l««i!0«Wft»«!tS««»««!«<8ita!^^ DiSSECnON METHODS IN. •Mfi'GQTI'ER GEO, W'AHP, PUBMSIIEl, (Cornell InroeraUg Slibraijg Stlfata. STetP ^atk BOUGHT WITH THE INCOME OF THE SAGE ENDOWMENT FUND THE GIFT OF HENRY W. SAGE 1891 arVlSOOg'^'"'™" """"""y Library ol.n,an? ^^24 031 267 994" Cornell University Library The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924031267994 sions skin, flaps dur- U V I) aj3 tf ^«-45 P. ll V fli/-» ^•s !rf g ■4H ■n •s § < 1 1 1 as a Si M g V m •d i5f ^ M ^~ t- t2 .s DISSECTION METHODS IN ANATOMY AN OUTLINE OF DISSECTION DESIGNED FOR STUDENTS OF MEDICINE AND DENTISTRY AT THE UNIVERSITY OF MICHIGAN BY ROLLO E. MCCOTTER, M.D. PROFESSOR OF ANATOMY IN THfi UNIVBHSITY OF MICHIGAN GBORGE WAHR, PUBLISHER ANN ARBORj MICH. I917 LL- COPYRIGHT, 1917 By GEORGE WAHR THE ANN ARBOR PRESS INTRODUCTION The object of this gniide is to bridge the gap between the text book and the dissecting table ; to supplement the directions to be given by the instructor in charge and to coordinate the work where large classes are involved. It has been arranged for the instruction in gross human anatomy in the University of Michigan where the required work for the degree of Doctor of Medicine can be completed during the first year of the medical course. Students working half of each day are expected to complete the dissection and systematic study of the entire body by the end of the first twenty-four weeks of the college year. For convenience the body is divided bilaterally into two regions with the arbitrary division at the level of the diaphragm. Each requires an equal amount of time. This makes twa in- terchangeable dissection periods of twelve weeks each. R. E. McC. DISSECTION OF THE UPPER PART OF THE BODY The Back. Surface Anatomy. Determine the location of the following surface markings; mastoid process, superior nuchal line, occipital protuberance, ligamentum nuchae, vertebra prominens, spinous processes of dorsal vertebrae, spinous and acromion processes of the scapula. Common Integument. Observe and study the general char- acter of the skin, hair, nails and glands. Removai, op the Skin. In cooperation with the dissectors of the lower part of the body make an incision from the external occipital protuberance to the tip of the coccyx ; a second from the twelfth dorsal spinous process lateralwards to the posterior axillary line; a third from a point about one-half inch above the external occipital protuberance lateralward to the pinna of the ear; and a fourth from the vertebra prominens to the acromion process of the scapula. Allowing the arm to hang over the edge of the table, begin in the mid line at the .upper corner of the upper flap, to reflect the skin. The separation should be made by cutting close to the under surface of the skin so as not to remove any of the underlying superficial fascia. After havv ing reflected the upper flap to a line joining the mastoid and acromion processes the inferior flap may be reflected in a similar manner. At this time the student should become familar with the gen- eral structure and distribution of the tela subcutcmea. Identify the cutaneous branches of the posterior divisions of the spinal nerves (cervical and thoracic). Which have special names? 6 UPPER PART OF BODY The remainder of the subcutaneous tissue may :be removed and the surface of the trapezius muscle cleaned as shown in figure 7I4-* Trapezius Muscle. Fig. 236. Origin, insertion and structure. Notice its three divisions. - What is meant by auscultation tri- angle f The trapezius muscle can be separated at its origin from the spinous processes of the vertebrae, the ligamentum nuchae and the superior nuchal line and 'reflected lateralward. In this operation care should be taken so as not to ipclude the rhomhoideus major and minor m,uscles which lie directly be- neath. Remove the fascia from the deep surface of the trapezius. Identify the suhtrapesial plescus of nerves, the suhtrapesial gland and demonstrate the distribution of the spinal accessory nerve-. — 3 — Rhomboideus Major and Minor Muscles. Fig. 238. Origin, insertion nerve supply and action. LevETor Scapulae. Origin, insertion and nerve supply. Sep- arate these muscles at their origin from the- vertebrae and re- flect. Observe the attachments, of the posterior supei^ior serratus and compare with the posterior inferior serratus. Separate the former from the spinous processes and reflect lateralwards. Splenius Capitis and Cervicis Muscles. -Fig. 239. After derhonstrating the striictu<-e, attachments and nerve supply of these muscles they can be separated at their origin and turned upward. In cooperation with the dissectors of the lower part of the body demonstrate the iliocostalis cervicis, the longissimus cervicis and capitis and the spinalis capitis ( ?) portions of the the saerospinalis muscle. — 4 — Cooperate with the other dissectors in the removal of the sacrospinal^. This exposes the semispinals capitis which should be studied and then entirely removed. Care should be taken sq * All references to figures refer to Sobotta McMurrich's Atlas and Text-book of Human Anatomy. UPPER PART OP BODY n as not to injure the branches of the deep cervical and occipital vessels which lie beneath. Observe the semispinalis cervicis and the suboccipital muscles. Rectus capitis posterier major; RectJus capitis posterior minor; Obliquus capitis superior; Obeiquus capitis inferior. Identify origin, insertion, nerve supply and action of these muscles. Demonstrate the suboccipital triangle and structures in relation to it, as shown in figure 696. The suboccipital muscles may be removed and the vertebrae cleaned preparatory to opening the vertebral 'canal. The chief characteristics of the vertebrae and the formation of the ver- tebral canal should be studied. Special study should be made of the osteology of the cervical and thoracic vertebrae. With chisels and bone cutters open the vertebral canal by cutting through the pedicles on each side and removing the arches of the vertebrae. .The student should be careful not to cut too deeply at first, in as much as the spinal nerves might be severed as they course in the intervertebral foramina. Notice the venous plexus surrounding the dura. — 6 — Joints. Read classification of joints. Prepare a list of and describe all joints in relation to upper half of vertebral column. Ligamentum flavum? ; In cooperation with the other dissectors trace the dural sheath outward over the ganglia and nerves, cutting away bone when jiecessary, and notice its direct continuation as a sheath for the nerve trunks of the cervical and thoracic nerves. Trace the dura to the foramen magnum. Fig. 608-610: UPPER PAM OF BODY Spinai, Meninges. Dura Mater. In cooperation with the other dissectors the dural sheath may be incised in the dorsal midline. Reflect lateralward and fasten with pins. Care should be taken so as not to include the arachnoid membrane which lies close to the deep surface of the dura. Subdural space? Arachnoid Membrane. After having observed the chief char- acteristics of arachnoid it may be incised in the dorsal mid line. Compare subarachnoid and subdural spaces.. PiA Mater. Observe pia mater and contained vessels. Blood supply of spinal cord? Demonstrate the number, structure and attachments of den- tate ligamients. Observe the cord segments, the levels in the vertebral canal and the root filaments arising from each. Com- pare lengths of spinal nerve roots. Trace root filaments to points of exit from 'dura. Do the anterior and posterior nerve roots pass through a common opening? _ 8 — Spinai, Cord. In common with the other dissectors study the form, length, enlargements and sulci of the spinal cord. Cut transverse sections ' J4 cm. thick from the upper and lower cervical and mid dorsal regions arid study under water with a binocular microscope. Observe the gray and white substance, the subdivisions of each and the characteristic form of the former at the diflferent levels. Compare these specimens with stained sections furnished by the laboratory and to figures in text-book or atlas (617 and 618). Note the nerve roots (anterior and posterior) and their con- nection with the cord. Trace them peripherally and determine their mode of exit from the vertebral canal. What is meant by spinal root ganglion? Note the formation of nerve trunks. Identify anterior and posterior divisions. UPPER PART OF BODY 9 — Demonstrate the origin, insertion and nerve supply of posterior and middle scalene mmscles after which these muscles may be removed. The articular processes of the cervical vertebrae may be ctit away to show the formation of the cervical and brachial plexuses. In order to expose the first thoracic nerve and its connection with the brachial plexus a portion of the first rib may be removed. Expose the vertebral artery, being careful not to destroy the inferior cervical ganglion which usually lies close to it near its origin from subclavian. — '10 Scalp (Posterior half). Fig. 714. Make an incision in the midline from below extending upward to the vertex of head. Begin at the lower medial corner and reflect skin flat upward. Identify the different layers and their structure. In the. sub- cutaneous layer find branches of following arteries (i) occipital; (2) posterior auricular; (3) superficial temporal. Identify the following nerves: (i) great occipital; (2) small occipital; (3) posterior auricular (branch of what nerve?). All fat and fascia of second layer should now be removed so as to expose posterior half of epicranius muscle. OcciPiTAWs Muscle. Origin, insertion and nerve supply. Notice character and attachments of galea aponeurotica. Transverse nmchal muscle? Observe character of fourth and fifth layers. ^-11 — > While the other dissectors are completing the gluteal region the dissector of the upper part of the body may remove the skull cap (calvarium). It will be found in most cases that this has already been done and the brain removed before the body was brought to the dissecting room. Structure of Cranium. Notice markings on inside of skull cap: (i) blood vessels; (2) granular fossae; (3) grooves for venous sinus. JO UPPER PART OF. BODY With a saw make several sections through skull cap to study- its structure and the distribution of the diploe. Diploic veins? Diploic arteries? Bmissary veins? Notice the anatomical con- ditions that tend to minimize blows upon the skull. Dura Mater.- Structure and distribution. Study shape and at-tachments of falAr cerebri, tentorium cerehelli, falx cerehelli and diaphragma sellae. Study all the meningeal arteries. What is their function? How is the venous blood returned? Nerve supply? . — 12 —^ Sinuses of Dura Mater. Fig. 589. Note their origin, course, termination and tributaries. Observe regions drained by them. I. Superior sagittal. 2. Inferior sagittal. 3- Rectus. 4- Transverse. s. Superior petrosal. 6. Inferior petrosal. 7- Cavernous. 8. Sphenoparietal. 9- Occipital. 10. Intercavernous. II. Basilar plexus. In tracing their connections it will be found helpful to split them open when they can be easily recognized by the dark blood slain. Preserve cavernous sinus, intact for' study later. The superior sagittal sinus, however, should be completely opened and its structure carefully noted. Notice arachnoid granulations. 'Note cerebral veins terminating in the sinuses. Notice arrange- ment of dura at foramen magnum. Identify all structures pass- ing through foramen. Trace spinal accessory nerve from its origin from the upper cervical neural segments of spinal cord upwaird to its' exit from the cranium. Review all the vessels by which arterial blood is supplied to structures within the cranium and the channels by which the UPPER PART Ot BODY II venous blood is again returned. It is recommended at this time to stvidy the relation of the different parts of the brain to the three cranial fossae in connection with a study of the base of the skull. Specimens illustrating the blood supply of the brain will be furnished by the laboratory and should be examined. — 13 — This cotnptetes the dissection of the back and the stjident pro- ceeds with the dissection from the ventral surface of the body. Before turning the subject on its back, however, all, attached muscles and skin flaps should be replaced and held in position by sutures. ' - ScAi,p (anterior half). Surface marking. Identify the fol- lowing : (i) frontal eminences; (2) supraciliary arches; (3) glabella; (4) nasion; (5) zygoma; (6) supraorbital notch; (7) lambda; (8) bregma; (9) fontanelles (?). Make an incision through the skin beginning at the vertex of the head and extending along the mid line to the glabella. Begin at the upper corner and separate the skin from the under- lying subcutaneous tissue and reflect downward to the level of the superior orbital margins. Compare the structure of the subcutaneous tissue of the scalp with that found in other regions. Identify in the subcutaneous .layer the following nerves and blood vessels : ' Nerves : (1) frontal; (2) supraorbital; (3) temporal branches of facial; (4) auriculotemporal. 12 UPPER- PART OP BODY Arteries : (1) branches of superficial temporal; (2) frontal; (3) supraorbital. Veins ? The supraorbital nerve is best found by separating the fibers of the orbicularis oculi muscle 'over the supraorbital notch, which can usually be localized with the finger, and picking up the nerve as it emerges from the bone. It can then be traced to its distribution by cutting furrows through the frontalis muscle. — 14.