DUPLICATE 
 
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 HBleference Ciljrarp 
 
THE 
 
 ANATOMICAL AND HISTOLOGICAL DISSECTION 
 
 OF 
 
 THE HUMAN EAE 
 
 IN THE NORMAL AND DISEASED CONDITION. 
 
 DR. ADAM POLHZEE, 
 
 PBOFESSOR OF OTOLOGY IN THE IMPERIAL ROYAL UNIVERSITY OF VIENNA, ETC. 
 
 §;i-attslafe6 from tl)c §exxnaix 
 
 GEORGE STONE. 
 
 WITH 164 ILLUSTRATIONS AND 1 PLATE IN THE TEXT. 
 
 LONDON : 
 BAILLIERE, TINDALL AND COX, 
 
 20 & 21, KING WILLIAM STREET, STRANH. 
 
 1892. 
 
 [^All riyhts rescrccd.] 
 


 PREFACE TO THE TRANSLATION. 
 
 A. (;iLANCE at the original work convinced me that I had to 
 deal with a task different from that which falls to the lot of 
 one who undertakes to render into readable Ensflish an 
 ordinary handbook of Otology, where considerable latitude 
 of style is allowed. 
 
 In the present work, where precise rules as to special 
 dissections and modes of preparing the various parts of the 
 organ of hearing are given, it has frequently been unavoid- 
 able to translate almost literally. 
 
 I hope, however, that reasonable limits have not been 
 exceeded when it was found advisable to sacrifice smoothness 
 of style to faithful rendering of very minute, though most 
 important details, in the exhaustive treatment of the subject 
 by so eminent an authority as Professor Politzer. 
 
 Attention is called to the lettering in 29 of the 164 
 illustrations, which were printed from cliches used for the 
 Enoflish edition of the Author's Text-Book of Diseases of 
 the Ear. 
 
 GEORGE STONE, 
 
 88, PtODNKY Street, Liverpool, 
 
 S^ October, 1891. 
 
 CD 
 05 
 
 IS. 
 
 01 
 
 < 
 
 356765 
 
Digitized by tine Internet Arciiive 
 
 in 2010 witii funding from 
 
 Open Knowledge Commons (for the Medical Heritage Library project) 
 
 http://www.archive.org/details/anatomicalhistolOOpoli 
 
To Mr. George Stone, Aural Surgeon, Liverpool: 
 
 Dear Mr. Stone, 
 
 I have read with much interest the translation of 
 my work, '' ZergHederung des Gehororgans," which you 
 were good enough to send me ; and I cannot but con- 
 gratulate you on the patience bestowed upon it, and on 
 the remarkable exactness in the renderino- both as reorards 
 scientific interpretation, and clearness and conciseness of 
 style, which invest the translation with the character of 
 an original work. 
 
 As our confreres in England and America, in common 
 with the Otologists in other parts of the world, highly 
 esteem the memory of your great countryman, Joseph 
 Toynbee, the founder of the Pathological Anatomy of the 
 Ear, and have always shown the liveliest interest in matters 
 of exact anatomical science, they will, no doubt, give your 
 work a favourable reception. 
 
 Accept my thanks for having honoured my monograph 
 with a translation into your beautiful mother- tongue, and 
 be assured of my best wishes for the success of your con- 
 scientious labours. 
 
 Yours sincerely, 
 
 PROF. DR. A. POLITZER. 
 Vienna, October, 1891, 
 
CONTEKTS. 
 
 PAGE 
 
 Introduction --------- xiii 
 
 First Part. The Anatomical and Pathologico-A.natomical Dissec- 
 tion OF THE Organ of Hearing ----- i 
 I. Instruments necessary for the Preparation of the Organ of Hearing 1 
 Precautions to be taken against Septic Poisoning while 
 Dissecting the Organ of Hearing - - 5 
 II. Removal of the Organ of Hearing prom the Dead Body 7 
 
 1. Removal of the Organ of Hearing from the Bod ij for Anatomical 
 Purposes ------- 8 
 
 Removal of one Organ - - - - - g 
 
 Removal of both Organs ----- 9 
 
 2. Removal of the Organs of Hearing from Bodies loithoitt externally 
 visible Injury to the Skull ------ 9 
 
 (a) Removal of the Organs of Hearing together ivith the Naso- 
 pharynx and the Eustachian Tubes - - - - 10 
 
 Removal of the Organs of Hearing according to the 
 Methods of Wendt and Schalle - - - - 10 
 
 Removal of the Organs of Hearing according to the 
 Author ------- 12 
 
 (b) Removal of the Organs of Hearing ivithout the Structures of 
 
 the Naso-Pharynx, and ivithout the Eustachian Tubes - - 14 
 
 Method of the Author - - - - - 14 
 
 Removal of the Pyramids - - - - - 16 
 
 Removal of the Organs of Hearing according to the 
 
 Method of Dr. Tschudi - - - - - 17 
 
 Removal of the Organs of Hearing from the Cranial 
 Cavity of the New-born Infant - - - 18 
 
 3. Examination of the Cranial Cavity and Brain in Middle-Ear 
 Supjjurations, and Cerebral Disturbances of Hearing terminating 
 fatally - - - - - - - -18 
 
 Examination of the Cranial Cavity in Otitic Meningitis, 
 Abscess of the Brain, and Sinus Phlebitis - - 19 
 
 Examination of the Cranial Cavity in Tumours of the 
 Brain - - - - - - - 22 
 
 III. Dissection of the Macerated Temporal Bone - - 23 
 
 1. Dissection of the Temporal Bone in the New-horn Infant - - 23 
 
 Technique of the Dissection - - - - 23 
 
 Sections of the Temporal Bone of the New-born Infant 24 
 Development of the Osseous Meatus - - - 30 
 
 2. Sections through the Temporal Bone of the Adult - - 33 
 
 Sagittal Sections throush the Temporal Bone of the 
 Adult - - ^ - - - - - 34 
 
 Measurements of the Transverse Diameter of the Meatus 35 
 
 Relation of the Mastoid Antrum and of the Mastoid 
 Cells to the Osseous Meatus - - - - 36 
 
 Sagittal Sections through the Tympanic Cavity and the 
 Osseous Eustachian Tube - - - - 37 
 
 Frontal Sections through the Temporal Bone - - 39 
 
Vm CONTENTS. 
 
 PAGE 
 
 Frontal Sections through the External Meatus, Tympanic 
 
 Cavity, and Labyrinth - - - - - 42 
 
 Measurements of the Dimensions of the Middle Ear on 
 
 the Temporal Bone - - - - - 43 
 
 Horizontal Sections through the Temporal Bone - 44 
 
 Frontal Sections of the Skull through both Temporal 
 
 Bones - - - - - - -47 
 
 Preparation of the Styloid Process in the Temporal Bone 
 
 of the New-born Infant and of the Adult - - 48 
 
 IV. Anatomical and Pathologico-Anatomical Pkeparation of 
 
 THE Organ of Hearing - - - - - - 51 
 
 Introduction - - - - - - 51 
 
 1. Preparation of the Auricle and Cartilaginous Meatus - - 53- 
 
 Preparation of the Auricle - - - - 63 
 
 Preparation of the Cartilaginous Meatus - - - 54 
 
 Preparation of the Muscles of the External Ear - - 57 
 
 2. Opening the External Meatus — Laying Bare of the Outer Surface 
 
 of the Tympanic Memhrane - - - - - 58 
 
 (A) Opening the External Meatus in the Anatomical Dissection 
 
 of the Normal Organ of Hearing - - - - 58 
 
 (B) Opening the External Meatus and Laying Bare the Outer 
 Surface of the Tympanic Membrane in Pathological Dis- 
 sections - - - - - - -60 
 
 Experiments before Opening the Meatus in Pathological 
 Dissections - - - - - - 61 
 
 Ascertaining the State of the Tympanic Membrane after 
 Opening the Osseous Meatus - - - - 62 
 
 3. Opening the Tympanic Cavity hy the Removal of the Tegmen 
 Tymp. --------64 
 
 Examination of the Tympanic Cavity in Pathological 
 Dissections - - - - - - 65 
 
 Ascertaining the Pathological Condition of the Middle Ear 66 
 Method of Demonstrating the Pathological Changes in 
 the Tympanic Cavity - - - - - 66 
 
 4. Separation of the Tympanic Memhrane, with the Malleus and 
 Incus, from the Pyramid - - - - - - 68 
 
 Method of Opening the Tympanic Cavity according to 
 
 Luc« .--..-- 70 
 Making Sagittal Sections of the entire Middle Ear - 71 
 
 5. Preparation of the Tym^mnic Membrane - - - - 73 
 (a) Loosening the Tympanic Membrane from the Sulcus 
 
 Tympanicus - - - - - - -75 
 
 (6) Laying Bare of the Duplicatures on the Inner Surface of 
 the Tympanic Membrane - - - - - 77 
 
 (c) Preparation of Shrapnell's Membrane - - - 78 
 
 (d) Representation of the Ligamentous Apparatus in the Vicinity 
 of the Malleus and Incus, and of the System of Cavities be- 
 tween the Body of the Malleus and Incus and the External 
 Tympanic Wall - - - - '- - - 80 
 
 Preparation of the Ligamentum Mallei Superius - 81 
 
 Preparation of the Ligamentum Mallei Anterius 81 
 
 Preparation of the Ligamentum Mallei Externum - 82 
 
 Preparation of the Ligamentum Incudis Posterius - 82 
 
 Preparation of the Mucous Membrane Folds in the 
 
 Vicinity of the Malleus and Incus - - - 83 
 
 (e) Representation of Prussak's Space, situated above the Short 
 Process of the Malleus - - - - - - 84 
 
 Examination of the Ligamentous Apparatus of the 
 
 Malleus and Incus - - - - - 85 
 
 Pathological Changes in the Malleo-Incudal Niche - 87 
 
 6. Inner Wall of the Tympanic Cavity: its Examination in Patho- 
 logical Dissections - - - - - - 89 
 
CONTENTS. IX 
 
 PAGE 
 
 Examination of the Promontorial Wall in Pathological 
 Dissections - - - - - .90 
 
 Examination of the Pelvis Ovalis in Pathological Dis- 
 sections - - - - - - 92 
 
 Examination of the Pelvis Ovalis in Anchylosis of the 
 
 Stapes - - - - - - - 93 
 
 Examination of the Niche of the Fenestra Rotunda in 
 
 Pathological Dissections - - - - 94 
 
 7. Ossicula --------95 
 
 8. Preparation of the Intra- Tymjyanic Muscles - - - 98 
 
 Preparation of the Musculus Tensor Tymp. - - 98 
 
 Preparation of the Muscnlus Stapedius - - - 99 
 
 9. Preparation of the Cartilagino- Membranous Eustachian Tube and 
 
 of the Tubal Muscles ------ 100 
 
 Preparation of the Musculus Levator Palati Mollis - 102 
 
 Preparation of the Musculus Tensor Palati Mollis - 103 
 
 Preparation of the Tubal Muscles of both Sides - - 104 
 Preparation of the Cartilagino-Membranous Eustachian 
 
 Tube - - - - - - - 105 
 
 10. Preparation of the Mastoid Process - - - - 105 
 
 Representation of the Internal Structure of the Mastoid 
 
 Process ------- 10(5 
 
 Horizontal Sections of the Temporal Bone and of the 
 
 Mastoid Antrum - - - - - 107 
 
 Sagittal Sections through the Mastoid Process - - 110 
 
 Preparation of the Mastoid Process in Pathological Cases 113 
 
 11. Preparatio7i of the Labyrinth - - - - -114 
 (a) Preparation of the Osseous Labyrinth - - - 114 
 
 Preparation of the Labyrinth of the New-born Infant - 114 
 Preparation of the Labyrinth of the Adult - - 116 
 Opening the Vestibule - - - - - 119 
 Frontal and Sagittal Sections through the Vestibule - 120 
 Sections through the Cochlear Capsule - - - 121 
 (J)) Preparation of the Membranous Labyrinth - - - 122 
 Preparation of the Semicircular Canals - - - 123 
 Preparation of the Cochlea - - _ - 125 
 Topographical Sections through the Membranous Laby- 
 rinth ---.--- 127 
 
 12. Preparation of the Aquceductus Vestibidiet Cochlece. {Ductwi Endo- 
 
 et Perilymphaticus} ....-- 128 
 
 (a) Aquceductus Vestihidi ------ 130 
 
 Preparation of the Aquseductus Vestibuli on Macerated 
 
 Temporal Bones - - - - - 130 
 
 Preparation of the Intradural Sac of the Aquaeductus 
 
 Vestibuli- ------ 132 
 
 Preparation of the Intratemporal Portion of the Aqufs- 
 
 ductus Vestibuli - - - - - - 133 
 
 (&) Aquceductus Cochlew. (Ductus Pertly mphaticus^ - - 134 
 
 13. Preparation of the Bloodvessels and Nerves of the Organ of 
 Hearing - - - - - - - -136 
 
 Preparation of the Bloodvessels and Lymphatics - - 135 
 
 Preparation of the Arteries of the Organ of Hearing - 13(i 
 
 Preparation of the Arteria Auricularis Profunda - 137 
 
 Preparation of the Arteria Auditiva Interna - - 138 
 
 Preparation of the Veins of the Organ of Hearing - 138 
 
 Preparation of the Nerves of the Organ of Hearing - 140 
 
 Preparation of the Nervus Auricularis Magnus - - 140 
 Preparation of the Nervus Auriculo-Temporalis, with its 
 
 Radiations on the Temple - - - - 141 
 Preparation of the Origin of the Nervus Auriculo- 
 Temporalis and of the Chorda Tymp. - - - 14J 
 Preparation of the G-anglion Oticum - - - 142 
 
X CONTENTS. 
 
 PAGE 
 
 Preparation of the Ramus Auricularis Vagi - - 143 
 
 Preparation of the Nervus Acusticus and Eervus Facialis 144 
 14. Mahing Topographical Sections of the Organ of Hearing for 
 
 Instruction Purposes ...... I47 
 
 (a) Topographical Sections of the Temporal Bone prepared for 
 Preservation in Spirit - - - - - -147 
 
 1. Horizontal Section through the entire Temporal Bone - 148 
 
 2. Frontal Section through the Auricle, External Meatus, 
 Tympanic Membrane, Tympanum, and Labyrinth - 149 
 
 3. Sagittal Sections through the External Meatus, Mastoid 
 Process, and Maxillary Articulation - - - 150 
 
 4. Frontal Section through the Base of the Skull and both 
 Eustachian Tubes ------ 152 
 
 5. Frontal Section through the entire Skull and the Brain 
 
 in the Frontal Plane of the two External Meatuses - 153 
 (h) Topographical Sections of the Organ of Hearing on 
 
 Decalcified Temporal Bones ----- 156 
 (c) Representation of Topographical Preparations of the Organ 
 of Hearing by the Dry Process - - - - 158 
 
 Topographical Pi'eparations of the Tympanic Membrane 
 
 and of the Eustachian Tube - - - _ 164 
 
 Representation of the Tympanic Membrane in its Rela- 
 tion to the Inner Tympanic Wall - - - 165 
 Topographical Sections of Pathologico-anatomical Pre- 
 parations of the Ear- - - - -166 
 
 V. Making Preparations of the Organ of Hearing by the 
 Process op Corrosion - - - - - - 167 
 
 1. Preparation of the Bone hy Corrosion - - - - 169 
 
 (a) Representation of Preparations by the Medium of Wax 
 
 and Resin - - - - - - -169 
 
 Details of the Corrosion Cast - - . . 171 
 
 Galvanoplastic Coating of the Corrosion Preparations - 172 
 Making Preparations of the Labyrinth by the Wax and 
 Resin Process - - - - - -173 
 
 (b) Representation of Metallic Corrosion Preparations of the 
 Organ of Hearing - - - - - - 174 
 
 Metallic Corrosions of the Ear after Prof. v. Brunn - 175 
 
 Metallic Corrosions of the Ear after Dr. Siebenmann - 177 
 
 Metallic Corrosions of the Ear after the Author's Method 178 
 
 Metallic Casts of the Labyrinth - - - - 178 
 
 2. Corrosion Prep)arations of Soft Parts - - - - 179 
 
 Corrosion Preparations of the Auricle and of the Ex- 
 ternal Meatus - - - - - - 179 
 
 Corrosion Casts of the Middle Ear - - - 180 
 
 Corrosion Casts of the Middle Ear by the Medium of 
 Celloidin and Parafl&n - - - - - 182 
 
 VI. Mounting and Preserving of Anatomical and Pathologi- 
 cal Preparations of the Ear - - - - - 184 
 Preparatory Methods - - - - - -184 
 
 1. Soaking the Preparations in Water . - - I84 
 
 2. Bleaching the Preparations Intended for Preserva- 
 
 tion - - - - - - - 184 
 
 Mounting of the Preparations - - . _ - 185 
 
 1. Mounting of Spirit Preparations . . - - 185 
 
 Mounting of Pathologico-anatomical Preparations - 186 
 
 2. Mounting of Dry Preparations ----- 188 
 
 Protection of Dry Preparations from Destruction by 
 
 Insects ------- 190 
 
 Second Part. The Histological Examination of the Organ of Hear- 
 ing IN its Normal and Pathological Condition - - - 193 
 Introduction ...... 193 
 
 Preparatory Methods - - - - - 194 
 
CONTENTS. XI 
 
 l'A(.i; 
 
 1. Fixing and Hardeninr/ - - - - - . 194 
 
 1. Chromic Acid and its Salts.— Miiller's Fluid.— 2. The 
 Fixing Fluid of Tafani.— 3. The Fixing Fluid of Vla- 
 kovic, Urban Pritchard's Fixing Fluid, Flemming's 
 Solution - - - - - - 19.'; 
 
 I. Gold-staining .-.--. i<j(^ 
 
 II. Osmium Treatment ------ 198 
 
 2. Decalcification - - - - - - - 199 
 
 Methods of Decalcification : 
 
 1. Miiller's Fluid. -2. Chromic Acid Method.~3. Picric 
 Acid. — 4. Decalcification by Nitric Acid. — 5. Decalci- 
 jfication by Hydrochloric Acid - - - 200-202 
 
 3. Emhedclivg and Sectioning . . - - _ 202 
 
 Mode of Preparing the Celloidin Solution - - 203 
 
 Method of Celloidin Embedding - - - - 204 
 
 Making Microscopical Sections of the Organ of Hearing- 205 
 
 4. Staining of the Sections ------ 206 
 
 1. Carmine Staining. — 2. Eosin Staining. — 3. Haema- 
 
 toxylin Staining . - - - . 206 
 
 Bacteria Staining on Sections - - . - 2U7 
 
 5. Clearing U2) and Mounting of the Sections - _ . 208 
 
 6. Serial Sections of the Organ of Hearing - - - - 209 
 
 Special Part - - - - - - - - -211 
 
 I. Histological Examination of the Auricle and of the 
 Cartilaginous Meatus - - - - - ' - 211 
 
 II. Histological Examination of the Lining of the Osseous 
 
 Meatus - - - - - - - - 213 
 
 III. Histological Examination of the Membrana Tympani - 214 
 (o) Histological Examination of the Tympanic Membrane on 
 
 Surface Preparations ------ 214 
 
 (li) Histological Examination of the Tympanic Membrane on 
 
 Sections - - - - - - - 218 
 
 Horizontal Serial Sections of the Tympanic Membrane 
 
 and of the Handle of the Malleus - - - 221 
 
 Horizontal Sections through Tympanic Membrane and 
 Manubrium ------ 222 
 
 Vertical Sections through Tympanic Membrane and 
 Manubrium _.---- 225 
 
 Histological Examination of the Tympanic Membrane in 
 Pathological Cases - . - . - 226 
 
 lY. Histological Examination of the Mucous Lining of thk 
 
 Tympanic Cavity ------- 227 
 
 1. I^xamination of the Mucous Lining of the Tympanum on Surface 
 Preparations ------- 227 
 
 Examination of the Pathologically-altered Mucous 
 Lining of the Tympanum on Surface Preparations - 229 
 
 2. Examination of the Mucous Lining of the Tympanum on Sections 229 
 
 Histological Examination of the Folds and Filaments of 
 
 the Tympanum ------ 231 
 
 Examination of the Pathologico-anatomical Changes in 
 
 the Mucous Lining of the Tympanum on Sections - 232 
 The Histological Examination of the Pathologiccd Changes in the 
 two Labyrinthine Fenestrce . - . . - 232 
 
 Histological Examination of the Changes in the Fenestra 
 
 Ovalis and its Niche ----- 233 
 Histological Examination of the Membrane and Niche 
 
 of the Fenestra Rotunda - . - - 235 
 
 V. The Histological Examination of the Ossicula - - 236 
 
 1. Histologiccd Examination of the Malleo-incudal Articulation - 236 
 
 2. Histological Examimition of the Lncudo-stapedial Articulation - 237 
 
Xll CONTENTS. 
 
 PAGE 
 
 3. Histological Examination of the Stapedio-vestibular Connection - 238 
 Histological Examination of the Articular Connections 
 of the Ossicles in Pathological Cases - - . 239 
 
 VI. Histological Examination of the Intra-tympanic Muscles 240 
 
 VII. Histological Examination op the Eustachian Tube - 241 
 
 Microscopical Sections through the Cartilagino-mem- 
 branous Eustachian Tube . . . _ 241 
 
 Histological Examination of the Osseous Eustachian 
 Tube - - - - - - - 243 
 
 Structural Changes in the Eustachian Tube in Patholo- 
 gical Cases -.---. 243 
 
 Addenda. Histological Examination of the Mastoid 
 Process ------- 243 
 
 Vlir. Histological Examination of the Labyrinth - - 244 
 
 1. Histological Examination of the Vestibular Structures - - 246 
 
 Examination of the Vestibular Structures on Horizontal 
 Sections ---___ 246 
 
 Examination of the Vestibular Structures on Frontal 
 Sections ------- 248 
 
 Structure of the Vestibular Saccules - - - 248 
 
 2. Examination of the Amjmllce and of the Membranous Semicircu- 
 lar Canals - - - - - - -250 
 
 3. Histological Examination of the Membranous Structures and of 
 
 the Terminal Apparatus in the Cochlea - . - - 251 
 
 Examination of Sections through the Cochlea under 
 
 Low Magnifying Power . . _ _ 252 
 
 Examination of Corti's Organ - _ - - 253 
 
 Histological Examination of the Internal Auditory Meatus and of 
 the Nervus Acusticus ------ 255 
 
 Examination of the Nervus Acusticus on Longitudinal 
 Sections ------- 255 
 
 The Ganglion Spirale ----- 256 
 
 Examination of the Internal Meatus, of the Nervus Acus- 
 ticus and of the Nervus Facialis on Transverse Sections 256 
 Histological Examination of the Aqueducts of the Labyrinth - 257 
 TojJograjMcal Serial Sections of JSormal and Pathological 
 Organs of Hearing ...... 258 
 
 IX. Histological Examination of the Central Course of the 
 
 Nervus Acusticus .--..- 260 
 
 Methods of Hardening, Fixing, and Staining - - 260 
 
 1. Weigert's Method - - - - - 261 
 
 2. Pal's Method - - - - - - 261 
 
 Transverse Sections through the Medulla Oblongata in 
 
 the Lowest Planes of the Acusticus - - - 262 
 Transverse Sections of the Oblongata in the Higher 
 
 Planes of the Acusticus ----- 262 
 
 Origin and Central Continuations of the N. Acusticus - 264 
 The Microscopical Dissection of the Medulla ^Oblongata 
 
 and of the Temporal Lobe in Pathological Cases - 265 
 
 Literature - - - - - - - - - 266 
 
 ludex of Authors ..--.-.- 271 
 
INTRODUCTION. 
 
 The progress which during recent years has been attendant upon 
 medical research in the field of Otology has been most marked. No 
 doubt the sound pathological methods pursued in modern investiga- 
 tion into this subject have contributed very largely to this desirable 
 condition of things, and have materially assisted to popularize the 
 hitherto neglected study of the anatomy of the human ear. Ever 
 since the labours of Toynbee, it has been fully realized that a know- 
 ledge of the pathological anatomy of the organ under discussion 
 is absolutely necessary to a right comprehension and successful treat- 
 ment of its diseases. The complicated character of the structure of 
 the organ of hearing, and the involved nature of its connections with 
 the adjoining structures and cavities, are such that they can only be 
 intelligently studied by frequent practice in the preparation of speci- 
 mens. Those who look for instruction on the subject of the structure 
 of the ear from preparations ready to hand, or are satisfied with 
 pictorial illustrations and letter-press description, will never acquire a 
 thorough knowledge of the topographical position of the various 
 parts of the ear. To the aural surgeon in particular, piactice in 
 dissection work is indispensable. It is onlj^ by unremitting study and 
 manipulation of specimens that he can hope to attain to that deo-ree 
 of confidence so necessary to produce satisfactory results, when per- 
 forming an operation in such close proximity to organs of vital im- 
 portance. If any further argument were necessary to show that a 
 methodical study of models is a sine qua non of proficiency in this 
 department of medical research, it is to be found in the fact that it is 
 only by a thorough acquaintance with the topographical relations of 
 the parts of the normal ear that anything like a safe theory can be 
 formulated as to the conditions obtaining in the abnormal ear under 
 observation. The beautiful anatomical work of Scarpa, Breschet, and 
 the artistic preparations of Sommering, Ilg, Hyrtl, and others, are 
 greatly to be admired, although the methods of dissection bequeathed 
 them by the older anatomists could only be denominated imperfect. 
 For ordinary purposes, however, a more simple type of model sufiices. 
 
xiv INTRODUCTION. 
 
 Specimens should be prepared either for practice in dissection, or 
 for illustration in teaching ; and the simpler their construction, pro- 
 vided of course they are scientifically true, the more efl&cacious will 
 they prove. 
 
 The first recorded attempt to arrive at a knowledge of the organ 
 of hearing by the assistance of dissection, dates back to the sixteenth 
 and seventeenth centuries, when the revival of the science of anatomy 
 gave so great an impetus to the study of such phases of medical science. 
 In spite of this, however, Fallopius, Ph. Ingrassias, Bartholomeo 
 Eustachio, Valsalva, Cassebohm, Casserius, Fabricius ab Aquapen- 
 dente, have transmitted to posterity but few practical hints relative 
 to the dissection of the human ear. From this period, down to a 
 comparatively recent date, the subject has hardly attracted that 
 .attention and consideration which its importance merits. Toynbee, 
 Hyrtl, Van den Broek, Sappey, Von Troltsch, Kolliker, Voltolini, Moos, 
 Zaufal, Brunner, Rlidinger, Zuckerkandl, Lucse, Wendt, Schalle, 
 Schwalbe and others, while they have given to the world an elaborate 
 wealth of detail relative to aural anatomy, have hardly treated the 
 matter with that comprehensive scope which is so necessary to enable 
 students to obtain a grasp of the whole subject. 
 
 This fact, combined with the expressed wish of many of those who 
 attended my lectures, has induced me to venture to bring together in 
 a clear manner the result of modern scientific research in this most 
 interesting field of anatomical inquiry. For the past twenty-five years 
 I have pursued, during the intervals of leisure from my professional 
 otological work, an uninterrupted study of the normal and patho- 
 logical anatomy and histology of the ear, and I may say that the 
 resultant knowledge and experience thus gained, together with 
 matter collected for lectures, form a basis which has proved invaluable 
 to me in preparing the present work. 
 
 In dealing with the various methods of preparation which are 
 employed in the anatomical and histological dissection of the ear, 
 I have endeavoured to be as minute as possible, and the aim kept in 
 view has been the finding and the representing with facility the 
 various parts of the organ in their respective positions. The same 
 section of the work treats of the best methods of preserving a collec- 
 tion of preparations, whether wet or dry, and the means to be em- 
 ployed in adjusting and mounting them. I have contented myself, 
 relative to making the technical proceeding available for pathologico- 
 anatomical study, merely with the main features, because the manifold 
 morbid changes in the middle ear, and the frequently complicated 
 alterations in the temporal bone, would render it impossible to give 
 a description of all cases occurring in dissection. I am convinced 
 
INTRODUCTION. XV 
 
 that the best means of hitting upon the right method of preparation 
 in comphcated pathological cases, is to be thoroughly acquainted 
 with the technicalities of the work of dissecting the normal ear. 
 
 A considerable portion of the work is devoted to the histological 
 examination of the organ of hearing. I need hardly point out how 
 important is this section of the subject. Those who have studied the 
 results of recent researches in this branch uf the subject, and more 
 especially in the pathological histology of the labyrinth, must admit 
 that this phase of the science is yet in its infancy, and that it offers a 
 most enticing field for original investigation. The difficulties, how- 
 ever, presented by the complicated relative structures of the mem- 
 branous labyrinth are necessarily very great, but these will be 
 reduced in proportion as the methods of examination employed 
 increase in efficiency. As an example of what recent investigation 
 has achieved, I need only allude to the important progress made in 
 the histological representation of the human labyrinth on the basis of 
 the latest results of microscopical investigation, results which un- 
 doubtedly are the foreshadowing of great advance in the pathologico- 
 anatomical examination of the labyrinth. 
 
ERRATA. 
 
 Page 7, line 13 from foot, for 'section' ri-ad 'dissection.' 
 
 Page 18, line 9 from top, omit ' that.' 
 
 Page 28, line 20 from foot, for ' canal, tensor. -tymp.' read ' canal, tensor tjmp.' 
 
 Page 64, line 6 from top, /or ' mastoid eum ' 7-ead 'mastoideum.' 
 
 Page 97, line 16 from foot, /or ' making 'read ' mounting.' 
 
 Page 105, first line, /or 'Representation of read 'Making.' 
 
 Pages 129, 131, 135, 169, 170 and 176,/or ' aquseducts ' read 'aqueducts.' 
 
 Page 134, lines 2, 6, 12 from top, and line 17 from foot] 
 
 Page 135, line 4 from top, and line 18 from foot r for ' aquseduct ' read ' ac 
 
 Page 177, line 5 from top J 
 
 Page 189, line 11 from top, place bracket after the word ' high.' 
 
 Page 203, line 11 from top, insert bracket after ' Corti's organ.' 
 
 Page 211, line 7 from top, insert ' and ' after elder-pith, 
 
 Pagd 232, line 6 from top, for ' will be ' read ' are.' 
 
 Page 242, at the lowest extremity of Fig. 152, place the letter ' h.' 
 
 In the chapter on ' Preparatory Methods, '/or ' Gilding ' read ' Gold-staining,' 
 
FIRST PART. 
 
 THE ANATOMICAL AND PATHOLOGICO- ANATOMICAL 
 OF THE ORGAN OF HEARING. 
 
 DISSECTION 
 
 I. 
 
 Insteuments necessaky for the Preparation of the Organ 
 
 OF Hearing. 
 
 The work of preparing tlie organ of hearing is materially facilitated 
 by the use of instruments adapted to the purpose. Their number 
 and selection must always depend upon the object of the examination. 
 Those who merely wish to study the coarser anatomical relations of 
 the organ will find a few, such as scalpel, saw, hammer, chisel, fixing 
 
 Fig. 1. 
 
 forceps, quite sufl&cient. But those who desire to thoroughly investigate 
 the organ, or to make a complete pathologico-anatomical dissection 
 of it, must employ a more complete set of instruments, and I will 
 here briefly describe what I use in my preparations : 
 
 An anatomical saw, similar to an amputation saw, for opening the 
 
 Fig. 2. 
 
 cranial cavity, and for removing the organ from the base of the skull. 
 For the latter purpose a curved saw (Fig. 1) is recommended, the 
 blade of which can be tightened by means of a steel screw. 
 
 A short fret-saw (Fig. 2) for sawing the organ of hearing and the 
 
 1 
 
2 INSTRUMENTS. 
 
 Structures of the naso-pharynx out of the base of the skull. The 
 length of this saw measures 10 cm., the breadth at the posterior 
 end 1 cm., at the anterior end 3 mm. 
 
 Tig. 3. Fig. 4. 
 
 A strong chisel 2|-3 cm. broad for the purpose of chiselling off the 
 preparation from the base of the skull ; further, two smaller straight 
 ones (Fig. 3), 5 mm. and 3 mm. broad, and a hollow chisel (Fig. 4), 
 
 Fig. 5. 
 
 3 mm. broad, for removing the walls of the auditory meatus, the 
 roof of the tympanic cavity, and for opening the mastoid process 
 and the cavity of the labyrinth. 
 
 Fig. 6. 
 
 A large and a small iron hammer, also a wooden mallet (Fig. 5) ; 
 the former for chiselling out the preparation from the base of the 
 skull, the latter for the finer work on the bone. 
 
 Fig. 
 
 An elevator (Fig. 6) and a fixing forceps (Fig. 7) for lifting out from 
 the base of the skull the preparation when separated with saw and 
 chisel, but still connected with the soft structures. 
 
 Fig. 8. 
 
 A large scalpel, so-called cartilage knife (Fig. 8), for separating the 
 soft parts, when taking out the preparation isolated by saw and chisel, 
 and for dividing the temporo-maxillary articulations. 
 
 Several scalpels of various sizes, for the anatomical preparation of 
 
INSTRUMENTS. 
 
 the soft parts, also a narrow knife (Fig. 9) for cutting through the 
 tendon of the tensor tympani and the incudo-stapedial articulation. 
 
 Fig. 9. 
 
 A raspatory made of hard steel, running to a point and provided with 
 a wooden handle (Burckhardt-Merian), for thorough removal of the soft 
 
 Fig. 10. 
 
 structures, the insertions of tendons, and the periosteum from the bone. 
 A good-sized spring bone forceps ending in a point (Fig. 10), for 
 
 s s< 
 
 Fig. 11. Fig. 12. Fig. 13. 
 
 breaking off the larger pieces of bone, and tAvo smaller forceps, for taking 
 away the smaller particles (Leiter, Vienna). 
 
 1—2 
 
INSTRUMENTS. 
 
 A large and a small curved fret-saw, for making sections and for 
 cutting away the larger portions of bone. For coarser sawing, blades 
 Nos. 2, 3, 4, and for finer, Nos. 00, 0, 1, are used (Schadelbauer, Vienna). 
 
 Three or four graving tools (French burin) of different widths 
 (Fig. 11) (Yautier 45-38, Fig. 12, a, b, c), and several adjusting tools 
 
 Fig. 14. 
 
 (Fig. 12, j) which are chiefly used in the preparation of the osseous 
 labyrinth. For the finer work on the latter, use may be advan- 
 tageously made of various scrapers, as shown in Fig. 13, s, s'. 
 
 A strong, coarse file, two sharp flat files, two or three round files 
 of different strengths, sevetal pointed files and needle files. 
 
 Fig. 15. 
 
 A drill (Fig. 14). 
 
 Several preparing needles, blunt and pointed hooks (Fig. 15). A 
 straight, strong pair of scissors, one blade blunt and the other pointed ; 
 a pair of bone scissors ; a pair of scissors curved on the flat, and two 
 pairs of finer pointed scissors; a grooved director (Fig. 16), metal and 
 
 Fig. 16. 
 
 whalebone probes. A strong, but finely-pointed, anatomical pincette 
 (Fig. 17), several smaller, finer pincettes, and various camel's-hair 
 brushes. 
 
 A ball syringe or wash bottle ; several glass vessels of various sizes, 
 some deep and some shallow ; small saucers and watch glasses ; conical 
 
 Fig. 17. 
 metal canulas and wooden olives fixed on india-rubber tubing, the 
 latter for condensing and rarefying the air in the external meatus. 
 
 A lens or a microscope, for magnifying the details during the 
 preparation, and a reflector for illuminating from time to time the 
 external meatus, the membrana tympani, and the tympanic cavity. 
 
PRECAUTIONS AGAINST SEPTIC POISONING. 5 
 
 Several glass tubes 2-4 mm. wide, terminating in a point; thin 
 small manometric tubes 5-6 mm. long and 0, 5 mm. wide, for 
 measuring the labyrinthine pressure and for proving the mobility 
 of the stapes, and a number of glass threads, for testing that of the 
 ossicula. 
 
 For the preparation of the organ of hearing a small vice is 
 indispensable, notwithstanding the contrary assertions of some 
 anatomists. Although for many manipulations, holding fast the 
 preparation with the left hand in a linen cloth, or resting it against 
 a board, on which two strong projecting ledges are fastened in one 
 corner, is sufficient, yet for cutting fine sections and for carefully 
 chipping off and filing away remains of bone, the fixing of the 
 preparation in the vice cannot be dispensed with. The manner of 
 fixing, however, requires care, because some parts of the temporal 
 bone, especially the outer wall of the tympanic cavity and the parts 
 surrounding the sulcus tymp., may be fractured, and the membrana 
 tympani torn, from too strong pressure of the vice. Best adapted 
 for fixing the preparation in the vice are the squamous portion of the 
 temporal bone, the mastoid process and its place of union with the 
 posterior end of the petrous bone, and for some cases, the anterior 
 portion of the pyramid. 
 
 Precautions to be taken against Septic Poisoning while 
 dissecting the Organ of Hearing. 
 
 In the preparation of the organ of hearing, the same rules as 
 regards preventive measures against any wounds and their conse- 
 quences are generally to be observed, as in making post-mortems- 
 The most frequent injuries occur with beginners, chiefly in consequence 
 of faulty handling of the pointed forceps. When the preparation is 
 held in the left hand, it very easily happens that in breaking off 
 particles of the bone, or in opening the upper wall of the tympanic 
 cavity, the forceps slip, and the points forcibly enter the left hand. 
 One should therefore, from the first, accustom one's self so to hold 
 the preparation and forceps that, when the instrument slips, the points 
 may glide in a direction opposite to the palm of the hand. When 
 using the saw in cutting sections, or when removing portions of bone, 
 the preparation should always be fixed in the vice, and never held 
 with the left hand, because any shifting of the saw might cause very 
 dangerous lacerated wounds. 
 
 Another frequent cause of injury in the work of preparing lies in 
 the spiculse of bone which remain behind, when the preparation is 
 taken out of the skull, and which, for want of sufficient care on the 
 
6 PRECAUTIONS AGAINST SEPTIC POISONING. 
 
 part of tlie operator, cause rather severe scratches on the skin. One 
 should therefore never neglect, before working at a preparation of 
 the temporal bone, to remove all projecting bits of bone with forceps 
 and file. 
 
 Bearing in mind the sad examples of cadaveric infection, the 
 utmost caution should be observed, as frequently preparations are 
 made, where the patient has died of some infectious disease, such as 
 typhus, scarlatina and diphtheria. Especially dangerous are cases 
 where individuals have died of sinus phlebitis and pyaemia, and 
 where consequently the greatest caution should be exercised in handling 
 the preparations of the ear. 
 
 One ought never to neglect, in such an examination, to see that 
 hands and fingers are free from scratches or excoriations. Where 
 this is the case, it is advisable to postpone the work of preparation, 
 and for the purpose of preserving the object, it should be placed 
 either in Riidinger's Preservative Fluid (consisting of 800 parts 
 glycerine, 190 parts carbolic acid, and 12 parts alcohol), or in 
 Wywodzew's Solution (thymol 5'0, alcohol 45*0, glycerine 2160*0, 
 aqua destillata 1080-0), and not to undertake the dissection until 
 the scratch in the hand has cicatrized. The same precaution should 
 be observed in the dissection of less dangerous objects, yet one may, 
 in pathological preparations, where the morbid appearances would 
 be too much changed by a preservative fluid, and a postponement of 
 the dissection would be detrimental, so protect the excoriated parts 
 with a bandage, prepared with iodoform-, carbolized-, or sublimate- 
 gauze, or by means of an indiarubber glove, that infection of the 
 injured parts becomes impossible. 
 
 As it is well known that there are individuals who have a great 
 disposition to become infected with septic matter, so much so that 
 even with intact skin the poison penetrates through the epidermis 
 into the living tissue and produces sometimes lighter, sometimes 
 severer, forms of post-mortem boils or lymphangitis, it is advisable 
 for individuals so predisposed (Siichtige Individuen, Virchow) to 
 undertake the dissection only of such preparations as have been kept 
 for some days in one of the above-mentioned preservative fluids, and 
 thus been completely disinfected, so that septic poisoning of injured 
 parts is hardly possible. 
 
 If, during the dissection, an injury occur to the finger or hand, no 
 matter whether the preparation be disinfected or not, it is advisable, 
 as Nussbaum suggests, to immediately firmly tie the place above the 
 injury with a tape always kept at hand, so as to prevent the reflux 
 of the venous blood and the septic poison from being drawn into 
 the general circulation. After that, a continuous stream of water 
 
REMOVAL OF ORGAN OF HEARING FROM DEAD BODY. 7 
 
 should be allowed to flow over the wound for several minutes, while 
 with the other hand, the blood is pressed from the parts above the 
 wound towards it, whereby the poison, on reaching it, is washed out 
 with all the more certainty. 
 
 When the wound has been sufficiently washed, the ligature which 
 has been checking the circulation may be removed, and an antiseptic 
 bandage applied. As the effect is the more certain the more quickly 
 the wound is disinfected, it is strongly to be advised that the operator 
 should always have close at hand in a box with a tightly-fitting lid, 
 a small phial containing 5°/^ of carbolized water, a small box with 
 iodoform powder, a small quantity of chloroform, some gutta-percha 
 tissue, Billroth cambric, Bruns' wadding and gauze. The wound, after 
 being irrigated, is washed out with a tuft of cotton-wool dipped in 
 carbolized water, then sprinkled with iodoform powder, wrapped up 
 with a moist piece of gauze, and this either enveloped in Billroth 
 cambric and tied with a tape, or the gauze covering is wrapped round 
 with gutta-percha tissue, which may be fastened by being brushed 
 over with chloroform. The injury heals in a short time by first 
 intention without further consequences. 
 
 II. 
 
 The Removal of the Organ of Hearing from the Dead Body. 
 
 The opening of the cranial cavity, for the purpose of removing the 
 organs of hearing, does not differ from the method practised in the 
 anatomical institutions. This being familiar to every student, a 
 detailed description of the proceeding may here be dispensed with. 
 It should, however, be specially pointed out that in private post- 
 mortems, where, after the corpse has been put upon the bier, aU traces 
 of the section should, as far as possible, be concealed, the opening 
 of the cranial cavity must be made with special care, and that the 
 incision from one ear to the other for the separation of the scalp from 
 the calvarium should be made, not across the vertex, but as it is 
 usually done in the institutions of Vienna, across the occipital region. 
 As this is most efficiently carried out by trained, practical, anatomical 
 attendants, it is always advisable, where possible, to secure in private 
 post-mortems such assistance. 
 
 The mode of proceeding in the removal of the organs of hearing 
 from the skull differs materially when the body, as in the Anatomical 
 Schools, is at the disposal of the operator, from that of those cases 
 where, having regard to the placing of the body on the bier, every 
 outwardly visible trace of injury to the head must be avoided. Again, 
 
8 EEMOVAL OF ONE ORGAN. 
 
 the method will be different in post-mortems where, on account of 
 co-existing disease at the naso-pharynx and Eustachian tubes, these 
 parts have also to be examined, from what it will be in those cases 
 where, during life, disease of these parts could be excluded, so that 
 their examination would seem to be superfluous. 
 
 1. REMOVAL OF THE ORGAN OF HEARING FROM THE DEAD BODY FOR 
 ANATOMICAL PURPOSES. 
 
 The simplest proceeding in the removal of the organs of hearing from 
 bodies intended for anatomical examination, and not requiring special 
 regard to be taken, but which, under certain circumstances, may also 
 be observed with bodies about to be laid out, is the following : 
 
 After removing the skull-cap in the regular way, the brain is taken 
 out, and at the same time the acoustic and the facial nerves are 
 carefully divided close to their exit from the medulla oblongata. 
 Next, with a strong scalpel, the skin is divided by a perpendicular 
 incision 8-10 cm. long, commencing 2 cm. behind the insertion of the 
 auricle, that is, immediately behind the mastoid process; and the 
 anterior flap of skin, together with the auricle after detachment from 
 the cartilaginous meatus, is dissected away up to the zygomatic arch. 
 Now, in case only one of the organs is to be removed, a cut is made 
 with the anatomical saw, commencing behind the mastoid process 
 (Fig. 18p, p. 12) and dividing the posterior cranial fossa up to that 
 point of the medial line of the clivus, which lies midway between the 
 sella turcica and the anterior edge of the occipital foramen (o). "With 
 a second cut, almost parallel to the transverse diameter of the skull, 
 the middle cranial fossa is sawn through in a vertical plane, which 
 unites the middle of the zygomatic arch with the tubercle of the sella 
 turcica (z s), and separates the most anterior portion of the pars 
 squamosa, as well as the great wing of the sphenoid and the proc. 
 pterygoid, close to the superior maxilla. The median ends of these 
 two cuts (s o) are united by breaking through, with a broad chisel, 
 the base of the skull in the median line of the sella turcica and the 
 clivus. 
 
