 spiralis, 412 dental anterior, 401 inferior, 402 posterior, 401 descendens noni, 390 digastric, 392 dorsal, 41 3 eighth ])!iir, 393 facial, 391 femoral, 417 fifth pair, 398 INDEX, 573 Nerves — continued. first pair, 38G fourth pair, 390 frontal, 399 gastric, 397 • genilo-crural, 417 glossopliaryngeal, 393 gluteal, 420 inferior, 421 gustatory, 402 hypo-glossal, 389 ilio-scrotal, 415 inferior maxillary, 399 infra-troehlear, 399 inguino-cutaneous, 416 intercostal, 414 intercosto-humeral, 414 inter-osseous anterior, 410 posterior, 413 iacliiaticus major, 422 minor, 421 Jacobson's, 394 lachrymal, 401 laryngeal inferior, 397 super. 396, 430 lingual, 389 lumbar, 415 lumbo-sacral, 419 masseteric, 401 maxillaris inferior, 401 superior, 399 median, 410 molles, 431 motores oculorum, 388 musculo-cutan., arm, 409 leg, 424 musculo-spiral, 412 mylo-hyoidean, 402 nasal, 399 obturator, 418 occipitalis major, 407 minor, 405 olfactory, 386 ophthalmic, 398 optic, 387 orbital, 401 palatine anterior, 427 posterior, 427 palmar, deep, 411 superficial, 411, 412 pathetici, 390 perforans Casserii, 409 perineal, 421 peroneo-cutaneous, 424 peroneal, 424 petrosus minor, 429 pharyngeal, 395, 430 phrenic, 406 plantar external, 423 internal, 423 pneumogastric, 394 popliteal, 422 portio dura, 391 mollis, 387 pterygoid, 402 pudendalis, 421 pudic internal, 421 pulmonary, 397 Nerves — continued. radial, 412 recurrent, 397 respiratory external, 408 sacral, 419 saphenous external, 422 long, 418 short, 418 second pair, 387 sixth p*r, 389 spinal, 403 spinal accessory, 397 splanchnicus major, 433 minor, 433 stylo-hyoid, 392 sub-occipital, 406 subscapular, 408 superficialis colli, 405 cordis, 430 superior maxillary, 399 supra-orbital, 397 scapular, 408 trochlear, 399 sympatheticus major, 424 minor, 393 temporal, 401 temporo-facial, 392 malar, 401 third pair, 388 thoracic long., 408 short, 408 tibialis anticus, 424 posticus, 423 trifacial, 398 trigeminus, 398 trochlearis, 390 tympanic, 394 ulnar, 411 vagus, 394 vestibular, 461 Vidian, 427 Neurilemma, 357 Nipple, 550 Nose, 435 NympliBB, 549 (Esophagus, 500, 509 Omentum, gastro-splenic, 494 great, 494 lesser, 492 Omphalo-mesenteric vessels, 559 Optic commissure, 377 thalami, 369, 372 Orbiculare os, 452 Orbits, 61 Ossicula auditus, 452 Ossification, 21 Ostium abdominale, 547 Ostium uterinum, 547 Otoconitcs, 461 Ovaries, 547 Ovula Graafiana, 549 Naboth, of, 546 Pacchionian glands, 363 Palate, 496 Palmar arch, 297 PalpebrtD, 446 574 Palpebral ligaments, 447 sinuses, 448 Pancreas, 423 Panizza, researches of, 430 Papillce of the nail, 467 of the skin, 464 of the tongue, 462 "caljciformes, 463 circumvullatDB, 462 conicae, 463 • filiformes, 463 fungifornies, 463 Parotid gland, 497 Pelvis, 86 viscera of, 529 Penis, 534 , Pericardium, 470 Perichondrium, 21 Pericranium, 21 Periosteum, 21 Peritoneum, 491 Perspiratory ducts, 467 Pes accessorius, 370 anserinus, 391 hippocampi, 370 Petit, notice of, 445 Peyer, notice of, 508 Peyer's glands, 508 Phalanges, 84 Pharynx, 499 Pia mater, 366, 383 Pigmentum nigrum, 440 Pillars ofthe palate, 497 Pineal gland, 373 Pinna, 450 Pituitary gland, 377 membrane, 437 Pleura, 489 Plexus, aortic, 434 axillary, 407 brachial, 407 