— After these structures are identified, remove the subcutaneous tissue and expose : Bpicraneus Muscle; (a) fontalis : study its origin, insertion and relation to skin of eyebrow and the ' orbicularis oculi and procerus muscles; (b) gala aponeurotica ; study its attachments and relation to temporal fascia and ear muscles; (c) occipitalis : Has already been studied. Note the extrinsic muscles of the, auricle and their nerve supply. After the completion of the epicraneus muscle its aponeurosis may be reflected by a median incision. Observe : (a) character of subaponeurotic space; (b) pericranium (periosteum) ; (c) temporal fascia. Summarize the blood and nerve supply of the scalp. — 15 — The Region of • the Face. Surface markings : symphysis, body and angle of mandible and zygoma. Reflect the skin from above downward to the level of the lower border- of mandible. The following incisions may be made to facilitate its removal: (i) parallel with the orbital margin; (2) encircling the base of pinna; UPPER PART OF. BODY 1 3 (3) encircling naris; (4) encircling oral orifice; (5) an incision in mid line downward to symphysis menti. Care should be taken so as not to include any of the sub- cutaneous tissue in the removal of the skin flap. Parotid Gi,and. Fig. 542. Notice character and attachments of parotid fascia. Remove fascia from the superficial surface of the gland and outline, very carefully, the anterior margin. Identify the accessory parotid gland and parotid duct. The deep portions of the gland should be observed and studied along with its removal in the dissection of the structures passing through it. Faciai, Nerve. Fig. 692. Observe branches of the facial nerve radiating from beneath the anterior border of parotid gland. Lift up its anterior margin and follow these branches' back- ward, separating the superficial from the deeper portion of the gland where necessary. The superficial portion of the gland may now be carefully removed. This exposes the common trunk of the facial nerve with its terminal division and anastomosing loops (pes anserinus). Identify and trace all the terminal branches of the fascial nerve to the muscles they supply. Note communications with trigeminal nerve. — 16 — Notice arteries and veins of the face. The veins may be removed as soon as identified. Facial Group of Muscles. Fig. 260. These are cleaned and their attachments studied. Orbicularis oculi: (a) orbital; (b) palpebral; (c) lachrmal (?). Frontalis (and procerus). Corrugator. 14 UPPER PART OF' BODY Quadratus labii superioris — ^three heads; (a) zygomatic; (b) infraorbital;. (c) angular. Zygomatic. Caninus. Triangularis. Quadratus labii inferioris. Mentalis. Buccinator. Nasalis : (a) transverse; (b) alar. Auricular muscles : (a) intrinsic ( ?) ; (b) extrinsic; (i) posterior; (2) superior; (3) anterior. Platysma (and Risorius). What other muscles belong to this group? — 17 — The quadratus labii superior should be divided to expose the infraorbital nerve, the three sets of branches are to be identified. In a similar manner divide the triangularis and expose the mental nerve and artery. Demonstrate all of the terminal branches of the trigeminal nerve that appear on the face. Fig. 542. Func- tion? — 18 — The dissector now returns to the interior of the skull and reviews the cranial nerves and their exit from the skull and relation to the dura. Fig. 679. By carefully stripping up the dura of the middle cranial fossa, there is exposed the trigeminal nerve and the cavernous sinus. Avoid injury to the third, fourth and sixth nerves. upper part op body 1 5 Trigeminai, Nerve. 1. Root: (a) portio major (sensory); (b) portio minor (mO'tor). 2. Semilunar ganglion. Structure and function. 3. Divisions: (a) ophthalmic; (b) maxillary; (c) mandibular. Compare formation of the trigeminal nerve to a spinal nerve. To expose to advantage the motor root it might be advisable to separate the semilunar ganglion from the remainder of the sinus vyall and reflect antsrolaterally into the middle fossa. The motor root may then be seen coursing over the deep surface of the ganglion to the foramen ovale. Cavernous Sinus. On stripping off the dura the interior of the sinus is revealed by darkly stained walls due to the contained blood. Notice size, shape and structure of the sinus. Also its tributaries and termination. What structures pass through the .sinus ? Internal carotid artery. Third, fourth, sixth and ophthalmic division of fifth nerve. Carotid sympathetic plexus. — 19 — These nerves are now traced forward into the orbit. Review bones forming walls of orbit. With chisel or bone cutters re- move thin bony roof of the orbit and lesser wing of the sphenoid. Fig. 682. Reflect orbital periosteum and find frontal nerve and branches v/hich should now be traced from the first division of the fifth to its distribution in the scalp. Note lachrymal nerve. Notice trochlear nerve entering the upper margin of the superior oblique muscle. Dissect it free from surrounding structures backward to its proximal extremity and reflect medially. Incise the frontal nerve and reflect ends. 1 6 UPPER PART OF BODY Remove fascia from the surfaces of levator palpehrae su- perioris and rectus superior muscles. Demonstrate their origins and insertions after which they are divided and ends reflected. Notice the nerve supply of each. Trace these branches to third nerve. With these structures divided the orbital fat can be easily removed without stretching nerves and muscles and thereby destroying relations. Observe the relation of the structures in the superior orbital fissue. After identifying the ophthalmic veins and tributaries they may be removed. Notice the naso- ciliary nerve as it crosses the optic nerve. Trace it through the orbit and determine' its branches. Fig. 546. Follow the course of the nerve backward through the superior orbital fissure to the ophthamic division of the fifth nerve. At the same time find the ciliary and ganglionic branches. Follow the ganglionic branch forward to the ciliary ganglion. Ciliary Ganglion. Rtfots : (a) motor (inferior division of oculomotor) ; (b) sensory (nasociliary) ; sympathetic (carotid plexus). Branches; short ciliary nerves. — 20 — Notice origin of muscles from the common ring tendon (liga- m.ent of Zinn). Find the insertion of the superior oblique muscle and demonstrate its action. Fig. 756. Incise the common ring tendon between origins of lavator palpehrae superioris and superior oblique and reflect ends so that the optic nerve may be raised. Identify the origin course and branches of the ophthalmic artery. The lower division of the oculomotor is now exposed and its branches traced forward. Observe the abducens nerve entering the medial surface of lateral rectus muscle. Follow this nerve dorsalward throughout its entire course. Relations ? Notice sheath of optic nerve, and fascia of bulb (Tenon's Cap- sule). Study origin course and function of optic nerve. Review- all nerves of the orbit and their branches. UPPER PART OB BODY 1 7 Before removing the eyeball the lachrymal apparatus and eye- lids should be examined. At this time, however, the eyeball should be injected with a hyprodermic syringe with water until tense. Introduce the needle near the equator and obliquely to insure closure of the puncture. EyEWds. Fig. 766-768. Examine eye and eyelids from in front and compare with living eye. Determine distribution and function of conjunctiva. Note character of cornea, pupil and iris. Note semilunar fold of conjunctiva, lachrymal xaruncle , lachrymal papilla, lachrymal pore, and lachrymal pool. Note attachment of eyelashes and tarsal {Meibomian) glands. Remove the skin from eyelids. Observe character of sub- cutaneous tissue and compare with that found in other regions of the body. Clean palpebral portion of orbicularis oculi and study character and action of the muscle. Reflect, orbicularis oculi toward median line and expose tarsofascial layer: (Fig. 770.) (a) tarsal plates; (b) orbital septum. Note insertion of levator palpebrae superioris and the medial palpebral ligament. Study cross-section of eyelid showing layers from skin to conjunctiva. — 21 — Lachrimai, Apparatus. Figs. 764, 771. Examine position, shape and structure of lacrimal gland. Draw gland forward and demonstrate the ducts of lacrimal gland passing to conjunctiva. They appear as small thin walled veins passing through the deep interlobular fascia of the gland. Study the course of the lacrimal secretion. Introduce a fine probe or wire into the lachrimai pore and through lachrimai canal to lachrimai sac. IJsing it as a guide dissect out the lachrimai canals to their entrance into sac. Nasolachrimal duct? The orbital septum together with the palpebral conjunctiva may be separated from the orbital margin and reflected medially Demonstrate the lachrimai portion of the orbicularis oculi muscle (Horner's muscle). Raise the eyeball and determine origin, insertion, nerve supply and action of obliquus inferior. 1 8 UPPER PART OF. BODY. Review the orbital muscles and summarize the nerve supply. Bisect the remaining orbital muscles and remove eyeball to- gether with the fascia of the bulb. Examine bulbar fascia and interfasciat space and determine the relation of the tendons of the orbital muscles to them. Remove bulbar fascia and examine surface of eyeball : (a) muscular attachments; (b) optic nerve entrance; (c) arteries, nerves and veins. Eyeball. Bisect right eye through equator and left eye through the sagittal plane and study under water. Study struc- ture of different tunics. Carefully remove vitreous body and study fundus of eye. Study structure and attachments of lens and iris. Structure and function of ciliary body? Examine vascular tunic, and identify ciliary arteries and vorticose veins. Central artery and vein of retina? Ora serrata? Nerve supply of muscles in ciliary body and iris? The dissection of the deep parts of the face is facilitated, by bisecting the head. This cannot be done, advantageously, how- ever, until after the neck and thorax have been completed. The head should be wrapped in muslin and kept moist while the dissectors continue the dissection of the neck region. Neck (anterior part). Note the surface anatomy of the neck, iiicluding 1;he sternomastoid muscle, hyoid bone, thyroid and circoid cartilages and trachea. Make the following incisions: (i) from symphysis of mandible downwards in midline of neck and sternum to xyphoid cartilage ; (2) from upper extremity of sternum upward along anterior border of sternocleidomastoid muscle to mastoid process ; (3) from upper extremity of sternum lateralward along the clavicle to acromion process ; (4) in common with the dissectors of the abdomen from the xyphosternal junction "laterally to posterior axillary line. The flaps thus outlined are reflected, being care- ful not to include the subjacent fascia and muscle. UPl'EK PART OP BODY ig Platsyma Myoides Muscle. Figs. 267 and 697. Clean sur- faces of this muscle up over the border of the mandible and downward onto the thorax. Determine its relation to superficial fascia and skin. Note the superficial nerves piercing the muscle in the. region of the clavicle. After its outlines have been de- termined the muscle should be bisected transversely and the halves carefully reflected upward and downward, without in- juring the superficial nerves and external and anterior jugular veins, which lie directly under it. Notice facial nerve supply. — 23 — Superficial Cervical Nerves. (Cutaneous branches of cerv- ical plexus,) Fig. 698. Ascending — I. lesser occipital; 2. great auricular. Transverse — i. Cervical cutaneous. Descending — I. Supraclavicular: (a) anterior; (b) middle; (c) posterior. Determine connections of external and anterior jugular veins. Note variations in size and position in different bodies. Read about the deep fascia of the neck, noting its character- istics as the dissection progresses. Sternocleidomastoid Muscle. Clean the superficial surface of this muscle over its whole extent, being careful to preserve the nerves. Determine its insertion and double origin. Action' — 24 — Determine boundries of the anterior and posterior triangles of the neck and their contents. Clean and identify the muscles forming the floor of the an- terior triangle without disturbing them. Posterior Cervical Triangle. Remove the deep fascia bridg- ing in the space between the sternocleidomastoid and trapezius 20 UPPgR PART OF BODY muscles and expose the contained structures. The remainder of this dissection may be combined with that described under Sec- tion 25. As soon as the spinal accessory nerve is found, it is desirable to complete Section 25 and after that to come back and finish Section 24. Boundries : (1) sternocleidomastoid; (2) trapezius; (3) clavicle. Contents : (i) spinal accessory nerve; (2) muscular branches of cervical plexus; (3) upper border of brachial plexus; (4) posterior branches of supraclavicular nerves ; (5) superficial cervical artery; (6) transverse scapular artery; (7) external jugular vein; (8) transverse cervical vein. Floor : (1) splenius capitis; (2) levator scapulae; (3) anterior middle and posterior scalene muscles ; (4) omohyoid. — 25 — After identifying the spinal accessory nerve it should be fol- lowed distally to where it disappears under the border of the trapezius. Then it should be followed centrally through the sternocleidomastoid muscle, cutting away the segment of muscle overlying it. Note branches given to the muscle and the anastomosis with the second cervical nerve. The tipper third of the muscle may then be removed .by dis- secting it free from the mastoid process. This exposes the origin of the lesser occipital nerve. The lower two-thirds of the sternocleidomastoid is then re- flected downwards, after dissecting free the nerves supplying it. This exposes the cervical plexus and the carotid sheath which are now to be dissected. Fig. 700. UPPER PART 0? BODY 21 Cervicai, Plexus (continued). The superficial branches of the cervical plexus and many of the muscular branches have been dissected. Examine very carefully the anterolateral wall' of the carotid sheath and find the ansa hypqglossi with its anterior and posterior limbs. Follow the anterior limb, descendens hypoglossi, proximally and observe its relation to hypoglossal nerve. In a similar manner follow the posterior limb, and determine the