 If the base of the skull has been successfully divided, the preparation 
 can be easily removed. Where this is not the case, the bridges of 
 bone, remaining behind, must be cut away with the chisel. The pre- 
 paration is now merely left in connection with the soft structures and 
 the maxillary joint. In order to disconnect it from the latter, the 
 muscular and tendinous attachments to the mastoid process must first 
 of all be quickly dissected up ; the preparation should then be pressed 
 forward and upward, and after cutting through the posterior capsular 
 
REMOVAL OF BOTH ORGANS. » 
 
 wall, the maxillary joint is disarticulated with the cartilage knife. It 
 now suffices to cut through the soft parts of the neck and naso- pharynx, 
 still connected with the preparation, in order to allow the temporal 
 bone to be removed. In such preparations the entire Eustachian tube, 
 with the adjoining parts of the naso-pharynx, are retained. 
 
 In a like manner one proceeds in the removal of both organs from 
 bodies which are to be laid out, with this difference, that the cuts with 
 the saw through the base of the skull are not made up to the median 
 line, but only as far as the lateral borders of the sella turcica and the 
 clivus, and that the cuts are joined, on either side, by a chisel breach 
 (Fig. 18 i i' and u u'), running parallel with the long diameter of the 
 skull. By this means the sella turcica and the clivus will be preserved 
 as a firm bridge between the anterior and posterior parts of the skull, 
 and its collapse will be thus prevented when the body is laid out. 
 If the dissection be made with some care, the cranial cavity filled up 
 with chopped straw or grass, and after accurate readjustment of the 
 calvaria, the cutaneous incision behind the ear and across the occiput 
 be well stitched up, and the body skilfully laid out, nothing will be 
 noticed which might betray any sign of the skull having been inter- 
 fered with. 
 
 The removal of both organs in connection, for definite anatomical 
 purposes, e.g., for showing the angle of inclination of the tympanic 
 membrane, can only be effected when the body is entirely at the 
 disposal of the operator. In this case the anterior saw- cut, made 
 parallel with the transverse diameter of the skull, passes through the 
 entire base of the latter near the tubercul. sellse (Fig. 18 z z'), while 
 the posterior cut, parallel with the anterior, is also carried through 
 the entire base of the skull behind the mastoid processes and through 
 the middle of the foramen occipitale magnum (m m'). As in the 
 former method so here, after disarticulating the maxillary joint; 
 dividing the soft parts, and loosening the occipito-atloid connection, 
 the preparation is removed. It is a matter of course that in normal 
 anatomical preparations, where auricle and cartilaginous meatus are 
 included, these parts should be allowed to remain in connection with 
 the temporal bone. 
 
 2, REMOVAL OF THE ORGANS OF HEARING FROM BODIES WITHOUT 
 EXTERNALLY VISIBLE INJURY TO THE SKULL. 
 
 The proceeding differs materially in the removal of the organ from 
 a body where, externally, no trace of the operation be visible. As 
 in these cases the main object is the examination of pathological 
 changes in the organ, the mode of removal will vary according to the 
 
10 REMOVAL OF ORGANS ACCORDING TO WENDT AND SCHALLE. 
 
 diagnosed seat of the disease during life. Thus if, during life, no 
 morbid changes in the external meatus, in the Eustachian tube, and 
 in the naso-pharynx were proved to exist, these portions of the organ 
 will be excluded, and attention be directed mainly to the removal of 
 the tympanic and labyrinthine structures. 
 
 (<x) Removal of the Organs of Hearing, together with the 
 Naso-pharynx and Eustachian Tubes. 
 
 1. A method of removing the organs of hearing, in connection with 
 the naso-pharynx, without apparent external injury to the skull, was 
 first pointed out by Wendt. He made use of the chisel for gouging 
 out the circumscribed parts of the base of the skull, a proceeding 
 which, even with considerable practice, may easily lead to splintering 
 of the external meatus and tympanic cavity. Much safer, though 
 more troublesome, is the method suggested by Schalle,* which we 
 here briefly describe. 
 
 After taking off the skull-cap and removing the brain, an incision 
 is first made across both clavicles, from the top of one shoulder to 
 the other, then one on either side, which, commencing 4 cm. behind 
 the auricle, passes over the sterno-cleido-mastoid muscle downward 
 and somewhat forward, and meets the incision made along the clavicle 
 at an acute angle. 
 
 Grasping the flap of skin at the upper point of departure, it is 
 separated by a few sweeping strokes, taking as little of the soft parts 
 as possible ; the cartilage of the external meatus is cut through close 
 to the bone, and the maxillary joint, as well as the entire lower edge 
 of the ramus of the corresponding inferior maxilla, are laid bare. 
 When this has been done on both sides, the skin on the anterior 
 surface of the neck is severed from the soft parts, until the lower 
 edge of the maxilla is exposed all round. 
 
 The knife is then pushed in a direction corresponding with the 
 origin of the genio-hyoid muscle through the floor of the mouth, and, 
 while keeping close to the lower jaw, the incisions on both sides are 
 enlarged up to the angles of the maxilla ; the tongue is drawn down 
 and cut away with the soft parts of the pharynx down to the lower 
 border of the larynx. Tongue, larynx, trachea, and oesophagus are, 
 for the purpose of gaining space, dissected off from the vfertebral 
 column with a few ample strokes and pushed down, or entirely taken 
 out. 
 
 After completely removing the soft parts from the cavity of the 
 mouth and naso-pharynx, the capsule of the maxillary joint on both 
 
 * Virchow's Archiv, Bd. 71. 
 
REMOVAL OF ORGANS ACCORDING TO SCHALLE. 11 
 
 sides is divided close to the lower jaw, and the latter drawn so far 
 forward out of the socket that it luxates on the tubercul. articul. 
 In this position the inferior maxilla is fixed by means of a proper 
 chin-holder, and the posterior wall of the pharynx dissected away from 
 the vertebral column. 
 
 In order now to saw out the organs of hearing, together with the 
 structures of the nasal cavity and pharyngeal space, the two surfaces 
 of the maxillary joint are broken through with the chisel from below 
 upward, so as to cause, at the corresponding parts of the middle cranial 
 fossa, a gap large enough to allow a narrow saw-blade to be inserted. 
 This having been done in the breach on the left side, the ends of the 
 blade are connected with the bow of the saw in such a way that its 
 handle rests on the side of the cranial cavity. The operator may 
 now proceed with his work in a sitting position, having the head of 
 the body on a level with his shoulder. The cuts should be carried in 
 a direction as nearly as possible corresponding to the long axis of the 
 .body, and vertically to the base of the skull. The course which the 
 saw should take is, according to Schalle's description, as follows : 
 
 The line of the cut runs from the left breach forward and a little 
 outward, including the anterior median corner of the squamous 
 portion of the temporal bone, then through the great wing of the 
 sphenoid bone, meeting about 1 cm. outward from the superior orbital 
 fissure the roof of the orbital cavity, whence it passes in a curve 
 forward, thub including the greater portion of the latter, reaches, 
 about 15 mm. from the crista galli laterally, the ascending portion of 
 the frontal bone, turns, while keeping close to this in front of the 
 crista, through the foramen coecum to the other side, and meets the 
 right breach in the reverse order. Here it turns in a somewhat short 
 curve outward, and reaches, through the plane of the maxillary joint, 
 without touching the fissura petro-squam., the wall of the cranium 
 again ; keeping close to this, it comes to the posterior edge of the 
 sigmoid sinus, in which it descends with a slight curve to the foramen 
 jugulare, turns, corresponding to the opening of the inferior petrosal 
 sinus, round the tubercul. jugul. dextr., divides the pars basilaris, and 
 avoiding the tubercul. sinistr., passes to the left foramen jugulare ; from 
 here it encircles the left temporal bone in the same manner as on the 
 right side. 
 
 But this method, by which both organs of hearing, together with 
 the structures of the naso-pharynx, may be completely removed, 
 proves in practice too complicated and occupies too much time, nor 
 is the object of effacing outward traces of interference quite attained. 
 
 2. In a more simple manner it may be done by the following 
 method, which I myself use. 
 
12 
 
 EEMOVAL OF ORGANS ACCORDING TO THE AUTHOR. 
 
 By means of a strong drill (Fig. 14) two perpendicular channels (a a') 
 are made in the anterior cranial fossa, 1 cm. right and left of the crista 
 galli, running downwards through the nasal cavity to the lower surface 
 of the hard palate ; through the right channel the small saw repre^ 
 sented in Fig. 2 is introduced from the cranial cavity. A cut (a b) 
 is made with this through the base of the skull, passing first in the 
 anterior cranial fossa backwards and somewhat outwards as far as the 
 inner third of the crista sphenoidalis of the lesser wing of the sphenoid 
 
 Fig. 18. 
 
 bone (2| cm. from the middle line of the base of the skull). At this 
 point the cut takes a strong sweep outwards in the middle cranial 
 fossa (b 1) towards that part of the base of the skull which corresponds 
 to the root of the zygomatic arch, dividing thus the greater wing of 
 the sphenoid bone, and in the temporal bone the maxillary joint and 
 the outer section of the maxillary fossa. When the saw has arrived 
 behind the maxillary joint, that is, in front of the anterior wall of the 
 osseous meatus, a point which projects inwards corresponding to the 
 middle of the clivus of Blumenbach, the instrument should keep 
 
REMOVAL OF ORGANS ACCORDING TO THE AUTHOR. 13 
 
 close to the point where the upper surface of the pyramid turns to 
 the squamous portion of the temporal bone (1) , and the cut be carried 
 as far as the sinus trans versus (1 n). 
 
 This part of the cut divides the middle portion of the osseous meatus 
 and the inner portion of the mastoid cells. The saw now turns from n 
 inwards and somewhat forwards, passes through the open sinus trans- 
 versus to the foramen jugulare, and from here through the posterior 
 third of the dorsum sellse, so that the cut falls immediately in front 
 of the condyloid process (e). In the same manner the base of the 
 skull is sawn through symmetrically on the left side also, and the two 
 channels made with the drill are united laterally from the crista galli 
 by a transverse cut. The cutting through the maxillary joint and 
 osseous meatus up to the sinus transversus occupies considerable time, 
 owing to the thickness and density of the bone to be sawn through, 
 while the division of the anterior, and in a great measure also of the 
 middle and posterior cranial fossse, is accomplished much more 
 quickly. 
 
 The piece of the base of the skull round which the saw-cut has 
 been carried is now loosened by a few vigorous blows with the chisel ; 
 the firm connections still existing at the posterior and lateral parts of 
 the breach are divided by means of a chisel 4-5 cm. broad, while in 
 the region of the naso-pharynx the separation of the remaining bridges 
 must be effected with the fret-saw, partly from the cranial cavity 
 and partly from the mouth. With the object of detaching the 
 preparation from the soft parts, two parallel cuts (r, r') are carried 
 8 cm. right and left of the crista occipitalis int. on the occipital bone 
 downwards as far as the posterior edge of the foramen occipitale, and 
 the two cuts united below by means of a curve. Thereby a longish 
 breach is caused on the occiput, which renders it possible to manipu- 
 late in a horizontal direction towards the lower surface of the base 
 of the skull. While an assistant, with a long branched forceps (Fig. 7) 
 lays hold of the preparation at the sella turcica and at the posterior 
 cut of the dorsum sellse, and raises it up towards the front, first the 
 posterior membraneous wall, then the lateral walls of the pharynx, 
 are cut through with a strong scalpel ; after that the posterior capsular 
 wall of the maxillary joint is divided on both sides, the joints themselves 
 are disarticulated, and the still existing muscular and ligamentous 
 connections are detached with knife and scissors, to completely 
 separate the preparation. In order to effectually close the gap in 
 the occipital bone when laying out the body, the cuts right and left 
 of the crista occipit. int. are so made that their surfaces are directed 
 inwards, in order that the piece of bone, in being fitted in, ma}'' be 
 retained in its position by the mass filling up the cranial cavity. 
 
14 
 
 REMOVAL OF THE ORGANS OF HEARING 
 
 (6) Removal of the Organs of Hearing without the Structures of the 
 Naso-pharynx and without the Eustachian Tubes. 
 
 1. Where, from tlie objective examination during life, no morbid 
 changes in the naso-pharyns and the Eustachian tubes were proved 
 to exist, and where the examination of these parts may thus be 
 dispensed with at the autopsy, the organ can be removed from the 
 
 Fig. 19. 
 skull in a short time, and in a very simple manner. The proceeding 
 is indicated by the lines 1, 2, 3, 4, 5, in Fig. 19. With the broadest 
 chisel (3 cm.), which must be appHed as far as possible horizontally 
 and in a direction parallel with the base of the skull, the fissura petro- 
 basilaris is first cut, from the apex of the pyramid to the foramen 
 jugulare (1). As the edge of the chisel advances outwards along the 
 lower surface of the pyramid, the connections of the soft parts of the 
 
WITHOUT THE NASO-PHARYNX AND EUSTACHIAN TUBES. 15 
 
 temporal bone are also cut below. Then the sinus transversus is 
 broken through by one or two blows with the chisel, from the foramen 
 jugulare to where the sin, petros. super, passes into the sin. trans vers. 
 (2) A third perpendicular cut with the chisel (3) is directed outwards 
 and backwards from the anterior point of the pyramid, between the 
 latter and the foramen ovale, 1 cm. beyond the foramen spinosum. 
 
 The fourth breach (4) made with the chisel to the length of 1 cm. 
 at the posterior external angle of the middle cranial fossa is joined 
 with breach 2. The next following cut (5), carried with the chisel as 
 far as possible outwards at the boundary between the lower surface 
 of the middle cranial fossa and the vertical squamous portion of the 
 temporal bone, divides the osseous meatus about the middle. If the 
 chiselling be not done with care, not only the meatus will be splintered, 
 but cracks in the bone may be caused in all directions, whereby the 
 tympanic membrane will be torn and the ossicles dislocated. 
 
 Before proceeding to this — the most important part of the operation 
 — the breaches 1, 2, 3, 4 made with the chisel are united where their 
 extremities approach each other, by means of smaller chisels, and the 
 connection of the preparation with the neighbouring parts is loosened 
 as much as possible by cutting them sideways with the chisel. Not 
 until then can the osseous meatus be divided in the direction from 
 the cranial cavity, by weaker blows of the mallet, which will drive the 
 chisel gradually deeper. The direction of breach 5 must be such that 
 its ends meet with those of 3 and 4. 
 
 The preparation, being separated from its connections with the bone, 
 is loosened and slightly raised, by introducing the elevator in the 
 breaches 1 and 2, after which any still adhering soft parts are cut 
 through ; the maxillary connection is divided, and the preparation 
 removed. This contains the inner section of the osseous meatus^ the 
 membrana tympani, the tympanic cavity with part of the mastoid 
 cells, and the whole of the labyrinth as well as the auditory and 
 facial nerves. This method is, therefore, adapted not only for such 
 cases where, during life, a labyrinthine affection was diagnosed, but 
 also, and especially, for those so frequently occurring middle-ear 
 processes running their course without perforation of the membrana 
 tympani, in which pathological changes, mostly in the form of 
 adhesions and fusions, set up exclusively in the tympanic cavity, 
 especially in the vicinity of the ossicula, but in which Eustachian tube, 
 mastoid process and external meatus are not affected by the patho- 
 logical process in the tympanic cavity. 
 
 The method here described may be materially simplified in cases 
 of undoubted affection of the labyrinth or of anchylosis of the stapes 
 in the fenestra ovalis ; when it will, of course, be merely a question 
 
16 EEMOVAL OF THE ORGANS OF HEARING 
 
 of removing tlae pyramid. For this purpose, after removal of the 
 tegmen tymp. with a few blows of the chisel (see chapter on Methods 
 of Preparation), the tympanic cavity is inspected, and having ascer- 
 tained that the memb. tymp. and the malleo-incudal articulation are 
 normal, the tendon of the tensor tympani and the incudo-stapedial 
 connection are cut through. With three or four blows with the chisel 
 through the connection of the petrous bone with the clivus, then 
 through the apex, and, in the vicinity of the sinus trans versus, through 
 the base of the pyramid, these parts may be broken off in a few 
 minutes and removed from the skull, the tympanic membrane with 
 the malleus and incus remaining behind. 
 
 2. A new method for obtaining preparations of the temporal bone 
 without disfiguring the body, we owe to Dr. Arthur Tschudi, whose 
 description we here give. 
 
 In order to take out the organs of hearing from bodies where it is 
 not advisable to open the cranial cavity by the removal of the skull- 
 cap, as usually practised, and with the object of avoiding all visible 
 mutilation, the following process may be employed with perfectly 
 satisfactory results. 
 
 Over the planum mastoideum an incision, similar to Wilde's, 
 is made on either side through the scalp, separating it to the 
 length of 10-12 cm. The cut will, therefore, as a rule, fall within 
 the region of the hair. The soft parts are then dissected away by 
 drawing the edges of the incision in the scalp forwards and backwards, 
 in the latter direction so far that the entire mastoid region becomes 
 exposed ; forwards, by separation of the cartilaginous portion of the 
 meatus, and consequently detachment of the auricle up to about the 
 middle of the zygomatic arch. 
 
 By means of an American drill, with a screw-head, an opening is 
 made in the squamous portion of the temporal bone on one side at 
 a height of 4 cm. above the external meatus, which, corresponding 
 to the size of the drill, measures 9 mm. in diameter. The instrument, 
 which is double-edged, has a length of 23 cm., and may thus be driven 
 transversely through the entire skull to penetrate the squamous 
 portion of the temporal bone on the opposite side. The drill can now 
 be taken out of the screw-head, and the blade of a saw is then fixed 
 in at the posterior extremity of the metal borer, where there is a slit, 
 through which a peg passes. The saw-blade, made out of a watch- 
 spring, is 5 mm. wide and 32-33 cm. long. At its ends it is filed 
 out, so as to form hooks, which admit of its being fixed in the above- 
 mentioned pegs in the slits of the borer. The blade of the saw thus 
 fastened is then pulled through the bore-hole by means of the drill, 
 in the same way as drainage tubes are drawn through fistulous 
 
DR. TSCHUDI'S METHOD. 17 
 
 passages. Next the saw-blade is set. The frame of the saw, specially 
 constructed for this purpose, is rectangular, has a span of 37 cm., 
 measures in breadth 14 mm., in thickness 4 mm., and in depth 11 cm. ; 
 it is provided with screw fastenings for tightening it in the handles, 
 both of which are used in sawing. The work of sawing is done 
 starting at the bore-holes, proceeding in a curve forwards and back- 
 wards round the entire exposed surface described above. While doing 
 this the two persons sawing must guide the saw with uniform strokes, 
 first towards the front in a gentle curve in the direction of the 
 zygomatic arch, which is divided on the passage of the saw backwards ; 
 then directing it towards the ascending ramus of the inferior maxilla, 
 this also is divided. The cut leaves the insertion of the tendon of the 
 temporal muscle intact, thus securing a support to the inferior maxilla, 
 which is a matter of consideration in regard to any possible disfigure- 
 ment. When the lower jaw is cut through, the blade of the saw is 
 loosened from the frame and withdrawn ; as before, it is then pulled, 
 by means of the metal borer, through the bore-hole, to be again set 
 in the frame, so as to enable the operators to commence the cut in a 
 backward direction. 
 
 This simply passes in a curve round the mastoid process, and 
 below it joins the first cut. The bone and soft parts being cut all 
 round, the cylinder can now be easily removed. It must be borne in 
 mind, however, that it will be much easier to do so if the surface 
 round which the cut has been carried be larger on one side than on 
 the opposite one, so as to obtain, not exactly a cylindrical, but a 
 slightly conical preparation, which is to be driven out base forward. 
 The mere pressure of the finger is often sufficient to accomplish this. 
 To avoid the somewhat tedious circular cut, the preparation may also 
 be obtained in the form of a wedge. In this case two bore-holes must 
 be made on each side, one 4 cm. perpendicularly above the maxillary 
 joint, the other at the same height, a little behind the mastoid process. 
 The saw is now introduced, and the two bore-holes are united by a 
 horizontal cut, and converging cuts carried from them in a backward 
 direction (in a curve round the mastoid process) till they meet. 
 
 The cutaneous incision must, in such a case, be made T-shape, unless 
 the scalp, as is usual in post-mortem examinations, can be separated 
 from one ear to the other and turned back. 
 
 The preparation thus obtained contains both petrous bones in 
 connection. Anteriorly the cut passes through the sella turcica and 
 divides the Eustachian tubes in such a way that about half a 
 centimetre of the cartilaginous portion of the tube, as well as the 
 entire maxillary articulation, remain in the preparation, while the 
 condyle is separated. 
 
 2 
 
18 EXAMINATION OF THE CRANIAL CAVITY AND BRAIN 
 
 Posteriorly the cut meets tlie base of the skull at the posterior 
 periphery of the occipital foramen 1 cm. behind the articular surface 
 for the atlas. Thus there are in the preparation the two pyramids, 
 together with the mastoid process, the terminal portion of the sinus 
 sigmoideus, as well as the whole of the clivus, a considerable part of 
 the cartilaginous Eustachian tube, and finally the major portion of the 
 cartilaginous external meatus. 
 
 The chief advantage of this mode of preparation consists in this : 
 that after the removal of the petrous bones the roof of the skull is 
 kept intact and the outward shape of the skull preserved, so that after 
 filling up the temporal region with paper or such-like, to prevent a 
 sinking in of the ears, the incisions in the scalp being also stitched up, 
 any disfigurement of the body is avoided. 
 
 It is also to be observed that it is dijSicult, when boring through the 
 temporal bones, to reach the precise spot on the opposite side ; it is, 
 therefore, advisable to drill a hole in each temporal bone separately, 
 marking by exact measurement the spot from the external meatus 
 and from the zygomatic arch. When the boring has been completed 
 it is easy, by introducing the borer into one of the openings, to find 
 the other. 
 
 To remove the organs of hearing from the cranial cavity of the 
 new-born infant, neither chisel nor saw is required. As the sutures 
 between the various bones of the skull are not yet ossified, and the 
 bones themselves still spongy and offer little resistance, a stout pair of 
 scissors is sufficient to cut out those parts of the organ from the base 
 of the skull which are intended for the preparation. In the case of 
 children who have reached the age of several weeks, a stout pair of 
 scissors alone will not accomplish this, and the removal of the organs 
 can only be effected by the use of strong bone scissors, forceps, and 
 sometimes the chisel. 
 
 3. EXAMINATION OF THE CRANIAL CAVITY AND BRAIN IN MIDDLE EAR 
 SUPPURATIONS, AND CEREBRAL DISTURBANCES OF HEARING 
 TERMINATING FATALLY. 
 
 In those morbid processes in the organ of hearing where death 
 is the result of extension of a suppuration of the middle ear to the 
 cranial cavity, or where, during life, a cerebral derangement of hearing 
 was diagnosed, it is necessary, after opening the cranial cavity, to take 
 note of the changes occurring in the meninges, in the cerebral 
 sinuses, and in the brain itself. 
 
 Should, during life, symptoms of meningeal or cerebral affection 
 have existed, it is necessary, after removal of the calvaria, to test 
 
IN OTITIC MENINGITIS, CEREBRAL ABSCESS AND SINUS PHLEBITIS. 19 
 
 the degree of tension of the dura mater. In diffuse meningitis of the 
 convexity of the brain, at times also in basilar meningitis, especially 
 when combined with purulent or serous effusion in the ventricles of 
 the brain, further, in acute and chronic hydrocephalus, the dura mater 
 over the cerebral hemispheres is found tightly stretched and little 
 yielding. On the other hand, in abscesses of the cerebrum, 
 particularly when extensive and situated superficially, a frequently not 
 inconsiderable degree of relaxation and pliancy is found in the corre- 
 sponding parts of the dura mater. 
 
 When the latter has been removed in the usual manner from the 
 upper surface of the cerebral hemispheres, note should be taken of the 
 degree and extent of the hypersemia and serous moistness, or of the 
 purulent infiltration of the pia mater and subarachnoid spaces, and of 
 any casual fluctuation which may be perceived on lightly touching the 
 surface of the brain, and which frequently occurs in superficial cerebral 
 abscesses, and in hydrocephalus. Next, the anterior lobes of the 
 cerebral hemispheres are raised up with the left hand, and the olfactory 
 and optic nerves, both carotid arteries, the infundibulum, and the 
 oculo-motor nerves are cut through in succession. Should, upon 
 raising the anterior lobe, any purulent infiltration be found on the 
 under surface of the brain, the middle lobe must be raised with 
 great care, in order to note any existing adhesions between the dura 
 mater and the brain in the middle fossa of the skull, especially in 
 the region of the tegmen tymp. 
 
 Now follows, on either side, the division in the usual manner of 
 the tentorium cerebelli from the proc. clin. postic. along the upper 
 edge of the pjrramid, the trochlear and trigeminus nerves being cut 
 at the same time. Gradually raising the cerebellum and medulla 
 oblongata from before backwards, we are enabled to cut in succession, 
 as they come into view, first, the abducent, facial, and auditory nerves, 
 further backwards the glosso-pharyngeal, the vagi, accessory nerves of 
 Willis, and the hypoglossal. It now sufiices to separate the connection 
 of the medulla oblongata with the spinal cord, with a scalpel carried 
 along the clivus through the occipital foramen into the vertebral 
 canal, in order to allow the entire brain to be removed from the 
 cranial cavity. 
 
 It should, however, be remarked that in cases where, during life, 
 symptoms of a cerebellar abscess have existed, attention must be 
 directed, when lifting out the cerebellum, whether, and at what point, 
 an adhesion of the latter with the posterior wall of the pyramid exists. 
 Such adhesions between the dura mater and brain in the middle 
 and posterior cranial fossae are not infrequently found, when a middle 
 ear suppuration breaks through at the tegmen tymp., at the antrum 
 
 2—2 
 
20 EXAMINATION OF THE CRANIAL CAVITY AND BRAIN 
 
 mastoid., and at the posterior pyramidal wall. They are the result of 
 inflammation which precedes the breaking through of the suppura- 
 tion on the inner surface of the dura mater, and which from here 
 spreads to the adjoining arachnoid membrane, pia mater, and the 
 brain substance. In the great majority of cases these adhesions are 
 met with in otitic brain abscesses, less frequently in diffuse meningitis, 
 unaccompanied by any such abscess, and affect mostly the immediate 
 neighbourhood of the breach in the bone, and of the opening of the 
 abscess frequently corresponding- with it. After removing the brain 
 from the cranial cavity, the parts at its lower surface, corresponding 
 to the breach in the bone, are next minutely examined, and the 
 intensity and extent of the purulent infiltration at the base of the 
 brain determined. If the brain, at the spot where the bone appears 
 ulcerated, should show a discoloured depressed place, where, on 
 slightly pressing the neighbouring parts, pus oozes out, the corre- 
 sponding lobe should be cut through longitudinally, so as to ascertain 
 the size and seat of the abscess, its contents, the condition of its walls, 
 and of the neighbouring brain substance. Not infrequently the 
 abscess communicates directly with the seat of the suppuration in 
 the temporal bone ; sometimes, however, even on a most minute 
 examination, no connection between these two purulent foci can be 
 found to exist. Finally the ventricles of the brain must be closely 
 examined. They very often contain, in consecutive middle ear sup- 
 purations which have extended to the cranial cavity, cloudy purulent 
 fluid, their walls appear injected, ecchymosed, and in places softened. 
 After noting down the result of the examination of the brain, the 
 base of the skull should once more be closely examined before the 
 organs of hearing are removed, in order to ascertain whether there are 
 any changes in the dura mater within the region of the temporal bone, 
 and to what extent it may be ulcerated, before stripping it off. The 
 region above the tegm. tymp. and antrum mastoid., sometimes also 
 the superior and posterior walls of the pyramid, appear dark-blue, livid, 
 discoloured, loosened, and infiltrated with pus ; or white and yellowish, 
 if caseous or cholesteatomatous masses in the temporal bone are lying 
 upon the external surface of the dura mater. Where the latter has 
 been broken through in the direction from the temporal bone, there is 
 mostly found a gap bounded by jagged edges, which is filled with pus 
 or caseous masses ; less frequently multiple roundish perforations are 
 met with in the dura mater, which is thickened by infiltration. In 
 order to ascertain the extent of the defect in the osseous roof of the 
 tympanic cavity, the dura mater should be detached in the direction 
 from the squamous portion of the temporal bone as far as the posterior 
 superior edge of the pyramid (sin. petrosus superior), without, however. 
 
IN OTITIC MENINGITIS, CEREBRAL ABSCESS AND PHLEBITIS. 21 
 
 entirely separating it from the preparation. In the same manner, if 
 there be a breaking through at the posterior surface of the pyramid, 
 the dura mater may be detached from the inferior towards the superior 
 edge of the pyramid. Only in this manner can it be shown whether 
 the gap in the bone corresponds with that in the dura mater, or 
 whether it is somewhat further removed from it. In the latter case 
 the two openings communicate, by means of a channel running in a 
 slanting direction through the thickened dura mater. By holding the 
 latter up to the light, it is possible to judge, from the degree of 
 opacity in the vicinity of the place of rupture, to what extent it has 
 been infiltrated and thickened. In making post-mortems on children 
 who have died of meningitis, or epidemic cerebro-spinal meningitis, 
 the processes of the dura mater, which penetrate into the sutures and 
 fissures of the temporal bone, especially of those vascular cones of 
 connective tissue which enter the hiatus subarcuatus, must be more 
 minutely examined, since the purulent inflammation sometimes finds 
 its way through these from the spaces in the middle ear to the 
 cranial cavity (v. Troltsch, Lucse). 
 
 In a case of sinus phlebitis terminating fatally^ the sin. longi- 
 tudinalis superior should first of all be split, to ascertain the con- 
 dition of the coagula found in it. Then, after removing the brain 
 from the cranial cavity, the sin. transversus is opened with scissors 
 and pincette, from the foramen jugulare to the confluens sinuu'm, and 
 the divided sinus wall turned over to either side to obtain a clear 
 view into the sinus. The condition of the clots found here should 
 first be examined, then the state of the sinus wall, whether it be 
 smooth, or inflamed and covered with clots adhering to it; finally, 
 whether the wall of the sinus adjacent to the bone has been broken 
 through at any spot. With every thrombosis in the sin. transversus, 
 it is necessary to open at the same time the sin. petrosus superior 
 running along the posterior superior edge of the pyramid ; likewise, 
 the sin. petrosus inferior, which passes along the posterior inferior 
 edge; and if pathological thrombi are found there, the examination 
 should be extended also to the sin. cavernosus. The latter should 
 always be done when, during life, symptoms of phlebitis of the sin. 
 cavernosus, inflammation of the retrobulbar connective tissue, ex- 
 ophthalmus cedema, or erysipelas of the eyelids had existed. Should 
 the thrombous formation extend downwards beyond the foramen 
 jugulare, then the examination of the vena jugularis should not be 
 neglected, so as to ascertain the extent of the inflammation and 
 coagulation towards the lower parts of the vein, especially if, duriDg 
 life, a painful cord-like formation in the course of the jugular vein was 
 proved to exist. ^- 
 
22 EXAMINATION OF THE CKANIAL CAVITY IN TUMOURS OF THE BEAIN. 
 
 When the venous sinus wall has been detached from the underlying 
 bone, it is possible to judge of the position, size, and form of the 
 existing ulceration. This is found, in the majority of cases, in that 
 portion of the sinus transversus which borders on the mastoid cells, 
 and from here a probe may be passed either into the cavity of the 
 mastoid process, or into the tympanic cavity direct. Oftener, however, 
 even in severe sinus phlebitis, no trace of any ulceration in the bone 
 is found, but, corresponding to the inflamed wall of the vein, a livid 
 or yellowish -green discolouration of the bone, showing the symptoms 
 of a septic inflammation, which has spread from the tympanic cavity 
 or mastoid cells to the sinus. Sometimes it is by means of the fine 
 venous trunks discharging from the mastoid cells into the sinus that 
 this septic inflammation reaches the sinus wall. 
 
 In deafness the result of hydrocephalus, it is necessary to examine 
 the floor of the sinus rhomboideus and the condition of the strise acus- 
 ticse, which not infrequently are found completely obliterated ; further 
 the auditory nerve, which appears atrophied, flattened, or, as I have 
 observed in a case of chronic hydrocephalus of high degree, combined 
 with atrophy of the brain, lying, in the form of a slender cord, within 
 the internal meatus, which was dilated to several times its natural 
 size. 
 
 In disturbances of hearing consequent on tumours of the brain, 
 attention should be directed to the relations of the tumour to the 
 auditory nerve and the meduUa oblongata. To gain information upon 
 this we must, previous to cutting through the cerebral nerves which 
 pass from the medulla, slightly raise the latter and the cerebellum, 
 cutting, if necessary, the hemispheres partially away, by which the 
 displacement of the brain, of the medulla oblongata, and of the nerves 
 caused by the tumour, may be plainly seen. 
 
 It depends upon the size of the tumour, its close connection with 
 the brain or with the petrous bone, whether it should be removed 
 with the brain, or left in connection with the petrous bone. The 
 latter is always done when the new formation invades the internal 
 meatus, and when the auditory nerve passes through the tumour and 
 appears completely imbedded in it. 
 
 In dissections on deaf-mutes it is also necessary to subject the 
 brain to a close examination, and special note should be taken of any 
 changes occurring in the ventricles, in the sinus rhomboideus, and in 
 the auditory nerve trunks. The medulla oblongata should, for the 
 purpose of future microscopic examination of the nuclei and roots of 
 the acoustic nerve, be placed in a weak solution of chromic acid, to 
 be hardened. Considering the relations which have lately been proved 
 to exist between the acusticus and the temporal lobe, it might be 
 
DISSECTION OF THE TEMPOKAL BONE OF THE NEW-BORN INFANT. 23 
 
 advisable, in the dissection on deaf-mutes, to remove that part of the 
 brain, for the purpose of microscopic examination. 
 
 In conclusion, let it be observed that also in fractures of the skull 
 extending to the temporal bone, before removing the organs of hearing, 
 a close examination of the dura mater and the cranial bones should be 
 made, in order to determine the extent and direction of the fissures in 
 the skull, and the rents in the dura mater. 
 
 III. 
 
 Dissection of the Macerated Temporal Bone. 
 
 An exact knowledge of the temporal bone, which forms the osseous 
 framework of the auditory apparatus, is indispensable for the study 
 of the anatomy of the ear. Before beginning the work of preparation, 
 the anatomical details of the temporal bone must first of aU be studied 
 not only on its external surface, but also on good sections. As there 
 are material differences of form between the temporal bone of the 
 new-born infant and that of the adult, a comparative study of both is 
 of great advantage, since thereby we obtain information, not only as 
 to the growth of the bone, but also as to certain pathological occurrences 
 in the ear during the first years of life. 
 
 1. dissection of the temporal bone in the new-born infant. 
 
 No bone of the skeleton undergoes after birth such great changes 
 of form as the temporal bone. Its growth can, therefore, only be 
 studied on a series of preparations, commencing with the temporal 
 bone of the new-born infant, and followed, in succession, by those of 
 children aged respectively three months, six months, nine months, 
 twelve months, up to five years. 
 
 The macerated temporal bone of the new-born infant (Figs. 20 and 
 21) can be divided without difiiculty into three pieces ; pars squamosa, 
 pars tympanica, and pars petrosa, which, having in foetal life a 
 separate development, are in the new-born infant but loosely 
 connected, and do not become intimately united until the first few 
 years of life. 
 
 The details of the temporal bone of the new-born infant can only 
 be studied from its various parts after anatomical dissection. 
 
 This is not attended- by any special difficulty ; still, in order to 
 avoid splinterings, certain precautions ought to be observed. 
 
 We begin by detaching the tympanic ring (annulus tymp., a), 
 inserting a small knife rounded off at the point, or the blade of an 
 ordinary penknife, into the fissura petro-tympanica (fissura Glaseri), 
 
24 DISSECTION OF THE TEMPORAL BONE OF THE NEW-BORN INFANT. 
 
 which Hes between the anterior crus of the ring and the tegmen tymp., 
 so as to loosen, by shght lateral pressure, the anterior crus, which 
 has its attachment immediately behind the process, articularis post., 
 from the pars squamosa. If, now, the connection between the lower 
 and posterior periphery of the ring and the corresponding edge of the 
 pars petrosa et mastoidea be loosened, by pushing the point of the 
 knife into the loosely constructed suture, a gentle pressure sideways 
 will free the upper end of the posterior crus of the ring from the 
 squamous portion, whereby the separation, intact, of the annulus is 
 effected. 
 
 This is followed by separating the pars squamosa from the pars 
 petrosa, which are united on the inner side of the temporal bone 
 (Fig. 21) by means of the sutura petro-squamosa (su su'), and on the 
 outer surface through the sutura mastoideo-squamosa (Fig. 20, d d). 
 
 Pig. 20. Outer view of the temporal bone 
 of a new-born infant. (Left ear.) — a = 
 upper portion of the squama ; b = its 
 inferior portion below the linea tem- 
 poralis passing backwards ; c = annulus 
 tympanicus ; d d = suture between the 
 squamous portion and the mastoid pro- 
 cess, extending to the foramen stylo-mas- 
 toideum; e = foramen stylo-mastoideum'; 
 f =fenestra ovalis ; g = fenestra rotunda. 
 
 Fig. 21. — View of the inner side of the tem- 
 poral bone of a new-born infant. (Left 
 ear.) — su su' = sutura petro-squamosa; 
 cs = tegmen tymp. ; mi = meat, audit, 
 int. ; hi = fossa subarcuata ; an = fissure 
 of the aquseduct. vestib. ; ch_=: elevation 
 of the horizontal semicircular canal ; si = 
 place of the later sulcus transversus. 
 
 By cautiously pushing the blade of the knife into the latter, and by 
 gentle lateral movements of the instrument, the connection of the 
 two bones can be loosened, so that by moderate pressure on the inner 
 side of the squamous portion the connection at the sutura petro- 
 squamosa may also be loosened, and the pars squamosa isolated. 
 
 The temporal bone, thus divided into its three constituent parts, can 
 now be accurately examined in all directions ; and without entering into 
 an exhaustive treatment of the subject, we will give a short description 
 of the different pieces of the os temporale in the new-born infant as 
 
ANNULUS TYMPANICUS. 25 
 
 far as this appears necessary for understanding the anatomical details 
 of the temporal bone in the adult, and for technical work. 
 
 The tympanic ring (annulus tymp., Figs. 22 and 23) presents an 
 osseous frame, open above and in front for the reception of the 
 membrana tympani, and attached by its ends to the anterior lower 
 part of the external surface of the squamous portion, while its lower 
 and posterior circumference unites with the lower external edge of 
 the pars petrosa, and with the mastoid portion of the latter. On the 
 outer side of the ring are two projecting tubercles, tuberculum tymp. 
 antic, (a) and postic. (p) (Zuckerkandl) which should be noticed, 
 because the development of the osseous meatus out of the tympanic 
 ring commences at these two spots. The inner side of the ring 
 (Fig. 23) presents a groove (sulcus tympanicus, st), intended for the 
 reception of the tympanic membrane. The inner lip of the groove at the 
 anterior crus of the ring runs above into a point (s) directed backwards 
 and inwards, which Henle calls spina tymp. post., in contradistinction 
 to the spina tymp. ant. (t), which, lying somewhat lower, projects at 
 the anterior edge of the crus. The two processes are joined by an 
 
 Fie. 22. — Outer side of the annulus tym- Fig. 23. — Inner side of the annulus tympani- 
 panicus. (Left ear.) — a = tuberc. tymp. cus. (Left ear.) — st = sulcus tymp. ; 
 
 anter. ; p = tuberc. tymp. post. (Zucker- p = tuberc. tymp. post. ; t = spina tymp. 
 
 kandl.) ant. ; s = spina tymp. post. (Henle). Be- 
 
 tween the two, the crista spinarum, with 
 the sulcus malleolaris passing below. 
 
 inwardly-projecting ridge (crista spinarum, st), below which the sulcus 
 malleolaris, serving for the reception of the proc. long, mallei, passes 
 in an oblique direction forwards and downwards. The fissure situated 
 between this portion of the anterior crus and the anterior outer edge 
 of the tegm. tymp. is called fissura petro-tympanica (fissura Glaseri), 
 through which pass part of the ligam. mallei ant., the art. tymp. inf., 
 and the chorda tymp. 
 
 The second piece of the temporal bone in the new-born infant, the 
 pars squamosa (Figs. 24 and 25), shows on the anterior part of its 
 outer surface the slender processus zygomaticus, the root of which is 
 bounded below by the still faintly marked and shallow articular fossa 
 of the inferior maxilla. The upper edge of the proc. zygomaticus is 
 extended as a slightly curved ridge (linea temporalis), which divides 
 the squamous portion into an upper and a lower segment. The latter 
 portion, which has the form of a triangle with its apex directed 
 
26 
 
 PARS SQUAMOSA. 
 
 downwards, lies below tlie linea temporalis, and claims our special 
 attention, since it takes an essential part in the later development 
 of tlie osseous meatus and of the mastoid process. The anterior edge 
 and section of this triangle are divided into three parts. The upper- 
 most part (a r), lying behind the proc. articuL, serves for the apposition 
 of the squamiform end of the anterior crus of the tympanic ring ; the 
 middle part (r r') forms, in common with the annulus, the so-called 
 incisura Rivini (margo tymp. of the squamous portion); while the 
 posterior third (r' 1), with which the extremity of the posterior crus 
 of the ring coalesces, is joined to the tuberc. mast, of the pars 
 mastoidea. The posterior section of the triangular part of the squama 
 (1 q), which, through the sutura mast, squamosa (Fig. 20, d d), is 
 united with the mastoid portion of the pyramid, forms the outer 
 covering of the antrum mast.; and as especially the lower portion, 
 
 Fig. 24. — Outer surface of the pars squamosa 
 of a new-born infant. (Left ear.) — g = 
 anterior lower edge of the squama ; above 
 it the shallow cavit. glenoid. ; a r= place 
 of attachment of the anterior crus of the 
 ring to the squama ; r r' = margo tymp. 
 squamse ; r' 1 slower point of the pars 
 squamosa in apposition with the tuberc. 
 mast. ; 1 q = posterior edge of the pars 
 squamosa, forming the sutura mast, squa- 
 mosa. 
 
 Fig. 25. — Inner view of the pars squamosa 
 of a new-born infant. (Left ear. ) — It = 
 inner projecting lamella of the squama ; 
 Im — inferior triangle of the squamous 
 portion ; g = smooth part of this lamella ; 
 z = its cellular portion ; o = posterior 
 boundary of the sutura petro-squamosa ; 
 r = anterior, groove-like border of the 
 lamella. 
 
 adjoining the tuberc. mast., takes part, during the growth of the 
 mastoid process, in the formation of the anterior section of the latter, 
 Zuckerkandl has designated it lamina mast, externa. 
 
 On the inner side of the squamous portion (Fig. 25) the lower part 
 of the surface is formed into a triangle by a projecting horizontal 
 jagged ridge (o r). The upper lamella of this triangle (o r) is united, 
 by means of the sutura petro-squamosa, with the tegmen tymp. et 
 mast. (Fig. 26), arising from the upper surface* of the pyramid. The 
 posterior and middle portion of this edge is sharpened as far as the 
 anterior superior angle of the triangle, and overlapped by the corre- 
 
 * Syn., inner anterior surface (Henle), anterior superior surface (Luschka). 
 
PARS PETROSA. 
 
 27 
 
 sponding sharpened plate of the tegmen. tymp. (Fig. 26, 1). The 
 anterior broader part (Fig. 25, r), on the other hand, appears 
 depressed into a groove to receive the correspondingly thickened 
 edge of the tegmen tymp. 
 
 The lower lip of this groove (proc. inf. tegm. tymp., Kirchner) 
 is wedged in between the anterior lower border of the squama and 
 the anterior crus of the ring, and is visible on the temporal bones ot 
 the new-born infant and adult as a long ridge between the squama 
 and the upper edge of the os tymp, (Fig. 29, g). The fissure 
 remaining between this lip and the os tymp. is the fissura petro- 
 tymp., or fissura Glaseri. This is connected in the new-born infant 
 (Fig. 28) with that triangular gap which lies in the anterior angle 
 of the temporal bone, called by Henle canalis musculo-tubarius, and 
 which is divided by the ledge of bone projecting from the median 
 wall of this canal into two not quite distinct canals, the lower and 
 wider of which represents the tuba Eustach. ossea, the upper narrower 
 
 u r St f 
 
 Fig. 26. — Pars petrosa of a new-bom infant, after removal of the pars squamosa et tympanica. 
 — o = fenestra ovalis ; r = fenestra rotunda ; st = sinus tymp. ; u = outer border of 
 the lower surface of the pyramid ; f = foramen stylo-mastoid. ; 1 = lamella of the 
 tegmen tymp. ; an = antrum mastoid. ; t = ost. tjrmp. tubae Euat. ; c = canalis caroticus. 
 
 one the semicanaHs pro tensore. The anterior corner of the tegm. 
 tymp. sometimes shows, at the spot where the upper and lower lips 
 of its lateral edge meet, a roundish surface about the size of 1 mm. 
 covered with cartilage and surrounded by a low elevation. 
 