cardiac, 432 carotid, 429 cavernous, 429 cervical anterior, 404 posterior, 406 choroid, 369, 374 cceliac, 433 coronary, 432 gastric, 433 hepatic, 433 hypogastric, 434 lumbar, 415 mesenteric inferior, 434 superior, 434 oesophageal, 397 pharyngeal, 395 phrenic, 433 prostatic, 338 pterygoid, 327 pulmonary, 397, 432 renal, 433 sacral, 420 solar, 433 spermatic, 434 splenic, 433 Hul)maxillary, 404 supra-renal, 433 Plexus uterine, 338 vertebral, 431 vesical, 338 Plica semilunaris, 448 PliciE longitudinales, 503 Pneumogastric lobule, 376 Polypus of the heart, 473 Pomum Adami, 480 Pons Tarini, 378 Varolii, 378 Pores, 468 Portal vein, 344, 517 Portio dura, 391 mollis, 388 Porus opticus, 439 Poupart's ligament, 188 Prepuce, 534 Presbyopia, 446 Processus e cerebello ad testes, 376 clavatus, 384 vermiformes, 376 Promontory, 454 Prostate gland, 532 Prostatic urethra, 536 Protuberantia annularis, 378 Pulmonary artery, 489 plexuses, 489 sinuses, 475 veins, 346 Puncta lachrymalia, 447 vasculosa, 367 Pupil, 441 Purliinje, corpuscules of, 21 Pylorus, 500 Pyramid, 456 Pyramids, anterior, 378 posterior, 374 of Wistar, 45 Raph6, corporis callosi, 367 Receptaculum chyli, 354 Rectum, 503 Regions, abdominal, 490 Reil, island of, 377 Respiratory nerves, 408 tract, 408 Rete mucosum, 465 testis, 542 Retina, 442 Ribcs, ganglion of, 425 Rima glottidis, 484 Ring, external abdominal, 180 femoral, 257 internal abdominal, 249 Ruga;, 504 Ruysch, notice of, 441 Sacculus laryngis, 484 proprius, 460 Salivary glands, 500 Saphenous opening, 257 veins, 338 Scala tympani, 459 vestibuli, 459 Scarf-skin, 466 Scarpa, notice of, 461 Schindylesis, 100 Schneider, notice of, 437 575 Schneiderian membrane, 437 Sclerotic coat, 438 Scrotum, 53J Searle, Mr., researches of, 477 Sebaceous glands, 467 Semicircular canals, 457 Semilunar fibro-cartilages, ]31 valves, 473 Septum auricularum, 471 crurale, 259 lucidum, 371 pectiniforme, 535 scroti, 539 Serous membrane, structure, 496 Sesamoid bones, 99 Sheath of the rectus, 192 Sigmoid valves, 475 Sinuses, structure, 331 Sinus aortic, 476 basilar, 334 cavernous, 333 circular, 333 fourth, 332 lateral, 333 longitudinal inferior, 332 superior, 331 occipital anterior, 334 posterior, 333 petrosal inferior, 333 superior, 334 pocularis, 537 prostatic, 536 pulmonary, 475 rectus or straight, 332 transverse, 334 Skeleton, 23 Skin, 464 Skull, 33 Socia parotidis, 498 Soemmering, notice of, 443 Soft palate, 499 Spermatic canal, 250 cord, 539 Spheno-maxiliary ganglion, 427 Spigel, notice of, 514 Spinal cord, 384 nerves, 403 veins, 343 Spleen, 524 Spongy part of the urethra, 538 Stapes, 452 Stenon, notice of, 463 Stenon's duct, 498 Stomach, 500 StriaB, muscular, 141 Sub-arachnoidean fluid, 365 space, 365 tissue, 365 Sublingual gland, 498 Submaxillary gland, 498 Substantia perforata, 377 Sulcus hepatis, 515 longitudinal chorda3 spinal. 