origin. Trace the branches of the ansa to the hyoid muscles. The branch to the posterior belly of the omohyoid usually en- ters near the central tendon. Note the relation of the central tendon to the cervical fascia. Identify the origin of the phrenic nerve. It can be identified readily where it lies on the anterior surface of anterior scalene muscle. Identify the anterior divisions of the cervical nerves that take part in the formation of the cervical plexus. Review cervical plexus and make a schematic drawing illustrating its formation and branches. _ 26 — Carotid Sheath. Study its structure and contents. In re- moving the fascia that forms the carotid sheath the student should observe carefully for the small vagus and sympathetic cardiac nerves which usually lie medial and posterior, but may be found well anterior, especially in the lower portion of the neck. Read about the lym-phatics of the neck. By picking up the deep cervical glands, vessels will be found leading from them to the right and left lymphatic ducts. Jugular lymphatic trunk? Thoracic Duct. Read about its course and identify the point and manner of its junction with the blood system. Variations? This communication should be carefully preserved for study later. The other lymphatics of the neck need not be preserved. In order to more completely expose the deeper parts of the neck the internal jugular vein may be divided and ends reflected after learning its formation course and tributaries. Also divide the posterior belly of om,ohyoid muscle and the sternohyoid and sternothyroid muscles close to the sternal attachment that their nerve supply may be preserved, 22 . UPPER PART 01? BODY — 27 — Subclavian Artery. Figs. 551, SS2. Note the manner in which it emerges from the thorax, its relation to the pleural dome, its relation to the scalene muscles and the first rib. Branches? Trace branches of thyrocervical trunk. Identify vertebral, internal mammary and costocervical arteries. Identify cervical symphthetic cord. Thyroie Gland. Note its shape, structure, blood supply, posi- tion and attachments. Compare with those seen on other bodies. Pyramidal lobe and its significance? Accessory thyroids f Parathyroids. Number, size, shape, position, structure and function. Identify the anterior divisions of the cervical nerves that take part in the formation of the brachial plexus. — 28 — The superficial fascia of the thorax is now studied. The supraclavicular nerves have already been recognized and dis- sected out. In addition to these find the anterior and lateral cutaneous branches of the intercostal nerves and the perforating branches of the internal mammary artery. Mammary Gland. Study its position, attachments and struc- ture. Notice particularly its blood and lymph supply. Notice character of nipple and surrounding areola. In female subjects dissect out the lactiferous ducts, and gland lobules. If gland is not well developed simply make a median section of gland through nipple. Supernumerary glands? Those working on male subjects should visit a table having a female subject. The superficial and deep fuscia are now removed and the pec- tnralis major cleaned over its whole extent. Pectoralis Major Muscle. Identify its abdominal, sternal and clavicular heads. Notice character and direction of fibers, and manner of insertion. Cephalic Vein? UPPER PART OF BODY 39 23 AxinA. Remove skin from axillary fossa. Notice area of sudoriferous glands on the deep surface of skin. Examine axillary fascia. Find lateral cutaneous branches of first and second intercostal nerves. Read about axillary lymph glands. Remove fat, fascia and lumph glands and thereby display the boundries of axilla. Contents of axilla? — 30 — Pectoralis major may be divided at its origin and turned out- ward. The nerves supplying it on its deep surface are to be noted and then dissected free from the muscles. What is meant by costocoracoid membrane and what structures traverse it? Pectoralis Minor Muscle. Clean the surface of this muscle and study origin, insertion, action and nerve supply. The costo- coracoid membrane may be removed and expose the subclavious muscle. Study its origin, insertion, nerve supply and action. In order to expose the brachial plexus more completely the clavicle must be raised. Disarticulate the sternoclavicular joint, noticing its character, accessory ligaments and interarticular fibrocartilage. The clavicle is then raised outward, and at the same time the subclavius muscle is separated from its under- surface, care being taken to preserve its nerve supply. Bisect the subclavius and pectoralis minor muscles. — 31 — Observe the axillary vein. Identify all its tributaries after which they may be reinoved to simplify the dissection. Axillary Artery. Determine relations and branqhes. Begin with the spinal nerves and dissect and study the formation and branches of the brachial plexus as follows: (i) anterior divisions of spinal nerves; (2) formation of trunks ; 24 UPPER PART OF BODY (3) division of trunks; (4) formation of cords; (5) branches of cords. Make a schematic drawing of the formation and branches of brachial plexus. — 32 — Clean surfaces of and study: (i) serratus anterior; (2) latissimus dorsi; (3) subscapularis ; (4) teres major. Separate the serratus anterior from its origin on the ribs. Make a list of all the muscles attaching the shoulder girdle to the trunk giving their origin, insertion, nerve supply and action. The arm with attached muscles can now be removed by disecting transversely the spinal cord above and below the origin of the brachial plexus and then by a mid sagittal section of the same portion of the cord. The arms should be moistened and then well wrapped with attached skin flaps and muslin and laid away for future study. — 33 — Examine sternum, ribs and costal cartilages. Make careful study of the osteology of all bones entering into formation of thoracic walls. Intercostai, Spaces. Select a wide intercostal space, prefer- ably the s or 6, and clean surface of external intercostal muscle and ligament. Adjacent to the above remove carefully the ex- ternal intercostal muscle and ligament and clean surface of in- ternal intercostal muscle and ligatnent. Compare these muscles with one another. Compare the direction of the fibers in each case with the abdominal muscles. The remainder of the inter- costal muscles, with exception of lower two or three, may be removed and the arteries, veins and nerves dissected and pre- served. Demonstrate a typical thoracic nerve and all its branches. Review intercostal arteries and veins. The intercostal structures UPPER PART OS BODY 25 are now removed or reflected to expose the parietal layer of the pleura. The upper ten ribs are then cut at the angles and loosened from the pleura by using the finger or a blunt instru- ment. The lower two or three ribs and the lower costal margin being left to preserve the attachment of the diaphragm. It is now possible by cutting the sternum transversely at the sixth chbndrosternal junction to remove the sternum with the attached costal cartilages and ribs. In raising the sternum be careful to preserve the internal mammary artery. On the under surface of sternum notice transversus thoracis muscle. It should be laid aside for use later in determining the topographical relations of the thoracic viscera. — 34 — Pi,EURA. Expose the anterior reflection of the pleura by removing excess fascia and fat and compare right and left sides. Incise the parietal pleura along the mid axillary line and ex- pose the pleural sac. Determine the distribution and structure. Notice particularly lines of pleural reflection. Compare with text-book and atlas and determine their relation to sternum and ribs. Do the pleural sacs open into one another? Pulmonary ligament? Function of pleura? In many bodies the pleura will be found thickened and adherent, owing to previous inflammation (pleurisy) ; in such cases the dissectors should study the pleura on other tables. In cases where the pleural sac contains blood and exudate it should be thoroughly cleaned out with sponge. Pleura. A. Visceral (pulmonary). B. Parietal; (i) costal; (2) diaphragmatic; (3) mediastinal. — 35 — Anterior Mediastinum. What is meant by mediastinum and what determines its subdivisions? Examine boundries and con- tents of anterior mediastinum. J 6 UPPER PART OF BODY Superior Mediastinum. Boundries and contents? Examine thymus gland after which it may be reflected or removed en- tirely to expose the great vessels. Examine the innominate veins. Determine their origin, course and termination. Left superior vena cava? Determine length, position and tributaries of the superior vena cava. Make a schematic drawing illustrat- ing the superior vena caval system of veins. Identify phrenic nerve and follow it to the diaphragm. — 36 — Expose the vagus and sympathetic cardiac nerves ; the vagus and recurrent nerves; ansa subclavia. Demonstrate the arch of aorta and large vessels arising from it. Ligamentum Ductus arteriosus? Trachea. ' — 37 — Middle Mediastinum: Pericardium. Notice relation of pleura and pericardium. Strip pleura loose and expose the form of the pericardial sac. Open pericardium on a curved line extending from ascending aorta to apex of heart. Reflect pericardium and expose pericardial sac. Demonstrate : (a) fibrous pericardium; (b) serous pericardium; (i) parietal; (2) visceral; (c) transverse sinus; (d) oblique sinu§; (e) ligament of left superior vena cava. Heart. Determine surfaces and borders of the heart and their relation to replaced sternum. Notice relation of aorta to sternum. Note atria and ventricles. Demonstrate the sulcL Re- move visceral pericardium and demonstrate blood supply of heart-wall. Identify right and left coronary arteries and branches, and the coronary system of veins; the coronary sinus UPPEK PART OF BODY 27 and the great, middle and small cardiac veins and the oblique vein of the left atrium. Observe anterior cardiac veins terminat- ing in right atrium. — 38 — Open the heart in situ by making incisions with scissors or knife as indicated in the accompanying figure: The incisions indicated in this figure are planned so as to expose tlie whole interior of the heart without disturbing its connections or relations ; and so that by replacing the flaps the outer form may be again restored. In A the heart is viewed from the right and in front ; in B the posterior and inferior surfaces are shown, as seen when the apex is pulled upward and to the right. (After Streeter.) On some tables it is desirable to remove the heart unopened, together with attached vessels, for the study of its surface anatomy. Study the valves, orifices and accessory structures in the different chambers, noting the mechanics of blood propulsion. Foetal circulation? Make a list of all the structures found in the adult, known as ligaments, folds, etc., that represent obliterated portions of the path in foetal circulation. Note the structure of the cardiac walls, and the differences in the muscula- ture of the atria and ventricles. — 39 — Examine the blood vessels connecting the heart and lung. Study their relation to bronchi. Bronchial arteries? Notice re- lation of vagus nerve to root of lung. The structures forming the root of the lung may now be incised and the lung removed. 28 UPPER PART OF BODY Lung. Identify surface, borders and impressions due to con- tact with other structures. Note character of lobes and fissures. Study foot of the lung, identifying the component structures and their relations. In soft specimens these structures may be dis- sected downward into substance of lung. Note air cells. Note character of bronchial tree, comparing with illustrations in text books. Pulmonary circulation? Blood supply of lung tissue. After completing the, study of the heart and lungs the dis- sector should keep them moist by wrapping in muslin for subse- quent review. — 40 — Observe the formation and distribution of the cardiac and pulmonary plexuses of nerves. The components of the roots of the lung having been dissected free the heart may be turned upward and to the left exposing trachea and bronchi. Trachea. Examine position, diameter, length and structure of trachea. Observe the difference in the position, diameter and length of bronchi. Separate trachea from oesophagus and reflect upward. The pericardium may be reflected downward. The course and branches of the vagus nerve in the thorax should be worked out. Oesophagus. Observe position in relation to midsagittal plane. Study length, course and structure of oesophagus. Ob- serve thoracic aorta and branches. The oesophagus, vagus nerve and aorta may be incised just above diaphragm and turned up- ward. Thoracic Duct? The parietal pluera may now be removed from the posterior wall of the thorax and an examination made of the sympathetic trunk : (i) Sympathetic trunk: (a) rami communicantes ; (b) splanchnic nerves ; (c) communications with cervical and lumbar portion; (d) pulmonary branches. Trace the sympathetic cord upward into the neck observing the middle and inferior cervical ganglia. UPPER PART OP BODY 29 Demonstrate the asygos system of veins. Make a drawing of this system of veins at natural size and with the bodies of the vertebrae to denote levels. These drawings are to be retained by the laboratory for statistical purposes. — 41 — Having finished the study of these structures, the upper part of the body may be separated from the lower by cutting through the 6th thoracic intervertebral cartilage. In doing this the fol- lowing structures are also divided: (i) inferior vena cava; (a) thoracic duct; (3) aorta; (4) oesophagus; (5) vena azygos system; vagus and sympathetic nerves. Note their relation to diaphragm and their manner of passing from thorax to abdomen. Trace phrenic nerve into substance of diaphragm. After completing the thorax the dissector returns to the neck and head. The structures situated in the median line (larynx and constrictor muscles of the pharynx) are to be dissected first, so that the head can be divided into bilateral halves as soon as possible. In order to properly dissect this region it must be separated with the front part of the head from the vertebral column. Before doing this, however, the joints and ligaments between the occipital bone and the first and second cervical vertebra should be dissected. Figs. 185-188. Separate with the fingers the oesophagus, etc., from the pre- vertebral muscles up to the base of the occipital bone and then disarticulating the atlantooccipital joint, which separates the skull and dependent structures from vertebral column. Study longus colli and capitis muscles. — 42 — The interior of the skull is then examined and the exits of the twelve cranial nerves reviewed. Note particularly the glos- sopharyngeal, vagus, spinal accessory amd hypoglossal nerves. Note also the hypophysis or pituitary body, its size, position and two lobes. Ductless gland? 