 The triangular surface of the squama situated below the jagged 
 ledge is smooth at its anterior portion, but cellular at the posterior. 
 The anterior smooth portion (g) forms, with the jagged ledge over- 
 lapping it, a niche in the upper tympanic space, in which the malleus 
 and incus are lodged, while the posterior cellular portion (z) of the 
 triangle represents, as already mentioned, the outer roof-plate of the 
 antrum mast. 
 
 The third piece of the temporal bone of the new-born infant, the 
 pars petrosa (Fig. 26), contains in its anterior and middle part the 
 cavity of the labyrinth ; in the posterior, the first indications of the 
 mastoid process, and the antrum mast. On its external surface there 
 are to be noticed the fenestra ovalis (o) and rotunda (r) ; the 
 
28 PARS PETROSA. 
 
 promontory projecting in front of these; the portion of the facial 
 canal running obliquely backwards and downwards above the fenestra 
 ovalis, with the prominence of the horizontal semicircular canal 
 adjoining it posteriorly; the eminentia stapedii projecting behind 
 the fen. ovalis ; and, in the anterior part of this wall, the lower inner 
 limit of the osseous Eustachian tube, with the semicanalis pro tensore 
 tymp. (t) above it. The longish oval antrum mast, (an), situated 
 behind the tympanic cavity, measures in its long diameter 9-11 mm., 
 and in height 7-9 mm. The mostly smooth but often also porous 
 inner and lower wall of the antrum does not attain until later, during 
 the growth of the mastoid process, a distinctly cellular structure. 
 
 The inner wall of the tympanic cavity and the antrum mast, 
 are roofed over by the previously-mentioned triangular lamella (1) 
 (Fig. 26), which proceeds from the anterior superior wall of the 
 pyramid, and which with its sharp edge pushes the tegmen. tymp. 
 et mast, over the inner lamella of the pars squamosa (Fig. 25, It), 
 projecting towards it from the opposite side. The traces of this 
 superposition of the two lamellse can be shown to exist on frontal 
 sections of temporal bones in adults, and on the sections of the 
 superior wall of the osseous meatus and of the antrum. A groove 
 (sulcus N. petr. sup. maj.) commencing above the anterior orifice of 
 the canal, tensor. -tymp., or at the canalis caroticus, and running 
 backwards and laterally along the boundary of the anterior edge of 
 the pyramid and of the tegmen tymp., leads to the hiat. canal. 
 Fallopii. The facial canal, at this spot uncovered, appears here, on 
 an average, larger in the new-born infant than in the adult. 
 
 Noteworthy among the details on the posterior surface of the 
 pyramid (Fig. 21) are, besides the porus acusticus intern, (mi) in the 
 anterior segment, the niche (fossa subarcuata — hi) which, lying below 
 the superior semicircular canal, interrupts the upper margin of the 
 pyramid, and is occupied by a vascular process of connective tissue 
 proceeding from the dura mater (Wagenhauser), but during growth 
 becomes so obliterated that in the temporal bone of the adult only 
 traces of it are to be found; secondly, the superior crus of the 
 posterior semicircular canal (ch), which projects at the same height 
 with the porous acusticus intern, behind the inner crus of the canal, 
 semicirc. super., as a roundish eminence; and, lastly, the depressed 
 orifice of the aqsed. vestibuli, situated below this elevation. The 
 slightly concave surface of the most posterior section of this wall of 
 the pyramid (Fig. 21, si), shows as yet scarcely any indication of the 
 future sulc. sinus trans versus. 
 
SECTIONS THROUGH TEMPORAL BONE OF NEW-BORN INFANT. 29 
 
 For the study of the topography of the temporal bone in the new- 
 born infant a few sections through the entire bone are required. 
 Three in particular are absolutely necessary for understanding the 
 respective details in the temporal bone of the adult. One of these is 
 a frontal cut passing vertically through the posterior part of the 
 squama, through the tuberculum mast, and the foramen stylo- mast., 
 and dividing, in addition to the squamous and mastoid portions, the 
 posterior part of the petrous bone. It shows (Fig, 27) the outlines of 
 the antr. mast., its height and transverse diameter, and the share the 
 pars squamosa et petrosa take in the formation of its walls. Very 
 plainly visible in such sections is the overlapping of the lamella (t), 
 proceeding from the superior surface of the pyramid, and of the 
 lamin. mast. int. of the squama (1) ; also the apposition of the cellular 
 portion of the squama (a) to the tuberc. mast. (tu). The second 
 frontal cut (Figs. 31, 32) passes through a plane, which lies on the 
 
 SV mi 
 
 Fig. 27. — Frontal section through the an- 
 trum mastoid, of a, new-born infant : 
 posterior view. (Bight ear.) — a = outer 
 lamella of the antrum belonging to 
 the squamous portion ; 1 = lamin. mast, 
 int. of the pars squamos. sutura petro- 
 squamosa ; t = tegm. tymp. ; tu = tuber- 
 culum mastoid. ; e = fossa subarcuata ; 
 c = cochlea. 
 
 Fig. 28. — Horizontal section through the 
 temporal bone of a new-born infant. 
 (Right ear.) — a = section of the posterior 
 crus of the ring ; p =: section of the sheath 
 of the proc. styloid. ; m — lower end of 
 antr. mastoid. ; f = section of the canal, 
 facialis ; v = vestibule ; s = section of the 
 canal, semic. sup. and of the fossa subar- 
 cuat. ; CO = cochlea ; mi := meat, intern. ; 
 = canal, caroticus. 
 
 one side through the greatest diameter of height of the squama, the 
 Kivinian segment, the posterior crus of the annulus (midway between 
 the entrance of the canal, carotic. and the foram. stylo- mast.), and on 
 the other side through the internal auditory meatus. It meets the 
 promontorial wall close in front of the niche of the fenestra ovalis. At 
 the anterior part of this section (Fig. 32) we notice the transition of 
 the tympanic cavity into the canalis musculo-tubarius ; at the posterior 
 piece (Fig. 32), the passage of the upper tympanic space (c) into the 
 antr. mast. This section, an illustration of which is given in the 
 following chapter, is, as we shall see, also of importance for the study 
 of the growth of the external meatus. The horizontal cut through the 
 temporal bone (Fig. 28) falls in a plane lying through the tubercul, 
 mastoid,, the lower wall of the osseous Eustachian tube, and the 
 
30 
 
 DEVELOPMENT OF THE OSSEOUS MEATUS. 
 
 internal meatus. It effectually shows the mode of apposition of the 
 annulus tymp. to the edge of the lower and posterior walls of the 
 tympanic cavity (a) ; the relative position of the canal, carot. (c) to 
 the osseous Eustachian tube, and to the anterior wall of the tympanic 
 cavity ; the shape of the pars mastoidea in transverse section ; at the 
 posterior boundary of the cavum tymp., the position of the facial 
 canal (f ) and of the sheath of the styloid process (p) ; and lastly, at 
 the inner edge of the pars petrosa, the section of the hiat. sub- 
 arcuatus (s). 
 
 The sections through the petrous bone of the new-born infant, 
 which are to represent the cavities and canals of the osseous labyrinth 
 
 Fig. 29. — Temporal bone of a child one year old. (Right ear.) — v = osseous growth arising 
 from the tubercul. ant. of the tjrmpanic ring ; h = osseous growth from the tubercul, 
 postic. ; o — gap left between the anterior and posterior osseous growths, meeting at the 
 anterior lower wall of the auditory canal ; g g = cavitas glenoidal. with the root of the 
 proc. zygomat. : the lower g marks likewise the inferior lip of the tegm. tymp. thrust 
 between the squama and the os tymp. ; s = apex of the pyramid ; m = proc. mastoid. 
 
 for the purpose of study, will be discussed more fully in the chapter 
 ' Preparation of the Osseous Labyrinth.' 
 
 Those who desire to gain information as to the various stages of 
 the growth of the temporal bone as they present themselves in early 
 infancy up to the age of the adult, may with advantage make use of a 
 collection of skulls arranged according to age, such as are to be found 
 in great anatomical institutions. A model collection of this kind is 
 that of the Anatomical Museum of Vienna, the inspection of which 
 will be found very instructive. 
 
 From the examination of a number of skulls arranged according 
 to age, we generally find that the growth of that part of the osseous 
 meatus which proceeds from the pars tymp. progresses most rapidly 
 
DEVELOPMENT OF THE OSSEOUS MEATUS. 
 
 31 
 
 and terminates soonest ; that, however, the upper wall of the meatus, 
 formed by the pars squamosa (horizontal portion) does not attain until 
 later its permanent length and width ; and that the mastoid process 
 is fully developed last — often not until puberty, and is even after that 
 time subject to internal changes. 
 
 Should a series of skulls or temporal bones arranged according to 
 age not be accessible, the development of the osseous meatus after 
 birth may be followed on three or four temporal bones : of the new- 
 born infant (Fig. 20), of children aged respectively one and two years 
 (Fig. 29), and of the adult (Fig. 30). 
 
 The growth of the osseous meatus, in the formation of which the 
 squamous and tympanic portions of the temporal bone chiefly partici- 
 pate, proceeds in the following manner : As early as a few weeks after 
 birth an increase of substance may be observed on the tubercles at the 
 lateral side of the tympanic ring, which have been called tuberc. antic. 
 
 Fig. 30. — Outer view of the osseous meatus of an adult. (Left ear.) — a = horizontal 
 portion of the squama, upper wall of the meatus ; b = pars tympanica ; c = lumen of the 
 auditory canal ; d =; mastoid process. 
 
 and postic. (Fig. 22, a p, Zuckerkandl). The rapid growth of these 
 tubercles (Fig. 29, v h), and the simultaneous increase of substance in 
 the whole of the tympanic ring, mostly lead as early as the first year 
 of life to a bridge-like union between them. There remains between 
 the lower periphery of the annulus and the osseous bridge, which 
 forms the outer section of the anterior and lower walls of the meatus 
 a gap (o), varying in size, and closed by fibrous tissue, and which 
 frequently up to the third year of life is filled with bone ; often, how- 
 ever, it persists up to the fifth or sixth year, and even sometimes 
 throughout life (Ossificationslucken of Arnold and v. Troltsch). 
 
 On the temporal bone of the adult the part of the osseous meatus 
 formed by the pars tymp. presents itself as a groove-like convoluted 
 osseous plate (Fig. 30, b), which looks as though pushed from below 
 into the sulcus, facing downwards, and which is formed by the hori- 
 zontal portion of the squama (a), the process, articul. post., and the 
 
32 
 
 DEVELOPMENT OF THE OSSEOUS MEATUS. 
 
 mastoid process.* The limits of apposition of the os tymp. to the 
 squamous and mastoid portions are generally recognisable by the 
 trace of a suture, rarely quite obliterated. 
 
 The formation of the superior wall of the meatus out of the 
 squamous portion proceeds in such a manner that the squama proper 
 above the linea temporalis (Fig. 31) retains its position ; while that 
 part (p p, superficies meat. Schwalbe) which is situated below this 
 line, between the process, artic. postic. and the tuberc. mastoid., 
 gradually assumes during growth a horizontal position. 
 
 Fig. 32. — Frontal section 
 through the middle of the 
 temporal bone of a new- 
 born infant : anterior view. 
 (Left ear. ) — p p' = lower 
 portion of the pars squa- 
 mosa (superficies meat, 
 ext.) ; 1 = lamin. int. of 
 the pars squamosa ; s = 
 sutura petro - squamosa ; 
 t = tegm. tympan. ; e = 
 fissura petro - tympan. 
 (Glaseri); i = canalis mus- 
 culo-tubarius ; c = coch- 
 lea ; mi = meat. int. ; 
 f = canalis facialis. 
 
 Fig. 33.— Vertical (frontal) 
 section through the osseous 
 meatus and the tympanic 
 cavity. (Left ear.) -— 
 a = squama ; b' = hori- 
 zontal portion of the pars 
 squamosa ; b = upper wall 
 of the osseous meatus ; 
 c = lower wall of the 
 osseous meatus ; d = 
 meatus; e = tympanic 
 membrane with the mal- 
 leus ; f = tympanic cavity. 
 
 Fig. 31. — Frontal section 
 through the middle of the 
 temporal bone of a new- 
 born infant : posterior 
 view. (Left ear.) — p p 
 = lower portion of the pars 
 squamosa (superficiesmeat. 
 ext. ) ; n = attachment of 
 the posterior crus of the 
 ring to the pars mastoid. 
 OSS. petros. ; a = suture 
 between the lower peri- 
 phery of the annulus and 
 the margin of the pars 
 petrosa ; 1 = lamin. int. of 
 the pars squamosa ; s = 
 sutura petro - squamosa ; 
 t = tegmen tymp. ; f = 
 hiat. can. Fallopii ; c = 
 upper tympanic space ; 
 o = cochlea ; mi = meat, 
 intern. 
 
 If the sections of the temporal bone of the new-born infant 
 (Figs. 31, 32) and those of the adult (Fig. 33), as shown in the 
 accompanying illustrations, be placed side by side, it is easy to see 
 that the piece marked p p' of the pars squamosa (Fig. 32) is the one 
 which becomes during growth the portion (b) shown in Fig. 33, 
 forming the upper wall of the meatus, and standing at a right angle 
 to the squama proper. After what has been said, the anterior and 
 lower walls of the osseous meatus are thus formed exclusively out of 
 
 * Du Verney, Traits de Torgane de I'ouie, 1731. 
 
SECTIONS THROUGH THE TEMPORAL BONE OF THE ADULT. 
 
 33 
 
 the OS tympan., the upper wall almost entirely by the pars squamosa ; 
 while in the formation of the posterior wall the tympanic, mastoid 
 and squamous portions participate, the latter in a great measure by 
 the lamina mastoidea, which forms the anterior surface of the mastoid 
 process. 
 
 2. SECTIONS THROUGH THE TEMPORAL BONE OF THE ADULT. 
 
 For the study in detail of the temporal bone in the adult, a series 
 of sections running parallel in a sagittal, frontal, and horizontal 
 direction are made by means of a fine fret-saw (No. 12) through three 
 different temporal bones. In order not to miss the direction of the 
 cuts, it is well to mark them, as to their position and distance from 
 each other, by drawing lines on the outer surface of the bone. As the 
 sections of the cavitv of the labyrinth will be discussed in the chapter 
 
 'sp 
 
 ' '/I 
 
 Fig. 34. — External opening of the osseous 
 meatus on the macerated temporal bone of 
 an adult. (Right ear.) — t = pars tymp. of 
 the osseous meatus ; m = pars squamosa 
 (horizontal portion) of the osseous meatus ; 
 sp = spina supra meatum (Bezold) ; p =: 
 proc. articularis of the maxillary joint ; w = 
 mastoid process. 
 
 Fig. 35. — Sagittal saw-cut, 5 mm. 
 medially from the external open- 
 ing of the osseous meatus on the 
 same preparation. — v = anterior 
 lower wall of the osseous meatus 
 belonging to the pars tymp, ; c =: 
 pneumatic cell-spaces of the 
 middle ear, situated along the 
 posterior upper wall of the 
 meatus ; o = upper edge of the 
 pyramid ; s — sin. sigmoideus ; 
 st = proc. styloideus. 
 
 on the preparation of the osseous labyrinth, we will in the following 
 chiefly consider the sections of the osseous meatus and of the middle 
 ear. 
 
 The first series of sections through the temporal bone in a sagittal 
 direction is made perpendicular to the axis of the external meatus. 
 Three parallel sections, from the external orifice to the incisura Rivini, 
 suffice to bring into view the change of the transverse section of the 
 external meatus from without inwards, and its topographical relations 
 to the glenoid cavity, to the mastoid cells, and to the antrum 
 mastoideum. 
 
 3 
 
34 SAGITTAL SECTIONS THROUGH THE TEMPORAL BONE. 
 
 As the width of the osseous meatus in the normal state is subject 
 to very great variations, a number of temporal bones should be chosen 
 for making the sections, which should include, besides specimens with 
 meatuses of average width, also such having extremely wide and very 
 narrow ones. The sections here illustrated are taken from a temporal 
 bone with a meatus having a lumen of average width. 
 
 The first cut commences at the inner surface of the squamous 
 portion, close to the boundary between the lower and lateral walls of 
 the middle cranial fossa, falling thus on an average 5 mm. medially 
 from the inferior rough edge of the pars tymp. A comparison of the 
 transverse diameter of the external orifice of the meatus (Fig. 34) 
 with that of the first section (Fig. 35) shows that the height of the 
 latter has diminished by 2|-3| mm., and the transverse diameter by 
 2-3 mm. In the following cut, made 3 mm. medially through about 
 the middle of the lower wall (Fig. 36), the height of the elliptic trans- 
 
 FiG. 36. — Sagittal section, 3 mm. medially from the previous one. — v = anterior lower wall 
 of the meatus ; an = lateral portion of the antrum mast. ; c = pneumatic cell-spaces ; 
 o = upper edge of the pyramid ; h = its posterior edge. 
 
 verse section, which is strongly inclined forward, is found but slightly 
 less ; the transverse diameter, however, shows a decrease of 2-3 mm. 
 Lastly, on the third cut (3 mm. towards the median line) passing 
 through the incisura Eivini and the posterior superior portion of 
 the sulcus tymp., the height again increases by 1-1| mm., while the 
 transverse diameter (1 mm. less than on the previous section) is here 
 narrowest. 
 
 The narrowest place (isthmus meat, ext.) of the osseous meatus, 
 diminishing from without inwards, especially in the transverse dia- 
 meter, is thus, on an average, between the posterior superior edge of 
 the membrana tympani and the anterior inferior wall of the meatus 
 opposite, which is here most strongly curved backwards. Sometimes 
 the isthmus commences 1 J mm. laterally from the posterior margin of 
 the tympanic membrane. 
 
 The osseous meatus in the adult resembles a laterally compressed 
 cylinder, the transverse section of which takes the form of an irregular 
 
MEASUREMENTS OF THE TRANSVERSE DIAMETER OF THE MEATUS, 35 
 
 oval with its greatest diameter strongly inclined forwards. Such being 
 the form of the section, it is, as Bezold (I.e.) rightly observes, impos- 
 sible to sharply define the limits of the walls of the meatus. Indeed, 
 one may, not only on corrosion sections, but also on sagittal sections 
 of the temporal bone, and by a glance into the meatus in a macerated 
 skull, become convinced that, in consequence of the lateral flattening 
 of the auditory canal, two of its walls are more strongly marked, viz., 
 the posterior upper and the anterior lower, which meet in a short 
 curve at the extreme points of the long diameter of the oval. 
 
 The measurements of the transverse diameter of the meatus must 
 be made, not only on sagittal, but also on horizontal and frontal 
 sections of the temporal bone ; likewise on corrosion preparations, 
 according to Bezold's {I.e.) method. When determining the dimensions 
 from the latter, one should, notwithstanding the great advantages 
 gained thereby, not dispense with taking the measurements of bone 
 sections also into account. Considering the great importance of the 
 subject, anatomists and otologists have directed their attention 
 especially to the measurements of the auditory canal, and Yon Troltsch, 
 Sappey, Hyrtl, and Bezold have already given such detailed information, 
 that hardly anything new remains to be added. I can, however, on 
 looking over these measurements, not avoid observing that I do not 
 quite understand the mode of determining the average number from 
 a long list of single measurements. Not infrequently, average numbers 
 occur, which are not found in any single case of the series in question. 
 Now, as such average measure does not exist in reality, it is, in my 
 opinion, of no practical value. More simple does it appear to me to 
 quote such measurements as mean results which have been found in 
 the greatest number of preparations, and along with these to state how 
 far, in the smaller number of preparations, these figures are exceeded 
 or not. 
 
 The measurements made by me on sagittal sections of the meatus 
 gave, in the majority of temporal bones, the following results : At the 
 external opening of the osseous meatus in the vertical plane of the 
 anterior edge of the pars tymp, a high diameter of 12 mm., transverse 
 diameter 10 mm. In the middle of the osseous meatus, high diameter 
 9 mm., transverse diameter 5 mm. At the inner extremity of the 
 superior wall (incisura Kivini), high diameter 10 mm., transverse 
 diameter 4 mm. In the smaller number of temporal bones, with very 
 wide and very narrow meatuses, these numbers vary between 1-3 mm, 
 and above. Bezold found, on corrosion sections, the following average 
 measurements : at the commencing portion of the osseous meatus, 
 a high diameter of 8.67 mm., a transverse diameter of 6.07 mm. ; at 
 the end of the meatus in the vertical plane of the incisura Rivini, a 
 
 3—2 
 
36 RELATIONS OF ANTRUM MAST. AND MASTOID CELLS TO MEATUS. 
 
 high diameter of 8.13 mm., a transverse diameter of 4.6 mm. The 
 reason of this perceptible difference between the results of the two 
 measurements is probably to be found in the fact that the majority 
 of Bezold's corrosion casts were taken from unmacerated organs of 
 hearing, in which the lumen of the meatus, from the periosteal and 
 cuticular lining, must appear materially less than in the macerated 
 temporal bone. 
 
 The sagittal sections through the external meatus here illustrated 
 (Figs. 35 and 36) give a general view of the relations between the 
 posterior superior wall of the meatus and the pneumatic spaces of the 
 mastoid process. As the mastoid process proper lies more laterally 
 than the external opening of the osseous meatus, the previous cut, 
 dividing the squama and zygomatic process, will include also the 
 entire mastoid process (Fig. 34, w), and a part of the sinus sigmoideus. 
 
 On the first sagittal section, made medially from the external 
 opening of the meatus (Fig. 35), appear those pneumatic cellular spaces, 
 situated between the posterior superior wall of the meatus on the one 
 side, and the sinus transversus, as well as the posterior surface of the 
 pyramid, on the other side, which effect the communication of the 
 medially placed antrum mast, with the lateral cellular spaces of the 
 mastoid process. Their exceedingly varying number and arrangement 
 stands, as may be seen especially on horizontal sections, in a certain 
 relationship to the pneumatic or diploetic condition of the mastoid 
 process. 
 
 When the series of sagittal cuts has passed the middle of the 
 meatus (sometimes before), the lateral boundary of the antrum mastoid, 
 is very often met with (Fig. 36). It thus extends in a lateral direction 
 considerably beyond the boundaries of the tympanic cavity. Its 
 position, behind and above the osseous meatus, sufficiently explains 
 the not infrequent spreading of suppurative processes in the antrum 
 and adjoining cellular spaces to the osseous meatus. But this 
 anatomical relationship shows, at the same time, that the operation 
 of opening the antrum mastoid, may also be performed from the meatus, 
 a proceeding which was first proposed by K. Wolf,* and which, no 
 doubt, will be more extensively practised in future than has hitherto 
 been the case. 
 
 The sagittal cut (Fig. 37), made through the iAcisura Rivini and 
 the posterior portion of the sulcus tymp., strikes the anterior wall of 
 the meatus at a distance of 4-5 mm. from the most medially situated 
 anterior lower portion of the sulcus tymp. It exposes that part of 
 the antrum which lies behind the tympanic cavity and the promon- 
 torial wall of the latter. Owing to the obtuse angle which the axis 
 
 * Berl. klin. Wochenschr. 1877. 
 
SAGITTAL SECTIONS THROUGH TYMPANUM AND OSSEOUS BUST. TUBE. 37 
 
 of the pyramid forms with that of the external meatus, this cut 
 meets also the horizontal (h) and the posterior (n) semicircular 
 canals. 
 
 This inclination forwards and inwards of the pyramid is also the 
 cause why the sagittal sections made vertically to the axis of the 
 meatus further inwards, strike the tympanic cavity and the pyramid 
 in so slanting a direction that they gradually become similar to the 
 frontal ones, which are carried perpendicularly to the axis of the 
 pyramid. 
 
 The medial cuts of the sagittal series here described, meeting the 
 tympanic cavity as well as the pyramid in an oblique direction, it is 
 necessary to make a sagittal cut through the tympanic cavity on a 
 second temporal bone, in such a way that it brings into view the pars 
 squamosa et tymp. with the annulus tymp. on the one side, and the 
 pars petrosa, along with the inner wall of the tympanic cavity, on the 
 
 Fig. 37.— Sagittal section, 3 mm. medially from the previous one. (The section as here 
 represented, is supposed to be turned 90° forward.)— v = section of the anterior lower 
 wall of the meatus ; s — sulcus tymp. ; an = antrum mast. ; t p m = osseous ledge in the 
 upper t3Tnpanic space, from the rostr. cochleare to the spina tymp. post. ; m = cavit. cap. 
 mallei ; u = lower wall of the tympanic cavity ; h n = sections of semicircular 
 canals. 
 
 other side. The cut must thus pass in a sagittal direction through 
 the tegmen tymp. and through the floor of the tympanic cavity, 
 between the lower segment of the sulcus tymp. and the inner tympanic 
 wall. As on the intact temporal bone the direction of the cut may be 
 easily missed, it is better to make sure of it by opening the tegmen 
 tymp. to the width of 1 J-2 mm. with a graver or forceps, in a line 
 drawn from the anterior outlet of the canalis musculo-tubarius towards 
 the incisura parietalis. This gives a free view into the tympanic 
 cavity, and enables us to divide the lower tympanic wall, between the 
 sulcus tymp. and the promontory, exactly in the middle. The temporal 
 bone thus cut in two, shows, on the one side (Fig. 38), the outer wall 
 of the tympanic cavity and the lateral wall of the osseous Eustachian 
 tube (d) ; behind it, the roundish elliptic gap for the reception of the 
 tympanic membrane, the sulc. tymp. (a) ; at the upper segment of 
 
38 SAGITTAL SECTIONS THROUGH TYMPANUM AND OSSEOUS EUST. TUBE. 
 
 the tympanic frame, the Rivinian notch (b), to receive Shrapnell's 
 membrane; above that, the malleo-incudal niche (b c) and the transition 
 of the smooth surface into the cellular wall of the antrum mastoid. 
 The inner aspect of this section shows, when the preparation is in a 
 normal position, the strong inclination of the tympanic frame and 
 of the entire external wall of the tympanic cavity to the horizontal, 
 and the acute angle which the anterior lower wall of the meatus, 
 ascending almost perpendicularly from the lateral side of the sulc. 
 tymp., forms with the plane of the annulus tymp. 
 
 On the inner piece of the temporal bone, sawn through in a 
 sagittal direction (Fig. 39), we find the details of the inner wall of the 
 tympanic cavity already mentioned on the pars petrosa of the new-born 
 infant (p. 27). Fenestra ovalis (o) et rotunda (r), sinus tymp.. 
 
 Fig. 38. — External tympanic 
 wall with the sulcus tympani- 
 cus. (Right ear. ) — a = sulcus 
 tymp. ; b = incisura Eivini 
 (margo tympanicus) ; d = 
 lateral wall of the Eustachian 
 tube. 
 
 EiG. 39.— Sagittal section through the middle of the 
 tegm. tymp. and of the lower tympanic wall. Lateral 
 view of the inner half. (Left ear.)— te = tub. Eust. 
 OSS, ; ct = canalis pro tens. tymp. ; c = lower, ridged 
 tympanic wall ; o = fenestra ovalis ; r = fenestra 
 rotunda ; an = antrum mastoid. ; f = canalis Fallopii, 
 communicating, towards the front, with the cavit. 
 stapedii ; w = mastoid process. 
 
 promontorium, canalis pro tens. tymp. (ct), median wall of the 
 Eustachian tube (te), eminentia staped. and the protuberance of the 
 horizontal semicircular canal extending into the antrum mast, appear 
 almost exactly of the same dimensions and relative positions as in the 
 new-born infant. Merely by the increase of substance at the apex of 
 the pyramid, at the tegmen tymp., at the lower wall of the tympanic 
 cavity, but especially through the growth of the mastoid portion, 
 does the pars petrosa in the adult reach, in all its dimensions, almost 
 more than double of what it is in the new-born infant. 
 
 Now, while the details of tte inner tympanic wall appertaining to 
 the labyrinthine capsule undergo after birth scarcely any change, the 
 canals running in the temporal bone become in the adult considerably 
 
FRONTAL SECTIONS THROUGH THE TEMPORAL BONE. 39 
 
 longer, and their position is somewhat altered. Most remarkable is 
 the increase in the dimensions of the carotid and facial canals, con- 
 current with the growth of the os tymp. and of the anterior point of 
 the pyramid, these canals attaining almost double the length they 
 have in the new-born infant. 
 
 According to ray measurements, the length of the canalis caroticus 
 in the new-born infant amounts to 10-12 mm., in the adult to 
 25-30 mm. ; the greatest diameter at the lower opening of the canal 
 in the new-born infant 4|-5 mm., in the adult 8-9 mm. ; the greatest 
 diameter at the upper opening of the canal in the new-born infant 
 3-4 mm., in the adult 6-7 mm. 
 
 The sagittal cut here described meets the middle portion of the 
 sin. sigmoid, so far medially as to leave the entire mastoid process 
 with the incisura mast, on the outer piece of the temporal bone. At 
 the same time the facial canal on the posterior wall of the tympanic 
 cavity is struck in such a way that its lowest portion also falls in the 
 lateral piece of the divided temporal bone. If, in dividing the 
 temporal bone, it is intended to retain the entire facial canal as far as 
 the foramen stylo-mast, on the inner of the two pieces, the sagittal cut 
 should pass through the lateral side of the foramen, as shown in 
 Fig. 39, dividing thus the sulcus tymp. in such a direction as to leave 
 a small portion of the lower wall of the meatus on the inner piece of 
 the preparation. 
 
 Equally instructive for forming an idea as to the relative positions 
 of the cavities and canals in the temporal bone will be found a series 
 of sections, made in a frontal direction nearly vertically to the long 
 axis of the pyramid, from its apex to the hindmost portion of the 
 mastoid process. From eight to ten cuts, carried with the saw through 
 the temporal bone at various distances, in front, 3-4 mm., in the 
 middle and behind 5-6 mm. from each other, give a good idea of the 
 section of the Eustachian tube and tympanic cavity, as well as of the 
 topographical position of the labyrinthine cavity to the cavum tymp. 
 Considering the practical importance of the middle ear, the anatomical 
 relations of this series of sections will be briefly sketched here. 
 
 First cut (Fig. 40) about 1| cm. behind the apex of the pyramid 
 and about 5 mm. behind the anterior opening of the canalis musculo- 
 tubarius. The osseous Eustachian tube (tu) is cut through about its 
 middle, the lamella of the canalis pro tens. tymp. (1) in its anterior 
 portion. The form of the section of the tube is mainly a triangle, 
 having its base at the tegmen tymp. (tg), and its apex (tu) directed 
 downwards. The thick lateral wall of this triangle (lateral wall of the 
 tube) belongs to the pars tymp., the inner thin one to the canalis 
 caroticus (c). 
 
40 DETAILS OF THE SECTIONS THEOUGH THE TEMPORAL BONE. 
 
 Second cut (Fig. 41), 3 mm. behind the first. It meets the 
 anterior segment of the lower turn of the cochlea (co), the anterior 
 section of the canal of the tube (tu), which is here quadrangular and 
 generally quite separate from the canalis pro tens. tymp. (m), and 
 bounded medially by the compact and dense wall of the labyrinth (w). 
 
 Tig. 40. — Section through the middle portion 
 of the osseous Eustachian tube. (Eight 
 ear.) — tg = tegmen tymp. ; tu = trans- 
 verse section of the tub. Eust. ossea ; 
 c = its medial wall, formed by the canal, 
 carot. ; m = inferior osseous lamella of the 
 canal, pro tens, tympani. 
 
 Fig. 41.— Frontal section of the temporal 
 bone in the vicinity of the anterior seg- 
 ment of the lower convolution of the 
 cochlea, 3 mm. behind the previous section. 
 — tu = transverse section of the osseous 
 Eustachian tube in the neighbourhood of 
 the ostium tymp. tubse ; w = its inner 
 compact wall ; m =: canal, pro tens. tymp. ; 
 CO = cochlea ; mi = meat, audit, int. ; 
 cp = crista tympanico - petrosa (crista 
 petrosa). 
 
 Third cut (Fig. 42), 3 mm. behind the previous one. This meets 
 the tympanic cavity anteriorly, between the ost. tymp. tubse and the 
 anterior segment of the sulcus tymp., the distance between which 
 
 m CO 
 
 cp ^ u j 
 
 Fig. 42. — Frontal section, 3 mm. behind 
 ' the previous one, through the axis of the 
 cochlea. — ct = transverse section of the 
 tympanic cavity, immediately behind the 
 ost. tymp. tubse ; m = canal, pro tens, 
 tymp. ; v = lateral tympanic wall be- 
 longing to the pars tymp. ; co = cochlea ; 
 mi = meat, audit, int. 
 
 Fig. 43. — Frontal section, 3 mm. behind 
 the previous one. — me = anterior wall of 
 the auditory canal ; s = sulcus tymp. ; 
 o = most anterior portion of the upper 
 tympanic space ; u = lower tympanic 
 wall ; ve = vestibulum ; pr = promontory 
 with the section of the first cochlear con- 
 volution. 
 
 is 1-1| mm. The cut here passes almost exactly through the modiolus 
 of the cochlea (co), the apex of which points directly towards 
 the canalis pro tens. tymp. (m). Above the second convolution of the 
 cochlea the plane of this section shows, as a rule, the hiatus canalis 
 Fallopii. 
 
DETAILS OF THE FRONTAL SECTIONS THROUGH THE TEMPORAL BONE. 41 
 
 Fourth cut (Fig. 43), 3 mm. behind the preceding. This passes 
 through the anterior portion of the upper and middle tympanic space 
 and through the external meatus, the anterior (me) and lower (u) walls 
 of which are divided close to the sulcus tymp. At the medial side of 
 the section of the tympanic cavity, the promontory, the processus 
 cochlearis, and the canalis Fallopii are cut through close to the 
 anterior edge of the fenestra ovalis, and with the first turn of the 
 cochlea the vestibule (ve) also is exposed. By this transverse section 
 the relations of the fossa jugularis (j) to the inferior wall of the 
 tympanic cavity and to the lower surface of the pyramid become like- 
 wise visible. 
 
 Fifth cut, 5 mm. behind the last (Fig. 44). It gives a clear topo- 
 graphical view of the antrum mastoid, in its relation to the tympanic 
 
 Fig. 44.— Frontal section in front of the posterior wall of the tympanic cavity.— me = meat, 
 extern. ; s = lower segment of the sulcus tymp. ; w = posterior tympanic wall ; an = 
 antrum mast. ; cr = crista longitud. antr. mast. : cs = canal, semicirc. super. ; h h' = 
 openings of the section of the canal, semicirc. horizontal. ; p p' = opening of the section 
 of the canal, semicirc. post. ; f = opening of the section of the facial canal ; j — fossa 
 jugularis. 
 
 cavity and the external meatus. As the cut falls behind the vestibule 
 it meets all the semicircular canals and the descending portion of the 
 canalis facialis (f). 
 
 The sections farther back concern the antrum mastoid, and the 
 mastoid process, and will, therefore, be noticed in the chapter ' Prepara- 
 tion of the Mastoid Process.' 
 
 Frontal cuts carried, as here described, in parallel planes, necessarily 
 strike the external and internal meatuses in a slanting direction, as the 
 axis of the latter forms with the long axis of the pyramid an obtuse 
 angle opening outwards and towards the front (comp. Fig. 47). In 
 order, therefore, to obtain a section through the temporal bone, show- 
 ing most clearly the anatomical relations of the external meatus to 
 the middle ear, a cut is carried in such a way as to pass through the 
 long axis of the external meatus, and also through that of the internal, 
 
42 FRONTAL SECTIONS THROUGH EXTERNAL MEATUS, TYMPANUM, ETC. 
 
 which lies in nearly the same direction. The cut thus goes through 
 the axis of the external meatus, and through the middle portion of 
 the tympanic cavity, meets the inner wall of the latter in front of the 
 fenestra ovalis, divides the anterior part of the vestibule and the first 
 turn of the cochlea, and terminates at the internal meatus. The tem- 
 
 co uc ot si u 
 
 Fig. 45. — Anterior half of a temporal bone, sawn through in a frontal direction in the long 
 axis of the external meatus. (Right ear.) — me := meat, audit, extern. ; o = upper wall 
 of the meatus ; u = its lower wall ; st = sulcus tymp. ; t = tegm. tymp. ; uc = lower 
 tympanic wall ; ot = ost. tymp. tubae ; tt = canal, pro tens. tymp. ; ct = fovea capit. 
 mallei ; mi = meat, audit, int. ; f f = canal, facialis ; co = cochlea. 
 
 ants sfv 
 
 Fig. 46. — Frontal section through the temporal bone. (Posterior half.) — me = meat, audit, 
 ext. ; o = upper wall of the meatus ; u = its lower wall ; te = tegmen tymp. ; ca = lower 
 wall of the tympanic cavity ; ty = sulcus tymp. ; p — promontory ; an — antrum mast. ; 
 s = eminentia staped. ; f = canalis facialis ; v — vestibule ; co = cochlea ; mi — meat, 
 audit, int. ; ma — proc. mastoid. ; si = fossa jugularis. 
 
 poral bone, thus divided into an anterior and posterior half, shows on the 
 surfaces of both sections the length and thickness of the inferior (u) and 
 
MEASUEEMENTS OF DIMENSIONS OF MIDDLE EAR ON TEMPORAL BONE. 43 
 
 superior (o) walls of the meatus, the relative position of the latter to 
 the middle cranial fossa ; the transverse section of that part of the 
 tympanic cavity in which the ossicula are situated, the section of the 
 tegmen tymp. (t te), and of the inferior wall of the tympanic cavity 
 (uc and ca), and the important relative position of this wall to the fossa 
 jugularis. In addition to this we notice, on such sections, what is of 
 so much importance in chronic suppurations of the middle ear, the 
 relations of the upper tympanic space (cav. epitympan., Schwalbe), 
 which passes into the antr. mast., to the posterior upper wall of the 
 meatus (o), the inferior sharp edge of which is roofed over by the 
 external portion of the cav. epitympan. This part of the latter which, 
 as we shall see later on, serves for the reception of the head of the 
 malleus and of the body of the incus, is sometimes the seat of an 
 independent suppuration, leading to perforation of the membr. flaccida 
 and to fusion of the margo tymp. with the adjoining wall of the 
 meatus. 
 
 Frontal sections through the temporal bone are especially suited for 
 measuring the width and height of the osseous Eustachian tube and of 
 the tympanic cavity. The determination of the transverse diameter of 
 the latter, in the vicinity of the tympanic membrane, can only be made 
 on unmacerated temporal bones. The measurements noted by me on 
 a large series of sections may be gathered from the following : Height 
 of the osseous Eustachian tube in the middle of the canal (Fig. 40) 6-7 
 mm., width of tube below the canalis pro tens. tymp. 4-5^ mm, ; height 
 of the ost. tymp. tubse 4-5| mm., its width 3|-4 mm. (according to 
 Bezold, height 4.5, width 3.3 mm.). Anterior portion of the tympanic 
 cavity, immediately in front of the ost. tymp. tubse (Fig. 42), height 
 9-10 mm., width 3-4| mm. Middle portion of the tympanum, where 
 the upper tympanic space is largest (Fig. 45), height from the floor to 
 the roof 14-16 mm. (Bezold, on corrosion preparations, 11.73 mm.). 
 Height at the hindmost portion of the tympanum in conformity with 
 Yon Troltsch 15 mm. The width of the tympanic cavity immediately 
 below the tegmen tymp. varies between 6 and 7 mm., from the incisura 
 Kivini to the inner tympanic wall, between 5 and 6 mm., at the most 
 posterior portion 5-6 mm. The breadth of the inferior tympanic waU 
 shows, in the majority of temporal bones, a transverse diameter of 5 mm. 
 The height of the posterior tympanic wall is 7-8 mm., that of the 
 anterior wall, ascending obliquely from the floor of the tympanum to 
 the lower edge of the ost. tymp., 2-3 mm. The distance from the floor 
 of the tympanic cavity to the lower edge of the sulcus 2i-4 mm. 
 (according to Bezold, on an average, 2.71 mm.). The height of the 
 opening leading to the antr. mast, above the posterior tympanic wall 
 from the lower angular depression to the tegmen mast, varies between 
 
44 HORIZONTAL SECTIONS THROUGH THE TEMPORAL BONE. 
 
 5 and 7 mm., its width from 6-7 mm. (according to Bezold's sections 
 from corrosion preparations, height 5.68, width - 6.69 mm.). In 
 exceptional cases the height exceeds the width. 
 
 The superior wall of the osseous meatus (Fig. 45), which is of 
 variable thickness, presents sometimes a nearly compact structure ; 
 not infrequently, however, diploetic or pneumatic cellular spaces, 
 which as a rule are situated in the neighbourhood of the superior 
 lamella of the wall of the meatus, and which rarely are connected with 
 the cavum tymp. itself, but communicate with the antrum mast, and 
 the pneumatic cells lying at the posterior wall of the auditory canal. 
 They sometimes extend from here forwards as far as the root of the 
 zygomatic process (Kirchner). On frontal sections a longish fissure 
 (Fig. 46) is frequently met with in the superior lamella of the upper 
 wall of the osseous meatus ; it arises, as before stated, by the lamina 
 tegminis tymp. overlapping the lamina interna of the pars squamosa. 
 The section of the lower wall of the meatus passes inwards and down- 
 wards into the sharp edge of the crista petrosa. As, however, especially 
 towards the front, the pars petrosa, and to even a greater extent the 
 pars tymp,, take a part in its formation, this crest might be more 
 correctly called the crista tympanico-petrosa. 
 
 The great individual differences in the thickness of the tegmen 
 tymp. and of the lower wall of the tympanic cavity can best be 
 demonstrated on frontal sections made through a considerable number 
 of temporal bones. In the tubal section, especially over the ost. tymp. 
 tubse, the tegm. tymp. is much thicker than over the upper tympanic 
 space. Here it appears sometimes thick, compact, or cellular ; some- 
 times, again, as thin as paper, perforated like a sieve, or to a large 
 extent broken through (dehiscence of the tegm. tymp., Hyrtl.*), Also 
 the wall bounded by the fossa jugular, is sometimes thick and com- 
 pact, rarely cellular, and at other times thin, bulging out bladder-like 
 towards the tympanic cavity ; sometimes, again, dehiscent. 
 
 The third series of sections through the temporal bone is made in 
 a horizontal direction. Three parallel cuts complete the topographical 
 picture of the external, middle, and internal ear, as described on the 
 former sections. The uppermost cut commences at the spina supra 
 meatum — that is, close above the superior wall of the meatus — meets 
 the upper tympanic space and the antr. mast., divides the superior 
 semicircular canal, and terminates at the superior wall of the internal 
 meatus. The second cut, lying 5-6 mm. lower, passes through the 
 external meatus somewhat above its axis, consequently nearer to the 
 
 * The statement that these gaps in the tegm. tymp., arising during growth, are caused by 
 atrophy in the bone had ah-eady been made by Henle in his ' Anatomic des Menschen,' Bd. 1. 
 1870. 
 
HORIZONTAL SECTIONS THROUGH THE TEMPORAL BONE. 
 
 45 
 
 superior than the inferior wall, divides the boundary between upper 
 and middle tympanic space, and runs through the pyramid in a plane 
 lying in the middle of the internal auditory canal. The upper aspect 
 of this cut (Fig. 47) shows the section of the anterior (a), superior, and 
 posterior (h) walls of the meatus, with the Rivinian segment (iR), the 
 upper tympanic space (ct) behind it, the antr. mast, (am) communi- 
 cating with it, and the pneumatic cells of the mastoid process (c c') 
 situated in the vicinity of the sinus transversus (si) ; towards the 
 front, in the angle formed by the pyramid and the squama, the canalis 
 musculo-tubarius. On the pyramid the section shows most distinctly 
 the upper vestibular space (v), the cochlea (co), and the internal 
 meatus (mi). The surface of the cut on the lower piece (Fig. 48) 
 shows in a comprehensive manner the length of the anterior, inferior, 
 and posterior walls of the meatus, the relative position of the latter to 
 the mastoid cells, the width and length of the lower tympanic space, 
 and the details of the middle ear and labyrinth mentioned in con- 
 
 squilt 
 
 Fig. 47. — Horizontal section through the temporal bone of an adult. (Upper half.) — squ = 
 squama ; z = proc. zygomat. ; eg = cavit. glenoidalis ; me = meat, audit, extern. ; 
 ct = cavum tymp. ; iR — incisura Rivini ; te = Eustachian tube ; am = autr. mast. ; 
 c c' = cellulfe mast. ; mi = meat, audit, intern. ; v = vestibule ; ch = canal, semic. 
 horizontal. ; co = cochlea ; ca = canal, caroticus ; si = sinus sigmoideus. 
 
 nection with the previous series of sections, and marked in the 
 accompanying illustration (Fig. 48). 
 