384 Supercilia, 446 Superficial fascia, 246 Supra-renal capsules, 525 Suspensory ligament, liver, 513 penis, 535 Sutures, 54 Sylvius, notice of, 3G6 Sympathetic nerve, 424 Symphysis, 100 Synarthrosis, 100 Synovia, 103 Synovial membrane, 103 Tapetum, 440 Tarin, Peter, notice of, 369 Tarsal cartilages, 447 Tarsus, 94 Teeth, 63 Tendo Achillis, 236 oculi, 150 Tendon, 140 Tenia semicircularis, 369 Tarini, 369 Tentorium cerebelli, 383 Testes cerebri, 373 Testicles, 539 descent, 561 Thalami optici, 369, 372 Thebesius, notice of, 472 Theca vertebralis, 383 Thoracic duct, 354 Thorax, 469 Thymus gland, 556 Thyro-hyoid membrane, 481 Thyroid axis, 285 Thyroid cartilage, 480 gland, 498, 567 Tod, Mr., researches of, 451 Tongue, 462 Tonsils, 497 cerebelli, 376 Torcular Herophili, 332 Trachea, 485 Tractus motorius, 385 respiratorius, 390 Tragus, 450 Triangles of the neck, 162 Tricuspid valves, 473 Trigone vesicale, 532 Trochlearis, 149 Tuber cinereum, 377 Tubercula quadrigemiiia, 373 Tuberculum Loweri, 472 Tubuli lactiferi, 550 seminiferi, 541 uriniferi, 528 Tunica albuginea oculi, 439 testis, 541 erythroides, 540 nervea, 509 Ruyschiana, 441 vaginalis, 541 vasculosa testis, 541 Tympanum, 452 Tyrrell, Mr., researches of, 187 Tyson's glands, 534 Umbilical region, 490 Urachus, 530, 560 Ureter, 528 Urethra, female, 543 male, 536 Uterus, 544 576 Utriculus communis, 460 Uvea, 442 Uvula cerebelli, 376 palati, 497 vesicse, 532 Vagina, 543 Valve, arachnoid, 375 Banhini, 505 coronary, 472 Eustachian, 472 ileo-CiEca], 505 mitral, 476 pyloric, 507 rectum, of the, 507 semilunar, 474, 475 tricuspid, 473 Vieussens, of, 375 Valvules conniventes, 505 Varolius, notice of, 378 Vasa efferentia, 542 lactea, 354 lymphatica, 353 pampiniformia, 540 recta, 542 vasorum, 263 Vasculum, abcrrans, 540 Vas deferens, 539 Vkins, structure, 328 angular, 329 auricular, 330 axillary, 337 azygos major, 343 minor, 343 basilic, 336 cardiac, 344 cava inferior, 341 superior, 340 cephalic, 337 cerebellar, 331 cerebral, 331 coronary, 344 corporis striata, 369 diploe, 330 dorsalis penis, 341 dorsi-spinal, 343 emulgent, 342 facial, 329 femoral, 338 frontal, 329 Galqni, 331 gastric, 346 hepatic, 342 iliac, 340, 341 innominata, 339 intercostal superior, 343 jugular, 334 lumbar, 342 mastoid, 331 maxillary internal, 330 median, 337 basilic, 337 cephalic, 337 medulli-spinal, 344 meningo-rachidian, 343 Veins — continued. mesenteric inferior, 3 14 superior, 345 occipital, 330 ovarian, 342 parietal, 330 popliteal, 338 portal, 344 profunda femoris, 338 prostatic, 341 pulmonary, 346, 475 radial, 336 renal, 342 salvatella, 336 saphenous external, 338 internal, 339 spermatic, 342 spinal, 343 splenic, 345 subclavian, 338 temporal, 330 temporo-maxillary, 330 Thebesii, 344 thyroid, 336 ulnar, 336 uterine, 341 vertebral, 335, 343 vesical, 341 Velum interpositum, 366, 371 pendulum, palati, 497 VentE comites, 325 Galeni, 372 vorticoso3, 441 Ventricle of Arantius, 374 Ventricles of the brain, fifth, 371 fourth, 374 lateral, 367 third, 373 of the heart, 473, 475 of the larynx, 484 Vermiform process, 375 Vertebral aponeurosis, 181 column, 25 Veru montanum, 536 Vesicula3 seminales, 533 Vestibule, 456 Vestibulum vaginas, 550 Vibrissffi, 435 Vidius Vidus, notice of, 427 Vieussens, notice of, 374 Villi, 507 Vitreous humour, 444 Vulva, 549 Wharton, notice of, 463 Wharton's duct, 4!)8 WiUis, notice of, 363 Wilson's muscles, 197 Winslow, notice of, 493 Wistar, pyramids (jf, 45 Wrisberg, nerve of, 410 Zinn, notice of, 4<14 Zonula ciliaris, 444 of Zinn, 444 Zygoma, 36 T HE EN D.