30 UPPER PART OF BODY A V-shaped portion of the occipital bone is then sawn out by two oblique cuts, paralkl with the petrous portion of the temporal bone, passing just behind the mastoid process and jugular foramen, and converging toward the basilar process. Afterward more of the basilar process is to be cut away with bone cutters to expose the upper end of the pharyngeal muscles. This produces the dissection like figure 693. Identify and determine relations of the following structures : Nerves — (i) hypoglossal; (2) spinal accessory ; (3) vagus (ganglion nodosum) ; (4) glossopharyngeus ; (5) cervical sympathetic and superior cervical gang- lion. Internal carotid artery. Internal jugular vein. Vagus Nerve. Study whole course of nerve. Make a list of all its branches and identify the more important ones. Their function ? — 43 — Pharyngeal Constrictor Muscles. Clean fascia from these muscles and determine their outlines and attachments. Action and nerve supply? Pharyngeal aponeurosis? The constrictors may then be divided in the median line, exposing the interior of the pharynx. Pharynx: (a) nasal; (b) oral; (c) laryngeal. Notice struc- ture of the wall of pharynx. Identify the following surface markings : (i) Vel-um palatinum. (2) Uvula. (3) Pharyngeal recess. (4) Epiglottis. (5) Vallecula epiglottica. UPPER PART OF BODY 3I (6) Pharyngoepiglottic folds. (8) Folds for laryngeal nerves. (9) Interarytenoid incisure. (10) Pharyngeal, palatine and lingual tonsils (tonsilar ring). Notice transition into oesophagus. Oesophageal isthmus? — 44 — Larynx. Spread open the superior laryngeal orifice and notice true and false vocal cords and rima glottidis. Dissect off the mucosa from the pharyngeal surface of the larynx and expose superior and inferior laryngeal nerves and accompany- ing arteries. Figs. 440 and 694. Arteries are branches of what? Clean the arytenoid and posterior cricoarytenoid muscles. On the ventral wall of the larynx determine the origin, insertion and nerve supply Of thyrohyoid and cricothyroid muscles. Re- move the cricothyroid and thyrohyoid muscles on the left side and study cricothyroid and thyrohyoid membranes. The posterior two-thirds of the left wing of the thyroid cartilage may be separated from the remainder and disarticulated from the cricoid cartilage and removed (Fig. 442) to expose the thyroarytenoid, thyroepiglottidean and lateral cricoarytenoid muscles. The larynx is then slit open in the dorsal midline and the interior examined. Study character of vocal folds. Laryngeal mucous membrane? Summarize motor and sensory nerve supply of larynx. Note differences in size between male and female larynx. — 45 — The entire head is divided into right and left halves, using knife for soft structures. Topography of Median Section of Head. Figs. 238 and 421-423. Frontal sinus and its connection. Sphenoidal sinus. Nasal fossa: (a) medial wall (nasal septum) ; 22 UPPER PART OP BODY (b) lateral wall; (i) conchae; (2) meatuses; Nasopharynx: (i) pharyngeal recess; (2) pharyngeal, tonsil ; (3) torus tubarius; (4) orifice of auditory tube; (5) salpingopharyngeal fold. Oral Cavity: (i) hard and soft palates; (2) mucosa of tongue; (3) foramen caecum; (4) frenulum; (5) sublingual fold; (6) palatine tonsil; (7) glossopalatine fold; (8) pharyngopalatine fold; (9) glossoepiglottic fold. Observe character of nasal mucous membrane. Demonstrate nerve and blood supply. Olfactory nerves? Remove the middle and interior conchae by an incision near attached border and compare with figure 424. Demonstrate communications with the paranasal sinuses. - 46- Maxih.ry Nerve. The second division of the trigeminal nerve is best exposed from the medial side. Strip off the mucous membrane from the lateral wall of the nose, between the open- ing of the auditory tube and the posterior extremity of the in- ferior concha, from floor to roof. Observe the nasal branches of the sphenojpalatine ganglion entering mucosa near posterior extremities of conchae. Fig. 685-686. With bone cutters re- move the medial wall of the sphenopalatine fossa.' The sphenopalatine ganglion is exposed and its branches traced out completely to their distribution : (a) lateral nasal; (b) anterior, middle and posterior palatine; UPPER PART OF BODY 33 (c) nasopalatine; (d) sphenopalatine; (e) nerve of pterygoid canal. Remove the remainder of the- lateral virall of the nose and ex- pose the maxillary sinus. Notice nasolachrymal canal and frontal jinus. The infraorbital nerve is now exposed throughout its whole course. Anterior, middle and posterior alveolar and zygomatic nerves? — 47 — The third or mandibular division of the trigeminal nerve is "best exposed from the outside, and in order to do this the ramus of the mandible and attached muscles must be dissected and removed. Bisect the common trunk of the facial nerve and reflect forward. Massbter Musclb. Origin, insertion, structure and action.' Separate it from its insertion on mandible from below upward, and find masseteric nerve supplying it from underneath near upper end, coming over the mandibular notch. Determine at- tachment of temporal fascia after which it may be removed. Saw through at each end of the zygomatic arch and remove it. In removing the arch it is well to include the major part of i:he zygomatic hone. Tempokai, MtrsctB. Origin, insertion and direction of fibers. Action? This muscle is removed by reflecting from below up- wards, and the deep temporal nerves supplying it from un- derneath are picked up as they cross the infratemporal crest. To do this the coronoid process of the mandible must be cut ■off and raised with the muscle. A few of the anterior fibers of the muscle should be left in position, as the buccinator nerve lies in the fascia closely against the median surface of the tendon of insertion, otherwise the nerve is in danger of being removed with the temporal muscle. BuccophryngeaV fascia? After removal of the temporal, complete dissection of buc- xinator nerve and buccinator muscle. Never supply of latter? 24 UPPER PART OF BODY •Infratemporal Remon. To expose the pterygoid muscles a portion of the ramus of the mandible must be removed. Saw through the neck of condyloid process to preserve articulation. Then pull outward upper part of ramus, and stripping back periosteum watch for orifice of mandibular foramen with the entering inferior alveolar nerve and artery. The bone may be cut away from condyloid process to this point. Trace nerve backward towards origin identifying mylohyoid and linffual nerves. Trace alveolar nerve distally in canal to where it ter- minates as mental nerve. Note dental branches to roots of teeth. Study shape and structure of teeth including nerve and blood supply. Deciduous teeth? Manner of inplantation ? - 48- The internal maxillary artery can be examined at this time. Dissect it back to its source and identify all its branches and dis- tribution. Note particularly the middle meningeal. Review all the branches of the external carotid artery and demonstrate those not yet worked out. The internal, maxillary may then be removed and the pterygoid muscles exposed. In some cases this artery has a deep course and cannot be completely exposed until after dissection of external pterygoid muscle. Study character of temporomandibular articulation. Ncite articular disc and accessory ligaments. Disarticulate joint and determine origin, insertion and action of external pterygoid muscle. Carefully remove this muscle in fragments and ex- pose internal ptyergoid muscle and mandibular nerve. Demon- strate origin and course of auriculotemporal nerve. Observe infratemporal course of corda tympani nerve. The otic ganglion lies directly medial to the mandibular division as it emerges from the foramen ovale. It is best exposed by removing a sec- tion of bone from the temporal fossa medial and anterior to foramen ovale. Examine origin, insertion and action of the stylohyoid and digastric muscles. Demonstrate their nerve supply. Review course of external maxillary artery and then remove it. UPPER PART OP BODY 3^ — 49 — Submaxillary Triangle. Boundries? Divide anterior belly of digastric at its origin on mandible and reflect superficial por- tion of submaxillary gland dorsal ward to expose mylohyoid muscle. Nerve supply? Determine its origin and insertion and then detach from its origin on mandible and reflect downward. Observe : (i) submaxillary gland (deep position) ; (2) lingual nerve;. ( 3 ) submaxillary ganglion ; (4) submaxillary duct;. (5) hypoglossal nerve; (6) lingual vein. Determine distribution of lingual and hypoglossal nerves. Identify hyoglossus muscle and sublingual gland and ducts. Divide hyoglossus muscle along attachment to hyoid bone and expose . course of lingual artery. Notice carefully the relation of the hypoglossal nerve and lingual artery to hyoglossus and mylohyoid muscles. Complete muscles of tongue: (i) intrinsic; (2) extrinsic. Trace entire course of glossopharyngeal nerve. Follow it to mucous membrane at base of tongue. Summarize nerve supply, both motor and sensory, of tongue. Identify muscles of soft palate. The levator veli palatini must be separated at its origin and reflected downward to expose the tensor veli palatini. Determine their action and nerve supply. — 50 — Read the structure of the external, the middle and- the in- ternal ear. Also read the course of the facial nerve, the situa- tion of the geniculate ganglion, and corda tympani nerve. These structures may be exposed in the following manner: With a small chisel and bone cutters remove the roof from the 26 UPPER PART OP BODY internal auditory meatus and facial canal as far as the geniculate ganglion. Identify cochlear and vestibular portions of auditory nerve, the facial nerve, geniculate ganglion and great superficial petrosal nerve. Remove roof of tympanum and observe its sub- divisions and contents. Identify tendon of tensor tympani muscle and follow it anteromedially and remove the bony roof of the auditory tube to expose the body of the muscle. The facial nerve can now be followed backward and downward through facial canal to stylomastoid foramen. Observe the branch to stapedius muscle and the origin of corda tympani. Follow corda tympani forward through middle ear to its union with lingual nerve. By carefully flaking off the bone the cochlea, vestibule and semicircular canals may be exposed. — 51 — After completing the head the dissector returns to the arm which has been previously removed. > Remove the skin from the arm, forearm, hand and fingers. Identify all of the superficial veins and cutaneous nerves of the upper extremity and compare with figures 710-713. Make a schematic drawing illustrating the cutaneous nerve supply of the upper extremity. — 52 — The subcutaneous tissue can now be removed and a study thade of the deep fascia of the upper extremity. Figs. 291-292. Shoulders. The brachial plexus should now be reviewed and its branches traced down into the arm. Make a schematic draw- . ing illustrating the formation and branches of the brachial plexus. Identify and finish cleaning the seventeen muscles attached to the scapula. Determine origin, insertion, nerve supply and action. The muscles inserted into the tuberosities of the humerus should be exposed by dividing the deltoid muscle near its origin. 7-.'ote branches of axillary nerve. Review blood supply of muscles in scapular region. UPPEK PART 01? BODY 37 — 53 — Arm. Remove the brachial fascia observing lateral and medial intermuscular septa. Clean surfaces and separate the following muscles : 1. Biceps. 2. Coracobrachialis. 3. Brachialis. 