 The length of the walls of the osseous meatus is best determined 
 on frontal and horizontal sections of the temporal bone; but in 
 making the measurements the same points at the external orifice of 
 the meatus and at the sulcus tymp. should always be chosen. The 
 following measurements of the wails of the meatus agree generally 
 
46 
 
 HORIZONTAL SECTIONS THROUGH THE TEMPORAL BONE. 
 
 with the results obtained by Von Troltsch, Bezold, and others : 
 Length of the superior wall of the meatus, between the incisura Rivini 
 and that point where the squama turns into the horizontal part, 
 14-16 mm. (Bezold, 14 mm.) ; length of the anterior wall, from the 
 anterior edge of the pars tymp. to the anterior segment of the sulcus 
 tymp., 15-16 mm. ; length of the inferior wall from the corresponding 
 edge of the pars tymp. to the inferior segment of the sulcus tymp., 
 15-16 mm. ; length of the posterior wall, 14-15 mm. 
 
 With these average measurements, on the one hand, we occasionally 
 meet with temporal bones on which the walls of the meatus appear 
 longer by 1-3 mm. and more; rarely such where the length of the 
 walls falls below the average. The measurements on temporal bone of 
 children under twelve months show the average length of the walls 
 of the meatus to be half of that in the adult. 
 
 Fig. 48. — Horizontal section through the temporal bone of an adult. (Lower half.) — a = 
 anterior wall of the meatus ; p = its lower wall ; st = sulcus tymp. ; f = canalis facialis ; 
 ct = canalis pro tens. tymp. ; v = vestibule, and at its floor, the fissure leading to the 
 scala tymp. of the cochlea ; ch = canalis semicirc. horizontal. ; co — cochlea ; ca = canalis 
 caroticus ; w — proc. mast. ; st = sinus transversas. 
 
 If, on a frontal section, a perpendicular line be drawn from the 
 incisura Rivini to the lower wall of the meatus, the distance of this 
 point to the lower segment of the sulcus tymp. amounts to 4-5 mm. 
 (Von Troltsch, 6 mm.). A horizontal line from the inner boundary of 
 the posterior to the anterior wall divides the same, 5-7 mm. from the 
 anterior segment of the sulcus. 
 
 The length of the inferior tympanic wall, measured between the 
 point where the ridged anterior wall bends towards the ost. tymp. 
 tubse and the boundary of the lower and posterior walls, varies from 
 10-12 mm. (according to Yon Troltsch, ] 3 mm. ; according to Bezold, 
 on an average, 1273 mm.). The length of the osseous Eustachian 
 tube fluctuates between 10 and 12 mm. ; that of the canalis pro tens, 
 tymp., between 12 and 14 mm. 
 
FRONTAL SECTIONS OF SKULL THROUGH BOTH TEMPORAL BONES. 47 
 
 On horizontal sections of the temporal bone made below the 
 Rivinian segment and the canalis pro tens, tymp., and which afford 
 on the upper piece a free view into the antr. mast, and cav. epitymp., 
 one may frequently notice, on the lower surface of the tegmen antr. 
 mast., an elevation running in a longitudinal direction as far as the 
 tegmen tymp., which laterally and medially is flanked by small ledges 
 of bone standing vertically to its line of direction. This elevation, 
 which is not mentioned in the anatomical works I had access to, is 
 either solid or contains a canal, and must be regarded as the inner 
 boundary of the lamin. mast. int. part, squam., which is overlapped by 
 the tegmen mast. (comp. Fig. 27). It may therefore be designated as 
 crista tegm. mast. A second ledge of rather frequent occurrence, the 
 crista trans v. tymp., first detected by Bezold in corrosion preparations 
 on the inferior surface of the tegmen tymp., and which describes an 
 arch, open downwards, on the roof of the tympanic cavity, from the 
 upper lamella of the proc. cochlearis to the spina tymp. major of the 
 Rivinian segment, gives attachment to a fold of mucous membrane 
 passing over to the tensor tendon. It may be called the anterior 
 boundary of the cavum epitymp., upon whose lateral smooth and 
 excavated surface (Fig. 45) lies the head of the malleus. 
 
 To obtain a clear notion of the position of the two meatuses, of the 
 tympanic cavities, and labyrinths, a frontal cut is made by means of 
 the saw through the base of a skull which has been freed from the 
 calvaria, passing on both sides through the axis of the external 
 meatus, porus acustici interni, and the posterior portion of the clivus. 
 The cut through each temporal bone thus corresponds to the frontal 
 one described on p. 42, and shown in Fig. 46. It is needless to 
 dwell further on the advantages which such sections through the skull 
 offer for estimating the relative inclination of the various cavities in 
 the temporal bone. 
 
 In order to make these serial sections available for study and 
 demonstration purposes, it is recommended to number the consecutive 
 pieces, and to fasten those belonging to one preparation in their 
 proper order with tacks on a blackboard, or to cement them on a 
 glass plate of the requisite size. The latter mode has the great 
 advantage of allowing the sections to be examined on both sides. 
 
 Another still simpler way of keeping serial sections of the temporal 
 bone is to bore a hole through each of the pieces, and to string them 
 on a piece of thin cord or wire. On preparations which are to be used 
 for lecturing purposes the canalis caroticus may for greater clearness 
 be painted over with red; the sulcus transvers., the sinus petrosus 
 superior et inferior with blue ; and the nerve-canals with yellow 
 water-colour. For studying the course of the canals, as well as the 
 
48 PREPAEATION OF THE PROC. STYLOIDEUS. 
 
 entrance and exit of vessels and nerves in the temporal bone, it is best 
 to make use of short and long stiff bristles, which for demonstration 
 may be allowed to remain. In order that they may not fall out, they 
 are provided with small heads or knobs by dipping their projecting 
 ends into melted sealing-wax. 
 
 PREPARATION OF THE PROCESSUS STYLOIDEUS IN THE TEMPORAL 
 BONE OF THE NEW-BORN INFANT AND OF THE ADULT. 
 
 At the lower edge of the external surface of the temporal bone of 
 the new-born infant there is, immediately behind the posterior crus of 
 the ring, between this and the foramen stylo-mast., an irregular gap, 
 which leads into a short osseous canal directed upwards. This is the 
 sheath of the styloid process, at the lower opening of which the upper 
 portion of the proc. styloid, may frequently be seen if it happens to 
 be ossified before birth. If at the time of birth the styloid process 
 was still cartilaginous, the sheath will after maceration be found 
 empty. 
 
 To more clearly define its position and boundary, the posterior 
 crus of the tympanic ring is broken off, and the lateral wall of the 
 sheath removed with a broad graver. In a few cases only does its 
 upper portion open with a wide orifice, at the side of and below the 
 eminentia stapedii, into the tympanic cavity. In most preparations, 
 however, the vagina proc. styl. is closed above, and its upper limit 
 marked by the protuberance on the posterior wall of the tympanic 
 cavity (eminentia styloidea), first described by me, which is situated 
 between the sulcus tymp. and the eminentia stapedii. 
 
 Removing the lateral wall of the sheath of the styloid process in 
 preparations where the upper piece of the latter is already ossified, we 
 find that the above-mentioned protuberance, which is visible on the 
 posterior tympanic wall, is caused by the club-like thickened upper 
 end of the proc. styl. (Fig. 49). This club-like swelling is in some 
 cases very pronounced, while in others it is only slightly developed. 
 It is probable that from this arises the great difference in the develop- 
 ment of the eminentia styloidea on the posterior wall of the tympanic 
 cavity in the new-born infant and the adult. 
 
 The position of the proc. styl., and the bulging caused by it on the 
 posterior tympanic wall, may also be demonstrated on successful 
 sections made parallel to the inner wall of the tympanic cavity, 
 through the eminentia styloidea, lying between the sulcus tymp. and 
 eminentia stapedii (Fig. 50). 
 
 In order to understand the anatomical relations of the upper piece 
 of the proc, styloid., which is inserted in the temporal bone, it is 
 
PKEPARATION OF THE PROC. STYLOID. IN THE NEW-BORN INFANT. 49 
 
 advisable to expose it with the knife or scalpel on an unmacerated 
 temporal bone of a new-born infant, after the bone has been decalcified 
 in nitric or hydrochloric acid. On preparations where the styloid 
 process is still quite cartilaginous, it can be completely drawn out 
 from its sheath. Its form (Fig. 51), which I was the first to describe, 
 
 Fig. 49. — Upper end of the ossifying proc. 
 styloid, from a new-born infant. — o — 
 fenestr. ovalis ; p = promontory ; a = 
 antrum mast. ; c = canal, proc. styloid. ; 
 st — upper extremity of the proc. styloid. 
 
 Fig. .50. — Section through the canal, sty- 
 loideus in the new-born infant. — o = 
 fenestr. ovalis ; r = fenestr. rotunda ; 
 p = promontory ; c = canal, styloideus ; 
 st — section of the upper ossified ex- 
 tremity of the proc. styloid., causing the 
 posterior tympanic wall to bulge forward. 
 After a preparation in my collection. 
 
 is that of a club with one or more lateral processes, enclosed, in front 
 of the canalis Fallopii, and laterally from the eminentia stapedii, by 
 the before-mentioned sheath. The knob-like process of its upper 
 portion is directed forwards, and causes the posterior tympanic wall 
 to bulge out more or less. The posterior process is lodged in a de- 
 
 Fic. 51. — Cartilaginous styloid Fig. 52. — Glenoid facet on the posterior wall of the 
 process from a new-born infant. canal, styl. in the temporal bone of a new-born 
 
 infant. Enlarged to double its size. — o = fenestra 
 ovalis ; r = fenestra rotunda ; p = promontory • 
 tp = semicanal, pro tens. tymp. ; a = antr, mast ; 
 c = canal, styl. ; g = glenoid facet. After a 
 preparation in my collection. 
 
 pression on the posterior wall of the vagina proc. styl. ; this depression, 
 which I was the first to describe, resembles an articular cavity, has 
 a direction forward, and lies 5-6 mm. from the lower opening of the 
 sheath. It is placed close to the external surface of the pars mast. 
 
 4 
 
50 PREPARATION OF THE PROC. STYLOID. IN THE ADULT. 
 
 (Fig. 52), and only to be found in rare cases, becausQ it generally 
 coalesces with the styloid process before birth. 
 
 The preparation of the processus styl. in the adult is very difficult, 
 because its outer compact osseous layer and the surrounding mass of 
 the temporal bone are so completely fused that its earlier boundaries 
 are but seldom to be recognised on sections. As, however, the styloid 
 process frequently possesses a distinct medullary space, it is possible, 
 on successful sections, to follow its course in the temporal bone as far 
 as its upper termination. For this purpose either macerated or un- 
 macerated temporal bones may be used, on which the tympanic cavity 
 must be opened from above, in order to search for the protuberantia 
 styl. on the posterior tympanic wall. This projection, situated laterally 
 from the eminentia stapedii, as well as the processus styl., standing 
 
 Fig. 53. — Section through the styloid process of an adult.— a = tympanic membrane ; 
 b = medullary space of the proc. styl. ; c = its upper extremity with the protuberantia 
 styl. on the posterior tympanic wall, first described by me. 
 
 out on the lower surface of the pyramid, serve as a guide when making 
 the cut. The work is considerably facilitated on the macerated tem- 
 poral bone if the squama and the superior wall of the meatus be first 
 sawn away. The preparation is now fixed in the vice in such a 
 manner that, on applying the blade of the saw to the anterior wall 
 of the meatus, the line in which the cut is to be made falls exactly 
 in the direction of the eminentia styl. on the posterior wall of the tym- 
 panic cavity and of the long axis of the processus styl. proper. On 
 the surface of the section the porous medullary space of the pro- 
 cessus styl. may in most cases be traced as far as the vicinity of the 
 
ANATOMICAL PREPARATION OF THE ORGAN OF HEARING. 51 
 
 eminentia styl. The latter consists nearly always of compact bone 
 substance. 
 
 On unmacerated preparations the medullary space of the styloid 
 process is more clearly differentiated. The cut here takes the same 
 direction as in the macerated temporal bone. If it be intended, how- 
 ever, when making the preparation, to preserve the tympanic membrane 
 intact, after opening the tegmen tymp. the cut is carried in the longi- 
 tudinal direction of the lower tympanic wall in such a manner that 
 it passes through the eminentia styl. on the posterior wall of the 
 cavity. 
 
 As the processus styl. in the temporal bone describes, from the 
 lower extremity of its sheath to the eminentia styl, on the posterior 
 tympanic wall, an inwardly convex curve, this cut divides only the 
 upper-end piece of the styloid process. In order now to expose also 
 the middle and lower portions of the medullary space, the osseous 
 mass overlying it is either sawn through in the direction of the styloid 
 process projecting on the lower wall of the pyramid, or filed down with 
 a coarse file until the medullary space of the process (Fig. 53) comes 
 into view. 
 
 IV. 
 
 Anatomical and Pathologico-Anatomical Preparation of 
 THE Organ of Hearing. 
 
 introduction. 
 
 For the preparation of normal organs of hearing, fresh temporal 
 bones, taken from the body soon after the post-mortem examination, 
 are most suitable ; but for anatomical study such as have been kept 
 in Riidinger's preservative fluid (p. 6) or spirit preparations may 
 also be used. The employment of objects of the latter description is 
 especially advisable where fresh temporal bones are not at all times 
 obtainable, or where the student is tied by circumstances to certain 
 times for his work. Those who do not wish to be interrupted in their 
 anatomical studies should take care to have a supply of preparations 
 of the ear kept in a preservative fluid, so that there may always be 
 sufficient material at hand in case fresh objects should not be pro- 
 curable. 
 
 It is different with the dissection of pathologico-anatomical pre- 
 parations. Here it is under all circumstances advisable to begin the 
 work of preparation on fresh objects soon after they have been removed 
 from the body, in order to obtain as clear a representation as possible 
 of the morbid changes in the auditory apparatus. If the preparation, 
 for the purpose of future dissection, be kept in spirits of wine or in a 
 
 4—2 
 
52 PATHOLOGICO- ANATOMICAL PREPARATION OF ORGAN OF HEARING. 
 
 preservative fluid, both colour and consistence of tlie object are altered 
 in many ways, which would not admit of a correct estimate of the 
 morbid process. 
 
 The mode of preparing in pathological cases agrees, on the whole, 
 with that of normal preparations of the organ, though not infrequently 
 the method is subject to certain modifications depending on the 
 locality of the morbid changes, and on the necessity of keeping intact 
 some parts of the object, or of entirely removing others, so as to bring 
 the seat of the disease clearly under observation. 
 
 As the task of the pathologico-anatomical dissection of the organ 
 of hearing lies not merely in the macroscopical representation of the 
 morbid changes, but also in the histological investigation of the 
 diseased tissues, it is evident that, where possible, the anatomical 
 examination should always go hand-in-hand with the histological. 
 This endeavour to do justice in both directions to the scientific 
 investigation of a preparation is not infrequently beset with insur- 
 mountable obstacles. Foremost among these will be the desire of the 
 operator to add to his collection of pathologico-anatomical preparations 
 for teaching purposes. Here, in the interest of the instructive macro- 
 scopic representation, the histological examination will often have to 
 be dispensed with ; while in cases where, for scientific investigation of 
 the morbid process, the importance of the histological examination is 
 first to be considered, the preparation must be sacrificed for that 
 purpose. The latter alternative will be the more readily chosen if 
 the collection of macroscopical preparations contains already several 
 similar specimens ; while very rare and specially instructive patho- 
 logical preparations will be selected for preservation as macroscopical 
 objects. It should, however, be observed that not infrequently there 
 are cases where some portion of the preparation, such as the mem- 
 branous labyrinth, small portions of the external meatus, of the walls 
 of the tympanic cavity, of the Eustachian tube, and of the mastoid 
 process, may be taken from the specimen for histological examination 
 without the remainder of the preparation losing anything of its value 
 as a macroscopical object. 
 
 In the preparation of the normal organ of hearing, it is best to 
 begin with the auricle and the external meatus, and from here to 
 proceed with the dissection in the direction of the middle ear and the 
 labyrinth. The manipulation is much facilitated if all the soft parts 
 and osseous portions of the preparation, which interfere with the 
 laying bare of the various parts of the organ, be first removed with 
 scissors, forceps, and saw. This applies, above all, to the parotid 
 tissue covering the lower wall of the cartilaginous meatus, to the soft 
 
PREPARATION OF THE AURICLE AND CARTILAGINOUS MEATUS. 53 
 
 parts on the squama and the lower surface of the pyramid, and to the 
 muscles and tendinous insertions on the mastoid process. The removal 
 of these, too tedious when done with knife and scissors, is most 
 expeditiously effected by taking a firm hold of the preparation with a 
 . piece of cloth in the left hand ; then, grasping the tissues by means of 
 a not very sharp pair of bone forceps, twisting it round on its long 
 axis, and giving it a vigorous pull, they are torn away. When there 
 are no special reasons for retaining the dura mater on the object — e.g., 
 for the preparation of the aquasductus vestibuli, of the sinus trans- 
 versus, etc. — the dura mater may also be stripped off with the forceps, 
 
 Fig. 54. — Auricle. — a = helix ; b = anti- Fig. 55. — Exposed cartilage of the auricle 
 helix, passing upwards into the crura (Left ear.) — h = helix ; h" = transition 
 
 bifurcata ; c = tragus ; d =: antitragus ; of the helix into the concha ; ah = anti- 
 
 e =^lobulus ; f = ojjicha<4 g = outer ori- helix ; s = fossa navicularis ; t = tragus ; 
 
 fice of the meatus. ' at = antitragus ; i = incisura intertragica ; 
 
 b = anterior pointed process of the lielix 
 (spina helicis) ; 1 = posterior pointed pro- 
 cess of the helix (proc. helicis caudatus) ; 
 me = cartilaginous meatus ; sq = squama. 
 After a preparation in my collection. 
 
 care being merely taken that the acoustic and facial nerves be not 
 drawn out of the internal auditory meatus. 
 
 1. PREPARATION OF THE AURICLE AND CARTILAGINOUS MEATUS. 
 
 In order to become acquainted with the shape and outlines of the 
 cartilaginous skeleton of the auricle, its integument and muscular 
 structure, as well as the lobe, must be completely dissected oft from 
 the perichondrium. On the posterior surface of the auricle, where 
 the skin is easily movable, this may be done without difficulty with 
 pincette and scalpel. On the anterior surface, however, especially in 
 the concha, at the antihelix, and in the fossa navicularis, where the 
 integument is very firmly adherent to the perichondrium, the cutis 
 
54 FREPAEATION OF THE CARTILAGINOUS MEATUS. 
 
 must be detaclied with scalpel or scissors, great care being taken to 
 avoid injury to the cartilage. The complete exposure of the auricular 
 cartilage requires, therefore, considerable time. 
 
 When laid bare, the cartilage of the auricle (Fig. 55) shows, on the 
 whole, the same depressions and elevations as it does when covered by 
 the cutis. The most striking change of form, after dissecting off the 
 integument, is caused by the removal of the lobe and by the spina 
 helicis (Fig. 55, b) and the proc. helicis caudatus (1) becoming visible 
 on the preparation. 
 
 The close connection of the cartilage of the auricle with the 
 cartilaginous portion of the external meatus by means of a broad 
 bridge 8-9 mm. wide, commencing at its lower portion (isthmus 
 cartilag. auris. Schwalbe), requires, for anatomical purposes, both parts 
 to be prepared together. This may be done by exposing the entire 
 cartilaginous structure of the auricle and meatus ; or the auricle, 
 with its integument, is left in its natural form, and the cartilagino- 
 membranous meatus in connection with it is dissected out from the 
 parts surrounding it. 
 
 On a head where the auricle has been left in situ, the skin at the 
 circumference of the attachment of the latter is divided by a circular 
 incision, after which all the adjacent soft parts are dissected away. It 
 is best to begin in the region above the auricle by removing, as com- 
 pletely as possible, the integument with the galea aponeurotica, the 
 fascia temporalis and the temporal muscle from the squamous portion 
 of the temporal bone as far as the Hnea temporalis and the root of 
 the processus zygomaticus. Then the fibrous ligament (ligamentum 
 auriculare anterius), which passes from the root of the zygomatic 
 process to the tragus and to the anterior superior wall of the cartila- 
 ginous meatus, as well as the fibrous connections stretching thence 
 along the superior wall of the meatus to the ligamentum auriculare 
 post., are separated, after which the posterior superior membranous 
 wall of the cartilaginous meatus is loosened with the narrow handle of 
 a scalpel from its attachment to the horizontal portion of the squama 
 (superior wall of the osseous meatus). 
 
 The skin and fasciae over the mastoid process having been dissected 
 off, we divide the insertion of the posterior surface of the auricle at 
 the external surface of the latter, as well as the ligamentum auriculare 
 post, passing from the anterior part of the external surface of the 
 mastoid process to the auricle, and then detach with the handle of 
 a scalpel the loose tissue-connection of the posterior wall of the 
 cartilagino-membranous meatus with the anterior surface of the 
 mastoid process and the outermost section of the posterior wall of the 
 osseous meatus. This done, the laying bare of the anterior and lower 
 
PREPARATION OF THE CARTILAGINOUS MEATUS. 
 
 55 
 
 walls of the cartilaginous meatus is proceeded witli by so far removing 
 with scalpel and pincette the surrounding soft parts, consisting in a 
 great measure of parotis and adipose tissue, that the inner tapering 
 end of the lower cartilaginous wall comes clearly into view. 
 
 The cartilaginous meatus, when thus exposed, is found united by 
 an easily movable intervening mass of connective tissue to the exterior 
 margin of the tympanic portion of the osseous meatus, which is 
 covered with dense elastic fibrous tissue. The posterior superior 
 membranous wall of the meatus, on the other hand, passes uninter- 
 ruptedly into the subcutaneous connective tissue of the posterior 
 superior wall, giving off, as we shall see, fibrous filaments to the 
 membrana tympani. 
 
 For the study of the topographical position of the cartilaginous 
 and osseous portions of the auditory canal, it is recommended to make 
 a series of preparations, some showing the cartilaginous meatus in its 
 natural position, with its intact walls ; while others display, partly on 
 
 Fig. 56. — Auricle and cartilaginous meatus. (Left ear.) — a = cartilaginous meatus; b = 
 inner pointed extremity of the cartilaginous meatus ; c c = incisurse Santorinianae. 
 
 horizontal, partly on frontal sections (comp. the chapter, ' Making 
 Topographical Sections of the Organ of Hearing for Instruction 
 Purposes'), the course of the external auditory meatus. 
 
 To obtain the auricle and cartilaginous meatus as a separate 
 anatomical preparation, the distinctly marked bridge of connective 
 tissue between the cartilaginous meatus and the pars tymp. of the 
 osseous meatus, as well as the posterior superior membranous wall of 
 the pars cartilaginea, are cut through. 
 
 The cartilaginous meatus after separation appears, as seen in front 
 (Fig. 56), as a channel gradually narrowing inwards, the lower inner 
 extremity of which terminates in a rounded point (b), which slightly 
 projects below the inferior wall of the osseous meatus.* 
 
 * This tapering extremity of the cartilaginous meatus, described by Schwalbe (Anatomie 
 des Ohres, 1886) as process, triangularis, was described and illustrated in the first edition of 
 my ' Text-book,' 1878, p. 6. 
 
56 
 
 PREPABATION OF THE CARTILAGINOUS MEATUS. 
 
 The cartilaginous portion of the external meatus is traversed 
 vertically to its long axis by two fissures (c c, incisur. Santorini), which 
 are occupied by connective tissue, and the anterior of which (incisur. 
 maior) lies within the region of the cartilage of the tragus. Parotid 
 abscesses not infrequently break through these fissures into the 
 external meatus. In the cartilage of the auricle, the thickness of 
 which varies at different points from 1-3 mm., there are also incon- 
 stant fissures and openings (Sommering, Schwalbe) closed by connec- 
 tive tissue, which, according to Parreidt (' Dissertatio Inauguralis,' 
 1864), allow of the anastomosis of the bloodvessels between the 
 anterior and posterior surfaces of the auricle. 
 
 To demonstrate the limits of that region up to which the 
 
 Fis. 57.— Posterior wall of the cartilaginous and osseous meatus.— a = orifices of glands in 
 the cartilaginous portion ; b = boundary between the cartilaginous and osseous meatus ; 
 c = pointed extremity of the triangular space, occupied by the orifices of the glands, which 
 projects into the osseous meatus. 
 
 ceruminous and sebaceous follicles extend in the external meatus, the 
 anterior wall of the cartilaginous meatus is cut away with scissors, as 
 seen in the accompanying illustration (Fig. 57), part of the anterior 
 lower wall of the osseous portion being broken off with bone forceps. 
 It will be seen from such preparations that the glandular elements do 
 not occur, as was formerly supposed, in the cartilaginous meatus 
 alone, but that they extend, as first proved by Von Troltsch, in the 
 form of a triangular wedge (b c) into the osseous meatus. 
 
 The cartilage of the ear, as a preparation, keeps its form best in 
 spirit ; while, if dried, it shrinks so as to become unrecognisable. To 
 obtain useful dry preparations of the auricular cartilage, or of the 
 auricle covered with its integument, the object, either fresh or de- 
 hydrated in alcohol, should be placed in glycerine and allowed to 
 
PREPAKATION OF THE MUSCLES OF THE EXTERNAL EAR. 57 
 
 remain from eight to fourteen days. The saturated preparation, fixed 
 with pins on a small wooden slip, and protected from dust, retains for 
 years its shape and pliancy, especially if from time to time it be 
 brushed over with glycerine. 
 
 Preparations of congenital or acquired deformities of the auricle : 
 neoplasms of this part, epithelioma, sarcoma, cysts, auricular append- 
 ages, etc., must for demonstration purposes be preserved in alcohol. 
 Where the new growth is also to be subjected to microscopical 
 examination, small portions of it should be cut off from the prepara- 
 tion, care being taken not to spoil the appearance of the object. 
 
 PREPARATION OF THE MUSCLES OF THE EXTERNAL EAR, 
 
 The representation of the muscular apparatus of the auricle, 
 which, according to Ruge's* investigations, must be considered as the 
 remnant of the platysma myoides, may, with sufficient care, be 
 successfully made on fresh preparations ; but it is more to the purpose 
 to follow Ruge's method, which is to place the object for some days in 
 a weak solution of chromic acid (1-2000), and then to harden it in 
 alcohol. The work of preparing is thus facilitated, as the muscular 
 fasciculi_, by their deeper colour, appear sharply defined against the 
 subcutaneous connective tissue and fasciae. 
 
 The muscular apparatus of the auricle is divided into two groups. 
 The first of these, consisting of three principal muscles, effects the 
 movement of the entire auricle. The m, attollens s. levator auriculse, 
 the most strongly developed, arises, with its fan-shaped radiating 
 bundles, at the galea aponeurotica of the temporal region, and is 
 attached, with its fasciculi converging downwards, to the convex 
 surface of the auricle. The m. attrahens auriculse, which draws the 
 auricle somewhat forwards and upwards, arises in front of the ear 
 from the root of the proc, zygomaticus, and has its point of attach- 
 ment at the crista helicis. The m. retrahens auriculse arises with 
 several distinct fasciculi from the mastoid process, and is inserted 
 at the posterior convex surface of the concha. Having ascertained 
 theoretically the position of this group of muscles, there will be no 
 difficulty in finding them during the preparation, if care be taken, 
 when dissecting off the skin, that only the most superficial layers 
 of the subcutaneous connective tissue are removed with the outer 
 integument. 
 
 The preparation of the second group of muscles, which have their 
 origin and points of attachment on the auricle itself, and which, even 
 if strongly developed, can only effect a slight change in the shape of 
 
 * Untersuchungen iiber die Gesichtsmusculatur der Primaten, Leipzig, 1887. 
 
58 OPENING OF THE EXTERNAL MEATUS. 
 
 the auricle, presents far greater difficulties, because the various pale 
 muscular bundles are for the most part very faintly developed, and, in 
 dissecting off the cutis, may easily be removed along with it. The 
 bundles of the m. helicis major pass from the anterior edge of the 
 helix to the spina helicis ; those of the m. helicis minor run on the 
 lower portion of the helix, which projects into the concha. The m. 
 tragicus passes, with its vertical fibres, on the outer surface of the 
 tragus ; the m. antitragicus in the direction of the lower extremity of 
 the antihelix to the antitragus. On the posterior surface of the 
 auricle the m. transversus auriculae, made up of several transverse 
 bundles corresponding to the convexity of the concha, is easily found, 
 because the skin, being movable, can be readily dissected off from the 
 underlying structure. 
 
 2. OPENING OF THE EXTERNAL MEATUS. LAYING BARE OF THE 
 EXTERNAL SURFACE OF THE MEMBRANA TYMPANI. 
 
 In the anatomical dissection of the normal organ of hearing, it 
 is advisable, considering the topographical relations of the external 
 meatus, to retain the cartilagino-membranous portion of it in situ ; 
 and, on opening the canal, to remove only the anterior cartilaginous 
 wall. In pathologico-anatomical dissections, on the other hand, where 
 there is seldom occasion to retain the auricle and the external portion 
 of the cartilaginous meatus on the preparation, the examination of 
 that part of the cartilagino-membranous meatus still connected with 
 the object will only become necessary if any morbid changes should 
 be noticeable in it. Where this is not the case, the work of preparing 
 is materially simplified if, before opening the osseous meatus, the 
 cartilagino-membranous portion be entirely removed. 
 
 {A) Opening of the External Meatus in the Anatomical Dissection 
 of the Normal Organ of Hearing. 
 
 The laying bare of the external meatus and of the external surface 
 of the tympanic membrane is, after removal of its anterior cartilaginous 
 wall, most easily effected by taking away the anterior and part of the 
 inferior osseous wall. The instrument most suitable for this purpose 
 is the bone forceps (Fig. 10) shown on page 3, with which the usually 
 thin anterior osseous wall may readily be broken away bit by bit. 
 Only in rare cases does this wall attain such thickness that it can only 
 in part be broken down by the forceps, and, in order to complete the 
 work more speedily, chisel and saw have to be employed. 
 
 The nearer we come to the tympanic membrane when opening the 
 osseous meatus, the more cautiously must forceps or chisel be handled. 
 
OPENING OF THE EXTERNAL MEATUS. 59 
 
 SO as not to injure the membrane or break its frame. It is therefore 
 advisable, when approaching the latter, to remove the lamellae of the 
 anterior wall of the meatus in very small pieces, using the smallest 
 forceps only. Any projecting bits of bone which cannot be grasped 
 with the forceps, and which intercept the view into the tympanic 
 cavity, are to be carefully scraped off by means of a narrow, sharp 
 hand-chisel or graver (Fig. 12). This part of the work requires, how- 
 ever, a steady hand and great caution, as a slight slip might lead to 
 the destruction of the tympanic membrane. 
 
 Projecting portions of the thick superior or inferior wall of the 
 meatus, which prevent the examination of the membrana tympani, 
 are chipped off, but in layers only, with chisel and hammer, or cut 
 away with the saw. The latter manipulation is, with some practice, 
 
 -f 
 
 b a c d 
 
 Fig. 58.— Outer surface of the tympanic membrane, natural si^.e. (Right ear.)— a = short 
 process of the malleus ; b = lower end of the manubrium (umbo) ; c = membrana fiaccida 
 Shrapnelli ; d = ca vitas glenoidalis ; e = mastoid process ; f = section of the zygomatic 
 process. 
 
 to be preferred, because it is more expeditious and less risky. When 
 operating with the bone forceps, the object, partly wrapped in a piece 
 of linen, is firmly held in the left hand ; but if chisel or saw be used, 
 it should be fixed in the vice. After the removal, in the regular way, 
 of the anterior inferior wall of the osseous meatus and a portion of the 
 superior wall as far as the vicinity of the sulcus tymp., the external 
 surface of the tympanic membrane appears completely exposed, as 
 shown in Fig. 58, and affords a clear view of its details : the short 
 process (a), the handle of the malleus (b), Shrapnell's membrane (c), 
 and the curvatures of the tympanic membrane. Thick flakes of 
 epidermis, which not infrequently, even in preparations of the normal 
 organ, cover the membrane wholly or partially, and which adhere 
 mostly to the cutis, interfering thus with the normal appearance of 
 the membrane, must be carefully brushed off, but not removed with 
 the pincette, as this would easily cause rents in the membrane. 
 
60 OPENING OF EXTERNAL MEATUS IN PATHOLOGICAL DISSECTIONS. 
 
 (B) Opening of the External Meatus and Exposure of the Outer 
 Surface of the Membrana Tympani in Pathological Dissections. 
 
 In pathological dissections, before laying bare the external meatus 
 and the outer surface of the tympanic membrane, the auditory canal 
 must be examined with the speculum and reflecting mirror, in order 
 to remove, by syringing, any ceruminous and epidermic masses or 
 purulent secretion which may have accumulated there. Every patho- 
 logical dissection requires, moreover, previous to the opening of the 
 external meatus, the following experiments to be made, which are of 
 importance for estimating the middle ear processes : 
 
 1. To obtain information as to the permeability of the Eustachian 
 tube, the presence of secretions in the tympanic cavity, and the con- 
 dition of the tympanic membrane, air is forced into the tympanum by 
 means of a canula provided with an india-rubber bag, and introduced 
 into the cartilaginous tube, the sounds arising therefrom being 
 examined with an auscultation tube inserted into the cartilaginous 
 meatus. 
 
 2. Then the tympanic membrane is illuminated, in order to observe 
 the mobility of its various parts while air is being forced into the 
 tympanic cavity. It will then be seen whether the membrane is 
 totally or partially thinned or thickened, whether extensive or partial 
 adhesions exist between it and the inner wall of the tympanic cavity, 
 or if it be perforated. Non-adherent, especially thinned portions of 
 the membrane and isolated cicatrices will bulge strongly outwards, 
 frequently in the form of bladders; while adherent spots remain 
 immovable, or show only traces of mobility. When the tympanic 
 membrane is perforated, air rushes with an audible noise through 
 the perforation, carrying at times secretion along with it from the 
 tympanum into the external meatus. 
 
 3. Where, in pathological dissections, rigidity or anchylosis of the 
 ossicula has been supposed to be the cause of the disturbance of 
 hearing during life, the opening of the tympanic cavity, which is to 
 be described further on, must precede the laying bare of the outer 
 surface of the tympanic membrane. If, after removal of the tegmen 
 tymp., the malleo-incudal articulation is exposed and does not appear 
 enveloped by masses of connective tissue, the mobility of this joint 
 can be most easily ascertained by fitting air-tight into the external 
 orifice of the ear, or into the lumen of the detached cartilaginous 
 meatus, an olive-shaped nozzle, with a piece of india-rubber tube 
 I metre long fixed to it, for the purpose of alternately rarefying and 
 condensing the air in the auditory canal. With normal mobility of 
 the malleo-incudal joint, it will be possible with the naked eye, but 
 
EXPERIMENTS BEFORE OPENING MEATUS. 61 
 
 better still with a lens, to notice any displacement of the surfaces of 
 the articulation ; while in anchylosis of the joint, the body of the 
 malleus and incus, as a whole, will prove to be movable only to a 
 slight degree. If, at the same time, the short process of the incus has 
 become firmly fixed in its saddle-shaped depression, or if its long 
 process should be found adherent to the posterior tympanic wall, the 
 small bone will not be movable at all. Still, the malleus may show a 
 certain degree of mobility while, in anchylosis of the incus alone, the 
 malleo-incudal articulation is not implicated, as I observed to be the 
 case on two preparations taken from deaf-mutes. 
 
 In those not very rare cases, where hearing was disturbed to a high 
 degree in consequence of anchylosis of the stapes in the fenestra 
 ovalis, its presence cannot be proved in the manner here described by 
 inspection from above, because, even with normal mobility of the 
 stapes, it will be found impossible, although a magnifying lens be 
 used, to perceive any locomotion in the incudo-stapedial connection. 
 Anchylosis of the stapes, however, may be demonstrated by a simple 
 method, first pointed out by me. It is as follows : The superior 
 osseous semicircular canal, recognisable by the eminentia arcuata on 
 the upper surface of the pyramid, is opened with chisel or file, and 
 then filled with a drop of fluid so as to let it bulge out above the level 
 of the canal. If now the air in the external meatus be condensed and 
 rarefied, or if slight pressure be exercised with a probe upon the short 
 process of the malleus, or upon the body of the malleus and incus, it 
 will be observed that — provided the malleus and incus are not fixed — 
 there is, with a movable stapes, a distinct locomotion of the speck of 
 light on the drop of fluid ; while, in anchylosis of the stapes, this light- 
 reflex will remain stationary. Introducing the tube of a manometer 
 containing coloured fluid air-tight into the superior semicircular canal, 
 for the purpose of demonstrating the fluctuations of the labyrinthine 
 fluid, is more suited for physiological experiments than for demon- 
 strating anchylosis of the stapes. 
 
 The proceeding in opening the external meatus in pathological 
 cases is, on the whole, the same as we have just described for the 
 normal organ of hearing. In rare cases only, where, previous to 
 opening the external auditory canal, it had been proved by ocular 
 inspection that there existed pathological changes on the anterior wall 
 of the cartilaginous or osseous meatus, such as breaking of a parotid 
 abscess through one of the Santorinian fissures, caries or fracture of 
 the anterior wall of the osseous meatus, formation of cholesteatoma in 
 the same, etc., it will be necessary, for the purpose of plainly showing 
 the pathological changes, to remove either the inferior or the superior 
 wall of the meatus. If there be any changes on the anterior wall, it 
 
62 ASCERTAINING THE STATE OF THE TYMPANIC MEMBRANE, 
 
 is, under certain circumstances, even necessary to remove part of the 
 posterior wall and the mastoid process, in order to obtain a clearer 
 view into the external meatus. 
 
 In private pathological dissections, where the auricle must not be 
 removed, and where the cartilaginous meatus has been cut through 
 about its middle, the remaining portion of the cartilagino-membranous 
 canal is, before opening the osseous meatus, removed in the following 
 simple manner : 
 
 The remains of the temporal muscle still attached to the squama, 
 the fasc. temporal., and galea aponeurot. are quickly drawn off with 
 the periosteum from above downwards as far as the entrance into the 
 osseous meatus. This is best done by firmly laying hold of the soft 
 parts close to the bone with the pointed bone forceps, and turning the 
 latter on its long axis. The soft structures having been removed as 
 far as the upper periphery of the osseous meatus, that part of the 
 cartilaginous meatus which is held by the ligamentum auriculare ant. 
 et post, is then also grasped with the forceps, and by a single steady 
 twist completely separated from the osseous meatus. If this be done 
 too quickly, the cutis of the superior wall of the meatus will be torn 
 out up to the tympanic membrane and Shrapnell's membrane, or the 
 posterior superior segment of the tympanic membrane injured. 
 
 In those pathological dissections where, during life, a chronic 
 middle ear suppuration with symptoms of caries of the temporal bone 
 had existed, the opening of the external meatus is followed by a 
 minute examination of its walls. After thoroughly washing away the 
 secretion, we notice in carious processes or in cholesteatomatous 
 formation in the temporal bone, most frequently on the posterior 
 superior wall of the meatus, jagged fistulous openings which, either 
 free or covered with granulation tissue, communicate with the mastoid 
 cells or the antrum, or else are in connection with fistulous passages 
 opening out at various spots in the neighbourhood of the ear. The 
 length and direction of these fistulous passages are to be ascertained 
 with fine elastic probes. Should the examination, on account of con- 
 siderable tortuosity of the fistulous channels, fail to give any result, it 
 is often possible, by injecting them, to demonstrate their outlet in the 
 external meatus. 
 
 The external surface of the tympanic membrane, being exposed, 
 becomes now the subject of thorough examination in every direction. 
 For this purpose layers of macerated epidermis, inspissated secretion, 
 etc., which are frequently present, are removed with a camel's-hair 
 brush dipped in water, or washed away with the ball syringe, an 
 examination being afterwards made to ascertain whether the tympanic 
 membrane be normal or appear morbidly changed. In the latter case 
 
AFTER OPENING THE OSSEOUS MEATUS. 63 
 
 it should be examined — best with the aid of a lens — whether the 
 cuticular layer of the membrana tympani be smooth or loosened ; 
 whether small ulcers, papillary excrescences, granulations, or polypoid 
 proliferations can be proved to exist on it ; whether it be normal in 
 its curvature or strongly retracted, and, funnel-like, indrawn, with 
 marked prominence of the proc. brevis and of the posterior fold. If 
 the membrane be perforated, particular note should be taken of the 
 exact spot, size, and form of the opening, and an examination made to 
 see whether its edges are free or in contact with the inner wall of 
 the tympanic cavity; or, finally, whether they are united with it. 
 Further, it must be ascertained if the opening of the perforation be 
 blocked with masses of epidermis or granulations, which latter not 
 infrequently find their way through the gap into the external meatus. 
 By direct inspection it is now also possible to see more plainly any 
 atrophied portions and cicatrices observed during the propulsion of 
 air into the tympanic cavity, also bubble-hke bulgings, as well as the 
 extent of any casual adhesions. 
 
 Should there be any extensive defects of the tympanic membrane, 
 the morbid changes of the inner, lower, and posterior walls may also 
 be observed through the gap. Attention ought first to be directed to 
 the condition of the mucous membrane, to ascertain if it be loosened, 
 granulating, hypertrophied from polypous growths, or shrunken and 
 sclerosed; whether the handle of the malleus appear abnormally 
 inclined inwards and adherent to the promontorial wall, or be carious, 
 and partially or totally destroyed ; whether the incudo-stapedial con- 
 nection be intact, or the long crus of the incus defective. Finally, 
 should there be complete destruction of the membrane, the changes 
 in the niches of the fenestra ovalis and the fenestra rotunda, 
 and in the vicinity of the ost. tymp. tub^, can now also be seen. 
 Inspissated secretions and epidermis masses lodging in the tympanic 
 cavity must, of course, first be thoroughly washed out with the ball 
 syringe. 
 
 Where, during life, a purulent process had existed in the middle 
 ear, note should further be taken, in laying bare the external surface 
 of the tympanic membrane, of the condition of Shrapnell's membrane, 
 which is situated above the short process. If it be perforated, generally 
 a small fistula-like opening will be found, through which, on intro- 
 ducing a probe, the smooth or carious neck of the malleus can be 
 reached. Not infrequently, however, cholesteatomatous masses, or 
 polypi connected with the neck of the malleus, find their way through 
 the gap into the external meatus (Eugen Morpurgo), proliferating 
 over part of the tympanic membrane, and alloAving its position to be 
 ascertained only by careful probing. If there be extensive gaps above 
 
64 OPENING OF THE TYMPANIC CAVITY. 
 
 the Rivinian segment, arising through fusion of the margo tymp. 
 above Shrapnell's membrane, it is very easy, after washing out the 
 secretion from the upper tympanic space, to discover whether the 
 malleo-incudal connection be intact or carious, and, by careful 
 probing, to make out the condition of the walls of the upper tympanic 
 space, and sometimes also of the antrum mastoid eum. 
 
 3. OPENING OF THE TYMPANIC CAVITY BY THE EEMOVAL OF THE 
 TEGMEN TYMPANI. 
 
 The external surface of the tympanic membrane having been 
 exposed, the opening of the tympanic cavity is proceeded with. This is 
 most expeditiously effected by cutting away the roof of the tympanum 
 (tegmen tymp.). If, after stripping off the dura mater from the pre- 
 paration, the tegmen tymp. be found firm and compact, the object is 
 fixed in the vice to remove, with a narrow straight chisel, that part of 
 the tegmen tymp. which lies to the side of the eminentia arcuata of 
 the pyramid, formed by the superior semicircular canal. But in order 
 to avoid, during the proceeding, dislocating the ossicula, which are 
 , situated immediately below the roof of the tympanic cavity, it is well 
 to keep at first so far behind that the tegmen antri mastoid, be first 
 chiselled away, and the tegmen tympani proper removed afterwards. 
 Should, however, the roof of the tympanum prove thin, transparent, 
 and in some places dehiscent, it is possible, while firmly grasping the 
 preparation in a piece of cloth in the left hand, to break away with 
 the pointed bone-forceps the roof of the tympanic cavity in a very 
 short time, and thus expose the contents. 
 
 To gain an unobstructed view into the tympanic cavity, the 
 tegmen tymp. is removed in its entire breadth, and the opening of the 
 cavum tymp. extended so far backwards and forwards as to expose 
 simultaneously the antrum mastoid, and the osseous Eustachian tube, 
 after previously drawing out the m. tensor tymp. from its osseous 
 canal. 
 
 When the tympanic cavity has been opened from above (Fig. 59), 
 the malleo-incudal articulation (ha) in the upper tympanic space 
 comes first into view. It divides the upper tympanic space (cavum 
 epitympanicum, Schwalbe) into an inner and an outer portion. The 
 anatomical relations of the latter will, on account of their great 
 pathological importance, be discussed more fully later on. 
 