4. Triceps (including anconeus). Note sheath of long head of biceps. Lacertus fibrosusf Fol- low radial nerve and brachial profound artery between the heads of triceps. Figs. 556-557. Observe course of ulnar nerve. Note the formation of the anterior cubital fossa and the structures passing through it. Compare with popliteal space. What in the lower extremity corresponds to the olecranon process. Note analogy between triceps and quadriceps muscles. Study brachial artery and branches. — 54 — Forearm. Remove fascia ■ of forearm, preserving the volar and dorsal carpal ligaments and expose and study following muscles : volar group: (Figs. 705-709.) (i) pronator teres; (2) flexor carpi radialis ; (3) palmaris longus; (4) flexor carpi ulnaris; (5) flexor digitorum sublimus; ^ ^ (6) flexor digitorum profundus; (7) flexor policis longus; \ : , ' (8) pronator quadratus. ' ' ■ i In dissecting these muscles use care so as not to disturb course and branches of the nerves and arteries. Superficial ulnar artery? Branches of radial and ulnar arteries? Sum- marize nerve supply of these muscles. ^8 UPPER PART OF BODY — 55 — Dorso-Radial Group: (Figs. 558-559.) (1) brachioradialis ; (2) extensor carpi radialis longus ; (3) extensor carpi radialis brevis; (4) extensor digitorum communis; (5) extensor digiti quinti proprius; (6) extensor carpi ulnaris; (7) supinator; (8) abductor pollicis longus; (9) extensor pollicis longus; (10) extensor pollicis brevis; (11) extensor indicis proprius. Study relation of tendons with bony landmarks at wrist. Avoid injury to tendon sheaths. Summarize nerve supply of these muscles. _ 56- Hand. Note character and attachments of palmar aponeurosis (Fig. 712). Identify palmaris brevis muscle and its attachment to skin. The palmar aponeurosis may be removed in order to clean and identify the muscles of the hand. Note synovial sheaths of the long tendons of the hand. Explore their in- terior with probe, and determine their extent and intercom- munication. Weeping sinew? Muscles of Little Finger (digiti quinti) : (1) abductor; (2) flexor brevis; (3) opponens. Muscles of Thumb (pollex) : (i) abductor pollicis brevis; (2) flexor pollicis brevis; ' (3) opponens pollicis; (4) adductor pollicis. Observe the formation and branches of the superficial and deep palmar arches (Figs. 562-563). Study nerves of hand. UPPER PART OF BODY ■ 30 — 57 — Notice the vaginal and annular ligaments of the fingers. These should be opened and the tendons of the long flexors studied. Identify attachment of Iwmbricales. Action? Interossei Muscles: (a) dorsal (abductors) ; (b) palmar (adductors). Summarize nerve supply of the twenty intrinsic muscles of the hand and compare terminology of muscles and distribution of nerves in the hand with those of the foot. The dissection of the hand is not complete until every finger is clearly dissected and the nerves are traced to the finger tips. — 58- After completing the hand the dissector should carefully re- view the arterial and nervous system of the specimen dissected and account for all branches. The instructor in charge will designate one specimen at each table from which the arterial and nervous systems are to be removed, after their branches have been properly labeled, and pinned out upon a board. Review all the muscles of the upper extremity and make a list showing what muscles are supplied by each of the follow- ing nerves : (i) axillary; (2) radial; (3) median; (4) musculocutaneous; (5) ulnar. — 59 — On specimens from which the nerves and arteries have been removed the ligaments and articulations of the shoulder, elbow and wrist joints should now be studied. The relations of muscles and tendons to the joints should be noticed, after which 40 UPPER PART OP BODY they are removed and the joint examined. Notice capsule and. the various accessory strengthening ligaments. The joint is then opened and its interior examined. Shculder joint: (1) articular capsule; (2) coracohumeral ligament; (3) glenohumeral bands; (4) coracoacromial ligament; The shoulder joint -is best opened by an incision through the posterior wall. Observe on the interior: (5) articiilar cartilage; (6) glenoid lip; (7) long head o^ biceps; (8) synovial membrane. Examine the acromioclavicular articulation and accessory liga- ments. — 60 — Ei-Bow Joint (Three articulations, hutneroulnar,- humeroradial and radialulnar) : (1) articular capsule; (2) collateral iilnar; (3) collateral radial; (4) annular ligament of radius; (5) synovial membrane. Compare with knee joint and note points of difference. Radioulnar articulation : (1) Proxymal joint: (a) annular ligament; (b) synovial membrane; (2) Intermediate ligaments : (a) oblique ligament; (b) interosseus membrane; UPPER PART 01 BODY 41 (3) Distal Joint: (a) anterior radioulnar ligament; (b) posterior radioulnar ligament; (c) articular die (triangular cartilage) ; (d) synovial membrane. Wrist joint: (1) articular capsule; (2) radial collateral ligament; (3) ulnar collateral ligament; (4) volar radiocarpal ligament; (5) dorsal radiocarpal ligament; (6) synovial membrane. Examine intercarpal, carpometacarpal, metacarpophalangeal and interphalangeal joints. DISSECTION OF THE LOWER PART OF THE BODY The Back. Surface Anatomy. Determine the location of the following surface markings; spinous processes of vertebrae, posterior su- perior spine and crest of ilium, lower ribs and intercostal spaces, posterior surface of sacrum, tip of coccyx. Common Ineggument: Skin, hair, nails and glands. Removai, of the Skin. In cooperation with the dissectors of the upper part of the body make an incision in the midline ex- tending from the occiput to the tip of the coccyx ; a second from the twelfth dorsal spinous process laterally to posterior axillary line; a third extending upwards and laterally to posterior su- perior spine and along crest of ilium to posterior axillary line; a fourth from the tip .of the coccyx curving lateralward and downward to the middle of the posterior surface of the upper part of the thigh. Begin in the midline at the upper corner of the upper flap to reflect the skin. Separate the skin from the underlying superficial fascia by cutting close to the under surface of the skin. After having reflected this flap laterally to the posterior axillary line the other flap may be reflected in a similar manner. The student should familiarize himself with the general struc- ture, distribution and function of the tela subcutania. Identify the cutaneous branches of the posterior divisions of the spinal nerves (lumbar, sacial and coccygeal). Which, on account of their peculiarities, have special names? The remainder of the LOWER PART OF BODY 43 subcutaneous tissue may be removed and the surface of the latissimus dorsi cleaned as shown in figure 236.* Demonstrate its relation to lumbardorsal fascia. Determine boundries of lumbar triangle. — 3 — Separate the latissimus dorsi at its origin from lumbodorsal fascia and reflect lateralward (Fig. 238). Care should be taken so as not to include the tendon of the posterior inferior serratus muscle. Demonstrate- the attachment of the posterior inferior serratus to lumbodorsal fascia and ribs. Separate its attachment to lumbodorsal fascia and reflect lateiralwards. Separate the posterior layer of the lumbodorsal fascia by a longitudinal incision along the spinous processes of vertebrae and reflect lateralward. Demonstrate the relation of the dorsal and ventral layers to one another and to the tendons of the abdominal muscles. Refer to figures in text book or atlas (Fig. 237), illus- trating transverse sections through the lumbar region showing layers of lumbodorsal fascia and their relation to the tendons of the muscles of the abdominal wall. Remove the fascia from the whole surface of sacrospinalis muscle and demonstrate the three columns (Fig. 239) — iliocos- talis, longissimus and spinalis. Demonstrate the tendons of origin and insertion of the subdivisions of the muscle as follows (Fig. 241): iliocostalis : (i) lumborum; (2) dorsi; (3) cervicis; longissimus : (1) dorsi; (2) cervicis; (3) capitis; spinalis : (i) dorsi; (2) cervicis; (3) capitis (?). * All references to figures refer to Sobotta-McMurrich's Atlas and Text-book of Human Anatomy. 44 LOWER PART OF BODY — 4 After the sacrospinalis muscle has been completely studied it can be removed. Sbmispinaws (first lay of short muscles), (i) dorsi; (2) cervicis; (3) capitis. After the origins and insertions of this muscle have been studied it may be removed. MutTiFiDus MuSGi,E. Study the origin, insertion tind extent of this muscle after which it may be removed. RoTATORfiS LONGI AND BrEVSS. Levatores Costarum. Interspinales. Intertransversarii. — 5 — After identifying " the chief characteristics of these short muscles they may be, removed and the vertebrae cleaned up to the cervical region preparatory to opening the vertebral canal. The important features of the vertebrae and the vertebral canal should be studied. Lumbar puncture region? The osteological features of the lumbar, sacral and coccygeal vertebrae should be studied. In cooperation with the other dissectors the canal should be opened with chisels and bone cutters by cutting away the vertebral arches. Care should be taken not to cut too deeply at first as there is danger of cutting the spinal nerves in their course through the intervetebral foramina. Notice the venous plexus surrounding the dura. — 6 — Joints. Read classification of joints. Prepare a list of and describe all joints associated with the lower part of the vertebral column. LOWER PART OF BODY 45 In cooperation with the other dissectors trace dural sheath out- ward over the ganglia of all the spinal nerves, cutting away bone where necessary, and notice its direct continuation as a sheath for the nerve trunks of lumbar, sacral aijd coccygeal nerves. Filum terminale externum? Figs. 608, 609, 610. — 7 — Spinal Meninges. Dtjra Mater. The dura may now be incised in the dorsal mid sagittal line, being careful not to include the arachnoid which lies close to its deep surface. Subdural space? After observ- ing the chief characteristics of arachnoid it may be incised in the dorsal mid line. Subarachnoid space? Examine pia mater with its contained blood vessels. Observe the lumbar, sacral and coccygeal cord segments, the levels in the vertebral canal occupied by them and the root filaments arising from each. Trace root filaments to points of exit from dura. Do the anterior and posterior roots pass through a common ope^iing in the dura? Cauda Bquina? Filum terminale. — 8 — Spinal Cord. In common with the other dissectors study the form, length, enlargements and sulci of cord. Cut transverse section, ^2 cm. thick, from the mid lumbar and mid sacial regions and study tinder water with a binocular microscope. Observe the gray and the white substance and the subdivision of each. Note the characteristic form of the gray substance at the two different levels. Compare these specimens with stained speci- mens furnished by the laboratory and with figures 619 and 620. Note conus medullaris. Why. does spinal cord end at about level of first lumbar vertebra? Note the nerve roots (anterior and posterior) and their con- nection with the cord. Trace them peripherally and determine their mode of exit from the canal. 46 LOWER PAET of body Observe the formation of nerve trunks. Identify anterior and posterior division. What is meant by spinal root ganglia? Double ganglia? Position of ganglia. Compare length of nerve roots at different levels. — 9 — Remove the ventral layer of the lumbodorsal fascia and dem- onstrate the quadratus lumborum muscle after which it may be removed. Identify the ventral division of the twelfth thoracic nerve (subcostal) iliohypogastric and ilioinguinal nerves. Trace these nerves from their origin, laterally until they pass between the layers of the muscles of the anterolateral abdominal walls. Remove the fascia from the posterior surface of kidney. Observe the portion of the diaphragm that occupys the upper part of the angle formed by vertebral column and 12th rib. Make a glass plate tracing of the kidneys showing their relation to eleventh and twelfth ribs, the diaphragm, the iliac crests and the pedicles of the lumbar vertebrae. — 10 — After having completed the dissection of the spinal cord and the origin of the spinal nerves the dissectors should prepare the field for the dissection of the sacrococcygeal plexus. In order to do this it is advisable to proceed first with the dissection of the ischiorectal fossa. It is well at this time for the dissector to familiarize himself with the bones forming the pelvis and the pelvis as a whole. Ischiorectal Fossa (Fig. 724 or 725). It will be found that the dissection is facilitated by having the thighs well apart, and placed at as near a right angle to the trunk as is possible. This can be accomplished either by placing a large block be- neath the lower part of abdomen or by letting the legs hang over the end of the table. Reflect the skin with a median incision tOWER PART 01? BODY 47 encircling the anal orifice. Carefully remove the fat and ex- pose following structures : (i) external splincter ani; (2) anal canal; (3) levator ani and coccygeus muscles; (4) superficial perineal and inferior hemorrhoidal nerves; (5) internal pudendal and inferior hemorrhoidal arteries. Determine the boundries of the ischiorectal , fossa. GtuTEAi, Region. After having identified the cluneal nerves (superior, medial and inferior) the superficial fascia may be re- moved. Figs. S77, 719- Notice the deep fascia and its relation to fascia lata. Gluteus Maximus Muscle; clean the muscle; determine its origin, insertion and action. The muscle is then divided at its origin and turned outward. In removing it be careful to sep- arate it from- the sacrotuberosal Ugatnent and not remove liga- ment and muscle together. In doing this the nerves and bloorl vessels supplying it on its deep surface are identified and then incised close to muscle. Superior and inferior gluteal nerves and z:esselsf Remove the gluteal veins leaving the arteries. This facilitates the dissection of the remaining structures. Clean the surfaces of all muscles exposed by the reflection of gluteus max- imus. Identify all structures and learn their relation to pri- formis muscle. Gluteus Medius. Origin, incertion, nerve supply and action. Piriformis Muscle. Origin, insertion, nerve supply and ac- tion. This muscle and the gluteus medius may be separated at their origin and turned outward. 12 Gluteus Minimus Muscle. -Origin, insertion, nerve supply and action. QuADEATus Femoris. Origin, insertion, nerve supply and ac- tion. 48 LOWER PART 01? BODY Obturator Internus and Externus Muscles. Note direction of their fibers. These muscles cannot be completely exposed at this time, so the dissector must refer to his text book or atlas. Gemellus Superior and Ineemoe Muscles. Note their rela- tion of obturator internus. With chisel and bone cutters cut away a portion of the ilium and sacrum in order to trace the continuation of the lower lumbar and sacral nerves into the formation of the sacral plexus. Demonstrate all the branches of this plexus. Make a chematic drawing. — 13 — The dissection of the back is now completed. The student proceeds with the dissection from the ventral surface of the body. Before turning the body over, however, it is advisable to replace all attached muscles and skin flaps and retain them in position by sutures. This prevents drying and consequent deterioration of dissected parts. Abdominal Wall. Before proceeding with the dissection notice the following surface markings : Costal arch. Xyphoid cartilage. Umbilicus. What does it represent? Anterior superior spine and crest of ilium. Symphysis, crest and tubercle of pubis. Inguinal ligament. Folds of recti muscles. Linea alba and semilunaris. Identify the nine abdominal regions and their boundries. Right hypochondriac Epigastric Left hypochondriac Right lateral abdominal Umbilical Left lateral abdominal Right hypogastric Fublic Left hypogastric. An optional method of subdividing the abdominal region con- sists in dividing it into right and left upper and lower quadrants by a vertical and a horizontal line passing through the umbilicus. MWER PART OF BODY 49 Make the following incisions: (l) extending from the xyphosternal junction downward in the midline to symphysis pubis, around the proximal portion of the body of the penis and continued to the tip of the scrotum by a line on each side of the raphe. In the fema:ie the lower part of this incision should be made along the free border of the labia majora and ex- tend dorsally to posterior commissure ; (2) from xyphosternal junction laterwards to posterior axil- lary line; (3) from symphysis laterwards along the inguinal ligament to anterior superior spine of ilium and then along the crest. Reflect skin flaps thus outlined. — 14 — Nerves. Identify the lateral and the anterior cutaneous "branches of the anterior divisions of the spinal nerves. Dis- sect them free from the subcutaneous tissue. Observe that the lateral cutaneous branches of the twelfth dorsal and of the iliohypogastric nerves pass over the crest of the ilium to gluteal region. Arteries : (a) superficial epigastric; (b) superficial circumflex iliac; (b) superficial external pudendal. "What arteries accompany the superficial nerves? Veins? SuPERMCiAi, Fascia. Study structure of superficial fascia of .abdomen and scrotum (tunica dartos). Incise the" superficial fascia according to instruction (l) for skin. A second incision :should be made from anterior superior ' spine transversely to median line. Reflect the fascia flaps outlined. Observe its two layers. Demonstrate the relation of the membraneous layer to fascia lata, tunica dartos and fundiform ligament -of penis. How is the abdominoscrotal opening formed? ■ The identification of the nerves and bloodvessels traversing the superficial fascia may be done before or after its reflection. 50 LOWER PAET OF BODY In fat subjects the latter is the better method. Note extensive plexus of bloodvessels covering whole abdomen. Commence the reflection of the fascia in the median line and proceed outward, picking up the nerves and vessels from the under surface, after which they are dissected out and left in position. Lymphatics : Inguinal lymphatic nodes, node groups and areas of drainage. — 15 — ExTEENAi, Abdominai, Obwque MusclE- Remove deep fascia from the fleshy portion of the muscle preserving the superficial nerves. The muscle should be cleaned upward to its interdigita- tions with serratus anterior and latissimus dorsi muscles. Ob- serve : (i) origin and insertion; (2) relation to ventral abdoqiinal aponeurosis; (3) inguinal ligament; (4) position- of subcutaneous inguinal ring with the crus su- perior and crus inferior; (5) intercrural fibers; (6) external spermatic fascia. Notice that the external spermatic fascia is apparently a sac like outpouching of the aponeurosis of the external oblique muscle. To facilitate the examination of the median attachment of the aponeurosis the fundiform ligament of the pinis should be sep- arated and turned downward. This exposes the decussation of the aponeurotic fibers of the right and left sides and their attachment to the pubis. The external oblique may then be divided at its origin and reflected forward. The incision is made along its attachment to the ribs, dissecting off each interdigitation, down along the latissimus dorsi then along the crest of the ilium to the anterior superior spine. From here divide the aponeurosis by a horizontal incision extending medially to the linea semilunaris. Then it is separated by an incision extending downward through the ■ subcuicmeous inguinal ring and along the anterior wall of the LOWER PART OF BODY 51 external spermatic ■ fascia to inferior pole of testis. This in- cision is facilitated by advancing the finger or some blunt in- strument under the aponeurosis and fascia while the incision is being made. Reflect the external oblique. — 16 — Internal Abdominal Oblique Muscle. Observe the ilio- hypogastric and ilioinguinal nerves which perforate this muscle not far from the antei-ior superior spine of ilium and course toward the pubis on its surface. Trace these nerves to terminal branches. Clean all the deep fascia from its surface. Observe structure, direction of fibers, origin, insertion and nerve supply. Determine its relation to inguinal ligament, inguinal canal and conjoined tendon. Follow the lowermost fibers of this muscle downward over the spermatic cord and testis to form the cremaster muscle. De- termine its origin, insertion and nerve supply. Action? Cre- master fascia? The internal abdominal oblique muscle may be separated from its attahcment to the lower ribs, the lumbodorsal fascia and the crest of the ilium. Make an incision from the anterior superior spine of the ilium downward and medially parallel to and over the inguinal canal and spermatic cord to lower pole of testis. Reflect the internal oblique and cremaster -muscles. Care should be taken in reflecting it so as not to in- clude the lower intercostal nerves which lie just underneath. Transversalis Abdominis Muscles. Identify the lower in- tercostal nerves that lie on the surface of this muscle. Arteries and veins? Clean the fascia from its surface and determine origin, insertion ,and nerve supply. Its relation to conjoined tendon and cremaster muscle? — 17 — After completing the study of the transversalis it may be divided in similar way to that of the internal oblique. Its fibers, •however, should be lifted up in bands between the intercostal nerves so as not to destroy their attachments. 52 lower part 01' body Conjoined Tsndon : (a) falx inguinalis; (b) interfoveolar ligament. Identify the medial and lateral inguinal fossae (weak spots). Reflected inguinal ligament . Transversalis Fascia. Structure and extent. Incise this . layer on a line extending horizontally medialward from anterior superior spine of ilium. Separate the lower portion very carefully from the peritoneum and observe formation of spermatic cord, abdominal inguinal ring and tunica vaginalis communis (infundibuliforra fascia); Spermatic Cord. Incise tunica vaginalis communis and ex- pose the constituents of the spermatic cord from testis to ab- ■ dominal inguinal ring : (i) ductus deferens; (2) deferential artery and veins; (3) testicular artery; (4) testicular veins; (5) nerves: (a) genital branch of genitofemoral: (b) branches of ilioinguinal. Incise tunica vaginalis proprius.. Structure and function? Re- place and study all the structures contributed by the layers of the abdominal wall that are considered coverings of the cord and testis. Scrotum. (Analogous to labia majora in fernale.) Scrotal septum? Scrotal ligaihent? Read descent of testis. — 18 — Inguinal Canal. Length, direction and boundries. What is the character, shape and situation of the subcutaneous and the abdominal inguinal rings. Study formation and attachments of the inguinal ligament. Lacunar ligament? lower part os body 53 Inguinai, Hernia. A. Oblique or external (the common form) Coverings: (l) in lateral half of canal; (2) in medial half of canal; (3) in scrotum; B. Direct or internal (the rarer form) Coverings. — 19 — Rectus Abdominus Muscle. The- sheath including this muscle should be opened by a vertical incision along the median line of the sheath. Reflect anterior layer of sheath. Structure of rectus muscle. Tendinous inscriptions (significance?). Pyra- midalis Muscle f Divide Rectus muscle at level of umbilicus and reflect ends. Observe superior and inferior epigastric arteries. Rectus Sheath. Study formation, structure and muscles at- tached to rectus sheath. Linea sendcircularis? Note difference in structure above and below umbilicus. Contents? Compare with lumbodorsal fascia. 20 Review the structure of the abdominal wall after which re- place all the layers and make the following incision through it: (l) from the xyphoid cartilage to the umbilicus; (2) from the umbilicus extending laterally to the crest of the ilium on each side. The lower portion of the abdominal wall is then raised and its inner surface examined, without disturbing the position of the viscura. Identify the following: (Fig. 412.) Folds. 1. Median umbilical (urachus). 2. Lateral umbilical (obliterated umbilical arteries). 3. Epigastric (Inf. eipgrastic arts.). Fossae. 1. Supravisical. 2. Median inguinal. 3. Lateral inguinal. Note variations in different bodies. 54 LOWER PART OF BODY After these structures have been seen the median incision may be continued from the umbilicus downward to the symphysis pubis. Identify femoral ring and compare its position with that of subcutaneous abdominal ring. 21 The examination of the abdominal viscera is now begun. Be- fore their position has been disturbed make a tracing with a glass plate, and transfer it to paper, showing the topography of the following organs : 1. Stomach (to be colored green). 2. Liver and gall bladder (red). 3. Colon, three divisions (yellow).. Indicate the nine abdominal regions, umbilicus, costal margin, inguinal ligaments and anterior superior iliac spines. When the colon does not appear on the surface it should be shown by dotted lines. Omit entirely the great omentum. 22 PERiToNfiuM. Fig. 405-4.15. Re9.d development of peritoneum and formation of two peritoneal sacs. Identify all of the folds of the peritoneum that are known as omenta, mesentaries and ligaments. Make a list of each. - 23 — Peritonea:, Fossae (the more important ones). Caecal region : (1) retrocolic; (2) ileocolic; (3) ileoca,ecal. Duodenal flexure : (i) superior duodenal; (2) inferior duodenal; (3) paraduodenal (?). Sigmoid region : Intersigraoid. Significance of peritoneal fossae? LOWER PART OF BODY 55 Bursa Omentalis. Examine the epiploic foramen and identify structures forming and adjoining it. The interior should then be exposed and the organs and peritoneal folds forming its boundries identified. In order to do this an incision should be made through the great omentum along the greater curvature of stomach. Care should be taken so as not to incise the gastroepiploic arteries. Note the four possible ways of enter- ing the bursa omentalis. — 24 — ' Determine the position and peritoneal relations of the fol- lowing organs without interruption of the continuity of the peritoneum : 1. Gastro-intestinal tract. 2. Iviver and gall bladder. 3. Pancreas. 4. Spleen. 5. Right and left kidneys and ureters. 6. Bladder. 7. Large blood vessels. 8. Uterus, vagina, ovaries and ovaduct in the female. 9. Ductus deferens. It is important to identify all these structures through the peritoneum, just as the surgeon has to. — 25 — After studying the peritoneal coverings of the different organs on his own table the dissector should visit other tables for com- parison, studying the variations in the organs themselves, and the folds of the peritoneum. Meckel's diverticulum? The student having made a careful practical study of the peritoneum as outlined above should now be prepared to trace the peritoneum on the cadaver in every plane. It is suggested that the dissector begin by .tracing it as follows: (i) medial sagittal plane; (2) transverse horizontal plane: (a) level of epiploic foramen. (b) level of umbilicus. 