 In front of the malleus, at the boundary between the middle and 
 upper tympanic space, the tendon of the m. tensor tymp. (s) passes 
 transversely through the tympanic cavity. In a Hne with this, farther 
 backwards, in the middle tympanic space, the incudo-stapedial 
 
EXAMINATION OF TYMPANIC CAVITY IN PATHOLOGICAL DISSECTIONS. 65 
 
 connection, with the tendon of the stapedius, is visible. But while 
 the capitulum of the stapes is clearly to be seen, its crura, when being 
 searched for in the cavity from above, are almost entirely hidden by 
 the upper wall of the niche of the pelvis oval is and the prominating 
 facial canal. With a favourable light the upper segment of the inner 
 surface of the tympanic membrane, with the handle of the malleus, 
 part of the inner tympanic wall, the ridged floor of the tympanic cavity, 
 and the transition of the tympanic walls into the osseous Eustachian 
 tube, may also be seen through the cavum epitympanicum. 
 
 Besides the details here enumerated, the tympanic cavity, when 
 opened, displays partly constant, partly inconstant, folds of mucous 
 membrane stretched in it. Concerning these, we refer to the descrip- 
 tion, to be given hereafter, of the preparation of the ligamentous 
 apparatus of the malleus and incus. For the present, attention need 
 
 Fig. 59. — View of the tympanic cavity after removal of the tegmen tymp. (Right ear.) 
 — ha = maUeo-incudal articulation ; t = muse. tens. tymp. ; s = tendon of the muse, 
 tens. tymp. passing across the tympanum ; f = nerv. facialis ; g = genu nervi facialis ; 
 n = nerv. petros. superf. major ; a = nerv. acusticus ; an = antrum mast. After a pre- 
 paration in my collection. 
 
 only be called to the fact that these inconstant delicate folds and 
 filaments, stretched between the tympanic membrane, ossicles, and 
 walls of the tympanum, are, as I was the first to point out, to be 
 looked upon as the residue of the gelatinous connective tissue which 
 during foetal life fills up the middle ear. Their occurrence is, in so far, 
 of importance, as these normal bridges of mucous membrane, which 
 may easily be taken for pathological connective-tissue new growths, 
 are without doubt, in inflammatory middle ear processes, the cause of 
 adhesive strands of connective tissue. 
 
 EXAMINATION OF THE TYMPANIC CAVITY IN PATHOLOGICAL 
 DISSECTIONS.. 
 
 In pathological dissections, after the removal of the tegmen tymp., 
 note is to be taken : 1. Whether serum, mucus, pus, or masses of 
 
 5 
 
66 ASCERTAINING THE PATHOLOGICAL CONDITION OF MIDDLE EAR. 
 
 epidermis have accumulated in the tympanic cavity, and what changes 
 its lining and the mucous membrane covering of the ossicula show- 
 after the secretion has been removed.* 2. Whether the tympanic 
 space be narrowed by swelling of the mucous membrane, or filled 
 partially or entirely by granulation tissue, polypous proliferations, or 
 organized connective tissue. The latter is most frequently found in 
 the upper tympanic space immediately below the tegmen tymp., as a 
 reddish-gray or yellowish-red succulent or dense connective tissue, 
 which completely envelops the malleus and incus, and often also the 
 stapes. In these cases the middle and lower parts of the tympanum 
 are often found free from any new formation of connective tissue. 
 Complete filling up and obliteration of the tympanic cavity by newly- 
 formed masses of connective tissue (Toynbee, Von Troltsch, Politzer) 
 are less frequently observed. 3. Whether newly-formed strands and 
 bridges of connective tissue appear stretched between the tympanic 
 membrane, the ossicula, and the walls of the tympanic cavity ; in 
 what manner the position of the ossicles is altered thereby ; and what 
 changes, in consequence of such adhesion bridges, may exist on the ex- 
 ternal surface of the tympanic membrane. 4. Whether the ossicula, 
 upon careful sounding, show normal mobility, whether they are rigid or 
 anchylosed with the tympanic walls ; finally, whether malleus and 
 incus have been dislocated, extruded, or partially or entirely destroyed 
 by caries and necrosis. 
 
 Frequently it is sufficient, in order to ascertain the pathological 
 changes in the tympanum, to simply remove the tegmen tymp. 
 With some pathological appearances, however, in the tympanum, such 
 as adhesion of the head of the malleus, or anchylosis of the body of 
 the malleus and incus with the upper tympanic wall, or proliferations 
 of the mucous membrane filling up the upper tympanic space, and 
 enveloping the body of the malleus and incus, where, consequently, 
 the examination of the tympanum from above is rendered very 
 difficult, it is often necessary — after previously opening and minutely 
 examining the osseous and cartilaginous Eustachian tube — to expose 
 the tympanic cavity from the front and from below, so as to obtain a 
 view into the middle and lower tympanic space. 
 
 According to the seat of the pathological changes, it sometimes 
 suffices in such dissections to break off, with the bone forceps, the 
 external wall of the osseous Eustachian tube and of the tympanum 
 up to the annulus tymp., while in other cases the entire Eustachian 
 
 * Fluid and semi-fluid secretions must be removed from the tympanic cavity by suction 
 with a pipette ; epidermis masses should be taken out, partly with the probe, and partly with 
 the ball-syringe. A strong stream of water for cleansing the cavity from secretion is to be 
 avoided, because thereby the mucous membrane is denuded of its epithelium, and seques- 
 trated portions of the ossicles may be washed away. 
 
PATHOLOGICAL CHANGES IN THE TYMPANIC CAVITY. 67 
 
 tube, along with the anterior extremity of the pyramid and the in- 
 ferior tympanic wall as far as the sulcus for the tympanic membrane, 
 must be removed with saw, chisel and forceps, so as to bring clearly 
 into view any coalescences between the handle of the malleus and 
 the inner tympanic wall, or adhesions between the membrana 
 tympani, the long process of the incus and the promontory, etc. In 
 adhesions, and especially pathological strand-like formations in the 
 middle tympanic space — if the preparation is to be kept for demon- 
 stration purposes — the space must be so cleared by removing any 
 portions of bone which might obstruct the view into the cavum 
 tymp., that the morbid changes may become clearly visible. 
 
 With some preparations this can only be done by sawing away, in 
 a horizontal direction, the upper third of the pyramid up to the 
 height of the tendon of the tensor tympani ; while with others, 
 where the changes are located in the middle and lower tympanic 
 space, it must be done by horizontally separating the lower third of 
 the pyramid as far as the immediate vicinity of the fenestra rotunda, 
 the niche of which then also comes into view. In a large number of 
 the preparations in my collection, the pathological changes in the 
 tympanic cavity have been laid bare after this method. 
 
 It is evident that even in preparations with instructive pathological 
 strand-formations in the tympanic cavity, the cutting through of 
 these, and the separation of the outer tympanic waU, along with the 
 membrana tympani from the pyramid, cannot be avoided if, in order 
 to render clear the morbid appearances, a minute examination of the 
 niches of the oval and round windows, or of the labyrinth, becomes 
 necessary. In those pathological dissections, however, where, after 
 opening the tympanic cavity, neither masses of connective tissue are 
 found in it, nor adhesions met with between the tympanic membrane 
 and the inner tympanic wall, the membrana tympani, together with 
 the malleus and incus, must, under all circumstances, be separated 
 from the pyramid, so as to submit the changes in the niches of the 
 fenestra ovalis and the fenestra rotunda to a thorough examination. 
 
 The proposal of Voltolini (I.e.) not to open the tegmen tymp. in 
 pathological dissections, but to examine the changes in the tympanic 
 cavity from the external meatus, after cutting out the tympanic 
 membrane and the handle of the malleus, has, for good reasons, not 
 found favour in any quarter. This proceeding not only leads to the 
 destruction of the morbid changes on the tympanic membrane and of 
 the frequently-occurring bridges of adhesion between the tympanic 
 membrane and the inner tympanic wall, but it excludes also a more 
 minute examination of the pathological products in the upper 
 tympanic space, and in the lateral recesses of the cavum tymp., since 
 
 5—2 
 
68 SEPAKATION OF TYMPANIC MEMBRANE FROM THE PYRAMID. 
 
 these parts, even after complete removal of the tympanic membrane, 
 can only be imperfectly inspected. 
 
 4. SEPARATION OF THE MEMBRANA TYMPANI, WITH THE MALLEUS AND 
 INCUS, FROM THE PYRAMID OF THE PETROUS BONE. 
 
 Where, in normal or pathological preparations, the inner surface of 
 the tympanic membrane on the one side, and the details on the inner 
 tympanic wall on the other side, are to be brought into view, it is 
 necessary to have recourse to a method of separating the tympanic 
 membrane from the pyramid, whereby dislocation of the ossicles may 
 be avoided with certainty. 
 
 The middle ear may be divided sagitally, either by carrying a cut 
 simultaneously through the tympanic cavity, the mastoid process, and 
 the Eustachian tube in its entire length, or without having regard to 
 the latter by simply separating the pyramid from the pars tymp. et 
 squamosa. In pathological dissections the separation of the pyramid 
 must always be preceded by the examination of the tubal canal (see 
 the chapter ' Preparation of the Eustachian Tube '). 
 
 As regards the separation of the pyramid from the pars tymp. et 
 squamosa, it is to be observed that after removal of the tegmen 
 tymp. the tendon of the tensor tymp. (Fig. 59 s), passing in front of 
 the malleus across the tympanic cavity, is divided with a narrow small 
 knife, and the incudo-stapedial connection also carefully severed. 
 The separation of the tympanic membrane, together with the malleus 
 and incus, from the pyramid, may now be proceeded with in the 
 following manner : The preparation, with the opened tympanum 
 directed exactly upwards, having been fixed in the vice, is sawn 
 through along the floor of the osseous Eustachian tube so far towards 
 the tympanic cavity, until the vicinity of the incudo-stapedial 
 articulation is reached between the tympanic membrane and the 
 inner tympanic wall. 
 
 Now, in order to guide the blade of the saw between the tympanic 
 membrane, malleus and incus on the one side, and the capitulum of 
 the stapes on the other side, without dislocating or injuring any of 
 the ossicles during the operation, the tympanic membrane, with the 
 handle of the malleus, and the long process of the incus, are pushed 
 so far outwards with a probe held in the left hand that the narrow 
 saw blade may, with due care, be carried through between the crus of 
 the incus and the head of the stapes towards the posterior tympanic 
 wall. This having been reached, it is possible without any further 
 caution being required, to complete the cut through the mastoid cells 
 and the sinus sigmoideus. 
 
SEPARATING THE TYMPANIC MEMBRANE FROM THE PYRAMID. 69 
 
 As, however, with insufficient practice, the incus may be dis- 
 located, or the crura of the stapes broken off, it is advisable, for the pro- 
 tection of the membrana tympani and the ossicula, to use a thin metal 
 plate bent to the shape of the letter U, measuring 3 cm. by 1 cm., its 
 anterior and lower edges being curved, to correspond with the 
 posterior and inferior tympanic walls. The distance between the two 
 branches of the plate, when bent towards each other, amounts to ^ mm., 
 which gives free play to the saw while passing to and fro between 
 them. Having penetrated with the blade of the saw, in the manner 
 previously described, up to the vicinity of the membrana tympani, 
 the metal plate is fixed on the posterior edge of the saw blade, then 
 carefully pushed in between the crus of the incus and the capitulum 
 of the stapes in such a way that the anterior curved edges of the 
 plate touch the posterior and lower walls of the tympanic cavity. 
 
 Now, pressing down the metal plate with the index-finger of the 
 left hand, the lower and posterior tympanic walls and the inner 
 portion of the pars mastoid, may be sawn through without injuring 
 the tympanic structures. 
 
 Another method of separating the external tympanic wall, with 
 the tympanic membrane, from the pyramid — which, however, should 
 only be employed after sufficient practice — consists in removing with 
 the forceps the anterior and lower tympanic walls, after having pre- 
 viously cut through the tendon of the tensor tympani and the incudo- 
 stapedial articulation. The preparation is then fixed in its normal 
 position in the vice, and by means of a chisel 1 cm. broad, and applied 
 vertically 1 mm. from the inner side of the short process of the incus, 
 the compact posterior tympanic wall, as well as the posterior wall of 
 the pyramid bordering on the anterior edge of the sinus sigmoid,, are 
 severed with a few blows of the chisel. 
 
 With greater certainty, and equally expeditiously, the task will be 
 accomplished with preparations of this kind if, instead of a chisel, a 
 strong pair of forceps be used, with which the posterior pyramidal 
 wall between the exposed antrum mastoid, and the bare floor of the 
 tympanic cavity is broken off close in front of the sinus sigmoid., after 
 which strong pressure applied to the apex of the pyramid is sufficient 
 to detach the latter entirely from the pars squamosa et tymp. 
 
 In the case of children the separation of the membrana tympani 
 from the pars petrosa may be most readily effected with small pointed 
 bone forceps. After removing, as in the former methods, the tegmen 
 tymp., and cutting through the tensor tendon, as well as the incudo- 
 stapedial articulation, the lower wall of the osseous Eustachian tube, 
 and the thin inferior tympanic wall as far as the foramen stylomast., 
 are removed with the forceps, whereby the anterior and inferior 
 
70 METHOD OF OPENING TYMPANIC CAVITY ACCORDING TO LUC^. 
 
 segments of the tympanic ring are laid bare. Now, the osseous sub- 
 stance of the pars mastoid, adjoining the posterior crus of the annulus 
 is also divided with the small bone forceps, but only so far as to leave 
 the point of the annular crus in connection with the pars squamosa. 
 If, then, the sutura mast, squamosa be also broken through, the 
 tympanic membrane (Fig. 60), framed in by the annulus and the 
 lower portion of the pars squamosa, will fall away from the pars 
 petrosa. 
 
 The method proposed by Lucse"^ of opening the tympanic cavity 
 and separating the pyramid, a short description of which here follows, 
 differs in some respects from the one given above : 
 
 ' Having examined the auscultatory appearances with catheter and 
 otoscope, I divide the entire crista petrosa into three equal portions, 
 and carry, 2 mm. behind, where the posterior third commences, a cut 
 across the whole of the temporal bone in a plane which divides the 
 
 Fig. 60. — Outer surface of the tympanic membrane with the annulus tymp. and the lower 
 portion of the squama of a new-born infant. After a photograph taken by Dr. Hrubesch. 
 
 crista petrosa exactly at a right angle. By this cut, which falls 
 behind the lower portion of the Fallopian canal, and behind the vertex 
 of the posterior semicircular canal, the greater part of the mastoid 
 process is separated from the pyramid, and access to the tympanic 
 cavity gained from behind. It must be admitted that there is one 
 drawback in this : sometimes sawdust will get into the tympanic 
 cavity during the operation, but it can easily be removed with a 
 camel's-hair brush. This cut, moreover, removes almost the whole of 
 the cartilaginous and part of the osseous meatus ; so that, with the 
 light falling directly into the tympanum, it is possible to obtain a 
 view of the tympanic membrane, for the more thorough examination 
 of which the anterior wall of the remainder of the osseous meatus is 
 entirely removed by means of the gouge-forceps. It is now very easy 
 to gradually remove, with the scissors, the roof of the tympanic cavity 
 
 * Virchow's Archiv., Bd. 29. 
 
MAKING SAGITTAL SECTIONS OF THE ENTIRE MIDDLE EAR. 
 
 71 
 
 from behind, without running the risk of injuring the ossicles, the 
 mostly visible short process of the incus serving as a guide. The 
 Eustachian tube, previously carefully examined with a probe, is now 
 completely opened with scissors and a small chisel,' when a sufficiently 
 clear view into the tympanum will be obtained from above. This 
 method of removing the tegmen tymp., recommended by Toynbee 
 and Troltsch, I consider absolutely necessary in order to ascertain 
 accurately the presence of any casual adhesions, etc. After severing 
 the tendon of the tensor tymp., and disarticulating the connection 
 between incus and stapes, I detach the lower half of the tympanic 
 membrane with a sharp knife, and then chip off, with a stout chisel, 
 the remainder of the osseous mass of the squamous and mastoid 
 portions, with the upper half of the tympanic membrane in connec- 
 tion. If the soft parts be then cut through, the separation of the 
 
 an n 
 
 Fig. 61.— Sagittal section through the entire middle ear, outer half. (Left ear.)— op = est. 
 pharyng. tubae ; te = canalis tubse Eust. ; it = isthmus tubas ; mt = membr. tymp. with 
 the malleus and incus ; n = niche of the body of the malleus and incus ; an = antrum 
 mastoid. ; w w = cells of the mastoid process. After a preparation in my collection. 
 
 tympanic membrane, and the malleus, incus, and chorda tjnnpani 
 from the pyramid, with the stapes and the other parts of the ear, is 
 effected, so that the membrana tympani on the one side, and the 
 tympanic cavity on the other, may now be more minutely examined.' 
 
 When making sagittal sections through the entire middle ear on a 
 preparation which has been removed from the cranial cavity after the 
 method described on page 8, the osseous Eustachian tube is opened 
 from above, after taking off the tegmen tymp. ; while the parts of the 
 sphenoid bone that cover the cartilaginous tube are so far removed 
 with chisel and forceps as to allow the tubal canal, from its pharyngeal 
 orifice to the isthmus, to be split in its entire length. 
 
 It will now depend whether, in dividing the temporal bone by 
 a sagittal cut into an outer and an inner half, the cartilaginous 
 Eustachian tube is also to be divided into halves, or whether the 
 
72 
 
 MAKING SAGITTAL SECTIONS THROUGH THE MIDDLE EAR. 
 
 greater portion of the tubal canal is to remain in connection with the 
 outer or the inner piece of the preparation. In the former case, after 
 the insertion of a probe into the canal, the roof of the tube (point of 
 curvature of the cartilaginous hook) is cut longitudinally, with a pair 
 of straight fine scissors, from the ostium pharyng. to the osseous tube, 
 the membranous floor of the canal being likewise divided in the same 
 direction up to the osteons portion, whereupon the cut through the 
 osseous tube, the tympanic cavity, and the mastoid process is con- 
 tinued with the fret-saw in exactly the same manner as previously 
 described. 
 
 As, however, by this mode of representation the relationship of 
 the tubal canal to the tympanic cavity fails to be sufficiently 
 characterized, it is advisable to make also preparations in which 
 the Eustachian tube is left in connection, some with the outer half 
 
 Fig, 62.— Sagittal section through the entire middle ear of an adult, inner half. (Left ear.) 
 — op = ost. pharyng. tubse ; te = canalis tubas Eust. ; ot = ost. tymp. tubs ; tp = muse, 
 tens. tymp. ; p = promontory with the anastomos. Jacobsonii ; u = lower wall of the 
 tympanic cavity ; st = stapes ; sp = muse, stapedius ; f = facial nerve ; an — antrum 
 mastoid. ; w w' = mastoid cells. After a preparation in my collection. 
 
 of the divided temporal bone (Fig. 61), and others with the pyramid 
 (Fig. 62). 
 
 In the first case the saw must be applied medially from the fully- 
 exposed Eustachian tube, between it and the pyramid, care being 
 taken, while advancing towards the tympanum, to keep as near as 
 possible to the inner tympanic wall. In the second case (Fig. 62) the 
 cut is directed laterally from the Eustachian tube, laid open at the 
 outer membranous wall, in such a way that it falls in the immediate 
 vicinity of the external tympanic wall and of the insertion of the 
 membrana tympani. 
 
 The sagittal sections through the middle ear here described are 
 
PREPARATION OF THE TYMPANIC MEMBRANE. 73 
 
 especially suitable for measuring the length dimensions of the 
 Eustachian tube, as well as the distance from the ost. phar3mg. tubas 
 to the tympanic membrane, to the promontory, and to the entrance 
 into the antr. mastoid. Although the average measurements of the 
 length of the entire Eustachian tube noted by me agree, in the 
 majority of preparations, with those given by Von Troltsch (35 mm.) 
 and Bezold (3G*4 mm.), there are not infrequently cases where the 
 length of tube measures only 33 mm., and, on the other hand, cases 
 where it amounts to 39 mm. Bezold in one case found it to be 
 even 40 mm. In the new-born infant the Eustachian tube is much 
 shorter than in the adult (Von Troltsch). According to Eitelberg 
 (' Zeitschrift flir Ohrenheilkunde/ Bd. 13), its length amounts on an 
 average to 19 mm., of which 11 mm. go to the cartilaginous, and 
 8 mm. to the osseous portion. The distance from the ost. phar3mg. 
 tub. to the anterior edge of the tympanic membrane amounts in the 
 adult, according to my measurements, on an average to 37 mm. ; to 
 the promontory, 40 mm. ; to the aditus ad antrum, 47-49 mm. An 
 acquaintance with these distances is in a practical respect so far of 
 importance, as when employing bougies for dilating the tubal canal, 
 or when introducing thin elastic tubes (Paukenrohrchen) into the 
 tympanum for the purpose of washing it out, we are enabled to judge, 
 from the length of the inserted portion of the instrument, whereabouts 
 in the middle ear its point may be. 
 
 5. PREPARATION OF THE TYMPANIC MEMBRANE. 
 
 The anatomical details of the tympanic membrane when it has 
 been separated, together with the malleus and incus, from the pyramid, 
 may be examined either on preparations in which the membrana 
 remains in connection with its osseous frame, or on such where it has 
 been loosened from its insertion in the sulcus tymp. and at the 
 Rivinian segment. 
 
 To represent the tympanic membrane, with its osseous frame, as 
 an anatomical preparation, the mastoid portion of the outer half of 
 the divided temporal bone is so fixed in the vice that, during the 
 operation of sawing, the external and internal surfaces of the tjntnpanic 
 membrane can be kept in view. 
 
 The external surface of the membrane is first exposed by sawing 
 through, with the finest fret-saw, the inner extremity of the osseous 
 meatus from the front backwards, -i-1 mm. laterally from the insertion 
 of the membrane, and as far as possible parallel to it, the cut being 
 continued 2-3 mm. into the pars mastoid. Next, a cut is carried with 
 the saw, lj-2 mm. from the insertion of the membrana, round the 
 
V4 
 
 PEEPARATION OF THE TYMPANIC MEMBRANE. 
 
 tympanic frame, comm.encing at tlie anterior superior segment, 2 mm. 
 in front of the head of the malleus, and continuing the cut along the 
 anterior, inferior, posterior, and superior periphery of the membrane. 
 The posterior cut passes 2 mm. behind the short process of the incus ; 
 the superior, 2 mm. above the malleo-incudal articulation. The pre- 
 parations thus obtained, and the appearance of which is shown by the 
 accompanying illustrations (Figs. 63 and 64) of the outer and inner 
 surfaces of the tympanic membrane, enlarged to several times its size, 
 are particularly adapted for instruction purposes ; but for a thorough 
 anatomical study of the details of the membrane and of the malleo- 
 incudal articulation, as well as of its ligamentous connections with the 
 
 Fig. 63. — Outer surface of the left tym- 
 panic membrane of an adult, enlarged 
 3J times, — v = segment of the tym- 
 panic membrane lying in front of the 
 handle of the malleus ; h = posterior 
 segment of the tympanic membrane ; 
 s s' = Prussak's striae, passing from the 
 short process of the malleus to the 
 spina tymp. post, et minor ; ms = 
 membrana Shrapnelli. 
 
 Fig. 64. — Inner surface of the right tympanic 
 membrane with the malleus and incus, 
 enlarged 3J times. — n — malleo-incudal niche 
 at the outer wall of the tympanic cavity ; 
 h — head of the malleus ; a = incus ; pi = 
 posterior fold of the tympanic membrane with 
 Von Troltsch's pouch ; ct = chorda tympani. 
 
 tympanic cavity, other methods of preparation have to be employed, 
 which shall here be discussed. 
 
 By laying bare the inner surface of the tympanic membrane, 
 certain pathological changes in it can be more conveniently inspected 
 than is possible by examining its external surface. Among these are 
 the extent and density of calcareous deposits, thickening of the 
 mucous membrane layer, hypertrophy of its fibrous trabecular struc- 
 ture, papillary proliferations ; further, the degree of inward curvature 
 of those parts of it which are thinned by cicatrices and atrophy, 
 adhesion of the membrane, or of any cicatrices on it, with the long 
 
LOOSENING OF TYMPANIC MEMBRANE FROM THE SULCUS TYMP. 75 
 
 crus of the incus ; finally, the pathological changes in Von Troltsch's 
 pouches (accumulation of mucus, connective-tissue adhesions). 
 Thickening of the capsular ligament of the malleo-incudal joint, 
 sometimes occurring in chronic middle ear catarrhs ; again, adhesions 
 and coalescence between malleus and incus with the upper and 
 external tympanic walls, caries and necrosis of the malleus and incus, 
 etc., can be best demonstrated on preparations of this kind. 
 
 (a) Loosening of the Memhrana Tympani from the Sulcus 
 
 Tympanicus, 
 
 The form and size of the tympanic membrane can only be 
 estimated after it has been prepared out of the sulcus tymp. and 
 incisura Rivini.* Removing the tympanic membrane intact from its 
 frame must, however, if disfiguring rents are to be avoided, be carried 
 out with some care. The simplest way to proceed is as follows : At 
 the inner side of the preparation, close to the anterior margin of the 
 membrana tympani, an incision l|-2 mm. long is made with a small 
 knife in the mucous membrane. Through this incision the point of 
 the knife is inserted between the edge of the tympanic membrane and 
 the sulcus tymp,, and with a few strokes the connection between this 
 and the annulus tendinosus is completely severed. If now the piece 
 of the latter thus loosened be lifted out with the point of the knife 
 from the sulcus tymp., the other portions of the tympanic membrane 
 still remaining in the sulcus can be readily raised. Having firmly 
 grasped with a strong but finely-pointed pincette the free piece of the 
 annulus tendinosus, a gentle pull, aided by the point of the knife, will 
 be sufficient to lift it out complete. This proceeding should, however, 
 only be carried as far as the vicinity of the incisura Rivini, where the 
 sulcus terminates, because further attempts to loosen, by traction, the 
 edge of the tympanic membrane at other points would lead to fibrilla- 
 tion of its upper portion. When the tendinous ring is loosened in 
 front and behind as far as the chorda tymp., the latter is cut through, 
 at the points of its entrance and exit, with a pair of finely-pointed 
 scissors ; the ligaments of the malleus and incus, which will be 
 described later on, being divided at the same time with a small 
 pointed knife. 
 
 The tympanic membrane is then, by pressure upon the lower 
 extremity of the manubrium, pushed so far towards the external 
 
 * Measurements made on the tympanic membrane after it has been prepared out give 
 somewhat higher figures (10-11 mm. for its greatest diameter, 9-10 mm. for its transverse 
 diameter) than those on a preparation where it has been left in its insertion (9^-10 mm. 
 for its greatest diameter, 8^-9 mm. for its transverse diameter). This is explained by the 
 fact that in the latter case the annulus tendinosus lying in the sulcus tymp. is not included 
 in the measurement. 
 
76 LOOSENING OF TYMPANIC MEMBRANE FROM THE SULCUS TYMP. 
 
 meatus that, after cutting througli the ligamentum mallei extern, (see 
 p. 81, Fig. 67), passing from the neck of the malleus to the Kivinian 
 segment, the upper attachment of the tympanic membrane and of the 
 membrana Shrapnelli can be seen. If now, with the point of a very- 
 sharp knife, the insertion of Shrapnell's membrane at the Rivinian 
 segment, and the attachment of the superior and lateral portions of 
 the membrane not yet divided, are cut through close to the bone, the 
 connections of the membrana tympani with its surroundings will be 
 completely detached. 
 
 Rolled up, and kept connected with the malleus and incus, the 
 membrane unfolds itself rapidly under water, and displays its exact 
 contours and the boundaries of the tendinous ring, which, as a white 
 marginal streak, gradually diminishes in an upward direction, and is 
 entirely lost in the neighbourhood of Shrapnell's membrane. In spite 
 of being detached, the tympanic membrane retains its original funnel- 
 shaped curvature (Helmholtz). 
 
 Yarious sized particles of the lining of the osseous meatus, less 
 frequently of the mucous membrane of the tympanic cavity, becoming 
 detached along with the tympanic membrane, are in all cases found 
 adhering to the preparation. These, which spoil the appearance of 
 the specimen, are best laid hold of under water with a fine pincette, 
 and removed bit by bit, with small curved scissors, close to the 
 tendinous ring. 
 
 The tympanic membrane, taken out of its osseous frame, may 
 either serve as an anatomical preparation for demonstration purposes, 
 or be used for microscopical investigation (see the Histological part). 
 In the first case, the membrane is kept in alcohol in small glass jars,* 
 where the details of the outer and inner surfaces of the object can be 
 examined with the aid of a magnifying lens. 
 
 The proceeding in disarticulating the pathological tympanic mem- 
 brane from the sulcus tymp. is the same as with the normal. The 
 separation of the membrane in pathological cases is, however, under- 
 taken only for the purpose of microscopical examination. 
 
 If the pathological preparation is to be used as a macroscopic 
 object, it must be left in its natural connection with the sulcus tymp., 
 the morbid changes on the membrane being so better preserved in 
 their original position than would be the case if it were prepared 
 out. 
 
 * See plate, Fig. IV. belonging to the chapter ' Making Normal and Pathological Pre- 
 parations for Instruction Purposes.' 
 
EXPOSURE OF POSTERIOR DUPLICATURE OF TYMPANIC MEMBRANE. 77 
 
 (b) Exposure of the Duplicatures on the Inner Surface of the 
 Membrana Tympani. 
 
 Besides the previously-mentioned details on the inner surface of 
 the tympanic membrane, there are two duplicatures (Fig. 65), one of 
 which, lying behind the handle of the malleus, claims our special 
 attention. It appears as a fold, concave downwards, projects from the 
 membrana, and, partially hidden by the body and long crus of the 
 incus, it passes in a strong curve from the posterior superior periphery 
 of the tympanic frame to the handle of the malleus, and is attached 
 below the middle of the latter. This, the posterior duplicature of the 
 tympanic membrane, which was first described in detail by Von 
 Troltsch, forms, with the inner surface of the membrane facing it, the 
 so-called posterior tympanic pouch. 
 
 To become acquainted with the connection of this duplicature with 
 the upper portion of the tympanic membrane, the incus must be 
 luxated and removed. As, however, by tearing away the incus by 
 force, the delicate ligaments and folds which connect the malleus and 
 incus with the superior and external tympanic walls may be torn, 
 and the preparation rendered useless for the examination of the 
 ligamentous apparatus of the malleus, it is advisable first to cut the 
 ligamentum incudis post, (see p. 82) and the inner side of the 
 capsular ligament of the malleo-incudal articulation, with a small 
 pointed knife, after which the incus can easily be loosened with the 
 pincette. 
 
 When the incus has been removed, the posterior duplicature of 
 the membrane becomes visible in its entire extent (Fig. 65). As 
 regards its relationship to the tympanic membrane, it varies greatly 
 in different individuals, and even in one and the same individual 
 differences in both ears are met with. The posterior lower section 
 of the duplicature (c) is not in direct connection with the tympanic 
 membrane, but arises from a slightly curved ledge of bone lying 
 within the sulcus. 
 
 Only from 2 to 3 mm. above the lower extremity does the fold 
 pass from the osseous ledge on to the tympanic membrane. Now, 
 while the upper border of the duplicature is frequently found united 
 with the upper periphery of the membrana, its archlike point of 
 attachment appears in other preparations from 1 to 2 mm. lower. 
 
 The anterior segment of the duplicature is sometimes divided into 
 two laminae, the superior of which, connected with the chorda tymp., 
 is attached close to the inner edge of the handle of the malleus, while 
 the inferior lamina is inserted in the angle between the posterior 
 surface of the manubrium and the tympanic membrane — sometimes 
 
78 PEEPAEATION OF SHRAPNELL'S MEMBRANE. 
 
 at a distance of 1 to 1^ mm. from the handle. The triangular space 
 thus formed is generally closed in above, and is not in communication 
 with the tympanic pouch proper. 
 
 The posterior pouch communicates, in the preparations which 
 have been examined by me frequently, though not always, with the 
 space above the short process of the malleus (Prussak), which will be 
 described later on ; often, however, its cupola terminates in a funnel- 
 shaped depression. As a rule, Von Troltsch's pouch is free, yet in some 
 cases delicate bridges or star- shaped ramified bands of connective 
 tissue are found stretched in it, similar to those one meets with in the. 
 niches of the oval and round windows, and in the antrum mastoid. 
 Coalescence of the posterior duplicature of the tympanic membrane 
 with the long crus of the incus, in which the chorda tymp. is also 
 
 Fig. 65. — Inner surface of the tympanic membrane after removal of the incus. — Is = liga- 
 ment, mall, super. ; la = ligament, mall. ant. ; f = posterior duplicature of Von Troltsch ; 
 V = anterior duplicature of the tympanic membrane ; c = chorda tymp. After a prepara- 
 tion in my collection. 
 
 frequently involved, as well as adhesions of the surface of the duplica- 
 ture to that of the membrana, are by no means rare. 
 
 The anterior tympanic pouch (Fig. 65 v), smaller in extent, is formed 
 by the spina tymp. posterior, facing the neck of the malleus, and by 
 that fold of mucous membrane which, inferiorly, encloses the ligament, 
 mallei ant., stretched in the direction of the Glaserian fissure, the 
 chorda tymp., and the arteria tymp. inf The apex of its cupola is 
 almost invariably closed above. 
 
 (c) Preparation of the Membrana Shrapnelli. 
 
 The external surface of Shrapnell's membrane (Fig. 63) requires no 
 special preparation, since it comes clearly and fully into view when 
 the outer surface of the tympanic membrane is exposed in the regular 
 way. Its rounded edge corresponds to the Rivinian segment (margo 
 
PREPARATION OF SHRAPNELL'S MEMBRANE. 79 
 
 tymp., Henle), its inferior boundary being, according to Prussak, 
 formed by two short tightly-stretched striae (Befestigungs-strang des 
 Hammers, Helmholtz — s s'), which extend from the corners of the 
 incisura Rivini to the tip of the short process of the malleus. 
 
 Especially clearly marked are these striae of Shrapnell's membrane 
 (Fig. 63 s s') in the living subject, while in anatomical preparations 
 they rarely appear so distinct. Schwalbe's opinion (I.e., p. 442), that 
 the posterior one owed its origin to the cutaneous fasciculus of fibres, 
 which passes from the upper wall of the meatus on to the tympanic 
 membrane, I am, from my own investigations, unable to share, since 
 this stria lies deeper in the membrane than the superficial one of the 
 cutis, and can, after removal of the latter, sometimes be demonstrated 
 as a fibrous filament connected with the osseous border of the margo 
 tymp. 
 
 In order to gain access to the inner surface of Shrapnell's mem- 
 
 FiG. 66. — Inner surface of the membrana Shrapnelli. — s = membrana Shrapnelli ; f = 
 posterior duplicatufe of the tympanic membrane ; v = anterior duplicature ; h = section 
 iif the neck of the malleus which has been broken away ; n — malieo-incudal niche. 
 
 brane (Fig. 66) for the purpose of examination, the incus is first 
 removed, the neck of the malleus being then forced away just above 
 its transition into the upper surface of the short process of the malleus 
 by means of fine forceps. 
 
 If now the remaining portion of the ligament, mallei extern., which 
 passes from the neck of the malleus to the outer tympanic wall, and 
 forms the superior wall of Prussak's space, be carefully removed with 
 a fine pincette, the inner surface of Shrapnell's membrane is laid bare, 
 and with the aid of a lens its boundary may be determined on all 
 sides. 
 
 The arch-like edge of Shrapnell's membrane is partly in immediate 
 connection with the osseous border of the incisura Rivini, and here 
 serves as the periosteum. Destruction of the membrane up to its 
 extreme edge, therefore, frequently leads to carious fusion of the 
 osseous wall adjoining the Rivinian segment, and to the formation of 
 
80 KEPRESENTATION OF THE LIGAMENTOUS APPARATUS. 
 
 large gaps in the upper and posterior walls of the meatus, thus allow- 
 ing a clear view into the upper tympanic space. 
 
 (d) Representation of the Ligamentous Apparatus in the Vicinity 
 of the Malleus and Incus, and of the System of Cavities between 
 the Body of the Malleus and Incus, and the External Wall of 
 the Tympanic Cavity. 
 
 Of late years special attention has been directed to the anatomical 
 relations of that space which lies between the external surface of the 
 body of the malleus and incus and the smooth niche of the external 
 tympanic wall facing it. Their great practical importance is due to 
 the fact that purulent processes frequently set up in this space, which 
 are accompanied by perforation of Shrapnell's membrane, and are 
 characterized both by their obstinate course and frequent complica- 
 tions with suppurations in the mastoid process. An exact acquaint- 
 ance with this part of the middle ear is, therefore, of special import- 
 ance to the aurist, and we here propose to enter more fully into the 
 discussion of the method of representing the anatomical details of this 
 space. 
 
 The ligamentous apparatus between the malleus and incus and the 
 adjacent tympanic walls consists partly of constant, compact, fibrous 
 ligaments, partly of inconstant, delicate folds of mucous membrane, 
 connective-tissue bands, and delicate threads. 
 
 The laying bare of the constant fibrous ligaments of the malleus 
 and incus presents no difiiculty, since they appear, on fresh as well 
 as on spirit preparations, strongly marked by their whitish tendinous 
 appearance. 
 
 1. The ligamentum mallei superius (Fig. 69, 1 s), a roundish or flat 
 band passing from the upper tympanic wall to the head of the malleus, 
 is exposed in such a manner that, after removal of the tegmen mastoid., 
 the roof of the tympanic cavity is taken away with the pointed bone 
 forceps from behind forwards, care being taken to avoid breaking off 
 that portion of the tegmen tymp. which lies above the body of the 
 malleus and incus. This is the more safely accomplished if, on the 
 body of the incus becoming visible, we keep medially from it. When 
 the tympanum has been opened in front so far as to allow the tensor 
 tendon (Fig. 59, s) to be plainly seen, it will be easy, by holding the 
 preparation slightly to one side, to find the ligament, mall. sup. If the 
 pyramid be now also separated from the preparation, both the origin 
 and insertion of this ligament can be clearly seen. Sometimes it arises 
 from a projection of bone on the upper tympanic wall bulging forward 
 towards the head of the malleus. Almost constantly, there are 
 
PEEPARATION OF THE LIGAMENTUM MALLEI SUPERIUS. 
 
 81 
 
 attached to the ligamentum mallei superius, in front, behind, and 
 laterally, transparent folds of mucous membrane, which will be con- 
 sidered more in detail in a future chapter. 
 
 This ligament is a check ligament for the excursions of the handle 
 of the malleus outwards. Not infrequently there is, in the normal 
 state, direct contact between the head of the malleus and the tegmen 
 tymp., in which case the ligamentum mallei superius cannot be de- 
 monstrated. This anatomical relation favours, in cases of inflamma- 
 tion in the upper tympanic space, adhesions of the head of the malleus 
 with the upper tympanic wall. 
 
 2, The ligamentum mallei anterius (Fig. 67), a strong, tendinous 
 band, which arises partly from the spina angularis of the sphenoid 
 bone (Henle), partly from the spina tympanica posterior (spina tym- 
 
 FiG. 67. — Ligament, mallei anter. et extern. (Right ear.) — h = head of the malleus ; 
 la = ligament, mallei anter, ; le = ligament, mallei extern. ; h = its posterior portion ; 
 k = osseous tip of the spina tympan. post, (major), projecting between the ligament, mall, 
 ant. et extern. ; a = antrum mast. After a preparation in my collection. 
 
 panica major, Helmholtz), and the border of the Glaserian fissure : it 
 surrounds in the new-born infant the processus Folianus of the malleus, 
 but embraces in the adult merely the stump of this process, and finds 
 its irisertion at the neck of the malleus and the lower portion of the 
 anterior and lateral surfaces of the head of the malleus. This short, 
 tense, though somewhat broad ligament becomes visible to its fuU 
 extent after removal of the chorda tymp., and of the fold of mucous 
 membrane which is stretched between the anterior surface of the head 
 of the malleus and the adjoining tympanic wall. That portion of 
 the ligament which is situated in the Glaserian fissure, cannot be seen 
 until after removal of the piece of the external wall of the tympanum, 
 and of the Eustachian tube lying in front of the sulcus tjnup. and the 
 fissura Glaseri, and is easily represented on decalcified preparations 
 and microscopical sections. 
 
 The important influence of the ligament, mall, anter. upon the 
 
 6 
 
82 PEEPAKATION OF LIGAM. MALLEI EXT. AND LIGAM. INCUD. POST. 
 
 position of the manubrium, and consequently upon the tension of the 
 tympanic membrane, may be seen from the following experiments 
 made by me. On cutting the tendon of the tensor tympani and 
 aspirating the air from the external meatus, the tympanic membrane 
 will be drawn outwards, but return to its former position as soon as 
 the aspiration ceases. If, now, the incudo-stapedial articulation be 
 severed, the incus detached from the malleus, and the ligament, mallei 
 super, et ext. cut through, the manubrium will move distinctly in an 
 outward direction, but, pressed towards the external meatus, it will 
 still spring strongly inwards. Not until the ligament, mallei anter, 
 is cut through, does this springing of the manubrium inwards entirely 
 cease. 
 
 3. The ligamentum mallei externum, a tendinous fan-shaped liga- 
 ment (Fig. 67, le), connects the upper posterior portion of the incisura 
 Rivini with the crista capitis mallei opposite ; it is, therefore, a check 
 ligament for the movements of the handle of the malleus outwards. 
 The posterior part of this ligament (h) has been termed by Helmholtz 
 ligamentum mallei posticum, and as its line of direction, prolonged 
 anteriorly by the malleus, meets the middle fibrous filaments of the 
 ligamentum mallei anterius, he calls these two fibrous fasciculi the 
 axis ligament of the malleus. To demonstrate this ligament the 
 tegmen tymp. is completely removed up to its lateral boundary, the 
 incus is also taken away, and the inconstant folds possibly remaining 
 between the head of the malleus and the external tympanic wall are 
 removed with the pincette. The removal of the incus allows, in the 
 majority of preparations, the boundaries of the tendinous, gray and 
 sharply-defined ligament to be seen. Where, owing to the narrowness 
 of the space between the malleus and outer tympanic wall, this is 
 not possible, the ligament is best exposed by breaking off the head 
 of the malleus above the neck with a pair of fine forceps. 
 
 According to Schwalbe (I.e., p. 504) the ligament, mall. ant. is 
 separated from the ligament, mall. ext. by a bridge of mucous mem- 
 brane, which, with the latter, forms the upper boundary of Prussak's 
 space. 
 
 In several cases I found this interspace occupied by the inwardly 
 projecting spina tymp. post, (compare Fig. 67, k), 
 
 4. The ligamentum incudis posterius (Fig. 68), which connects 
 the short process of the incus, covered with a layer of cartilage, with 
 the corresponding saddle-shaped and similarly covered niche on the 
 posterior tympanic wall, may be recognised without further prepara- 
 tion, with the naked eye, or by the aid of a magnifying lens, as a 
 whitish tendinous band surrounding, in the form of a fan, the short 
 process of the incus. 
 
MUCOUS MEMBRANE FOLDS IN VICINITY OF MALLEUS AND INCUS. 83 
 
 Not infrequently the middle portion of the ligament corresponding 
 to the tip of the short process is wanting, in which case (Fig. 68) 
 the latter is found to be fixed by a lateral (b') and a medial (b) 
 ligament.* 
 
 Besides the ligaments here described, the malleus and incus are 
 connected with the walls of the tympanic cavity by a number of 
 partly constant, partly inconstant folds of mucous membrane. The 
 most constant of these is the lateral incudal fold (Fig. 68, f), which 
 passes from the upper edge of the body of the incus or its external 
 surface to the lateral wall of the niche, and after removal of the 
 tegmen tymp. becomes clearly visible. It is connected behind with 
 the ligam. incud. ext. (b'), in front, though not constantly, with the 
 fold (lateral malleo-incudal fold), passing from the head of the malleus 
 to the wall of the niche. In the latter case the space between the 
 body of the malleus and incus and the lateral niche is found to be 
 
 Fig. 68. — Ligamentous apparatus of the malleus and incus. — h = head of the maUeus ; 1 = 
 ligament, mall. ant. ; e = ligament, mall. ext. ; f — outer fold of the incus ; b = inner, 
 b' = outer portion of the ligament, incud. post. ; t = tendon of the muse. tens. tymp. ; 
 st = incudo-stapedial connection ; an = antr, mast. After a preparation in my collection. 
 
 completely closed above. Frequently, however, there exists, between 
 the incudal fold and the lateral fold of the malleus, a gap, varying 
 in size, and in the incudal fold itself one or several openings are some- 
 times met with. 
 
 Among the constant bridges of mucous membrane in the vicinity 
 of the malleus and incus, there are further to be numbered : one, 
 passing from the crista transv. tymp. (p. 47) to the tendon of the 
 tensor tympani, and one stretched horizontally (Zaufal) from the 
 latter to the anterior mucous membrane duplicature of the tympanic 
 membrane. Not constantly, though frequently enough, broad bridges 
 of mucous membrane or delicate filaments are found between the long 
 process of the incus and the inner tympanic wall ; these are the 
 
 * Compare Summering, Abbildungen des menschlichen Gehororgans, Taf. 2, Fig. 20. 
 
 6—2 
 
84 EEPRESENTATION OF PEUSSAK'S SPACE. 
 
 residue of the mucous membrane fold, which at this spot occurs in 
 the embryo constantly (Urbantschitsch). We further notice : mucous- 
 membrane bridges between the manubrium and the long crus of the 
 incus ; a fold extended between the short and the long process of the 
 incus ; then, bridges and filaments between the malleus, the long crus 
 of the incus, and the stapes ; and, lastly, a ramified trabecular structure 
 stretched from the body of the malleus and incus into the antr. 
 mastoid., with the importance of which structure we shall become 
 acquainted hereafter. That these folds of mucous membrane, fre- 
 quently occurring in great numbers in the tympanic cavity, favour in 
 chronic middle ear catarrhs the setting up of adhesive processes has 
 already been mentioned. 
 
 The space situated between the body of the malleus and incus 
 and the lateral wall of the niche, and bounded above by the malleo- 
 incudal fold, below by the ligament, mall, ext., is also crossed by 
 inconstant folds of mucous membrane, which are more numerous in 
 the new-born infant than in the adult. The fold most frequently 
 occurring here is the vertical fold of the niche (Fig. 70 w s), which, 
 stretched between the malleus or malleo-incudal articulation and the 
 niche, is in connection below with the ligament, mall, ext., above with 
 the lateral malleo-incudal fold. It becomes visible after removal of 
 the incus, or after breaking away the head of the malleus (in glycerine 
 preparations). By this vertical fold a space is bounded off laterally, 
 in front of the head of the malleus, and above Prussak's space (see 
 later on), which communicates, through one or several apertures, with 
 the cavum tymp. and the space of Prussak. It is in this space 
 especially that those obstinate purulent processes, which accompany 
 perforation of Shrapnell's membrane, establish themselves, and which 
 often resist the most energetic treatment. 
 
 (e) Representation of Prussak's Space, situated above the Short 
 Process of the Malleus. 
 
 The space above the short process of the malleus (Fig, 69), first 
 described by Prussak, is formed externally by Shrapnell's membrane 
 (Fig. 63, p. 74), below, by the upper surface of the short process of 
 the malleus, as well as by the cupola of the posterior and anterior tym- 
 panic pouches, and above by the ligament, mall. ext. The exact limits 
 of this cavity can, however, only be shown on sections of decalcified 
 preparations, or in a series of microscopic sections. For the purpose 
 of macroscopic representation, the tympanic membrane and its osseous 
 frame, detached along with the malleus and incus from the pyramid, 
 mu^t be decalcified in a mixture of common salt and nitric acid 
 
EXAMINATION OF LIGAM. APPARATUS OF THE MALLEUS AND INCUS. 85 
 
 (5-10 %), then well washed in water, and hardened in alcohol. In 
 order to avoid the displacement of the various parts of the pre- 
 paration during the cutting, the depression formed by the external 
 surface of the tympanic membrane, and the adjoining remains of the 
 osseous meatus, is filled with melted paraffin, and after the setting 
 of the latter it is cut away on the flat, so that in turning the pre- 
 paration over, the inner surface of the tympanic membrane should 
 come to lie upwards, and in a horizontal position. With a sharp razor 
 used for microscopic purposes, a cut is now carried through the whole 
 of the preparation in the longitudinal direction of the malleus, exactly 
 in the middle line of its head and handle. After this the paraffin is 
 carefully removed, and the sections of the preparation are examined 
 under water or in alcohol. 
 
 If the cut has been carried exactly through the short process of 
 the malleus, we notice (Fig. 69) on the anterior surface of the section 
 the boundaries of Prussak's space (o), sharply defined above by the 
 ligament, mall. ext. (le) ; internally, by the neck of the malleus ; below, 
 by the upper surface of the short process of the malleus (s) ; and 
 externally, by Shrapnell's membrane (o s). The anterior part of this 
 space is mostly closed on all sides, but sometimes communicates, 
 between the body of the malleus and incus and the lateral wall of the 
 niche, with the space (Fig. 69, r) which is situated above the ligament, 
 mall. ext. The posterior part communicates frequently, though not 
 always, by a small aperture, with the posterior tympanic pouch ; but 
 one often finds also, on the posterior membranous wall of this space, 
 one or several apertures, which, after removal of the incus, can be 
 distinctly seen by holding the preparation a little to one side, and 
 through which there is communication between Prussak's cavity and 
 the space situated between the body of the incus and external 
 tympanic wall, and freely connected below with the tympanic 
 cavity.* 
 
 Most suitable for the examination of the ligamentous apparatus of 
 the malleus and incus are preparations which are either quite fresh, 
 or such as have been previously hardened in alcohol and afterwards 
 soaked in glycerine. Wet preparations which have been kept in spirit 
 are, for the examination of the ligaments and folds, quite as unsuit- 
 able as dry objects, on which these parts become fissured through 
 shrinking. To represent preparations of this kind which are to be 
 kept for demonstration, I make use of spirit preparations, over which 
 I pour, on taking them out of the liquid, a small quantity of glycerine 
 
 * Kretschmann's treatise on ' Fistulous openings at the superior pole of the membrana 
 tympani ' (Arch. f. Ohrenheilk, Bd. 25), which appeared while this chapter was in the press, 
 could not be noticed here. 
 
86 EXAMINATION OF LIGAM. APPARATUS OF THE MALLEUS AND INCUS. 
 
 sublimate (0,1:25,0), drying them afterwards in a place kept free 
 from dust. Treated thus, even the most delicate folds of mucous 
 membrane retain for years their natural form and position. Such 
 objects are best protected from dust when fixed on a small stand 
 provided with a glass shade (Plate Figs. I. and III.). Equally 
 instructive are sections of decalcified preparations, which, for the 
 purpose of representing the ligamentous apparatus on transverse 
 sections, should be made in a vertical as well as in a horizontal 
 direction to the malleo-incudal articulation. As, however, the colour 
 of the ligaments and folds on decalcified spirit preparations differs 
 but little from that of the surrounding bone, it is advisable to expose 
 fresh objects for several weeks to the action of Miiller's fluid (see 
 Histological part), or of a weak solution of chromic acid, and only 
 after such treatment to proceed with the decalcification by means of 
 
 !FiG. 69. — The space of Prussak : section 
 through the tympanic membrane, malleus, 
 upper and outer tympanic wall of a decal- 
 cified preparation. — Is = ligament, mall, 
 super. ; le = ligament, mall. ext. ; s = 
 membrana Shrapnelli ; o = Prussak's 
 space ; r = system of cavities between the 
 body of the malleus and incus, and the 
 external tympanic wall ; t = tendon of the 
 muse. tens. tymp. After a preparation 
 in my collection. 
 
 Fig. 70. — Elliptic opening of Prussak's space 
 on its posterior membranous wall after re- 
 moval of the incus. — h = head of the 
 malleus ; s = ligament, mall, super. ; 
 w s = Vertical fold of mucous membrane 
 between the malleus and the malleo-in- 
 cudal niche ; o = elliptic opening of 
 Prussak's space ; ch = chorda tympani ; 
 f = posterior duplicature of the tympanic 
 membrane. After a preparation in my 
 collection. 
 
 hydrochloric or nitric acid. In sections of such preparations the 
 osseous tissue appears dark green, while ligaments and folds are 
 distinguished by their whitish or light-green colour. To avoid tearing 
 the delicate folds of mucous membrane when making sections, the 
 decalcified preparation, after having previously been freed from 
 water in 90 % alcohol, is soaked in celloidin solution ; it is 
 then placed in dilute alcohol, and after setting of the medium the 
 sections are made (see ' Celloidin Embedding,' in the Histological part). 
 By the ligamentous apparatus of the malleus and incus here 
 
PATHOLOGICAL CHANGES IN THE MALLEO-INCUDAL NICHE. 87 
 
 sketched, and the folds of mucous membrane and bridges stretched 
 between them and the upper external tympanic wall, there is formed 
 in the outer portion of the upper tympanic space, between the external 
 surface of the malleus and incus and the niche opposite, a system of 
 cavities, first described by me (Wien. med. Wochenschrift, 1868), the 
 spaces of which communicate with each other and with the rest of 
 the tympanum. In new-born infants I found, on microscopical 
 sections of this system of cavities, in some of its loculaments, a yellow 
 serous or slimy fluid ; in the adult all the spaces of the mesh work 
 contain air. 
 
 The pathological changes which are developed in this region of the 
 upper tympanic space have hitherto not been sufficiently investigated 
 — at least, not to such an extent as the importance of the subject 
 would demand. It must, however, be taken as an undisputed fact 
 that the spaces of this system of cavities in chronic mucous middle 
 ear catarrhs, running on without perforation of the tympanic 
 membrane, are filled with succulent neoplastic connective tissue, and 
 that similar changes are sometimes met with at this spot as the result 
 of purulent inflammation. The latter, however, not infrequently leads 
 to destructive changes, especially to perforation of Shrapnell's mem- 
 brane, fusion of the margo tymp., and to carious and necrotic 
 destruction of the malleus and incus. 
 
 The purulent process in the above-mentioned system of cavities 
 accompanied by perforation of Shrapnell's membrane, may either 
 localize itself as an independent process without spreading to the rest 
 of the tympanic cavity, or — and this is more frequently the case — the 
 entire tympanic cavity is attacked from the commencement by the 
 suppurative inflammation. In the course of the process, however, the 
 suppuration in the middle ear may cease, while it obstinately continues 
 in the system of cavities between the body of the malleus and incus 
 and Shrapnell's membrane. It admits of explanation, that in a con- 
 siderable number of cases pus may be copiously secreted in these 
 cavities, and make its way through the perforated Shrapnell's mem- 
 brane, without it being possible to prove the presence of any secretion 
 in the rest of the tjT-mpanic space, when it is considered that the 
 scanty communications of this system of cavities with the tympanum 
 are obstructed through swelling, inspissated secretion, and cholestea- 
 tomatous masses, by proliferations of mucous membrane, and by 
 polypi (Morpurgo). We can also conceive the obstinacy of a purulent 
 process in a space occupied by a meshwork from which the stagnating 
 secretion is diflicult to remove, and the hidden crevices of which are 
 only with difliculty accessible to antiseptic treatment. 
 
 As regards the connection of purulent processes in this space with 
 
88 PATHOLOGICAL CHANGES IN THE MALLEO-INCUDAL NICHE. 
 
 simultaneous chronic suppuration in the antrum mastoid., there are, 
 in my opinion, two things of importance to be considered. We have 
 seen (p. 38) that the smooth surface of the malleo-incudal niche 
 merges behind into the outer cellular wall of the antrum mastoid. 
 Purulent inflammations in that niche may thus, with equal facility, 
 spread ex contiguo to the neighbouring mucous membrane of the 
 antrum mastoid. ; and, on the other hand, those occurring in the 
 antrum may find their way to the malleo-incudal niche. The latter 
 might, according to clinical observations, be much more frequently 
 the case than has hitherto been supposed ; thus purulent discharges, 
 with perforation of Shrapnell's membrane, would in such cases have 
 to be looked upon as the consequence of suppuration in the antrum 
 mastoid. 
 
 Another circumstance respecting the connection of purulent pro- 
 cesses in the antrum mastoid, with perforation of Shrapnell's membrane, 
 which so far has not been sufficiently appreciated, lies, in my opinion, 
 in the peculiarity of the inclination of the external wall of the antrum 
 and of the malleo-incudal niche. The strong inclination of these 
 osseous walls to the horizontal may be easily demonstrated on 
 macerated as well as on unmacerated skulls, after removal of the 
 tegmen tymp. The outer tympanic wall, with the malleo-incudal 
 niche and the external wall of the antrum, must therefore, in conse- 
 quence of their strong inclination, be designated the outer inferior 
 wall of the middle ear ; and it is thus evident that the purulent 
 secretion, flowing from the antrum at its outer inferior wall, must first 
 reach the malleo-incudal niche. This will happen especially in those 
 cases where, in the external malleo-incudal fold, either normal inter- 
 stices are found, or where breaches have been caused in it by the 
 purulent process. In such cases the pus, flowing out of the antrum, 
 must reach the system of cavities between the body of the malleus 
 and incus and the external tympanic wall, setting up suppurative in- 
 flammation therein, and eventually leading to perforation of Shrapnell's 
 membrane. This spreading of the suppuration from the antrum to 
 the system of cavities will be favoured if, at the same time, the com- 
 munication between the antrum and the tympanic cavity proper be 
 interrupted by normal or pathological bridges of connective tissue. 
 
 It has further been pointed out that in preparations of the normal 
 ear there is sometimes stretched out in the antrum mastoid, a tra- 
 becular structure connected with the osseous walls, and composed of 
 ramified bands of mucous membrane, which, as seen in several pre- 
 parations of my collection, extends into the tympanic cavity, and is 
 there connected with the ligaments and mucous membrane folds of 
 the malleus and incus. Now, it may be assumed, with some proba- 
 
ANATOMICAL DETAILS OF THE INNER TYMPANIC WALL. 
 
 89 
 
 bility, that where such normal formations occur in the middle ear, the 
 changes caused by inflammation in the vicinity of the malleo-incudal 
 niche may, through this trabecular structure, spread into the antrum, 
 and, in an opposite direction, from the antrum into the niche. 
 This was confirmed by a post-mortem case which came under my 
 notice. An individual who during life had shown symptoms of a 
 chronic mucous middle ear catarrh, was found to have died in conse- 
 quence of marasmus senilis. Examination of the left ear showed a 
 viscid, yellowish, transparent, elongated plug of mucus which reached 
 from the malleo-incudal niche into the antrum mast., and which, upon 
 
 Tig. 71. — Inner wall of the tympanic cavity. — a = fenestra ovalis with the stapes ; b = 
 fenestra rotunda ; c = promontory ; d = muse, stapedius ; e = canalis Fallopii ; f = 
 canalis pro tensore tympani ; g = mastoid process. 
 
 closer examination, proved to be the above trabecular structure, the 
 spaces of which were occupied throughout by the viscid mucous mass. 
 
 6. INNER WALL OF THE TYMPANIC CAVITY : ITS EXAMINATION IN 
 PATHOLOGICAL DISSECTIONS. 
 
 The pyramid, when separated from the pars tymp. et squamosa, 
 presents on its outer anterior wall, turned towards the tympanic cavity 
 (Fig. 71), the two physiologically important labyrinthine fenestrse 
 The fenestra ovalis (a), leading into the vestibular space of the 
 labyrinth, lies, with its strongly inclined plane, at the bottom of a 
 deep niche (pelvis ovalis), and serves for the reception of the stapes. 
 The long diameter of the fenestra ovalis measures rather more than 
 3 mm., the width being 1| mm. Below the niche of this fenestra a 
 second, nearly triangular niche, which is considerably inclined back- 
 wards, leads to the membrane of the fenestra rotunda, the latter 
 closing the lower scala of the cochlea (scala tymp.) towards the 
 tympanic cavity. In front of the two labyrinthine fenestrse lies the 
 
90 EXAMINATION OF THE PROMONTORIAL WALL. 
 
 most prominent part of the inner tympanic wall, corresponding to the 
 projection of the first cochlear convolution — the promontory. Over 
 this prominence passes, in a vertical direction, in an open or covered 
 groove, Jacobson's nerve, which effects the anastomosis between the 
 ganglion jugulare and the nervus petrosus superficialis minor. 
 
 Around the promontory and the two labyrinthine fenestrse are 
 grouped : superiorly, above the fenestra ovalis, in a direction slightly 
 backwards and downwards, the middle portion of the Fallopian canal, 
 with the facial nerve ; near this, in a backward direction, and pro- 
 jecting towards the tympanic cavity and the antrum mast., the 
 external crus of the horizontal semicircular canal ; behind the pro- 
 montory, the eminentia pyramidalis enclosing the muse, stapedius, 
 and bounded medially and posteriorly by the descending portion of 
 the facial nerve. In front, the inner tympanic wall, becoming 
 gradually flatter from the promontory towards the ostium tymp. tubse, 
 appears narrowed to a triangular space between the canalis pro tens, 
 tymp. (f) and the obliquely ascending anterior tympanic wall. 
 
 In pathological dissections, after the pyramid has been separated, 
 attention should first be directed to the condition of the mucous 
 membrane of the promontory and of the contiguous parts of the inner 
 tympanic wall. In acute inflammations, as well as in chronic suppura- 
 tions of the middle ear, the nature of the exudation lying upon the 
 surface of the mucous membrane, and in the depressions of the inner 
 tympanic wall, or of any epithelial deposits, should first be examined, 
 and after these have been carefully washed away, the degree of 
 hypersemia, of swelling, and proliferation of the mucous membrane 
 in the various parts of the tympanic cavity must also be ascertained. 
 
 Further, it should be ascertained by means of a lens whether the 
 mucous membrane, in spite of considerable swelling, presents a smooth 
 surface, or whether it be covered with granulations and papillary 
 proliferations. Partial thickening of the mucous membrane, circum- 
 scribed infiltrations and loss of substance, may also be demonstrated 
 by magnifying power. In addition to this, wherever, in purulent 
 middle ear processes, proliferations of the mucous membrane are met 
 with on the inner tympanic wall, or where, during life, appearances 
 of a carious affection of the temporal bone had existed, it must be 
 determined by careful sounding whether, and to what extent, rough- 
 ness of the promontorial wall of the tympanic cavity exists. In 
 extensive caries of the pyramid — further, in tubercular phthisis of the 
 lining membrane of the tympanic cavity — the extent of the ulceration 
 in the membrane and the bone will be perceptible in most cases with 
 the naked eye. 
 
 In non-purulent affections of the middle ear, and after suppura- 
 
IN PATHOLOGICAL DISSECTIONS. , 91 
 
 tions which have ceased, where the lining membrane of the promontory 
 appears at times pale yellow, atrophic, at other times tendinous, gray 
 and thickened, an examination should be made with a pointed pre- 
 paring needle, whether it be somewhat movable over the bone, as in 
 the normal state, or whether it be firmly adherent to it. 
 
 Of great importance in forming an estimate of the disturbances 
 of hearing in morbid changes on the inner tympanic wall is the 
 examination of the niches of the two labyrinthine fenestra. First, as 
 regards the niche of the fenestra ovalis, this is often found so free 
 that it is quite possible to see on its floor the external surface of the 
 foot-plate of the stapes, together with the points of attachment of 
 both its crura. In not a few cases, however, one finds in this niche, 
 even in the normal state, especially by magnifying power, delicate 
 filaments and fenestrated membranes stretched out in varying number, 
 by which the crura of the stapes are connected with the walls of the 
 niche. 
 
 In examining a large number of normal ears, great differences are 
 found to exist as to the capacity of the niche of the fenestra ovalis ; 
 sometimes it appears so spacious, and the distance of the crura of 
 the stapes from the walls of the niche so great, that it can be 
 accurately measured with the naked eye ; at other times, again, it is 
 strikingly narrowed, and the crura of the stapes are in immediate 
 contact with the inferior or lateral walls of the niche. There is no 
 doubt that such a congenital narrowness of the niche of the fenestra 
 ovalis favours, in inflammatory processes of the lining membrane of 
 the middle ear, adhesions of the crura of the stapes with the niche 
 of this fenestra. 
 
 The pathological results of this niche in diseases of the middle 
 ear vary according to the duration and peculiarity of the morbid 
 process. In recent mucous catarrhs the niche is often found filled 
 with viscid, glassy mucus, while the lining membrane of the niche, 
 as well as that of the rest of the tympanic cavity, are but slightly 
 softened and little injected. In acute purulent inflammations, on the 
 contrary, after removal of the purulent, or muco-purulent exudation 
 from the niche, its strongly reddened mucous lining shows considerable 
 tumefaction. Where the previously described connective-tissue fila- 
 ments and bridges are present in the niche, in acute inflammations, 
 viscid purulent exudation is retained in the interspaces of this net- 
 work, and the stapes in such cases appears as though enveloped in 
 a yellowish-red mass filling up the niche. 
 
 In chronic non-purulent middle ear catarrhs, in the course of 
 which not infrequently connective-tissue proliferations are developed 
 in the neighbourhood of the ossicula, especially often in the malleo- 
 
92 EXAMINATION OF PELVIS OVALIS IN PATHOLOGICAL DISSECTIONS. 
 
 incudal niche and in tlae upper tympanic space, tlie pelvis ovalis also 
 is frequently found filled with succulent, grayish-red connective 
 tissue, and the crura of the stapes absolutely embedded it it. They 
 constitute the foundation of pathological cord-like formations by 
 which the crura of the stapes become abnormally fixed to the walls 
 of the niche and the stapes loses its power of oscillation. 
 
 The most striking alterations in the niche of the fenestra ovalis 
 are met with in chronic suppurations of the middle ear. Here, in 
 most cases, in consequence of round- cell proliferation in the inflamed 
 lining membrane, the niche is so filled up by the dark-red or grayish- 
 red proliferation, that only the capitulum of the stapes projects 
 above the surface of the obliterated niche. After the cessation of 
 middle - ear suppurations, there not infrequently remain behind 
 in the pelvis ovalis grayish-yellow organized masses of connective 
 tissue, and the position of the almost completely obliterated niche is 
 only perceptible by the prominating capitulum of the stapes, and by 
 the ledge-like projecting tendon of the muse, stapedius behind it. 
 Should the crura of the stapes and the capitulum stapedis be destroyed 
 through the preceding purulent process, the obliterated niche of the 
 fenestra ovalis, the level of which reaches that of the rest of the 
 promontorial wall, can only be determined by its relative position to 
 the fenestra rotunda and to the canalis Fallopii. 
 
 In dissections, where during life the diagnosis of anchylosis of 
 the stapes was made, and where this was proved by the experi- 
 ment described on p. 61, the mobility of the stapes can also be 
 tested with the probe after separation of the tympanic mem- 
 brane from the pyramid. In the normal condition a slight lateral 
 pressure on the capitulum will be sufficient to prove the mobility of 
 this small bone. In rigidity of the stapes in the fenestra ovalis, the 
 mobility is markedly diminished, in anchylosis entirely destroyed. 
 The examination with the probe must, however, be made with great 
 care, because with even slight pressure the crura of the stapes break 
 off, and the preparation is rendered useless for demonstration purposes 
 and for histological investigation. 
 
 Where anchylosis of the stapes has been proved to exist, we have 
 to examine whether it is due to adhesion of the crura with the niche 
 of the fenestra ovalis (anchylosis of the crura of the stapes), or to 
 adhesion of the edges of the foot-plate with the circumference of the 
 oval window (anchylosis of the foot-plate of the stapes). In the 
 former case the adhesion of the crura occurs, as a rule, with the 
 inferior wall of the niche, and this may be easily seen with the naked 
 eye or with a lens. In two cases only of congenital deaf-mutism I 
 found, simultaneous with adhesion of the long process of the incus 
 
EXAMINATION OF PELVIS OVALIS IN ANCHYLOSIS OF FOOT-PLATE. 93 
 
 witli the posterior tympanic wall, the crura of the stapes adherent 
 to the superior wall of the pelvis ovalis. 
 
 The adhesion of the crura of the stapes with the niche of the oval 
 window is either one of connective tissue or an osseous one. The 
 former has been termed anchylosis spuria stapedis. A distinction 
 between the two forms is only possible if the preparation be either 
 decalcified and submitted to microscopical examination (see, with 
 reference to this, the Histological section), or if it has been completely 
 macerated. In the latter case, in adhesion of the crura by connective 
 tissue with the niche of the oval window, the stapes will fall out ; in 
 bony anchylosis, however, it will remain firmly attached to the bone. 
 In bony anchylosis of the foot-plate in the oval window, the stapes 
 in the macerated preparation remains inseparably fixed in its position. 
 
 In anchylosis of the foot-plate of the stapes, an accurate examina- 
 tion of it, and of the simultaneous changes in the ligamentum 
 orbiculare stapedis, is only possible if the labyrinthine side of the 
 stapes be exposed. For this purpose a cut with a fret-saw is carried 
 in the long axis of the pyramid, parallel to the inner tympanic wall, 
 through the middle of the petrous bone, thus dividing the vestibule 
 into an outer and an inner half. After washing the preparation, the 
 outlines of the inner surface of the foot-plate of the stapes in the 
 fenestra ovalis can now be plainly recognised on the external wall of 
 the labyrinth. If a normal preparation be held against the light, the 
 contours of the transparent ligamentum orbiculare stapedis will come 
 clearly into view. In calcification of this ligament, and in bony 
 anchylosis with the oval window, on the contrary, it becomes opaque, 
 like the adjoining bone. On the side of the labyrinth sometimes the 
 circumference of the oval window is found covered by a protuberant 
 osseous proliferation (Toynbee), or, as in a case observed by me, the 
 entire fenestra is, on the labyrinthine side, covered by osseous 
 neoplasm. 
 
 Equally important in pathological dissections is the accurate 
 examination of the niche of the fenestra rotunda, inasmuch as patho- 
 logical products there diminish the power of vibration of the membr. 
 fenestr. rotundae, and may impair hearing to a great extent. Since, 
 as before mentioned, the entrance into the niche is directed markedly 
 backwards, a view into its floor can only be obtained by partially 
 removing, with the forceps, the posterior and inferior tympanic walls 
 facing it. With a favourable light, the externally somewhat concave 
 membrane of the round window can be completely seen as it lies 
 stretched out on the floor of the niche. If the membrane be trans- 
 parent, the lamina spiralis membranacea behind it shines through as a 
 dark, slightly wavy line. Frequently, however, there are found on the 
 
94 EXAMINATION OF THE FEN. ROT. IN PATHOLOGICAL DISSECTIONS. 
 
 membrane gray, ramified trabeculse of connective tissue (Bezold), such 
 as are met with on the inner surface of the tympanic membrane and 
 at various spots in the lining membrane of the middle ear. On 
 several of the preparations examined by me I further found the 
 entrance to the niche covered by a band of mucous membrane with 
 one or more perforations, after the removal of which the membrane 
 of the round window came into view. That the niche of this fenestra 
 also shows, in normal preparations, many variations with regard to 
 capacity and inclination of its plane to the axis of the ear, is known. 
 
 Respecting the morbid changes in the niche of the fenestra 
 rotunda, we find it in catarrhal processes filled with serous fluid, or 
 with tenacious viscid mucus. In purulent inflammations with tough 
 muco-purulent exudation, very frequently a plug of this material is 
 met with filling up the whole of the niche, the removal of which with 
 the pincette is the more difficult the more firmly the exudation is 
 retained in the niche by bands of connective tissue or folds of mucous 
 membrane. Such plugs in the niche of the round window cause 
 impairment of hearing of a high degree, as I have convinced myself 
 by dissections of cases observed during life. 
 
 In chronic non-purulent processes on the lining membrane of the 
 middle ear which are accompanied with new formations of connective 
 tissue, most varied alterations are met with in the niche of the 
 fenestra rotunda. Sometimes its membrane shows simply a thickening 
 of its mucous covering ; at other times, again, the niche is hidden and 
 obhterated by succulent, tendinous, gray connective tissue ; lastly, as 
 rare results of chronic middle ear processes, terminating in sclerosis 
 of the mucous membrane, we observe calcification and ossification 
 of the membrana fenestrse rotundse (Toynbee, Von Troltsch), and 
 narrowing or osseous closure of the niche of this fenestra (Moos, 
 Politzer), resulting from hyperostosis of the bony walls. 
 
 Almost constantly pathological changes in the niche of the fenestra 
 rotunda are met with in chronic purulent middle ear processes, in 
 which, as is well known, the mucous membrane of the whole of the 
 middle ear undergoes hypertrophy through round-cell infiltration and 
 connective-tissue neoplasms. Accordingly, the niche of the fenestra 
 rotunda appears also to be filled up either by dark-red proliferation of 
 mucous membrane or granulation tissue, or by a small polypus (case 
 of the author's), or after suppuration which has ceased, covered over 
 and obliterated by yellowish-gray, glistening connective tissue. 
 
OSSICULA. 95 
 
 7. OSSICULA. 
 
 The isolated ossicles are best obtained after maceration of the 
 temporal bone, out of which they drop when slightly shaken. Of the 
 three small bones, the one which is most frequently missed is the 
 stapes, which often, after maceration of its annular ligament, falls into 
 the vestibule, out of which it can only be recovered with difficulty by 
 means of a fine pincette. The long process of the malleus (process. 
 Folianus, Fig. 72, d) is entirely preserved on a malleus obtained 
 through maceration of the temporal bone of the new-bom infant, 
 while in the adult merely a short pointed stump remains. 
 
 The axis of the head of the malleus is inclined to the handle at an 
 obtuse angle. On the posterior surface of the oblong head of the 
 malleus we notice a longish oval articular surface bounded by a slight 
 osseous projection, which passes from above and without downwards 
 and inwards to the border of the neck. Two surfaces are distinguished 
 
 ... d 
 
 Fig. 72. — Malleus. — a = Fig. 73.— Incus.— a = body ; Fig. 74. — Stapes, — a = 
 head ; b — neck ; c = b = short process ; c = capitulum ; b — crus ; c = 
 
 handle ; d = long process ; long process ; d = articular foot-plate. 
 
 8 = articular surface. surface ; e = lower check 
 
 cog, 
 
 on it, which meet at a nearly vertical edge. Corresponding to this, 
 we find on the body of the incus an articular surface made up of two 
 surfaces, the upper part of which (Fig, 73, d) is directed inwards, 
 while the lower part (e) faces laterally. Helmholtz compares the 
 mechanism of the malleo-incudal articulation with the check con- 
 trivance in the interior of a watch-key. With each movement of the 
 manubrium inwards the lower cog of the malleus (Fig. 72, e), will fall 
 into the lower one of the incus (Fig. 73, e), whereby the long process 
 of the incus is made to follow the movement inwards of the manubrium. 
 With the movement outwards of the latter, on the other hand, the 
 lower cog of the malleus will move away from the lower one of the 
 incus, so that the latter will only to a slight degree follow the move- 
 ment outwards of the malleus. This peculiarity of the malleo-incudal 
 articulation may be proved experimentally by alternately condensing 
 and rarefying the air by means of an india-rubber tube fitting tightly 
 into the external meatus on a fresh preparation from which the 
 tegmen tymp. has been removed, and observing, while doing so, the 
 movements of the manubrium and of the long process of the incus. 
 The action of the lower cog of the head of the malleus may also 
 
96 JOINING THE OSSICULA. 
 
 be demonstrated on macerated ossicles by fixing with sealing-wax, 
 vertically to the long axis of the malleus, a match upon the stump of 
 the long process, and connecting in a like manner also the short 
 process of the incus with another match. If now the articular 
 surfaces of the malleus and incus, by means of these little sticks, be 
 fitted one into the other, and the malleus be alternately turned 
 inwards and outwards, we can convince ourselves of the correctness of 
 Helmholtz's statement above alluded to. 
 
 To artificially join the various ossicles into a normal chain, it is 
 best to make use of liquid glue (ichthyocolla), such as is used for 
 mending broken glass, china, bone, etc. One drop is sufficient to 
 join the articular surfaces of the malleus and incus so firmly that it 
 is difficult to separate them afterwards. Less simple is the joining 
 of the capitulum of the stapes to the long process of the incus, on 
 which, in consequence of the maceration, the ossiculum lenticulare 
 Sylvii is mostly wanting. It can only be done successfully if, after 
 bringing the two articular surfaces into contact, the stapes, by means 
 of a fine pincette, be held in its normal position (5-10 minutes) until 
 the cement has dried. 
 
 The ossicular chain in its continuity, together with its capsular 
 ligaments, is best represented on preparations which have been 
 hardened in spirits of wine, then painted over with glycerine and 
 half dried. In order to loosen the connection of the stapes in the 
 fenestra ovalis, a horizontal cut is made by means of a fret-saw 
 through the pyramid, passing through the middle of the internal 
 auditory meatus, and opening the vestibule from above without 
 injuring the fenestra ovalis. After sufficiently widening the upper 
 gap of the vestibule, the vestibular surface of the foot-plate of the 
 stapes comes into view. If the upper border of the oval window be 
 now carefully broken off with the small pointed bone forceps, and 
 the superior edge of the foot-plate be exposed, it is easy so to loosen 
 the lower edge of the stapes also, with the pointed preparing needle, 
 that its connection with the fenestra ovalis is completely severed. If 
 the ligaments of the malleus and incus be now divided, and the 
 connection of the short process and of the manubrium with the 
 tyrapanic membrane separated, the connected ossicular chain can, with 
 careful handling, be lifted out of the tympanic cavity. 
 
 Mention might here be made of a simple manipulation by which, 
 with a little practice, it is possible to represent the ossicular chain in 
 its topographical relation to the superior and inner tympanic walls. 
 For this purpose an incompletely macerated temporal bone from a 
 new-born infant is used, in which the membrana tympani has already 
 been destroyed by maceration, while the connection of the chain of 
 
REPRESENTATION OF OSSICULA IN THEIR CONTINUITY. 97 
 
 ossicles with, the tympanic walls is still a tolerably firm one. If the 
 squamous portion of the temporal bone be first removed (sec p. 24), 
 and then the annulus tymp. carefully broken off in small pieces from 
 above downwards, without, however^ loosening the connection of the 
 malleus within the tympanic cavity, a preparation is obtained on 
 which, as the accompanying illustration (Fig. 75) shows, the articulated 
 ossicular chain appears in its normal position in the cavum tymp. 
 For the rest, as regards the study of the topographical position of the 
 ossicles, we refer to the frontal and horizontal sections of the organ of 
 hearing to be described in a later chapter. 
 
 Small particles of tissue adhering to the ossicles and disfiguring 
 the preparation are, while dry, singed off by holding them close io 
 the flame of a spirit-lamp. The separate small bones, as well as the 
 entire chain, are fixed with cement upon a small piece of wood or 
 glass 3 cm. high and 1^ cm. broad, which is fastened to a round stand, 
 and protected from dust by a small glass shade (see the plate. Fig. I., 
 
 r V 
 
 Fig. 75. — Position of the ossicles ; chain in the temporal bone of a child, after removal of 
 the annulus tymp., and of the squamous portion. — t = tegmentymp. ; o = ossicula audit. ; 
 an = antrum mastoid. ; r = fenestra rotunda ; v — vagina proc. styloid. 
 
 belonging to the chapter, ' Making and preserving Normal and Patho- 
 logical Preparations of the Ear for Instruction Purposes '). 
 
 In pathological dissections, after opening the tympanic cavity, 
 notice should be taken of the changes that have occurred in the 
 ossicles. An exact examination of their exposed surfaces is only 
 possible in those cases where the upper tympanic space is not filled 
 with morbid products. In acute suppurative inflammations, the 
 covering of the small bones is found loosened and reddened through 
 considerable vascularization. In chronic adhesive processes, the 
 mucous membrane covering, especially on the malleo-incudal articu- 
 lation, appears tendinous, gray, dull, and thickened. Less frequently, 
 there occur fine calcareous incrustations or dense calcareous deposits, 
 appearing as though dropped upon the malleo-incudal joint. In 
 chronic suppurative inflammations of the middle ear, the examination 
 is far more difficult, partly on account of the swelling and proliferation 
 of the mucous membrane covering the ossicula, partly in consequence 
 
 7 
 
98 PKEPARATION OF THE MUSC. TENSOR TYMP. 
 
 of the proliferation of tlie mucous membrane lining of the upper 
 tympanic space, whereby the small bones are on all sides so enveloped 
 by the proliferated mucous membrane that, in order to lay them bare, 
 they require to be dissected out of the mass which surrounds them, 
 with probe and pincette. Often enough the ossicula remain intact in 
 the proliferated mucous membrane surrounding them ; frequently, how- 
 ever, the head of the malleus and body of the incus are found carious, 
 or necrosed in the midst of the proliferated mucous membrane ; less 
 frequently are the capitulum, and the crura of the stapes, destroyed. 
 In most cases the long process of the incus perishes through fusion, 
 and in extensive defects of the tympanic membrane this may be seen 
 by inspection of the tympanum from the external meatus, when, on 
 the inner tympanic wall, the capitulum of the stapes is found discon- 
 nected from the long process of the incus. The examination of the 
 stapes in the niche of the fenestra ovalis has been already described 
 (p. 91). The accurate investigation of the relative position of the 
 ossicles to the newly formed connective tissue, wholly or partially 
 filling up the tympanic space, is only possible on a series of horizontal 
 sections of the entire decalcified organ, further details upon which will 
 be found in the Histological part, 
 
 8. PREPARATION OF THE INTRA-TYMPANIC MUSCLES. 
 
 For the preparation of the intra-tympanic muscles, fresh objects, 
 as well as those that have been preserved in spirits of wine, may be 
 used. If it be intended to represent the anatomical connection of 
 the muse, tensor tymp. with the muse, tensor veli palat., it is advisable 
 to lay the fresh organ for eight to fourteen days in a solution of 
 chromic acid (1 : 2000), which is to be changed several times ; by the 
 action of this the muscular fibres are sharply differentiated from the 
 surrounding tissue. 
 
 To lay bare the muse, tensor tymp., the roof of the tympanic cavity 
 is removed (see p. 64), and the malleo-incudal articulation and the 
 tendon of the tensor tympani are exposed. Then an elastic probe is 
 introduced into the osseous portion of the Eustachian tube below the 
 tensor tendon, and with a chisel, applied obliquely, the upper wall of 
 the canalis pro tens, tymp., from the rostrum cochleare to the place 
 of union of the cartilaginous with the osseous Eustachian tube, is, in 
 the direction of the latter, removed in layers. The anterior extremity 
 of the muscle, surrounded by a fibrous sheath, arises, partly from the 
 great wing of the sphenoid, partly from the uppermost portion of the 
 cartilaginous Eustachian tube. Sometimes the anterior extremity of 
 the muscle is connected by tendinous bands of fibres^ or by actual 
 muscular bundles, with the muse, tensor veli palat. (L. Mayer, 
 
PREPAEATION OF THE MUSC. STAPEDIUS. 
 
 99 
 
 Rudinger), In order to show this connection, the part of the great 
 wing of the sphenoid, roofing over the cartilaginous Eustachian tube 
 and adjoining the body of the sphenoid, is, together with the superior 
 portion of the proc. pterygoid., taken away with the chisel, and the 
 work completed with the scalpel. The spindle-shaped belly of the 
 
 m s 
 
 Fig. 76. — View of the tympanic cavity after removal of the tegmen tymp. (Right ear.) — 
 ha = malleo-incudal articulation ; t = muse. tens. tymp. ; s = tendon of the muse. tens, 
 tymp. passing across the tympanum ; f = nerv. facialis ; g = genu nervi facialis ; n = 
 nerv. petros. superf. major ; a = nerv. acusticus ; an = antrum mast. After a preparation 
 in my collection. 
 
 muscle receives also some muscular bundles, which spring, according 
 to Helmholtz, from the superior wall of the osseous canal. With a 
 little care the muscle, which exceeds 2 cm. in length, may be success- 
 fully raised out of the canal with a small knife rounded at the point ; 
 and after detaching its tendon at the rostrum cochleare, it may be 
 isolated and represented in connection with the malleus. 
 
 
 M 
 
 Fig. 77. — Posterior portion of the inner tympanic wall (Right ear). Enlarged to double its 
 size. — st = stapes ; cs = capitulum stapedis ; ms = muse, stapedius in the cavitas 
 stapedii, with its tendon inserted at the capitulum ; p = promontory ; f =;nervus facialis ; 
 V — vestibule laid open. After a preparation in my collection. 
 
 The muse, stapedius is most easily represented after separation of 
 the pyramid from the pars tymp. This small, pear-shaped muscle 
 (Fig. 77, St) is enclosed by the already mentioned eminentia pyra- 
 midalis, projecting at the inner part of the posterior wall of the 
 tympanic cavity. At the point of the emin. pyramidalis, directed 
 
 7—2 
 
100 PREPAKATION OF CARTILAGINO-MEMBRANOUS EUST. TUBE. 
 
 forwards and upwards, its tendon passes to the capitulum of the 
 stapes. The length of this muscle varies between 6 and 7 mm. 
 
 The muse, stapedius is exposed in the simplest way by carefully 
 removing the outer osseous lamella of the eminentia pyramidalis, the 
 position of which is given in the prolongation backwards and down- 
 wards of the tendon of the stapedius. For this purpose, either a 
 narrow, sharp hand-chisel or a broad graver (Fig. 12, a) is made use of, 
 with which, by moderate pressure, the osseous lamella covering the 
 muscle can be broken off. The exposed muscle is to be lifted out of 
 its bony groove by means of a narrow, small knife rounded at the 
 point, and may be preserved, in connection with the stapes, in spirits 
 of wine. 
 
 In order to make the intra-tympanic muscles easily distinguishable 
 on preparations which have been preserved in spirits of wine, and 
 which are intended for demonstration purposes, they are brushed over 
 with a solution of carmine, in doing which, care is to be taken that 
 the colouring fluid does not spread to the surrounding tissues. 
 
 In pathological dissections, one should never fail to examine the 
 intra-tympanic muscles. With the muse, tensor tymp. this is possible 
 under all circumstances ; with the muse, stapedius only when either 
 the dissection permits of separation of the membrana tympani from 
 the pars petrosa, or when, while leaving these two in connection, the 
 tympanic cavity is opened from behind after the method suggested by 
 Lucae (p. 70). In the latter case the facial nerve, lying behind 
 and laterally from the muscle, has to be removed in order to expose 
 the belly of the muscle. In non-purulent middle ear processes, patho- 
 logical changes in the muscles can only rarely, and then only in 
 advanced atrophy, be demonstrated macroscopically, for which reason 
 small portions of the belly of the muscle should always be taken from 
 the preparation for microscopic examination. More frequently one 
 finds in purulent middle ear processes on the intra-tympanic muscles, 
 appearances of hypersemia, discoloration, and, in carious processes, 
 erosion of the osseous sheaths of the muscles, and of the muscles 
 themselves, as also destruction of their tendons. Where, in patho- 
 logical dissections, the entire organ is to be subjected to microscopic 
 examination, and where, at the same time, the changes in the intra- 
 tympanic muscles are to be studied, in making the cut, regard should 
 always be had to the direction of the course of the muscles. 
 
 9. PREPARATION OF THE CARTILAGINO-MEMBRANOUS EUSTACHIAN 
 TUBE AND ITS MUSCLES. 
 
 The opening of the osseous Eustachian tube from the side of the 
 tympanic cavity, after removal of the muse, tensor tymp., has been 
 
PREPARATION OF THE MUSCLES OF THE TUBE. 101 
 
 previously described (see p. 64). The preparation of the cartilagino- 
 membranous Eustachian tube requires an accurate knowledge of its 
 situation on the lower surface of the basis cranii. The cartilaginous 
 structure of the tube, from its firm fibro-cartilaginous union with the 
 osseous tube to the ostium pharyng. tubse, lies in a groove known as 
 the sulcus tubse Eustachii on the lower surface of the base of the skull. 
 This groove, lying between the pyramid of the petrous bone and the 
 great wing of the sphenoid, passes forwards as a furrow on to the 
 medial lamella of the proc. pterygoid., to terminate at its posterior 
 edge, somewhat above the middle of the process. The cartilaginous 
 portion of the Eustachian tube is fixed in this groove in such a way 
 that the roof and the medial plate in the upper portion of the tube 
 are connected partly with the groove, partly with the fibrous tissue 
 which closes the fissura spheno-petrosa. At this spot the cartilage of 
 the tube is firmly fixed, and almost immovable. Lower down, however, 
 in the vicinity of the proc. pterygoid., the medial cartilaginous plate, 
 projecting coulisse-like at the lateral pharyngeal wall, appears to the 
 extent of 1-1 1 cm. easily movable. The anterior edge of this pro- 
 jecting part of the medial plate forms, with the thick fold of mucous 
 membrane (plica salpingo-pharyngea) passing downwards from it, the 
 posterior prominent portion of the tube. The reverse is the case, as 
 regards mobility, with the lateral plate of the cartilaginous tube, 
 known as the cartilage hook. While the major part of its posterior 
 portion shows greater mobility than the medial plate, the anterior 
 inferior extremity is fixed, by dense connective tissue, with the outer 
 wall of the sulcus tubse, and is only slightly movable. 
 
 It will be best to enter upon the representation of the anatomical 
 relations of the Eustachian tube by commencing with the preparation 
 of its muscles. In order to lay bare the levator palati mollis 
 (Fig. 78, 1 Y), the mucous membrane is laid hold of with a pincette in a 
 thin layer | cm. below the orifice of the Eustachian tube (os) in a skull 
 which has been divided into halves in a sagittal direction, then raised 
 and cut away with curved scissors. When the muscle comes into view 
 through the incision in the mucous membrane, the direction of the 
 course in which the muscular bundles run appears so sharply marked 
 that, guided by them, it is possible to expose the entire muscle, from 
 its origin at the lower surface of the point of the pyramid and the 
 contiguous part of the tubal cartilage (1), up to its radiation in the 
 velum palati (Y). 
 