55 LOWBR PAST OF BODY — 26 — MesEnTaky. Study structure and attachments of mesentary. Reflect peritoneum from the right side of the mesentary (Fig. 566) and expose : (i) Superior mesenteric artery and all its branches: (2) Superior mesenteric vein and tributaries; (3) Lymphatic vessels and lymph glands (lachteals?) ; (4) Nerves. Notice the manner of distribution of the terminal arteries to intestinal wall. Complete the dissection of the blood vessels, lymphathic and nerves supplying the intestinal wall as far as the beginning of the rectum, exposing: (i) iliocolic; (i) artery of appendix; (3) right colic artery; (4) middle colic artery; (5) left colic; (6) inferior mesenteric artery. Avoid injury to testicular artery. — 27 — Intestines. For convenience in studying the intestines they should be removed. Before doing this notice carefully the rela- tion of the colon to the viscera, especially the right and left kid- ney, liver and spleen. Place double ligature around jejunum, near duodenojejunal flexure and divide between the two. Divide the colon at the beginning of the rectum in the same way. (Boundary between colon and rectum?) Remove colon and small intestine together by dividing mesentary near its junction v/ith intestinal wall. Notice three external characteristic differ- ences in appearance between large and small intestine. Carry intestines to sink and with scissors slit open intestines along the line of mesenteric attachment except for four inches each side of ileocaecal junction. Observe character of contents LOWER PART OF BODY 57 in different parts of intestine. Wash off contents, and study character of mucus membrane of different parts of intestine. Note plush-like appearance of the small intestine due to villi as contrasted to the smooth appearance of large intestine where they are absent. Identify and note character of agminated lymph follicles (Peyer's patches). Determine occurrance, shape, and position. Solitary folicles? Observe differences between: (a) valvulae coniventes (small intestines) (b) semilunar folds (large intestines). — 28 — For a more careful examination of the character of the in- testinal mucus membrane the dissector should cut out pieces of the wall [(i) stomach; (2) jejunum; (3) ilium (near caecum); (4) colon] one-half inch square and study under water with low power binocular microscope in good illumination. Learn to dis- tinguish between them by study of villi and orifices of glands. Compare as many specimens as possible.. Dissect under water a piece of jejunum about two inches square showing : (1) peritoneal coat; (2) longitudinal muscular coat; (3) circular muscular coat; (4) submucus coat of arteries; (5) mucus coat. Compare muscular coats of large and small intestines and .note differences. In studying the structure of the wall of the alimentary canal it is desirable that the dissector read the process of digestion in a text-book of physiology. Examine the ileocaecal junction. Trace caecal termination of the three longitudinal hands of the colon: (a) mesocolic band; (b) omental band; (c) free band. ^8 wwer part op body Open caecum along line of free border and examine interior, particularly the ileocaecal valve and the orifice of the appendix. Slit open appendix and study character of its walls. After completing the study of the intestinal canal the specimen should be carefully wrapped in muslin, laid aside and kept moist for purposes of review. In like manner after having completed the study of each viscus it should be preserved in good condi- tion to the end of the laboratory period. — 29 — The dissector now studies the. different portions and rela- tions of the stomach and duodenum. Stomach. Compare the shape and position of the stomach in different bodies. Determine its visceral relation anteriorly and posteriorly. Examine and compare continuity with the oesophagus and duodenum and compare positions occupied by them to surface markings. Notice, (i) fundus; (2) lesser curvature; (3) greater curvature; (4) cardiac portion; (5) pyloric antrum; (6) pylorus. DuoEDBNUM. Determine peritonial and viscral relations of duodenum. Structure and subdivisions. Blood supply (Figs." 564-565). Dissect arteries of the stomach and duodenum by either drawing stomach down or raising it Up. Veins? — 30 — CoELiAc Artery. I. Left gastric: (a) gastric; (b) oesophageal; (c) hepatic (?). MWER PART OF BODY 59 2. Hepatic : (a) right gastric; (b) hepatic proper; (c) gastro-duodenal. 3. Splenic : (a) splenic branches ; (b) pancreatic; (c) gastric. Making a drawing, natural size, showing exact size and shape of stomach and the manner in which these branches are given off. Trace vagus nerve from oesophageal hiatus of diaphragm to their termination on stomach wall. Difference between vagus and splanchnic nerves ? Open stomach and study interior ; transi- tion between cardiac end and oesophagus ; pyloric end and transi- tion to duodenum. What elements enter into formation of pyloric valve? Study structure of stomach wall and compare with in- testinal canal. — 31 — Spleen. Examine its size, shape and relations. Examine specimens on other tables for determining the variations. Ac- ' cessory spleens? The vessels at the hilum of the spleen may then be divided, the sjpleen removed and examined more closely. Note character of capsule. Make incision and. examine cut sur- face. What is a hemolymph gland and what is supposed to be their function? Pancreas. Recognize the different portions of the pancreas and their relations to what lies in front and behind. Notice particularly its relations to portal vein and superior mesenteric artery and vein. Study structure and function. — 32 — For purposes of reference it is desirable that the dissector should make a memorandum, preferably a diagram, illustrating ihe ventral and dorsal view of the following organs showing ■'.isceral contact areas: (a) stomach; (b) spleen; (c) pancreas; 6o LOWER PART OF BODY (d) duodenum; (e) right and left kidneys. Compare them as identified on the table with illustrations and description in text book. Dissect out pancreatic duct by cutting a furrow in the ventral surface parallel with long axis of the organ (Fig. 392). By following the duct to the intestinal wall leads the dissector di- rectly to the common bile duct (ductus choledochus) . Ac- cessory pancreatic duct? Study development of pancreatic duct fjstera and account for the frequent variation seen in the lab- oratory. Biliary Tract. Slit open the descending portion of the 'Juodenum and locate the papilla which serves as the common termination of the pancreatic and common bile ducts. By in- troducing fine probes in the ducts a short distance from the intestinal wall it will be shown how they emerge from the papilla. Ampulla (of Vater) ? , — 33 — The common bile duct should be dissected back to its source. Demonstrate hepatic and cystic ducts. Portal System oe Veins. Dissect out portal vein from origin to liver. Determine tributaries to portal vein. Make a schematic drawing showing the formation of portal system. What areas of the body are drained by this system? Collateral circulation? Liver. Study topographical relation of the liver. Identify contact areas, surfaces and borders. Fixation of liver? The liver may be removed together with the duodenum and pancreas thus preserving the connection of the portal vein and bile duct. In some specimens the structures forming the anterior boundry of the epiploic foramen may be incised. Then the coronary, falcifrom and lateral ligaments divided. In some specimens the hepatic portion of the inferior vena cava may be removed with liver; in others it is to the left in place. LOWER PART OF BODY 6 1 — 34 — On removing the liver study its lobes, fissures, peritoneal and nonperitoneal surfaces. Identify all the systems of blood ves- sels associated with the liver. Describe the usual path by which the blood from the gastrointestinal tract reaches the inferior vena cava and thereby the right atrium. Incise the liver and ex- amine cut surface. Lobules? Observe hepatic trinity: (a) portal vein; (b) hepatic artery; (c) bile duct. Distinguish between interlobular and intralobular veins, liepatic veins? The dissector should now remove stomach, duodenum and pancreas, if this has not already been done, and preserve them for review purposes. Expose the kidneys and suprarenal glands together with their veins and arteries. Supernumerary renal arteries? Expose the abdominal portion of ureters and testiular (or ovarian) arteries and veins. Review all the branches arising from the ventral surface of abdominal aorta. — 35 — SuPRARBNAl, Gi,ANDS. CarcfuUy loosen the suprarenal glands from surrounding structures using special care so as not to mutilate the coeliac plexus of nerves. Note blood supply, shape and surfaces. Make an incision through them and observe char- acteristic arrangement of cortex and medulla. Kidney. Loosen the kidneys from their bed and determine their relation to other organs. Make a diagram illustrating the anterior and the posterior surfaces of the right and left kid- neys showing peritoneal and nonperitoneal and visceral contact areas. Note relation of structures entering hilum. Trace course of blood through kidney. On one side of the body the kidney may be removed by cut- ting vessels and ureter. Incise this specimen in the sagittal 62 LOWER PART OF BODY plane. Remove fat and fascia from sinus and observe branches of renal arteries entering kidney substance, the pelvis of ureter and its divisions. Also note : (i) kidney capsules; (2) calyces; (3) medullary substance; (4) renal papillae; (5) cortical substance; (6) medullary rays : (7) renal columns; (8) glomeruli; (9) interlobar, arhiform and interlobular blood vessels. Stellate veins? The ureter connecting one kidney with bladder should be left intact and the kidney placed in the pelvis. — 36 — Study the sympathetic plexuses of abdomen. Identify coeliac plexus, the coeliac ganglion and . subdivisions. Demonstrate its relation to splanchnic, vagus and phrenic nerves. Study the sub- sidiary plexuses, (i) gastric; (2) hepatic; (3) splenic; (3) diaphragmatic; (4) renal; (5) spermatic (or ovarian); (3) superior mesenteric; (7) aortic; (8) inferior mesenteric; (9) hypogastric. Demonstrate the lumbar portion of the sympathetic trunk; its connection with spinal nerves and visceral branches. Ob- serve its continuation upward into thorax and downward into pelvis. Study lymphatics of abdomen. Demonstrate cisterna chyli with tributaries: (a) right and left lumbar trunks; (b) intestinal trunk. Follow thoracic duct upward through diaphragm and note its relations. — 37 — Diaphragm. Remove peritoneum and fascia from under sur- face of diaphragm and study its structure and attachments. Note character of : LOWfiR PART Of BODY 63 (i) medial, intermediate and lateral crura; (2) medial and lateral lumbocostal arches; (3) aortic hiatus; (4) oesophageal hiatus; (5) foramen for inferior vena cava. Review all the structure passing through diaphragm. Nerve supply and action? ■ The psoas major, psoas minor, and iliacus muscles should now be cleaned and examined. In doing this identify the following nerves as they emerge from the substance of the psoas muscle: (i) genito-f emoral ; (a) external spermatic; ' (b) lumboinguinal ; (2) iliohypogastric; (3) ilioinguinal; (4) lateral femoral cutaneous ; (5) femoral; (6) obturator. '" -38- In cleaning these muscles follow the iliopsoas to where it passes under the inguinal ligament. Lumbar Pi,ex0S. The anterior divisions of the spinal nerves forming this plexus have been exposed in a previous dissection and many of its branches can be observed on the surface of the iliopsoas muscle. In order to observe the structural form of ihe lumbar plexus the psoas muscle must be removed down to the level of the inguinal ligament. Make a schematic drawing illustrating the formation and branches of the lumbar plexus. — 39 — The dissector now begins the study of the pelvic and genital organs and it is well during their dissection to frequently con- sult the demonstration skeleton for review of the bony land- marks. Before the relations have been disturbed the pelvic 64 lowsr part op body peritoneum should be reviewed and its reflection upon the pelvic organs determined. Note the following: Male. 1. Recto-vesical pouch. 2. Pararectal fossae. 3. Paravesicle fossae. 4. Rectovesical fold (sacro-genital fold). 5. Transverse vesical fold, 6. Pubovesical folds. Female. 1. Vesico-uterine pounch. 2. Recto-uterine pouch (of Douglas). 3. Broad ligament: (a) mesovarium; (b) mesosalphinx ; (c) mesometrium. 4. Ovarian ligament proper. 5. Ovarian suspensory ligament. 6. Round ligament. 7. Transverse vesical fold. After the general topography of the pelvic organs has been recognized the dissector begins the external genitalia and the urogenital triangle. Perineum. Identify and compare the external genitalia in male and female subjects. Male: (i) penis; (a) body; (b) glaris; (c) prepuce, (d) frenulum; (e) external urethral orifice: (2) scrotum. Female: (i) Mens pubis; (2) vulva; (3) labium major with anterior and posterior commissures ; (4) labium minor with anterior commissure (prepuce and frenulum of clitoris) and posterior commissure (frenulum of labia) ; (s) pudental slit; (6) clitoris; (a) body; (b) glans; (7) navicular fossa of vestibule of vagina; (8) vestibule of vagina;- (9) orifice of vagina; (10) orifice of urethra; (11) paraurethral ducts; (12) LOWER PART OP BODY 65 orifices of ducts of vestibular glands; (13) hymeneal caruncles; ( 14) hymen. -Review structure and arrangement of scrotum and spermatic cord. Observe the size, shape and structure of testis. Complete the reflection of the skin from the perineum. — 40 — Observe the perineal and posterior scrotal (or labial) nerves. Demonstrate the subcutaneous tissue of perineum, its two lay- ers and attachments. Compare with subcutaneous tissue of ab- domen and scrotum. The fascia may then be removed and the structures in the superficial perineal interspace dissected : (i) Muscles: (a) bulbocavernosus. (b) ischiocavernosus. (c) superficial transverse perinei. Observe the same muscles in the female subject. These muscles arc then reflected- to expose the crura of the penis (or clitoris), the bulbous portion of the urethra (or bulbs of vestibule and pars intermedia), and the inferior fascia of the urogenital diaphragm. Penis. Study structure of penis. The skin should be re- moved and the subcutaneous tissue examined and the superficial veins and nerves identified. The erectile bodies may be separated and their structure and attachments determined : (a) corpora cavernosa of the penis (or clitoris). (b) corpus cavernosum of the urethra (of female (?)). In some specimens where the penis is well hardened with formalin cross sections should be made through (a) distal part of glans; (b) proximal part of glans; (c) through body of penis and the structures studied as they appear in cross sec- tion." 66 tOWER PART OF BODY — 41 — The bulbus portion of the urethra should be left intact so that its connection with prostate and bladder may be studied. This is done by separating it entirely from the corpora cavernosa of the penis. The latter together with their crura are detached from the pubic arch, dissecting from the front backwards. Sus- pensory ligament of penis?. While doing this notice particularly the course of the dorsal artery and nerve of the penis. Notice connection of dorsal vein with pudendal venous flexus. Ueogbnitai, Diaphragm. Study its structure and attachment, forrnation of deep perineal interspace and contents : (i) inferior fascia; (2) superior fascia; (3) deep transverse perinei muscle; (4) sphincter urethrae muscle; (5) bulbo-urethral gland; (6) transverse ligament of pelvis. — 42 — In order to facilitate the dissection of the pelvic viscera two proceedures are to be recommended: (a) In some of