 If now, from the opening made below the ostium tymp., the 
 mucous membrane of the velum palati be dissected away in the direc- 
 tion of the fibres of the belly of the muscle, it is possible to accurately 
 trace the radiation of the muscular bundles on the posterior surface of 
 
102 
 
 PKEPARATION OF THE MUSC. LEVATOR PALATI MOLLIS. 
 
 the velum (1'). The greater number of them lie in the middle, between 
 the upper edge of the velum and the tip of the uvula. When the 
 lower portion of the muscle has been exposed, it is possible, after 
 splitting the mucous membrane below the median cartilaginousfplate, 
 to isolate also the upper portion of the levator by loosening, with the 
 narrow handle of a scalpel, the slight connection of the muscle with 
 the membranous floor of the Eustachian tube up to its origin at the 
 base of the skull. 
 
 By the levator palat. mollis, in consequence of the shortening and 
 
 Fig. 78. — Eustachian tube with its muscles ; natural size. (Right side.) — k = cartilaginous 
 plate of the Eustachian tube ; m = pars membranaeea of the Eustachian tube ; os = 
 ostium pharyng. tubse ; ch = choana ; 1 = muse, levator palati mollis ; 1' = radiation 
 of the levator in the velum palati ; h = hamulus pterygoideus ; 1 1 = muse, tensor palati 
 mollis, winding round the hamulus. After a preparation in my collection. 
 
 swelling of its belly, not only is the floor of the Eustachian tube 
 raised up, but the median cartilaginous plate is also pressed consider- 
 ably inwards, whereby the ost. pharyng. tubse is certainly diminished 
 in its high diameter ; but the resistance in the tubal canal itself is 
 lessened by the widening of the slit of the tube. It is beyond all 
 
PEEPARATION OF THE MUSC1. TENSOR VELI PALAT. MOLLIS. 103 
 
 doubt that the action of the tensor veli palat., as a dilator of the canal 
 of the tube, is materially assisted by the co-operation of the levator 
 veli palati. 
 
 Somewhat more difficult is the preparation of the muse, tensor veli 
 palat. (dilatator tubse, abductor tuboe, Von Troltsch). This muscle 
 arises partly from the inferior surface of the wing of the sphenoid 
 medially from the foramen ovalo (3t spinosum, along a line extending 
 forwards as far as the proc. pterygoid., partly, and with the great mass 
 of its bundles, from the whole length of the lower margin of the 
 lateral cartilaginous hook, and from the lateral membranous part of 
 the cartilaginous section of the tube. 
 
 The preparation and laying bare of this muscle is effected in part 
 from the naso-pharynx, and in part from the lateral side of the tube. 
 The work is materially facilitated if the divided skull be previously so 
 reduced in size that the muscle can be easily reached from its lateral 
 side. For this purpose the superior maxilla is sawn away 1-2 cm. in 
 front of the choame in a frontal direction, and in addition to this the 
 preparation is reduced at its posterior and outer portion, by removing 
 the OS occipitale and the squamous portion of the temporal bone. At 
 the same time the bones and soft parts adjoining the lateral side of 
 the Eustachian tube are removed by cutting out a wedge-shaped 
 section on the external surface of the skull. The posterior cut of this 
 wedge passes 1 cm. in front of the anterior wall of the meatus, and 
 parallel to it, through the glenoid cavity as far as the inner part of the 
 fissura orbitalis superior ; while the anterior one separates the still 
 remaining portions of the zygomatic process and of the superior 
 maxilla, and meets the former cut at the fissura orbitalis superior. 
 
 On the preparation, thus reduced in size, the levator veli palat. 
 (Fig. 78, IT), already prepared, is next lifted up from the side of the 
 naso-pharynx, and the lower portion of the muse. tens, veli palat. 
 (Fig. 78, 1 1), now visible, is so far exposed on that side as the 
 Eustachian tube, covering it in part, and the levator veli palat. will 
 allow. 
 
 To expose the muscle from its lateral side also, the remainder of 
 the articular capsule of the inferior maxilla and of the muse, pterygoid, 
 extern, in the space left on the outer surface of the preparation by the 
 removal of the wedge, is cut away up to a point where the external 
 lamella of the proc. pterygoid, comes into view. If we now break off 
 the latter with the pointed bone forceps from its lower edge up to the 
 foramen ovale, and afterwards remove the muse, pterygoid, intern, 
 with pincette and scalpel, we obtain a complete side-view of the muse, 
 tensor veli palat., with its origin at the sphenoid bone and at the 
 cartilaginous tube, as also the transition of the muscle (Fig. 78, 1 1) into 
 
104 PREPARATION OF THE TUBAL MUSCLES OF BOTH SIDES. 
 
 its tendon, winding round the hamulus pterygoid, (h), and radiating 
 into the soft palate. 
 
 The tensor veli, the tendon of which radiates in the fibrous pro- 
 longation of the hard palate, is the true dilator of the Eustachian 
 tube, as by its contractions the hook of the tubal cartilage is rolled up, 
 and the membranous portion of the tube is drawn away from the 
 cartilaginous (Von Troltsch). 
 
 A general view of the muscular apparatus of the tube on both 
 sides, and its relation to the soft palate, is obtained by dissection from 
 behind. We proceed in the following manner : By means of a frontal 
 cut with the saw through the skull, the occiput is removed as far as 
 the tuberculum pharyng., and the posterior membranous pharyngeal 
 wall cautiously exposed. On the intact pharynx it is now very easy 
 to prepare the superior portion of the constrict, pharyngis super., as 
 well as the upper part of the levat. veli palat., and laterally from this 
 the tensor veli palat. In order to show also the lower portions of 
 both muscles and their radiation in the velum palati, the posterior 
 pharyngeal wall is split in its middle by a vertical cut, and the pre- 
 paration completed from the opened naso-pharynx. 
 
 The preparation of the cartilaginous Eustachian tube itself is, 
 after what has been said, included in that of the muscles of the tube, 
 since, in exposing the latter, the greatest part of the median and 
 lateral wall of the tube is laid bare. The muscles and cartilagino- 
 membranous portion of the Eustachian tube having been exposed on 
 a preparation in the manner before described, it is necessary, in order 
 to expose the roof of the cartilaginous and its junction with the 
 osseous portion, to divide first, with a narrow scalpel, in the direction 
 from the naso-pharyngeal space, the attachment of the cartilaginous 
 roof of the tube at the base of the skull, and to remove, from this 
 incision, the body, along with the great wing of the sphenoid bone 
 by means of the fret-saw. If, now, any particles of the sphenoid, 
 left projecting over the tubal cartilage, are broken off with the forceps, 
 a complete representation of the position of the entire Eustachian 
 tube and of its muscles is obtained. 
 
 As regards the method of opening the tubal canal, we must, in 
 order to avoid repetition, refer to the previous description (pp. 71 
 and 72). The splitting of the cartilaginous roof of the tube, 
 from the ost. pharyngeum tubse to the isthmus, is best effected 
 with a narrow, small knife, or with scissors, taking as a guide a metal 
 probe pushed forward into the osseous tube, which has been 
 previously opened with the chisel from the side of the tympanic 
 cavity. 
 
 The representation of topographical preparations of the Eustachian 
 
PREPARATION OF THE CARTILAGINO-MEMBRANOUS TUBE. 105 
 
 tube is to be found under the heading ' Kepresentation of Topographical 
 Preparations of the Organ of Hearing.' 
 
 The insertion of the cartilaginous portion into the rough parts 
 around the osseous tube extends laterally higher up towards the 
 tympanic cavity, than it does in a median direction. The axes of the 
 osseous and cartilagino-membranous portions do not lie exactly in 
 the same line, but form an obtuse angle open downwards (p. 72, 
 Fig. 62), corresponding to the isthmus tubse. According to Henle the 
 canal of the tube occupies a position nearly exactly diagonal between 
 the transverse and the sagittal. The angle open in front, which the 
 axis of the tube forms with that of the external meatus, measures, 
 according to Schwalbe, 150°; with the horizontal, the axis of the tube 
 forms an angle of 40° (Henle). 
 
 The more exact anatomical relations of the cartilagino-membranous 
 Eustachian tube will be discussed in the Histological part. 
 
 In pathological dissections, where the principal object is to ascertain 
 morbid changes of the mucous membrane of the tubal canal, the 
 longitudinal splitting of the cartilaginous portion and the simultaneous 
 opening of the osseous tube is absolutely necessary. The proceeding 
 corresponds exactly with that of the opening of the canal of the tube 
 in the normal organ. 
 
 Attention is here to be directed to the accumulation of purulent 
 or mucous secretions in the canal of the tube, to the degree of 
 hypersemia and swelling of its mucous membrane, to the colour of 
 the same, to the presence of small ulcers and cicatrices (most frequently 
 in the neighbourhood of the ostium pharyngeum tubse), and to 
 Sfranulations and bridges of connective tissue in the tubal canal. 
 Where, during life, a stricture of the tube had been diagnosed, it is 
 better not to split the tubal canal, but to subject the cartilagino- 
 membranous portion, removed along with the osseous part of the 
 tube, to histological examination, because the degree of the stricture, 
 and the alterations in the tissue resulting therefrom, can thus be more 
 thoroughly investigated than is possible by anatomical preparation 
 and the splitting of the canal. In like manner, neoplasms encroaching 
 on the canal of the tube from the neighbouring structures, such as 
 carcinoma, sarcoma, or cyst formations in the vicinity of the canal, and 
 diverticular formations in the Eustachian tube (Kirchner), are better 
 examined on microscopic preparations. 
 
 10. PREPARATION OF THE MASTOID PROCESS. 
 
 To study the anatomical relations of the mastoid process, which 
 in the adult, as regards size, form, and internal structure, presents 
 many varieties, a considerable number of macerated temporal bones 
 
106 
 
 INTERNAL STRUCTURE OF THE MASTOID PROCESS. 
 
 will be required. With tlie preparation of sections on dry temporal 
 bones the comparative examination on fresh specimens must always 
 go hand-in-hand. 
 
 First, to become acquainted with the internal structure of the 
 mastoid process, a cut nearly parallel to the external surface is made 
 with the fret-saw, from the lower point of the mastoid process to the 
 level of the superior wall of the osseous meatus, by which about a 
 third of the process is removed (Figs. 79 and 80). 
 
 Its internal structure varies so much that even in one and the 
 same individual the interior of the one side hardly ever resembles 
 that of the other. 
 
 Although some of the older authors had noticed that the mastoid 
 process does not always consist entirely of pneumatic cell spaces, 
 but frequently wholly or in part of adipose, diploetic or sclerotic 
 
 Tig. 79. — Pneumatic mastoid process. 
 
 Tig. 80. — Diploetic mastoid process. 
 
 osseous substance, it was Zuckerkandl who, after numerous investi- 
 gations, first pointed out that only in 36.8% of the cases the mastoid 
 (Fig. 79) consisted, from its lowest point to its upper boundary (g), of 
 larger or smaller pneumatic spaces, but that in 43.2%, it was formed, 
 chiefly in its lower (Fig. 82) and posterior (Fig. 81, d' d) portion, of 
 diploetic osseous substance, while the anterior superior part (Fig- 
 81, d' p) contained pneumatic cell spaces ; and, finally, in 20% the 
 mastoid process was wholly made up of diploetic (Fig. 80), less fre- 
 quently of sclerotic tissue. 
 
 For the study of the anatomical relations which, in operations on 
 the mastoid process, are chiefly to be considered, it is necessary to 
 make a considerable number of sections of the temporal bone, on 
 which the position of the antrum mastoid, to the sinus transversus 
 and to the external surface of the mastoid process is brought under 
 observation. 
 
 As to the extent of the antrum, a general view may be obtained 
 if, after the method previously alluded to (p. 64), the tegmen antr. 
 
RELATION OF THE ANTRUM MAST. TO THE SINUS TRANSVERS. 107 
 
 mastoid, be removed along with the tegmen tymp. with chisel or 
 forceps. A glance from above enables us to see the anterior boundary 
 of the antrum, its extent backwards, its depth, as well as the size 
 and number of the openings by which it communicates with the 
 mastoid cells. 
 
 A correct impression of the greatly variable relative distances of 
 the antrum to the external meatus, to the sinus transversus and to 
 the cortical substance of the mastoid process, is, however, only obtained 
 on sections which are made through the process in a horizontal and in 
 a vertical direction. 
 
 The horizontal cut through the temporal bone, which is to expose 
 
 the antrum mastoid, in its greatest transverse diameter, commences 
 
 on the posterior surface of the petrous bone at the poms acustic. 
 
 P 
 
 Fig. 81.— Diploetic mastoid process with FiG. 82.— Mastoid process, with a pneumatic 
 few air-containing cell spaces in its structure in its upper, and a diploetic structure 
 
 anterior upper portion. in its lower portion. 
 
 intern., passes in a horizontal direction through the upper tympanic 
 space, and terminates at the external surface of the temporal bone, 
 immediately above the upper periphery of the external opening of 
 the osseous meatus. 
 
 Such sections are suitable for exact measurement of the distances : 
 from the inner boundary of the antrum to the sinus transversus; from 
 the external wall of the antrum to the external surface of the mastoid 
 process ; and from the sinus transversus to the posterior wall of the 
 meatus. 
 
 As regards the relative position of the antrum to the sinus trans- 
 versus, these are frequently enough found separated only by the thin, 
 but compact, rarely dehiscent lamella of the osseous wall of the 
 sinus ; oftener, however, antrum and sinus are separated by a broad 
 layer of pneumatic (Fig. 47, p. 45) or diploetic cellular spaces, which 
 latter afford a certain protection against the spreading of a purulent 
 inflammation from the mastoid process to the sinus. In the new-born 
 
108 RELATION OF SIN. TEANSV. TO POSTERIOR WALL OF MEATUS. 
 
 infant there lies constantly, between the antrum and the sin. 
 transvers., a broad layer of diploe (Zuckerkandl), which, as the 
 accompanying illustration (Fig. 83) shows, is generally to be met 
 with in the first few years of life. 
 
 Measurements on horizontal sections of the temporal bone are of 
 importance for the operation of opening the mastoid process, in order 
 to determine the distance between the external wall of the antrum 
 and the field of operation, situated in the anterior superiorfpart of 
 the outer surface of the mastoid process. Its upper boundary lies 
 almost on a level with the superior osseous wall of the meatus ; the 
 anterior boundary at the point of transition of the planum mastoid, 
 into the posterior wall of the osseous meatus. Numerous measure- 
 ments on horizontal sections made by me showed that the distance 
 from this point to the antrum varies between 6 and 15 mm. 
 
 Still more important is the study of the individually greatly 
 
 am cl me 
 
 Fig. 83, — Horizontal section through the temporal bone of a child one year old. Upper half 
 of the section. — me = meatus audit, extern. ; a = anterior wall of the meatus ; ct = 
 cavum tympani ; am = antrum mastoid. ; eg = cavitas glenoidalis ; mi = meat, audit, 
 intern. ; co = cochlea ; v= vestibule ; c = canalis semicircul. horizontal. ; st = sinus trans- 
 versus. 
 
 varying relative positions of the sinus transversus to the posterior 
 wail of the meatus and to the external surface of the mastoid process. 
 As a rule, especially with chieily pneumatic processes, the sinus, the 
 posterior wall of the meatus, and the planum mastoid., are separated 
 by a broad interspace formed of cellular spaces (Fig. 84), through 
 which, in opening the mastoid process, it is easy to penetrate as far as 
 the antrum mastoid, without incurring the risk of opening the sinus. 
 The osseous groove of the latter appears in such preparations flat, 
 very little curved, and only to a slight degree excavated at its 
 superior part, which is bridged over by the posterior continuation of 
 the upper edge of the pyramid. In other, but certainly much less 
 frequent cases, the groove of the sinus is found considerably 
 
TEMPORAL BONE WITH STRONGLY ARCHED GROOVE OF SINUS. 109 
 
 deepened, strongly curved, and in its middle and upper portions 
 arched so far outwards and forwards that between it, on the one side, 
 and the posterior wall of the meatus, as well as the external surface 
 
 Fig. 84.— Horizontal section through a pneumatic mastoid process.— a = posterior wall of 
 the auditory meatus ; b = tympanic cavity ; c = antrum mastoid. ; d = sin. transv. ; 
 e e' = place for operation on the outer plate of the mastoid process. 
 
 of the mastoid process, on the other side, merely a narrow bridge of 
 bone is present (Figs. 85 and 86). It is evident that in such cases 
 the opening of the mastoid process is attended with great danger, 
 since, while advancing towards the antrum, one may expose and 
 
 g w 
 
 Fig. 85. — Horizontal section through a 
 partly diploetic, partly pneumatic 
 mastoid process. — g = posterior wall of 
 the auditory meatus ; a = antr. mast. ; 
 s = sin. trans. ; w w' = seat of operation. 
 
 Fig. 86.— Horizontal section through a compact 
 mastoid process with but few diploetic spaces. 
 — t = tympanic cavity ; u = lower wall of 
 the meatus ; s = sin. transv. ; w — posterior 
 boundary of the seat of operation. 
 
 injure the sinus. Having made numerous sections of temporal 
 bones, I was the first to point out that this relation of the sinus, so 
 unfavourable for operating, is chiefly met with in temporal bones with 
 a diploetic or sclerotic structure. 
 
110 
 
 SAGITTAL SECTIONS THROUGH THE PROG. MAST. 
 
 For the purpose of representing in one and the same temporal 
 bone the position of the antrum mastoid, and the structure of the 
 mastoid process, after previously exposing the mastoid cells by means 
 of the vertical cut suggested on p. 106 (Fig. 87, ma), we carry parallel 
 to the upper surface of the pyramid a cut with the saw, describing a 
 curve with its concavity downwards (Fig. 87 s s' s"), which com- 
 mences in front of the pars squamosa (s), and runs towards the 
 posterior edge of the temporal bone in such a way that it meets the 
 root of the zygomatic process, the upper wall of the osseous meatus, 
 and the uppermost part of the antrum mastoid. The separated 
 
 Fig. 87. — Curved section through the temporal bone. — me = meatus auditor, extern. ; 
 ma = section of a pneumatic mastoid process ; s s' s" = curved section through the tem- 
 poral bone ; am = antrum mastoid. ; si = sinus transversus ; z — processus zygomaticus ; 
 st = processus styloideus. 
 
 parts of the temporal bone should be so connected with brass wire and 
 small brass hooks, that the posterior part, situated above the pars 
 mastoid, (s"), may be moved horizontally towards the lower part of 
 the preparation, by which means a general view of the position of the 
 antrum and its relations to the neighbouring parts is obtained. 
 
 In addition to the sections of the temporal bone so far mentioned, 
 it is necessary, in order to become familiar with the anatomical 
 relations of the mastoid process, to prepare a number of vertical 
 sections, both in a frontal and a sagittal direction. Successful 
 
VERTICAL AND HORIZONTAL SECTIONS THROUGH PROC. MAST. Ill 
 
 sagittal sections (Fig. 88), which pass through the antrum and the 
 tip of the mastoid process, give a good general idea of the length 
 and depth of the antrum., and of the arrangement of the mastoid 
 
 
 Fig. 88. — Sagittal section through the middle of the tegm. tymp. and lower tympanic wall : 
 lateral view of the inner half. (Left ear.) — te — tub. Eust. oss. ; ct = canalis pro tens, 
 tymp. ; c = lower ridgy wall of the tympanic cavity ; o = fenestra ovalis ; r = fenestra 
 rotunda ; an = antrum mastoid. ; f = canalis Eallopii, communicating towards the front 
 with the cavit. stapedii ; w — mastoid process. 
 
 cells opening into it. On frontal sections, moreover, particularly with 
 pneumatic mastoid processes, the relation of the mastoid cells to the 
 
 Fig. 89. — Frontal section through a pneu- 
 matic mastoid process and the incisura 
 mastoidea. — c cm = corticalis of the 
 pneumatic mastoid process ; im = 
 incisura mastoidea ; si = sinus trans- 
 versus ; ha = hiatus aqused. vestibul. ; 
 mi = porus acust. internus. 
 
 Fig. 90.— Vertical (sagittal) section through 
 the mastoid process and osseous meatus.— a = 
 mastoid cells ; b = posterior wall of the 
 osseous meatus ; c = anterior wall of the 
 osseous meatus. 
 
 incisura mastoidea is to be seen (Fig. 89). Here are not infrequently- 
 found on the section one or several cyst-like air-spaces, the wall of 
 which, thin as paper, borders immediately on the incisura mastoidea. 
 
112 VERTICAL AND HORIZONTAL SECTIONS THROUGH PROC. MAST. 
 
 Accumulation of pus in these cavities may, in some cases, lead to 
 rupture of the incisura and to sub-muscular and sub-fascial burrow- 
 ing of pus in the neck (Bezold). 
 
 Other sagittal and horizontal sections made through the mastoid 
 process and the osseous meatus give an instructive representation of 
 the position of the mastoid cells lying laterally from the antrum 
 mastoid., and of their relation to the posterior superior wall of the 
 osseous meatus. Sagittal sections (Fig. 90) which are to demonstrate 
 the relation of the mastoid cells to the osseous meatus must be made 
 parallel to the longitudinal axis of the pyramid, in a plane which 
 passes through the tip of the mastoid process, through the external 
 portion of the osseous meatus, and through the inner part of the 
 o-lenoid cavity. Horizontal cuts (Fig. 91), carried through the axis 
 of the osseous meatus, best show the extent of the mastoid cells 
 behind the meatus in a lateral direction. That the number and 
 
 Fig. 91. — Horizontal section through the external meatus and mastoid cells. (Right ear.) 
 — a = anterior wall of the meatus ; b = its posterior wall ; c — mastoid cells ; d = 
 auditory canal ; e = tympanic membrane ; f — tympanic cavity ; g = sinus transversus. 
 
 arrangement of these cellular spaces stand in a certain relation to 
 the pneumatic or diploetic condition of the mastoid process has 
 already been stated (pp. 33-36). (Compare also the chapter ' Sections 
 of the Temporal Bone of the Adult,' pp. 33-47.) 
 
 The anatomical relations of the antr. mastoid, in the new-born 
 infant were discussed in the dissection of the temporal bone of the 
 new-born infant (pp. 27-29). 
 
 In the anatomical dissection of the processus mastoid, on fresh 
 unmacerated preparations, the proceeding, on the whole, is the same 
 as that with macerated temporal bones. That in the normal organ 
 the antrum, opened from above, frequently shows fine, knotty 
 filaments, with those pedunculated, stratified formations first de- 
 scribed by me, as well as serrated membranes, which are inserted, 
 with delicate off- shoots, on the walls of the antrum, has already been 
 
PEEPARATION OF THE PROC. MAST. IN PATHOLOGICAL CASES. 113 
 
 mentioned. On longitudinal sections of the processus mastoid., the 
 morphological differences between pneumatic and diploetic structure 
 are even more marked than on the macerated temporal bone. The 
 pneumatic cellular spaces are large, pale, and tilled with air, while the 
 diploetic are small, and filled with a reddish or yellowish-red 
 substance, and, on the surface of the cut, present the appearance of a 
 section of a cylindrical bone. 
 
 The preparation of the mastoid process in pathological cases 
 depends upon the seat and extent of its morbid condition. A thorough 
 examination of the proc. mastoid, is particularly required in purulent 
 middle ear inflammations and their consequences, and even if, during 
 life, no symptoms of any atfection of the mastoid process had existed. 
 In acute, purulent, middle ear inflammations, the antrum and the 
 pneumatic cells are, without exception, filled with pus or muco- 
 purulent secretion ; ■ the lining membrane of the cellular spaces is 
 reddened and tumefied. In chronic middle ear suppurations, the 
 cellular spaces are also frequently filled with pus. The mucous 
 membrane lining of the mastoid cells appears dark red, tumefied, pro- 
 liferating, or degenerated by polypi (Trautmann). Accordingly, while 
 the suppuration lasts, but mostly after it has ceased (much less fre- 
 quently in non-purulent catarrhs), the antrum and mastoid cells are 
 found to be completely filled with newly-formed, gelatinous or fibrous 
 connective tissue. Should such proliferations of connective tissue, 
 after having existed a considerable time, become ossified, the whole of 
 the mastoid process is converted into a uniform mass of bone, in 
 which, when cut with the saw into sections, the cellular spaces are 
 either entirely wanting, or present only in small numbers. (Eburna- 
 tion of the mastoid process.) 
 
 In caries and necrosis of the mastoid process, after previously 
 opening the antrum from above, the cortical portion of the external 
 surface of the process is opened with chisel and forceps, in order 
 to ascertain the extent of the disease in the bone. If the outer 
 bony shell be perforated by a fistulous opening, the interior of 
 the process, mastoid, should be laid bare by widening the already 
 existing aperture in the bone by means of the forceps, and by 
 careful sounding it should be determined whether a movable or firmly 
 fixed sequestrum of the bone is present, and whether, after its removal,, 
 the osseous walls of the cavity feel rough, or are already covered 
 over with smooth granulation tissue. At the same time, by the use of 
 the probe, the direction and length of any fistulous canals between 
 the mastoid process and the external meatus or the sinus transversus 
 are determined, and in multiple fistulous formations in the neigh- 
 bourhood of the ear, their connection with the mastoid process,, 
 
 8 
 
114 PREPARATION OF THE LABYRINTH. 
 
 or with otlier parts of the temporal bone, is made clear by anatomical 
 preparation and exposure of the fistulous passages. 
 
 As in carious-necrotic processes, we proceed also with the so- 
 called cholesteatomatous formations in the mastoid process which, 
 as white, or whitish yellow tumours, iridescent on the surface, may 
 sometimes be taken out of the smooth tendinous, gray cicatricial 
 tissue-lining of the cavity of the process. More frequently there are 
 found in the latter shapeless caseous masses permeated by the detritus 
 of sequestra, simultaneously with retention products in the tympanum. 
 After removal of these masses, the temporal bone very often presents 
 a system of cavities and sinuses, which extends beyond the boundaries 
 of the mastoid process, and is caused by partial fusion of the cavities of 
 the process, of the tympanum and of the external meatus. 
 
 11. PREPARATION OF THE LABYRINTH. 
 
 {a) Preparation of the Osseous Labyrinth. 
 
 The preparation of the osseous labyrinth is much more easily 
 carried out on the petrous bone of the new-born infant than on that 
 of the adult, because the superjacent bone surrounding the osseous 
 labyrinth in the one case is still porous, soft, and only loosely con- 
 nected with the labyrinthine capsule, while in the other the con- 
 nection of the labyrinth with the solid mass of bone surrounding it is 
 so complete that the boundaries between the capsule and the over- 
 lying bone entirely disappear. On the petrous bone of the new-born 
 infant, therefore, it is possible, without special previous practice, 
 by careful scraping of the porous, overlying bone with a short, 
 sharp knife, to prepare out the osseous labyrinth in its outlines* 
 
 In the petrous bone of the infant it is best to begin by laying bare 
 the semicircular canals, first of all the superior one. Its position 
 is marked by the eminentia arcuata, and below this by a depression 
 ending in a cul-de-sac, and called fossa subarcuata (Fig, 21, p. 24). First, 
 the spongy and soft osseous mass lying behind this canal is removed in 
 layers with a knife, on the one side up to the point where the superior 
 and posterior canals meet, and on the other side up to the compact 
 wall of the horizontal canal. After this, the exposure of the posterior 
 sagittal canal is proceeded with. Its upper crus projects on the 
 posterior surface of the pyramid, and can therefore easily be laid bare. 
 The curve and the inferior crus of this canal are, however, surrounded by 
 a thick layer of the overlying bone, which must be carefully removed 
 to make the crus free. The preparation of the horizontal canal, the 
 
 * According to Ilg and Hyrtl, the proceeding is considerably facilitated by first boiling 
 the petrous bone for an hour in a solution of caustic potash ; this treatment, however, gives 
 the preparations a yellow colour. 
 
PREPARATION OF THE OSSEOUS LABYRINTH. 
 
 115 
 
 outer crus of which projects on the inner wall of the tympanic 
 cavity behind the fenestra ovalis, is effected by removing in layers the 
 osseous mass still remaining behind and below, the difference between 
 the porous structure of the bony covering, and the compactness of the 
 walls of the canals, serving as a yaluable guide while proceeding with 
 the preparation. 
 
 When the semicircular canals have been exposed in their rough 
 outlines, the finer work of preparing commences. In the first place, 
 the space below the superior canal is made accessible by piercing, 
 with a straight, sharp, awl-like instrument or drill, the remain- 
 ing mass of bone. Then a thin, round file is introduced into the bore- 
 hole, and the remainder of the overlying bone is filed away up to the 
 concavity of the canal. 
 
 The isolation of the posterior semicircular canal is more difficult, 
 as the inner crus of the horizontal crosses the posterior canal and partly 
 projects into the space within the concavity of the latter. In order, 
 
 CO mi 
 
 Fig. 92. — Posterior view of the osseous labyrinth, with the three semicircular canals, the 
 cochlea and the aquseducts of a new-born infant. (Enlarged to double its size.) — co = 
 cochlea ; mi = meat, audit, intern. ; ac = aquseductus cochleae ; av = aquseductus vesti- 
 buli. 
 
 therefore, to free the posterior canal, the osseous substance between 
 the inner crus of the horizontal, and both crura of the posterior canal, 
 is so far cut out with the point of a penknife as to obtain two slit-like 
 openings, which, being widened by a narrow, flat file, isolate the two 
 canals one from the other. The particles of bone remaining between 
 them are removed partly with the sharp point of the knife, partly 
 with the file. After this, the soft osseous substance lying within the 
 horizontal canal is pierced vertically with a drill or pointed, awl- like 
 instrument, and this canal likewise cleared by means of a round file. 
 Finally, by careful filing and scraping, with suitable instruments (Fig. 
 13), of any remaining roughness on the surface of the canals, the pre- 
 paration of the posterior portion of the osseous labyrinth is completed. 
 In order to represent the capsule of the cochlea in the new-born 
 infant, the soft, superjacent bone is removed with a short sharp knife 
 
 8—2 
 
116 , PREPARATION OF THE OSSEOUS LABYRINTH. 
 
 either from the side of the labyrinth or from the point of the pyramid, 
 until the inferior cochlear convolution is reached. In this manipula- 
 tion it is all the more easy to recognise the cochlear capsule, as the 
 space intervening between it and the superjacent bone is large-celled 
 and porous, and the gray capsule glimmers through as a uniform 
 and more compact structure than the spongy bone over it. Yet 
 the preparation of the capsule of the cochlea requires considerable 
 care, because its compact osseous substance is thin as paper and very 
 brittle, and breaks on the slightest pressure. Inequalities on the 
 exposed semicircular canals and the cochlea are removed by careful 
 rubbing with fine emery-paper. 
 
 On the pars petrosa of the embryo (6-8 months), in which the 
 labyrinthine capsule is surrounded merely by a thin layer of bone, the 
 osseous labyrinth can be much more easily dissected out than in the 
 temporal bone of the new-born infant. 
 
 Much greater are the difficulties met with in the preparation 
 
 Tig. 93. — Lateral wall of the pyramid. — o = fenestra ovalis ; r = fenestra rotunda; t = 
 semicanalis pro tens. tymp. ; c = canalis caroticus ; s = canalis semicirc. superior ; h = 
 canalis semicirc. horizontalis. 
 
 of the osseous labyrinth in the adult, the capsule and the over- 
 lying bone being here fused into an exceedingly dense mass, which 
 is no longer anatomically separable. Even if we succeed in pre- 
 paring out the form of the osseous labyrinth from this extremely 
 hard mass of bone, we must not by any means imagine that we have 
 the actual capsule. Although this preparation, in anatomical respects, 
 possesses much less value than the morphological representation 
 of the labyrinth by corrosion, yet, for the sake of completeness, we 
 did not feel justified in entirely passing over this method of preparing 
 the labyrinth in the adult. 
 
 The boundary of the capsule not being traceable in the mass 
 of the petrous bone of the adult, the semicircular canals must be 
 opened in order to obtain a guide for preparing it out. For this 
 purpose, the osseous mass bordering posteriorly on the canals is 
 first sawn away at a distance of 1 cm. behind the elevation of 
 
PREPARATION OF THE OSSEOUS LABYRINTH. 
 
 117 
 
 the superior canal. Then, by filing off the eminentia arcuata, 
 the canal is opened at its convex curvature. The slit now appearing 
 to view stands vertical to the axis of the pyramid, and gives us the 
 direction of the superior canal, which from this point can be easily 
 opened in its entire length, by filing off, in the direction of the slit, the 
 osseous mass in an outward direction up to the ampuUary dilatation 
 on the one side (Fig. 93), and inwards as far as the union with the 
 posterior canal on the other side (Fig. 94). 
 
 The preparation is now so fixed in the vice, that the posterior 
 surface of the pyramid faces upwards. If then the surface of bone 
 lying behind the p or. acust. int. be filed away, first the superior crus, 
 next the arch, and lastly the inferior crus of the opened posterior 
 canal (Fig. 94, h), come into view. 
 
 Next follows the opening of the horizontal semicircular canal, 
 
 Fig. 94. — Posterior wall of the pyramid. — c = meatus audit, int. ; o = canalis semicirc. 
 superior ; h = canalis semicirc. posterior ; e = sinus petrosus superior. 
 
 the preparation of which offers the greatest difficulties. If the 
 object be fixed in the vice, with the posterior extremity of the 
 pyramid directed upwards, the canalis horizontalis is seen after 
 filing off the osseous mass lying laterally from the curve of the 
 posterior canal. By continuing the filing in the direction towards the 
 inner wall of the tympanic cavity, the external crus (Fig. 93, h) 
 of this canal is also opened as far as its embouchure into the 
 vestibule. The laying bare of the inner crus is not effected until 
 later. 
 
 When the semicircular canals have been opened in the manner 
 described, the osseous mass between them must be removed for the 
 purpose of clearing them further. In order to take away the greater 
 portion of the bone between the superior and horizontal canals, the 
 preparation is again so fixed in the vice that the upper surface of the 
 pyramid is directed upwards. A fine fret-saw is now applied perpen- 
 
118 PEEPARATION OF THE OSSEOUS LABYRINTH. 
 
 dicularly, close behind the superior canal, which has already been 
 opened, and the compact bone is sawn through, but only as far as 
 the union of the superior and posterior canals. The saw is next 
 applied horizontally immediately above the horizontal canal, and the 
 cut carried up to the former vertical one, when the piece of bone 
 between the superior and horizontal canals will fall out. 
 
 By a second cut of the saw made perpendicularly downwards in 
 front of the superior canal, and extending about 2 mm. deep to the 
 vicinity of the vestibule, and below gradually assuming a horizontal 
 direction forward, the anterior side of the superior canal is likewise 
 freed from the adjoining osseous mass. The bone, still remaining 
 below the horizontal canal, is taken away with files and graver. 
 
 The removal of the osseous substance within the concavity of the 
 canals is effected by means of a drill, piercing first the surface of the 
 bone below the superior, and then that within the horizontal canal. 
 The bore-hole is now widened by using larger round files in suc- 
 cession, until so much of the bone is filed away that only a thin 
 lamella remains below the opened canals. 
 
 Most difficult is the clearing of the concave side of the posterior 
 and of the inner crus of the horizontal canal. This is most quickly 
 accomplished if the osseous mass, lying within the posterior canal, be 
 pierced in two places, close below the superior, and above the lower 
 crus, with a very fine drill, in the direction towards the inner wall 
 of the tympanic cavity. Between the two bore-holes there still 
 remains in the osseous mass the inner crus of the horizontal canal. 
 
 With thin, round files, and afterwards with a narrow, fine, flat file, 
 these two openings are gradually lengthened, and, making special use of 
 the latter instrument, the bone lying between the arch of the posterior 
 and the inner crus of the horizontal canal is taken away. The portions 
 of bone which cannot be filed off are removed by means of narrow 
 gravers and scrapers (p. 4), and with these instruments the inner 
 crus of the horizontal canal is likewise opened. 
 
 The preparation of the osseous capsule of the cochlea is now pro- 
 ceeded with. For this purpose the diploetic bone tissue, extending 
 from the point of the pyramid to the compact capsule, must first of 
 all be removed, partly with forceps, partly with file and graver. The 
 compact lamella of the posterior wall of the pyramid, however, which 
 serves as a basis for the cochlea, and helps to form the internal 
 auditory meatus, must be preserved intact, which is simply done by 
 removing, with a broad graver, the remaining diploetic osseous tissue 
 between it and the compact capsule. The form of the cochlea, with 
 its convolutions, can now be worked out, by means of gravers and files, 
 from the exceedingly hard mass of bone surrounding the cochlear 
 
OPENING THE VESTIBULE. 119 
 
 cavity, but as tlie boundary between the capsule and overlying bone 
 in the adult can no longer be detected, all such preparations are 
 to be regarded as artificial. In order, therefore, to dissect out the 
 cochlear convolutions in their true positions, it is necessary to open 
 them. Commencing at the fenestra rotunda, the lower convolution is 
 opened with file and graver to a width of ^ mm., and from here the 
 opening of the convolutions continued up to the proximity of the apex 
 of the cochlea. Not until they arc opened in such a manner that the 
 edges of the lamina spiral, ossea can be distinctly seen through the 
 slit, may the osseous mass which lies between the opened convolutions, 
 and is most strongly developed between the first and second turns, be 
 carefully filed out, in order to give the preparation externally the form 
 of the cochlea. 
 
 For the preparation of the osseous labyrinth the dental engine is 
 also well adapted, which, provided with variously shaped drills and 
 bits, renders it possible with a little practice to shorten the proceeding 
 of laying bare the labyrinthine capsule. 
 
 Model collections of preparations of the labyrinth are those of the 
 anatomist Ilg, of Prague, one of which is in the museum of that city ; 
 the other, formerly in the Josephinum, is now in the anatomical 
 museum of Vienna. 
 
 Laying Bare of the Vestibule. — If the roof of the vestibule, situated 
 between the frontal (superior) semicircular canal and the cochlea, be 
 removed by a horizontal cut, having its concavity upwards, and passing 
 above the fenestra ovalis, a view into the vestibular cavity is obtained. 
 It will reveal, posteriorly, the following : The three ampullar openings 
 and the two mouths of the semicircular canals, anteriorly, the entrance 
 into the scala vestib. of the cochlea, on the external wall (Fig. 
 96, o), the fenestra ovalis, on the inferior wall, the commencement of 
 the lamina spiralis ossea (sp), and the fissure caused by the macera- 
 tion of the first piece of the spiral membrane (lamina spiralis 
 secundaria). This fissure forms, in the macerated temporal bone, 
 the well-known communication between the vestibule and the scala 
 tymp. of the cochlea. 
 
 This, however, is by no means sufiicient for the study of the 
 details of the vestibule and cochlea. In order to obtain an exact 
 idea of the situation of the recess, hemiellipt. et hemisphseric, as well 
 as of the ampullar openings and the mouths of the semicircular canals, 
 of the labyrinthine fenestrse, etc., sections must be made through the 
 vestibule and cochlea in three directions, on several petrous bones. 
 The cuts are made with fine fret-saws, either on dry temporal bones, 
 or on such as have previously been lying for twenty-four hours in water. 
 
120 FRONTAL AND SAGITTAL SECTIONS THROUGH THE VESTIBULE. 
 
 A frontal cut at the posterior edge of the fenestra ovalis through the 
 vestibule brings into view on the posterior wall of the latter, and at its 
 transition into the upper and lower walls (Fig. 95) : the ampullar 
 orifices of the superior (as), of the horizontal (ah), and of the posterior 
 (s) semicircular canals, as well as the mouths of the horizontal (h) 
 canal and of the canalis communis (co), formed by the union of the 
 superior and posterior canals, groupe^ as shown in the accompanying 
 illustration. 
 
 On the anterior vestibular aspect of the frontal section are visible 
 the commencing portion of the lamina spir. ossea, the entrance into 
 the scala vestibuli of the cochlea, and medially from it a part of the 
 recess, hemisphser. 
 
 A sagittal cut in the longitudinal axis of the pyramid through the 
 
 st sK 
 
 Fig. 95. — Frontal section through the 
 vestibule : view of the posterior 
 vestibular wall. Enlarged to double 
 its size. — o = fenestra ovalis ; ah = 
 ampulla horizontalis ; as = ampulla 
 superior ; s = ampullary orifice of 
 the posterior semicircular canal ; h = 
 embouchure of the horizontal semi- 
 circular canal ; co = common embou- 
 chure of the frontal and sagittal 
 canals ; sp = commencing portion of 
 the lam. spiralis in the vestibule ; 
 st = scala tymp. of the cochlea ; 
 hs = hiatus subarcuatus. After a 
 preparation in my collection. 
 
 CO V 
 
 
 
 
 Fig. 96. — Section through the long axis of the 
 pyramid : view of the lateral half. The cut 
 passes through the middle of the vestibule and 
 through the lower convolution of the cochlea. 
 (Double its natural size. ) — • v = vestibulum ; 
 o = fenestra ovalis ; sp = lower wall of the 
 vestibule with the commencing portion of the 
 lam. spiralis ; c = canalis semicirc. inf. ; co — 
 lowest turn of the cochlea with the lam. spiralis ; 
 fo = tractus spiralis foraminulentus. After a 
 preparation in my collection. 
 
 middle of the vestibule, consequently parallel to the medial vestibular 
 wall, shows, on the lateral section, the details of the external and 
 inferior walls of the labyrinth (Fig. 96) ; the oval window (o) ; below 
 this, on the floor of the vestibule, the before-mentioned fissure (sp) 
 leading into the scala tymp., the ampullar openings of the superior 
 and horizontal semicircular canals situated above the oval window on 
 the outer wall of the labyrinth, the section of the lower crus of the 
 posterior canal (c), and the oblique, section of the lowest turn of the 
 cochlea (co) with the tract, spiralis foraminulentus (io). 
 
SECTIONS THROUGH THE CAPSULE OF THE COCHLEA. 
 
 121 
 
 On the medial wall of the vestibule (Fig. 97) are visible : parts of 
 the recess, hemiellipt. et hemisphEcric, oblique sections of the semi- 
 circular canals, the vestibular opening of the aquceduct. vestibuli, and 
 the sections of the meat, audit, int. and of the facial canal. As a 
 matter of course, the view of the outer and the inner wall of the 
 
 v; a f C 
 
 vaq J 
 
 
 Fig. 97. — Sagittal section through the long axis of the pyramid : view of the inner half of 
 the section. — v = inner wall of the vestibule with the recess, hemiellipticus ; c c' c" = 
 segments of the section through the osseous semicircular canals ; a = embouchure of the 
 canalis communis ; aq = vestibular opening of the aquseductus vestibuli, with its furrow- 
 shaped continuation downwards on the inner wall of the vestibule ; mi = section of the 
 meat, audit, intern. ; c (front) = portion of the lower convolution of the cochlea ; f — 
 section of the canalis facialis ; j = fossa jugularis. 
 
 labyrinth will vary, according to the section falling nearer to the 
 medial or to the lateral wall, and according to the more or less slanting 
 direction of the cut. 
 
 d f c 
 
 Fig. 98. — Section through 
 the osseous capsule and 
 the modiolus of the coch- 
 lea, with the lamina spiral, 
 ossea. — a = internal audi- 
 tory canal ; b = modiolus. 
 
 Fig. 99. — Horizontal section through the petrous bone of a 
 new-born infant. (Enlarged to double its size.) — a = 
 vestibule ; b = base of the cochlea ; c = cupola ; d d' = 
 sections of the superior semicircular canal ; e = internal 
 meatus ; f = stapes ; g = antrum mastoideum. 
 
 Sections through the cochlea are made either in a frontal direction, 
 perpendicularly to the long axis of the pyramid, or horizontally, note 
 being taken of the fact that the apex of the cochlea lies level with 
 the canal, pro tens. tymp. (see Fig. 42, p. 40). The interior of the 
 cochlea appears different, according to whether the scalte have been 
 
122 PEEPARATION OF THE MEMBRANOUS LABYRINTH. 
 
 opened by the cut laterally from the modiolus, or the latter divided 
 exactly in its axis. This section (Figs. 98 and 99) gives a clear repre- 
 sentation of the relationship of the modiolus to the lamin. spiral, ossea, 
 and of the diameter of the former, on which the canals for the blood- 
 vessels and nerves can be distinguished by magnifying power. Sections 
 which meet the cochlea outside of the modiolus bring under observa- 
 tion the external surface of the latter and the relative inclination of 
 the osseous spiral lamina winding round it. Instructive preparations 
 of this kind, showing also the relationship of the hamulus of the 
 lamina spiralis to the apex of the cochlea, are obtained if the cochlear 
 capsule, taken from the temporal bone of a child, be broken off in 
 small particles with a pair of small, finely-pointed forceps, special care 
 being taken to keep the lamina spiralis intact. 
 