the bodies make a mid sagittal section (in male subjects slightly to one side of the midline so as to preserve the urethra intact) through symphysis, and pelvic viscera; and (b) in other bodies disarticulate one of the innominate bones at the symphysis pubis and carefully separate it from the pelvis viscera. This makes it possible to study the organs both as they appear in median section and as they appear intact. Rectum. Note its relation to other pelvic organs, to the levator ani muscle and pelvic peritoneum. Its examination is facilitated by separating it from the other pelvic organs. When it is divided in the midline note the character of the interior: (a) transverse rectal folds; (b) rectal columns of Morgagni; rectal sinuses; and haemorrhoidal ring. The haemorrhoidal plexus. Note the character of muscular layer and compare with that of colon. Internal and external sphincter muscles? De- termine the nerve and blood supply of rectum. LOWER PART OF BODY 67 — 43 — Female Genitai, Organs. Observe the broad ligament, its subdivisions and identify all the structures contained virithin folds. Examine the vagina and determine its relations to the bladder, rectum, uterus and peritoneum. Structure and position? Study structure of the uterus, noting division into body and cervix. Fundus? Observe carefully peritoneal relations. Note the different orifices of uterus, significance of round ligaments. Carefully dissect out uterine and ovarian arteries and dem- onstrate blood supply of uterus. Note relation of uterine artery, cervix and vagina to ureter. Blood supply of vagina? Uterine Tubes. Observe: (a) position and relations ; (b) uterine portion; (c) isthmus; (d) ampulla; (e) infundibulum ; (f) fimbria. Ovary. Study structure and relations. Relation to peritoneum? Make an incision and observe character of cut surface. Ovarian follicles (Graafian follicles) ? Corpus luteum? Ligaments of ovary ? Demonstrate (a) epoophoron; (b) paroophoron; (c) vesicular appendix. — 44 — Urinary Bladder and Prostate. In order to expose the lumen of the urethra it should be slit open along its anterior wall and its connection with the bladder demonstrated. If not already done the incision should be continued upward on the important structures situated in the floor of the bladder and the urethra. Examine the bladder in different subjects, noting variation in size and shape. Peritonial relation? Note the loose attach- ment to pubis and its bearing on distention of the bladder and suprapubic cystotomy. Study the structure of its walls and 58 LOWER PART OF BODY character of its mucous membrane. Note particularly the base of the bladder and the manner in which, the ureters open into it. \'esicle triangle? Uvula? Review the relations of the ureter from kidney to bladder. Note size and shape of the prostate. Zvlake out its lobes and its relations to the neck of the bladder and the urogenital diaphragm. Structure and Function? — 45 — Urethra. Determine its three different portions and note structure. Size and form of lumen in each portion. Note the structures found in the floor of the prostatic portion: (i) urethral crest; (2) colliculis semihalis; (3) prostatic utricle; (4) prostatic ducts ; (5) orifices of ejaculatory ducts. Examine the urethra in the female and note differences. Seminai, Tract. Examine the seminal tract as follows: (1) testis (seminal gland) : (a) convoluted seminiferous tubule; (b) straight seminiferous tubules; (c) network; (d) efferent ductules ; (2) Epididymis : (a) ducts of epididymis; (3) deferent duct; (4) seminal vesicle; (5) ejaculatory duct; (6) urethra (?). The ejaculatory ducts can be demonstrated by following from the outside forwards through the substance of the prostate. A small probe may be introduced into the duct and by carefully pushing it forward it is possible to demonstrate the opening into the urethra. Observe carefully relations of seminal vesicles, deferential duct, ureter, bladder, prostate and rectum. LOWBR PART OP BODY (jg -46- Demonstrate the hypogastric plexus and subdivisions. Its re- lation to sacral nerves and sympathetic cord. Make a schematic drawing of hypogastric artery showing the artery and its branches in natural size. The viscera to which the arteries run need not be included. To simplify the dissec- tion the veins may all be removed. The genitourinary organs may now be removed and the inner walls of the true pelvis examined. Study pelvic fascia. Observe structure and attachment of diaphragm of the pelvis. Note arcus tendoneus (white line). Obturator Internus Muscle. Note the character of the fascia covering it. Determine its origin, insertion and action. Examine the obturator canal (weak spot) and structures pass- ing through it. — 47 — After having completed the dissection of the pelvis and con- tained viscera the dissectors begin the study of the lower ex- tremity. Remove the skin from the entire lower extremity, being care- ful not to remove the subcutaneous tissue with the skin flap and thereby destroy superficial structures. Demonstrate all the superficial veins and lymphatics of lower extremity. - 48- Identify and note distribution of all of the cutaneous nerves of the lower extremity: (Figs. 719, 720, 721, 584.) (i) cluneal; (2) lateral cutaneous branches of iliohypogastric and twelfth thoracic ; (3) ilioinguinal; (4) lumboinguinal ; "JO l'owbr part of body (5) anterior and lateral femoral' cutaneous ; (6) cutaneous branch of obturator; (7) saphenous; (a) medial crural cutaneous; (b) infrapatellar; (8) superficial peroneal; (a) medial dorsal cutaneous; (b) intermediate dorsal cutaneous; (9) lateral, sural cutaneous; (10) rnedial sural cutaneous; (11) sural; (a) lateral dorsal cutaneous; (13) digital branches of plantar nerves. — 49 — The remainder of the subcutaneous tissue may now be re- moved, preserving the connections of the larger veins and the attachment of the nerves. Cribriform fascia? Study the deep fascia of the extremity and identify its sub- divisions into : (a) fascia lata; (b) crural fascia; (c) plantar fascia; (d) fascia of the dorsum of foot. Demonstrate fossa ovalis. Note the thickening about the ankle in the form of annular ligaments : (i) cruciate ligament; (2) transverse ligament; (3) lanciniate ligament; (4) retinacular ligament. Determine the attachments and nerve supply of the tensor fasciae latae muscle. Iliotibial band? LOWER PART OF BODY 71 Popliteal Space. Fig. 718. Before disturbing the relation of the structures of the thigh and leg the size, boundries and contents of the popliteal space should be demonstrated. Re- move the deep fascia forming the roof and observe course of short saphenous vein. Note posterior femoral cutaneous nerve lying beneath the fascia. Remove fat and observe contents. — 50 — Demonstrate the boundries of the femoral triangle after which the deep fascia may be removed from this area. Note femoral sheath and its three compartments: (a) arterial; (b) venous; and (c) femoral canal. Study femoral hernia and verify cov- erings on the cadaver. What are the contents of the triangle. Adductor Canal. Determine its position and length. Remove the fascia lata over this area and expose and separate muscles forming wall. Demonstrate contents of the canal. — 51 — Remove the fascia lata from the ventral portion of the thigh and expose the sartorius and quadriceps femoris muscles. Prepatellar bursa? Femoral Artery. Separate more completely the muscles of the thigh so as to expose the femoral vessels. The small veins may be removed to simplify the dissection.. Review the su- perficial epigastric, superficial circumflex iliac, superficial ex- ternal pudendal , and deep external pudendal branches. Dissect following branches : (a) Deep femoral: (i) lateral circumflex; (2) medial circumflex; (3) three perforating branches. (b) Muscular branches. (c) Hightest genicular. Study anastomoses of femoral artery. 72 LOWSR PART 01? BODY 52 — Adductor Musci,es. Observe origin, insertion and relations of the adductor muscles. After the adductor longus and pectineus have been studied they may be separated at their origin. Identify obturator nerve as it emerges from obturator canal and follow its branches to destination. Adductor minimus muscle? luopsoAS Muscle. Complete the study of the iliopsoas down to insertion and note its relation to inguinal ligament. Muscular lacuna? Vascular lacuna? Complete the dissection of the external rotator muscles of the thigh (a) piriformis, (b) internal obturator -with superior and inferior gemelli; (c) quadratus femoris; (d) obturator ex- ternus. Follow posterior femoral cutaneous nerve to termina- tion. Dissect the hamstring muscles and follow their insertion down to tibia and fibula. Pes anserinus? Study course and branches of sciatic nerve. Blood supply? Observe anastomoses of branches of femoral artery with other systems. — 53 — The deep fascia of the leg and dorsum of the foot can be removed with the exception of the annular ligament about the ankle. In cleaning them notice the sheaths for the tendons, exploring them with probe to determine their extent. In cleaning the muscles of the leg be careful to preserve the relation of the tendons to the lateral and medial maleoli. The insertion of the peroneus longus cannot be seen until the muscles of the foot are dissected. Muscles of the leg. A. Anterior group : (i) tibialis anterior; (2) extensor digitorum longus; (3) peroneus tertius; (4) extensor hallucis longus. B. Lateral group : (i) peroneus longus; (2) peroneus brevis. LOWER PART OF BODY 73 — 54 — C. Posterior group ; (a) superficial muscles : (i) gastrocnemius; (2) plantaris; (3) soleus; (b) deep muscles : (i) posterior tibial; (2) flexor hallucis longus; (3) flexor digitorum longus. The heads of the gastrocnemius may be divided to expose the plantaris and soleus. After these muscles have been studied they may be separated at their origin and turned downward to expose the deep muscles. Observe the attachments of the intermuscular septa of the crural fascia that subdivide the leg muscles into four groups. — 55 — Study the course of the popliteal artery and its branches. Study anterior and posterior tibial arteries. After identifying the veins the smaller ones may be removed and the larger ones split open and the valves demonstrated. Observe the possibilities of col- lateral circulation in the knee, leg and ankle regions. — 56 — Foot. Notice character and attachments of plantar sponeurosis after which it may be removed. Clean and study flexor digitorum brevis. It may then be separated at its origin to expose the following deep muscles of foot as well as tendons of muscles of the leg: (1) abductor digiti quinti; (2) abductor hallucis ; (3) quadratus plantae, tendon of flexor digitorum longus and lumbricalis ; 74 LOWER PART OP BODY (4) tendon of flexor hallucis longus. Note particularly the manner of insertion of the flexor digitorum longus and brevis and compare them with analogus muscles of the fingers. — 57 — Study all the nerves and blood vessels of the foot. To expose the deep muscles of the foot it is well to divide the tendon of the flexor digitorum longus between the attachment of the quadratus plantae and lumbricales muscles. Study: (i) flexor hallucis brevis; (2) adductor hallucis; (a) oblique head; (b) transverse head; (3) flexor digiti quinti brevis; (4) opponens digiti quinti; (5) interossei; (a) dorsal (abductors) ; (b) plantar (adductors) ; (6) tendon of peroneus longus. The tendons of the lumbricales and interossei can be well ex- posed by dividing the transverse ligaments connecting the heads of the metatarsal bones and forcibly splitting apart the metatarsal bones. Summarize nerve supply of all intrinsic muscles of foot. Com- pare muscles of hand and of foot as to number, terminology, nerve supply and note differences. - 58- Review all of the muscles of the lower extremity, noticing points of attachment and nerve supply. Notice particularly the tendons and bony landmarks about the knee and ankle. Tabulate all of the nerves of the lower extremity, giving muscles and skin areas aupplied by each. The instructor in charge will designate certain specimens on which the arterial and nervous systems are to be labelled, then removed and pinned out upon a board. LOWER PART OF BODY 75 — 59 — The muscles are now to be removed from the specimen and a careful study made of the joints and ligaments. Study the capsule of each joint and its accessory ligaments. The joints may then be opened and the synovial membrane and articular surfaces examined. Hip joint: (I (3 (4 (5 (6: (7 (8 Knee (I (2 (3 (4 (5 (6 (7 cs: (9 (lO (II (12 (13 (14 (IS capsule ; iliofemoral ligament; pubocapsular ligament; ischiocapsular ligament ; round ligament; zona orbicularis; glenoid lip; transverse ligament. joint : capsule ; fibular collateral ligament; tibial collateral ligament; oblique poplitial; arcuate popliteal; patellar ligament; anterior cruciate ligament; posterior cruciate ligament; lateral meniscus; medial meniscus; transverse ligament; patellar synovial fold; alar folds; synovial membrane; articular surfaces. Study all bursae connected with these joints. yfi LOWER PART OF BODY — 60 — Tibiofibular joint: (a) superior joint; (i) articular capsule; (2) capitular ligament; (b) interossevs membrane; (c) inferior joint; (i) anterior ligament of lateral maleolus; (2) posterior ligament of lateral maleolus. Ankle joint: (i) capsule; (2) lateral strengthenings bands; (a) ant. talofibular ligament; (b) post, talofibular ligament; (c) calcaneofibular ligament; (3) medial strengthening band or deltoid ligament; (a) anterior talotibial ligament; (b) posterior talotibial ligament; (c) tibionavicular ligament; (d) calcaneonavicular ligament; (4) synovial membrane. Examine carefully all of the ligaments that aid in maintaining the arch of the foot. Demonstrate the intertarsal, the torsometatarsal, the metatar- sophalangeal, and the interphalangeal joints and their principal ligaments.