 Topographical sections of the entire labyrinth, which demonstrate 
 the relative position of the various parts of the labyrinthine cavity, are 
 made in a horizontal or sagittal direction through the pyramid. The 
 best horizontal sections through vestibule, cochlea, and internal 
 meatus are obtained if the cut lies in the middle of the latter, and a 
 little above the fenestra ovalis. Cuts which pass somewhat lower, 
 through the middle of the oval window, meet the cochlea only at its 
 lower turn. Two parallel sagittal cuts through the labyrinth in the 
 longitudinal axis of the pyramid are sufficient to make us acquainted 
 with the above-described details in the vestibule, as also with those of 
 the cochlea, which, being divided perpendicularly to its axis, will show 
 the transverse section of the modiolus. 
 
 (b) Preparation of the Mem,hranous Labyrinth. 
 
 The preparation of the membranous labyrinth is a most difficult 
 task ; but the obstacles which the first attempts meet with are soon 
 overcome with practice. It was Voltolini (I.e.) who first pointed out a 
 method by which the three membranous semicircular canals, in con- 
 nection with the utriculus, can be removed entire from the laby- 
 rinthine cavity. The proceeding, with some modifications of Voltolini's 
 method, is as follows : The canal, semicirc. superior is first opened by 
 carefully removing, with a moderately strong file or short scraper, the 
 osseous mass on the eminentia arcuata, until the canal shines through 
 the thin layer of bone. In the same manner the bone covering the 
 external and internal crura of the superior, as well as the entire 
 posterior canal, is cleared away by careful filing and scraping, until 
 both canals can be seen through. Next, the bone lying in front of 
 the superior canal and over the vestibule is removed in thin layers, 
 at first with the chisel, but in advancing deeper, with the short 
 
PREPARATION OF THE MEMBRANOUS LABYRINTH. 123 
 
 scraping-iron, until the vestibular cavity also shines through. Now, 
 at the spot where the superior and posterior canals, joining in a 
 common opening, enter the vestibule, a small hole about the size of a 
 pin's head is made in the roof of the vestibule with the point of a 
 small knife. Through this a thin preparing needle is introduced, with 
 which the bridges of connective tissue, uniting the utricle and the 
 ampuUai with the osseous walls of the vestibule, are loosened. In 
 order not to injure, during this manipulation, the saccules and 
 ampullae, the point of the needle should be kept close to the osseous 
 wall, and the loosening of the connective-tissue bridges effected with 
 care by slight lateral movements. Not until then can the roof of 
 the vestibule be carefully broken open from this aperture, with a 
 short pointed knife. 
 
 After this the superior and posterior canals, already shining 
 through, are opened by very cautiously cutting with a knife the thin 
 layer of bone still remaining, avoiding, in doing so, any injury to the 
 membranous canals. The whole preparation is now placed under 
 water in a wide saucer, and with a preparing needle, somewhat bent 
 at its point, the membranous canals, which are only slightly adherent 
 to a circumscribed spot on the bony wall (see the Histological part), 
 are cautiously lifted out of the osseous canals, without separating 
 their connection with the vestibular structures. Only when both 
 membranous canals are freely floating in the water is the preparation 
 again removed from it, the two canals being carefully pushed into 
 the vestibule with a needle. 
 
 To prepare out also the horizontal membranous canal, in connec- 
 tion with the utriculus, the now superfluous superior bony canal and 
 the upper crus of the posterior one, together with the osseous mass 
 between them, must be cleared away by a horizontal cut. To avoid 
 injury to the horizontal canal, this cut ought to be carried a little 
 above the outer crus of the latter, which projects behind the fenestra 
 ovalis on the inner wall of the tympanic cavity. Slow scraping and 
 filing of the surface of the cut will soon render the bone so far 
 transparent as to allow a view of the horizontal canal, which, under 
 the already described precautions, is opened out up to the vestibule, 
 whereupon the membranous canal is lifted out under water, and in its 
 turn pushed into the vestibule. 
 
 Semicircular canals, ampullse and utriculus, now form one lump 
 in the vestibule. In order to remove intact the whole mass, the 
 adhesions still existing between the membranous structures and the 
 osseous vestibular wall, and which can be perceived under water with 
 the aid of a lens, are carefully loosened with a needle, keeping the 
 point close to the osseous wall, and then the entire lump is allowed 
 
124 PREPARATION OF THE kEMBRANOUS LABYRINTH. 
 
 to glide out of the vestibule into a watch-glass filled with water. 
 Here the labyrinth is disentangled, not with needles, but by gently 
 shaking the watch-glass and by allowing water to fall in drops upon 
 it from a certain height, until saccules and membranous canals have 
 assumed their normal position. The preparation may either be pre- 
 served in spirits of wine in a correspondingly small glass jar (Fig. VI. 
 of the plate), or mounted as a miscroscopic object. This method is 
 recommended only for the purely anatomical representation of the 
 membranous labyrinth. For pathological cases, however, where it is 
 not only a question of observing the finer structural changes of the 
 membranous labyrinth, but also of ascertaining the presence of patho- 
 logical processes on its osseous wall, and the relation of this to the 
 membranous labyrinth (new formations of connective tissue and of bone 
 in the labyrinth), the histological examination on decalcified sections 
 of the labyrinth is to be preferred. (Compare the Histological part.) 
 
 If, in the examination of the membranous labyrinth, no regard is 
 to be paid to the connection of the membranous structures, the semi- 
 circular canals and ampullae may be obtained, though unconnected 
 with the utricle, in the following simple manner : on the pyramid of 
 a fresh temporal bone, placed upon a firm support, a chisel, 2-3 cm. 
 broad, is applied a few millimetres in front of the eminentia arcuata 
 superior, that is, above the middle of the vestibule in a frontal direc- 
 tion, and with one blow of the mallet the entire labyrinth is cut in 
 two. The two pieces are placed in water, and waved to and fro in it, 
 until portions of the utricle, of the ampullae, and the ends of some of 
 the membranous canals, are seen floating in the water. Although 
 the last-named structures are fixed to the wall of the osseous canal at 
 a circumscribed spot, they are very easily detached. If the ampulla 
 be now taken hold of with a fine pincette, it is possible by careful, 
 not too sudden pulling, to draw the three membranous canals from 
 the osseous, and to subject them to microscopic examination. Of 
 the utricle and saccule, it is true, only fragments are obtained, 
 which, however, in some cases, are sufiicient for pathologico-histo- 
 logical examination. 
 
 But should it be intended to obtain the saccules as intact as 
 possible, irrespective of their connections with the semicircular canals, 
 the attachments of connective tissue between the saccules and the 
 walls of the labyrinth are loosened with a fine needle, through a small 
 opening made in the upper labyrinthine wall after the manner 
 described at the commencement, and the aperture having been 
 widened, the still remaining connections are separated, and the 
 saccules, under water, taken out of the vestibular cavity. The utricle 
 may thus frequently be obtained quite intact, the saccule, however, 
 
PREPARATION OF THE COCHLEA. 125 
 
 being more intimately connected with the labyrinthine wall, only in 
 fragments. The removal of the saccules from the vestibule by Avay 
 of the oval window, when the stapes and surrounding osseous mass 
 have been taken away, is only successfully accomplished after long 
 practice and by careful preparation, notwithstanding the fact that 
 between the external wall of the labyrinth and the saccules there 
 exists a considerable perilymphatic space (Steinbrilgge), which is 
 favourable for laying them bare from the lateral side. 
 
 Rlidinger {I.e.) advises, for the purpose of general study of the fresh 
 labyrinth in the dissecting-room, applying a moderately-sized chisel 
 horizontally to the lateral edge of the internal meatus at its upper 
 part, and driving it in horizontally from behind forwards. The upper 
 half of the osseous labyrinth is thus forced away, and the vestibule 
 and cochlea are opened. Fragments of the membranous canals, of 
 the saccules and of the cochlea, can then be taken out under water 
 with needle and pincette. 
 
 The preparation of the cochlea in the fresh state presents diffi- 
 culties in so far as the opening of the capsule is necessarily attended 
 with injury to its membranes. For the study of the structure of the 
 cochlea, however, its anatomical preparation is indispensable. In 
 order to obtain at least part of the lamina spiralis membranacea 
 intact, after removal of the upper wall of the meat, audit, intern, 
 above the entrance of the ramus cochleae into the modiolus, the 
 lowest convolution of the cochlea is opened with a narrow chisel or 
 graver. The opening is enlarged far enough to allow a slightly 
 bent needle to be introduced, with which the broader margin of the 
 membranous spiral lamina is detached from the outer cochlear wall. 
 This having been done at the superior segment of the lowest turn of 
 the cochlea, that portion of the capsule is broken away in pieces with 
 a small, finely-pointed bone forceps, and from here the loosening of the 
 lamina spiralis, the severing of the structural supports, and the breaking 
 away of the capsule in the remaining turns should be continued. Thus 
 the upper portion of the cochlea is exposed, while the lower part of 
 the convolutions still remains in connection with the capsule. An 
 attempt is now made with the preparing needle to loosen from above, 
 as far as possible, the lower portion of the lamina spiralis from the 
 bone also ; then, with a small knife, the base of the modiolus is cut 
 through close to the internal meatus, after which the entire contents 
 of the cochlea, with the exception of the part of the first convolu- 
 tion bordering on the fenestra rotunda, can be lifted out with a fine 
 pincette. 
 
 If the cochlea, thus prepared out, be placed in dilute spirits of 
 wine, and the liquid gently shaken, the lam. spiral, membran. will 
 
126 PREPARATION OF THE COCHLEA. 
 
 expand, and under moderate magnifying power a clear representation 
 is obtained of the osseous and membranous spiral plate in its connec- 
 tion with the modiolus, and portions of it may be cut off with scissors 
 to be examined microscopically. For pathologico-anatomical research 
 this method is only applicable in exceptional cases, as for the study of 
 the histological changes microscopical sections of the entire cochlea 
 (see the Histological part) are infinitely better suited. 
 
 It is very easy to obtain the membranous cochlea, with its capsule 
 complete, from foetal organs (five or six months), by splitting with two 
 preparing needles the still soft cartilaginous capsule, and detaching it 
 from the membranous part. It is also possible, on the petrous bonies 
 of new-born infants, less frequently on those of adults, to prepare out 
 intact the membranous cochlea from its osseous capsule, if the pyramid 
 be first hardened by placing it for two or three weeks in a 2% solution 
 of chromic acid, and then slowly decalcified with nitric or hydrochloric 
 acid to such a degree that the capsule can be removed in layers with 
 needle and pincette. My collection contains several preparations of 
 the cochlea obtained in this manner. 
 
 Kecently Katz* has published a method of representing the mem- 
 branous labyrinth by which, through corrosion of its osseous capsule, 
 the membranous structures are exposed. A fresh petrous bone, or 
 even an old spirit preparation, is decalcified for six to eight days — if 
 from an adult in 15-25 %, if from a child in 8-12 %, hydrochloric acid ; 
 then 10-15 V nitric acid is added to the liquid, and the preparation 
 allowed to remain in it for eight to fourteen days longer, until it 
 appears changed into a gelatinous mass. 
 
 The corrosive liquid having been poured off, the preparation is 
 placed in water, where the softened bone is carefully removed with 
 needle and camel's-hair brush, so far as to leave only enough of 
 it to hold the preparation together. By this means are obtained, if 
 not always entirely, at least partially in connection, the membranous 
 saccules, ampullse, and semicircular canals ; also, especially clear, the 
 twigs of the ramus vestibuli, running in the petrous bone ; and, lastly, 
 the facial nerve. For preserving the preparation a 2% solution of 
 chromic acid is recommended. In the experiments made by me, I 
 always obtained mere fragments of the membranous labyrinth. 
 
 Another method, recommended by Barth, for representing the 
 membranous labyrinth by corrosion, is to be found in the chapter 
 ' The Preparation of the Organ of Hearing by Corrosion.' 
 
 Yery instructive for the macroscopical study, and. for the topography 
 of the membranous labyrinth, are those sections of decalcified petrous 
 bones on which the labyrinthine structures have been hardened before 
 
 * Beitrag zur anatomischen Praparation des hautigen Labyrinths (M. f^ 0., 1887, Nr. 7). 
 
TOPOGRAPHICAL SECTIONS THROUGH THE MEMBRANOUS LABYRINTH. 127 
 
 decalcification ; while, as regards tlie chemico-technical proceeding, we 
 refer to the Histological part of this work. We here only observe that, 
 when the decalcified pyramid, dehydrated by alcohol, is placed in a 
 solution of celloidin, the latter penetrates into the labyrinthine cavity ; 
 and after the hardening of the medium in diluted alcohol (70 %), the 
 membranous structures of the labyrinth are so fixed as to appear in 
 their original positions on the sections. 
 
 Especially suitable for such sections are petrous bones of new-born 
 infants, which are decalcified in a much shorter time than those of 
 adults. Horizontal sections through the internal meatus, modiolus, 
 vestibule, fenestra ovalis, and stapes yield very beautiful preparations, 
 
 Fig. 100. — Horizontal section through a 
 hardened, and afterwards decalcified 
 petrous bone of a new-born infant : lower 
 half. — u = transverse section of the lower 
 portion of the utricle ; b = floor of the 
 vestibule, with the commencing portion 
 of the lamina spiralis ; c = cochlea ; re = 
 ramus cochleae ; rv — ramus vestibuli. 
 
 Fig. 101.— Upper half of the same prepara- 
 tion. — u = the utricle, situated in the 
 vestibule ; st = transverse section of the 
 foot-plate of the stapes ; c = cochlea ; 
 re = ramus cochleae ; rv = ramus vesti- 
 buli. After a preparation in my collec- 
 tion. 
 
 which, preserved in dilute spirit, are of much service for demonstra- 
 tion purposes, especially when magnified with a lens. 
 
 The accompanying illustrations (Figs. 100 and 101) give a clear idea 
 of the relationship of the membranous structures of the labyrinth. On 
 the upper segment of the pyramid (Fig. 101, u) we notice, through the 
 transparent celloidin, the transverse section of the utriculus (u) fillino-, 
 in the shape of an elongated sac, the greater portion of the vestibule, 
 while in the lower segment (Fig. 100, u) it occupies only a small 
 part of the medial space of the latter. The section throuo-h the 
 cochlea, modiolus (c), and the internal meatus, allows the arrano'e- 
 ment of the cochlear convolutions, the mode of attachment of the 
 membranous spiral plate, and of Reissner's membrane to be recoo-nised • 
 
128 PEEPARATION OF THE AQUEDUCT. VESTIB. ET COCHLEAE. 
 
 finally, in the internal meatus the nerv. acusticus, with its division 
 into the ramus vestibuli (rv), and ramus cochleae (re), is visible. 
 The nerve bundles, sharply marked by their light-green colour, 
 may, with a magnifying lens, be traced on the one side into the 
 vestibule, and on the other, through the modiolus, into the lamina 
 spiral, ossea. 
 
 For the study of the topographical position of the semicircular 
 canals, ampullae and saccules, it is further advisable to make a series 
 of frontal sections through the previously decalcified pyramid, and 
 impregnated with celloidin after the method described. By carrying 
 a frontal cut through the posterior portion of the pyramid, 2-3 mm. 
 behind the superior semicircular canal, a preparation is obtained, on 
 which will be seen, as the accompanying illustration (Fig. 102) shows. 
 
 Fig. 102. — View of the topographical position of the irembranous semicircular canals within 
 the osseous : transverse section through the posterior part of the decalcified pyramid of 
 a new-born infant. (Right ear.) — s = transverse section of the superior semicircular canal ; 
 h h' = transverse sections of the horizontal semicircular canal ; p p' = transverse sections 
 of the posterior semicircular canal ; o = fossa subarcuata ; an = inner wall of the mastoid 
 antrum. After a preparation in my collection. 
 
 the relation of the diameter of the membranous to the osseous canal, 
 and the mode of attachment of the membranous canals to the osseous 
 wall. A frontal cut carried more anteriorly, close behind the superior 
 canal and behind the fenestra ovalis (see Fig. 103), meets the posterior 
 portion of the vestibule, in which the section of the utriculus (u) with 
 the cisterna perilymphatica, placed between it and the external 
 vestibular wall, are perceived ; likewise the ampulla of the posterior 
 canal (ai), that of the horizontal canal (ah), the inner crus of the 
 latter (ch), and a part of the intratemporal aquseduct. vestibuli (aq). 
 
 12. PREPARATION OF THE AQU^DTJCTUS VESTIBULI ET COCHLEA. 
 
 {Ductus endo- et perilymphaticus.) 
 
 The representation of the aquseducts of the labyrinth is one of 
 the most difficult tasks in the preparation of the organ of hearing. 
 This may be inferred from the remarkable fact that the important 
 anatomical discovery of the highly-gifted Domenico Cotugno, and his 
 
PEEPARATION OF THE AQUiEDUCT. VESTIB. ET COCHLEyE. 129 
 
 minute description of the labyrinthine aqua^ducts,* illustrated by- 
 diagrams, remained for nearly a whole century almost unnoticed b y 
 anatomists. In spite of the corroborating statements of F. Meckel, 
 Hyrtl,t and Van den Broeck, in whose excellent, though little known 
 anatomical atlas of the organ of hearing, J Plate IX., the intradural 
 sac of the aquseduct. vestib. is beautifully delineated, the vestibular 
 aquceducts were, until a few decades ago, looked upon as venous 
 canals, or osseous fissures containing processes of the periosteum. 
 Cotugno's discovery was fully confirmed by the excellent monograph, 
 
 Tig. 103.— rrontal section through the posterior portion of the vestibule, behind the fenestra, 
 ovalis. — u = utriculus ; p = cisterna perilymphatica ; ah = ampulla horizontal. ; ch = 
 section of the horizontal semicircular canal ; ai = ampulla inferior ; st = stapes ; aq = 
 section of the aquseductus vestibuli. After a preparation in my collection. 
 
 ' Entwicklung und Bau des Gehorlabyrinths ' (Leipzig, 1863), of A. 
 Bottcher, to whom we are indebted for having discovered the mem- 
 branous canals of the aquseduct. vestibuli discharging into the saccules ; 
 further, through the anatomical studies of C. Hasse (1870-73), through 
 the works of E. Zuckerkandl and Weber-Liel (M. f 0., 1869, Nr. 8), 
 and by Rudinger's§ more recent publication ; and it is to Zuckerkandl 
 
 * De aquoeductibus auris humanse internse. Viennas, 1774. 
 
 t VorlaufigeMittheilungen liber das Knochenlabyrinth der Saugethiere. Med. Jahrblicher, 
 1843. 
 
 + Ontleekundige en Physiologische Beschrijving van het zintuig des Gehoors door Dr. -J. 
 K. van den Broeck (Arnhem, 1853). A copy of this rare work was presented to me by Dr. 
 Moll, of Arnhem. 
 
 § ' Ueber die Abflusscanale der Endolymphe des inneren Ohres ' (Sitzungsbericht der kgl. 
 bayer. Akademie der Wissensch., 1887, Heft 3). 
 
 9 
 
130 PREPAKATION OF THE AQU^DUCTUS VESTIBULI. 
 
 in particular that credit is due for having, by his excellent treatment 
 of the subject, supplied definite data for the preparation of the 
 aquseductus vestibuli. 
 
 (a) Aquceductus Vestibuli. 
 
 If a cut be carried by means of a saw through the pyramid of 
 the petrous bone, corresponding to its long axis, and parallel to its 
 posterior surface, thus dividing the vestibule into halves, we find, 
 on the inner vestibular wall, in front of and below the common 
 embouchure of the superior and posterior semicircular canals, the 
 small internal aperture of the aquaeductus vestibuli (Fig. 104), 
 terminating below in a furrow. This opening leads into a very narrow 
 canal, which is rarely passable to a bristle, and which describes 
 a slight curve in the osseous mass of the petrous bone lying in front 
 
 -f-mi 
 
 Tig. 104. — Sagittal section through the long axis of the pyramid : view of the inner surface 
 of the cut. — V = inner wall of the vestibule, with the recess, hemiellipticus ; aq = vesti- 
 bular embouchure of the aquseduct. vestibuli, with its furrow-shaped continuation down- 
 wards on the inner vestibular wall ; f = section of the canalis facialis ; j = fossa jugularis. 
 
 of the posterior (sagittal) semicircular canal, and terminates at 
 the posterior surface of the pyramid behind the porus acustic. 
 intern, in a slit-like dilatation (apertura ext. aqueduct, vestibuli) 
 (Fig. 21, p. 24). 
 
 This osseous canal contains the extremely narrow membranous 
 canaliculus of the aquseduct. vestibuli. To expose the former in the 
 macerated temporal bone, from the apertura extern, aquseduct. 
 vestibul. (Fig. 105, av) to its opening into the vestibule (o), the osseous 
 lamella, bordering posteriorly on its external opening, is removed 
 by means ,of a broad graver, and the triangular space of this slit 
 (av) laid bare, up to the narrow part of the osseous canal. From this 
 point the work of preparation must be limited to the removal of small 
 pieces only, by means of a pointed file and fine graver, because the 
 narrow canaliculus is so easily choked with bone dust, that the 
 
EXPOSURE OF THE OSSEOUS CANAL OF THE AQUyEDUCT. VESTIB. 131 
 
 trace of it is lost in the mass of the petrous bone, and difficult to find 
 again. 
 
 In order, therefore, not to miss the direction of the course of 
 the small canal during the preparation, it is advisable first to 
 inject it with coloured wax. This is best done by inserting a small 
 tube air-tight into the fenestra ovalis, the round window being at the 
 same time closed up with putty. The injection may be considered 
 complete when the coloured wax can be seen at the hiatus aqueduct, 
 vestibul. on the posterior wall of the pyramid. When this is not the 
 case, which happens rather frequently, the cause of the failure must be 
 sought for in the blocking up of the canal by tissue-remains or other 
 products of maceration. 
 
 The colouring of the osseous canaliculus, for the purpose of more 
 easily finding it during the preparation, succeeds on well-macerated 
 
 mi 00 s 
 
 Fig. 105. — Posterior surface of the pyramid of the right temporal bone, with the opened 
 intratemporal canaliculus of the aquseduct. vestibuli and the embouchure of the aquaednct. 
 cochleae. — mi = meat, audit, intern. ; av = slit-like opening of the aquseduct. vestib. on 
 the posterior surface of the pyramid ; o = opening of the osseous canal of the aquseduct. 
 vestib. in the vestibule ; o' = canal, semicirc. super., opened ; s = canal, semicirc. post., 
 opened ; ac = funnel-shaped outlet of the aquseduct. cochl. ; si = sinus transv. ; w = proc. 
 mast. After a preparation in my collection. 
 
 temporal bones by placing the object in a coloured liquid, after 
 previously thoroughly soaking it in water for one or two days ; the 
 liquid will penetrate into the fine osseous canals without colouring 
 the bone itself. Carmine or hsematoxylin solutions are best adapted 
 for the purpose ; the colour of the latter can be eliminated, when 
 the preparation is completed, by placing the bone in dilute nitric acid. 
 On temporal bones of new-born infants, the two osseous aquteducts 
 may be successfully prepared out from the surrounding bone, with 
 graver and file. Several perfect specimens of this kind are to be found 
 in the celebrated collection of Professor Ilg, which has been added to 
 
 9—2 
 
132 PREPARATION OF INTRADURAL SAC OF AQUiEDUCT. VESTIB. 
 
 the anatomical museum of Vienna. The accompanying illustration 
 (twice the actual size) is taken from a preparation in this collection. 
 
 The preparation of the membranous aquseductus vestibuli (ductus 
 et saccus endolymphaticus) , is divided into that of the intracranial, 
 and that of the intratemporal portion. The tracing of the intra- 
 cranial portion, a sac-shaped space, 5-9 mm. broad and 8-15 mm. long, 
 situated between the layers of the dura mater covering the posterior 
 surface of the pyramid, presents, after a little practice, no special 
 difficulty. A most important guide is the protuberance, 3-4 mm. 
 behind the porus acusticus internus, which is found in front of the 
 apert. ext. aquseduct. vestibuli, and which, as in the macerated 
 bone, also projects in the posterior surface of the pyramid covered by 
 the dura mater. From this protuberance, in a slanting direction 
 backwards and a little downwards towards the lower curvature of the 
 sinus lateralis, lies the intradural sac of the vestibular aquseduct 
 alluded to. In some preparations, as I repeatedly noticed, its position 
 
 CO mi 
 
 Fig. 106. — Posterior view of the osseous labyrinth, with the three semicircular canals, the 
 cochlea and the aquseducts of a new-born infant. (Enlarged to double its size.) — co = cochlea ; 
 mi — meat, audit, intern. ; ac = aquffiductus cochleae ; av = aquseductus vestibuli. 
 
 and extent can be clearly distinguished by a slight fluctuation, which 
 becomes perceptible when the place is touched with the point of 
 a probe. In order to expose the sac, a short incision is made behind 
 the protuberance, i.e., at the point of transition of the sac into the 
 intratemporal portion, and air is forced into it through a small tube 
 introduced into the opening. If this is successful, the inflated sac will 
 show itself sharply defined in its limits and extent. 
 
 With the object of laying bare the inner surface of the sac, a 
 whalebone sound is now inserted into the opening of the incision, 
 then carefully moved backwards and downwards, and the medial wall 
 of the sac is cut in its longitudinal direction, by means of fine scissors. 
 For the purpose of exposing the floor of the sac (lateral wall), the 
 slit in the medial wall is divided by two transverse cuts, and the four 
 triangular flaps thus made are turned back, as shown in Fig. 107, av. 
 
PREPARATION OF INTRATEMPORAL PORTION OF AQUEDUCT. VESTIB. 183 
 
 In order to demonstrate the capacity of the sac, Zuckerkandl 
 suggests making an incision and stuffing the whole cavity with cotton 
 wool, whereby the entire intracranial portion of the aqua3duct in its 
 outlines stands out in relief on the posterior surface of the pyramid. 
 The sac may also be injected with a quickly setting coloured mixture 
 of wax and resin, if an incision be made at its most anterior boundary, 
 to receive the fine canula of a sj^inge. 
 
 In the above-mentioned treatise of Cotugno there are figured 
 several lateral canals branching off from the intradural sac and 
 runninef on in the dura mater. The existence of these small canals, 
 passing off from the floor of the sac, was confirmed by Zuckerkandl 
 and Weber-Liel. Recently Rlidinger (Lc.) has proved, by a series of 
 microscopical sections on embryonic heads of various animals, that 
 from the floor of the endo-lymph sac tubular prolongations pass out 
 
 Fig. 107. — Posterior surface of the pyramid of the right petrous bone of an adult, with the 
 opened intradural sac of the aquseduct. vestibuli. — mi = meat, audit, internus, with the 
 nerv. acusticus ; av =: opened intradural sac of the aquseduct. vestibuli ; si = upper section 
 of the sinus transv. ; si' = its lower section. After a preparation in my collection. 
 
 and penetrate the dura mater, and he regards these as channels for 
 the discharge of the endo-lymph from the membranous labyrinth. 
 These tubes are, according to Eildinger, completely surrounded 
 by large and wide lymph sheaths, to which externally the connecting 
 substance of the dura mater is closely attached. 
 
 Considerably more difficult is the representation of the intra- 
 temporal membranous tube of the aquseduct. vestibuli, which runs in 
 the petrous bone. Even after having repeatedly prepared it, one 
 frequently fails to discover this small tube, which, in the form of a 
 slender connective-tissue cord, passes through the densest portion of 
 the petrous bone and can only be demonstrated in its continuity by 
 carefully removing the bone in thin layers with small sharp chisels 
 and scraping irons. The work is materially facilitated if the object 
 
134 PREPARATION OF THE AQUEDUCT. COCHLEA. 
 
 has previously been lying for several weeks in a 10% solution of 
 chromic acid, when the connective tissue enclosing the aquseduct 
 contrasts, by its yellow colour, with the surrounding bone. The 
 position and direction of the small canal within the bone can also be 
 made perceptible by injecting it with a coloured liquid, provided the 
 intradural sac of the aquseduct can be successfully opened at its 
 posterior part, so that after loosening the dura mater from the 
 subjacent bone, the nozzle of a canula may be tied in the opening, 
 and the injection afterwards proceeded with. A still more simple 
 method of making the small membranous tube traceable in the 
 bone by colouring is, according to Weber-Liel, to dip the preparation, 
 with the opened intradural sac of the aquseduct, into a coloured 
 liquid, and through a small opening in the superior semicircular canal 
 to aspirate the labyrinthine fluid by means of a small glass tube until 
 the coloured liquid (Beale's blue) appears in it. 
 
 Still easier is the preparation of the aquseduct. vestibuli on petrous 
 bones which have been previously placed for two to three weeks in 
 dilute chromic acid, and afterwards decalcified (see decalcifying fluids 
 in the Histological part). By removing the decalcified bone in layers 
 with a flat scalpel or razor, it is possible in a short time to clear the 
 entire intratemporal portion up to its discharge into the vestibule. 
 For safety, it is advisable to begin the preparation at the hiat. 
 aquseduct. vestibuli, and to continue from here along the easily- 
 discernible strand of connective tissue, the removal in layers of the 
 petrous mass as far as the vestibule. In such preparations, if preserved 
 in spirit, the light-green connective-tissue strand of the aquseduct is 
 sharply defined from the dark^reen colour of the bone. 
 
 The representation of the commencing canaliculi of the aquseduct. 
 vestibuli discharging into the saccules, and which Bottcher discovered 
 by means of serial microscopical sections, is so difficult, that Zucker- 
 kandl, after many attempts, only succeeded once in seeing them 
 distinctly. By further improvements in the technical details of the 
 methods of injecting, the difficulties of anatomical demonstration may 
 be removed. 
 
 (6) Aquceductus Cochlece {Ductus perilymphaticus). 
 
 The laying bare of the osseous aquseduct. cochlese, which com- 
 mences with a small opening behind the groove of the fenestra rotunda 
 on the lower wall of the first cochlear convolution, and terminates, at 
 the edge between the posterior and inferior surfaces of the pyramid, 
 with a funnel-shaped dilatation (Fig. 105 av), is even more difficult 
 than that of the aquseduct. vestibuli. 
 
 For the preparation of the small canal on the macerated temporal 
 
PREPARATION OF THE BLOOD-VESSELS AND LYMPHATICS. 135 
 
 bone, it is here also advisable, according to the method already de- 
 scribed, to colour its walls by injecting with, or by dipping in a staining 
 fluid. We begin by chiselling away the bone at the above-mentioned 
 funnel-shaped outlet of the aquaiduct at the inferior edge of the 
 pyramid. The exposure of the lower and wider portion of the canal 
 is quickly accomplished ; much more difficult is it to trace the upper, 
 very narrow, straight, or somewhat curved piece up to its entrance 
 into the scala tymp., where the work must be done mainly with the 
 graver and finely-pointed files. 
 
 The method of representing the aqua3duct. cochleae on unmacerated 
 temporal bones is the same as that of the preparation of the aquse- 
 duct. vestibuli. The colouring of the narrow tube is here also effected 
 by dipping the funnel-shaped outlet in coloured liquid, and by 
 aspiration from the superior semicircular canal, but care should be 
 taken to avoid injuring the membranous canal while opening the 
 osseous one. According to Weber-Liel it is also possible, by aspiration 
 of the air in the external meatus, to fill the scala tymp. from the 
 aquseduct. cochlese ; frequently, however, this experiment proves a 
 failure, like the filling of the aquseduct. cochleae by injection of 
 the sub-arachnoideal space, with which the perilymphatic spaces 
 of the labyrinth communicate. 
 
 Most expeditiously will it be accomplished on decalcified petrous 
 bones, if the bone be removed in layers with a scalpel. It is best to 
 commence at the lower funnel-shaped outlet of the aquseduct, where 
 the triangular, at the narrow portion tapering, fasciculus indicates the 
 direction to be followed in removing the layers of the softened bone, 
 up to the embouchure of the canal into the lower scala of the cochlea. 
 
 The representation of the aqueducts by means of corrosion will 
 be discussed in the section 'Making Preparations of the Organ of 
 Hearing by Corrosion.' 
 
 13. PREPARATION OF THE BLOODVESSELS AND NERVES OF THE ORGAN 
 
 OF HEARING. 
 
 PREPARATION OF THE BLOODVESSELS AND LYMPHATICS. 
 
 Most suitable for the preparation of the bloodvessels of the organ 
 of hearing are those objects which have been injected, and in which 
 the injection substance, partly by its glimmering through, and partly 
 by its filling the tube of the vessel, materially facilitates the detection 
 of even the finer branches. The injection is always made on perfect 
 skulls, in adults from the carotis communis, in children preferably 
 from the aorta. 
 
 Instead of the hitherto generally used substance made of wax, with 
 
136 PREPAEATION OF THE AETERIES OF THE ORGAN OF HEARING. 
 
 the addition of turpentine, tallow, and olive-oil, the anatomical 
 institutions now employ one of putty, introduced by Teichmann, with 
 which the preparations are injected in the cold state. According to 
 Teichmann, not only fresh objects, but also older ones, or such as have 
 been kept in spirit, are suitable for injection. The composition of this 
 easily-prepared mass being generally little known, the proportions, as 
 given by Teichmann, may here be noted. 
 
 Red Mass for injecting the Arteries : 
 Whiting .... 5.00 g. 
 Yermilion .... 1.00 g. 
 Inspissated linseed-oil . . 0.9-1.00 ccm. 
 
 This well-triturated mass, large lumps of which may be kept in 
 water, is, before being used, dissolved in 0.75 ccm. of carbon bisulphide, 
 and this solution slowly injected by means of special screw syringes. 
 Should a large quantity of the substance be required, the proportions 
 of the various ingredients, as given above, should be strictly adhered 
 to. Only in those cases where the capillary vessels also are to be 
 injected is the finely-ground mass, free from grit, to be thinned by a 
 double quantity of carbon bisulphide. Capillary injections of the 
 membrana tympani, of the tympanic mucous membrane, and of the 
 labyrinth, it is safest to make by means of a coloured glue substance 
 (Berlin blue, or carmine). If it be intended to inject also the veins 
 and venous sinuses in the temporal bone, Teichmann's blue composition, 
 made up as follows, may be used: Oxide of zinc 15.00 g., ultramarine 
 1.00 g., boiled linseed-oil 2.0-2.5 ccm., carbon bisulphide or sulphuric 
 ether 1.00 ccm. To inject the larger lymphatic vessels, Teichmann 
 recommends a yellow substance consisting of: Oxide of zinc 2.00 g., 
 inspissated linseed-oil 3.0 ccm., and sulphuric ether 2.0 ccm. 
 
 PREPARATION OF THE ARTERIES OF THE ORGAN OF HEARING. 
 
 The preparation of the arteries of the external auricular region and 
 of the auricle is best made with that of the arteria carotis extern, and 
 its branches. After exposing, on a well-injected preparation, the 
 upper part of the arteria carotis extern, and finding, below the condy- 
 loid process of the inferior maxilla, the place where it divides into the 
 arteria maxillaris intern, and arteria temporalis superficialis, the last- 
 named branch, which ascends perpendicularly in front of the tragus 
 in a nearly vertical direction across the root of the zygomatic arch, is 
 dissected out, after which the laying bare of the rami auriculares an- 
 teriores, passing from the external or posterior periphery of the 
 arteria temporalis superficialis towards the auricle, is easily effected. 
 Two or three inferior branches of the arterise auriculares anteriores 
 
PEEPAEATION OF THE ARTERIES OF THE ORGAN OF HEARING. 137 
 
 supply the lobe, the tragus, and the anterior cartilaginous wall of the 
 meatus ; several superior branches, the upper part of the helix. 
 Somewhat more difficult is the preparation of the arteria auricularis 
 posterior, arising from that portion of the arteria carotis extern., 
 which passes through the parotid gland. To find this arterial branch 
 at its point of origin, the carotis extern, should first be exposed by 
 dissecting away the parotid tissue and the arteria auricular, post., 
 arising behind the posterior belly of the digastric muscle, must be 
 carefully prepared out. The preparation of the superior branches of 
 the arteria auricularis post., ramifying on the posterior surface of the 
 auricle, presents no difficulty. 
 
 Small twigs of the arteria auricularis post, penetrate between the 
 antitragus and the processus helicis caudatus, and through the 
 vascular canals of the auricular cartilage, also to the anterior surface 
 of the auricle, where the finer ramifications spread towards the superior 
 and lower portions. 
 
 By injecting the finer vessels it is also possible to trace the arteria 
 stylo-mastoid., which is given off from the arteria auricular, post., 
 and which enters the foramen stylo-mastoid., supplies the facial nerve, 
 and with a small branch passes through the canaliculus chordse into 
 the tympanic cavity, anastomosing here with the vessels of the tym- 
 panic membrane. 
 
 The arteries of the external meatus, which in the outer portion of 
 the cartilaginous part arise from the arteries auriculares anteriores et 
 posteriores, but in the deeper portion of the cartilaginous and osseous 
 canal from the arteria auricularis profunda, can only be represented 
 on such preparations where the injection fluid has penetrated into the 
 finest arterial branches. As the bloodvessels mainly run along the 
 posterior superior wall, it is necessary, in order to expose them, to 
 remove, on an injected preparation hardened in alcohol, the lower wall 
 of the cartilaginous and osseous meatus by a horizontal cut carried as 
 far as the neighbourhood of the tympanic membrane, and to take off 
 the thick epidermic layer, covering the bloodvessels with a camel's- 
 hair brush. If the injected fluid has also penetrated into the 
 radiating vascular ramifications of the membrana tympani, it will be 
 noticed that a strong arterial twig, running along the upper wall of 
 the meatus, passes at the posterior boundary of Shrapnell's membrane 
 on to the tympanic membrane, where it can be traced along the 
 posterior margin of the manubrium down to the lower extremity. 
 
 PREPARATION OF THE ARTERIA AURICULARIS PROFUNDA. 
 
 In order to find this artery, the masseter muscle, together with the 
 zygomatic arch sawn through before and behind, must be turned down 
 
138 PREPARATION OF THE VEINS OF THE ORGAN OF HEARING. 
 
 towards the angle of the maxilla, the terminal division of the arteria 
 caret, ext. having already been exposed by the previous preparation. 
 By sawing the ramus of the lower jaw transversely through, about 
 midway between the incis. semilunar, and the maxillary angle, and 
 dividing the neck of the maxilla below the capituL, a piece of bone is 
 made free, which is to be turned over in an upward direction, after 
 the tendon of the temporal muscle has been completely cut through, 
 whereby the commencing part of the arteria maxillaris intern, will 
 become exposed. At the posterior periphery of the last-mentioned 
 artery arises the arteria auricularis profunda, the branches of which 
 can be traced, by careful preparation, to the deeper parts of the ex- 
 ternal meatus. 
 
 The arteria tympanica, also arising from the arteria maxillaris 
 intern., can only be exposed up to its entrance into the Glaserian 
 fissure, after disarticulation of the condyle of the inferior maxilla. 
 
 PREPARATION OF THE ARTERIA AUDITIVA INTERNA. 
 
 This takes its origin mostly from the arteria basilaris, sometimes, 
 however, from the arteria cerebelli anter. Where it arises from the 
 arteria basilaris, it crosses the medulla oblongata longitudinally. 
 The origin of the artery may be best seen on a brain which has 
 been injected in situ and carefully taken out of the cranial cavity, 
 the artery being cut through close to the porus acust. int. along 
 with the nerve trunks entering the latter. If, however, it be 
 desired to retain it in its continuity, in order to follow it to the 
 floor of the internal meatus, it is advisable, after taking away the 
 roof of the skull, the cerebral hemispheres, and the entire tentorium, 
 to remove the cerebellum, pons and medulla oblongata in pieces, in 
 such a manner that the basilar arteries and their ramifications be 
 retained on the base of the skull. The arteria auditiva int. is then 
 seen passing from its origin at the base of the skull in a lateral 
 direction to the meat, audit, intern. With the object of examining 
 the further course of the artery towards the fundus, the superior wall 
 of the internal meatus is removed with chisel and forceps. For details 
 we refer to the section 'Preparation of the Acoustic and Facial 
 Nerves.' 
 
 PREPARATION OF THE VEINS OF THE ORGAN OF HEARING. 
 
 It is much more difficult to completely inject the veins of the 
 auditory apparatus than it is in the case of the arteries. It is not 
 sufficient, as in the filling of the arterial system, to inject from one 
 single spot, but it should be done from several points. As the vense 
 
PREPARATION OF THE VEINS OF THE ORGAN OF HEARING. 139 
 
 auditivas int., which accompany the artery of the same name, the 
 veins of the labyrinth and of the tympanic cavity enter, either directly 
 or through the intervention of the meningeal veins, into the neighbour- 
 ing sinuses of the dura mater (sinus petro-squamosus, petrosus 
 superior, petro-basilaris and transversus), they are best injected from 
 these sinuses. Most suitable for this purpose is a head severed from 
 a very lean and anaemic subject, on which one or both vense jugulares 
 communes are injected with Teichmann's blue or yellow mass. In the 
 latter case, for the purpose of injecting both jugular veins simul- 
 taneously, a bifurcated canula is made use of. Before the injection, 
 the vertebral canal and the foramina transversaria are firmly plugged 
 with cotton wool, and the stumps of the veins, appearing at the 
 surface of amputation, are ligatured. Should, during the operation, 
 the injection fluid ooze out at any part on the amputated surface, the 
 open vessel must be twisted or ligatured. 
 
 The veins of the external ear, injected after this method, are, 
 as a rule, more or less incompletely filled, as the valves prevent 
 the advance of the medium towards the periphery. By sinus injec- 
 tion the vense auricular, post, are most rapidly filled from the 
 emissarium mast. ; the venae auricular, ant. can be filled from the 
 vena temporal, superficial, which must be looked for on the temple, 
 and injected towards the centre. By this means the plexus venosus 
 pterygoid, in the fossa intratemporal. is frequently also injected, and 
 thence the fluid passes into the vense auricular, profundse. Should 
 the latter plexus have failed to be filled by the injection through the 
 venae jugular, communes et temporales superficiales, it is safest to fill 
 it from the vena temporalis media. This vein is to be found above 
 the zygomatic arch in the layer of fat between the superficial and 
 deep lamina of the fascia temporal., and when discovered it is cut 
 into, ligatured towards the periphery, and injected downwards. By 
 injecting the vena facial, ant., which is to be looked for at the 
 anterior margin of the insertion of the masseter, the plexus 
 pterygoid, may, as a rule, also be filled through the vena anasto- 
 motica facialis, which leads out of this plexus into the vena facialis 
 antica. 
 
 Heads from older individuals are better adapted for the injection 
 of the veins than those of younger ones, because the valves at a 
 maturer age become not infrequently insufficient, and the venous 
 walls possessing greater firmness, extravasation does not so easily 
 occur as in younger subjects. 
 
 The injection of the lymphatic vessels of the external region of 
 the ear is effected either by means of metallic quicksilver or with 
 soluble Berlin blue. In the latter case it is preferable to make use of 
 
140 PREPARATION OF THE NERVUS AURICULARIS MAGNUS. 
 
 a well- working Pravaz syringe with a finely pointed canula, which is 
 inserted obliquely into the corium of the concha close to the orifice 
 of the ear, after which the injection is proceeded with by gradually- 
 increasing pressure. The quicksilver finds its way into the interstices 
 of the corium, and from here into the lymphatic vessels. The injec- 
 tion will fail if the point of the canula be forced into the sub- 
 cutaneous connective tissue, in which case numerous extravasations 
 will occur in the meshes of the tissue. The anatomical museum of 
 Paris contains several specimens of the auricle, in which the 
 lymphatic vessels have been successfully injected with quicksilver. 
 
 PREPARATION OF THE NERVES OF THE ORGAN OF HEARING. 
 
 Preparing the nerves of the organ of hearing in the fresh state, 
 when their finer branches are soft and liable to be torn, is much more 
 difficult than when, by the action of some chemical agent, they have 
 acquired the requisite degree of firmness and resistance. For this 
 purpose Dr. Dalla Rosa, of the anatomical institute of Yienna, injects 
 the head, separated from the trunk, for several days from the common 
 carotids with a 0.5^ aqueous solution of chromic acid, allowing 2-3 
 litres of this liquid to flow daily from an irrigator, placed about 1| m. 
 above the head, which after each injection is immersed in the same 
 solution, the liquid being changed every day. After a few days the 
 head is placed in water, which is either kept running or changed 
 several times in the day, and where it is allowed to soak for two 
 or three days, during which time water is also allowed to flow 
 repeatedly through the carotids from the irrigator. Finally the head 
 is injected by means of an irrigator with 2-3 litres of 50% alcohol, 
 and, after removal of the brain, preserved for the purpose of prepara- 
 tion in alcohol of the same concentration. 
 
 PREPARATION OF THE NERVUS AURICULARIS MAGNUS. 
 
 To represent this nerve the upper part of the platysma myoides is 
 prepared. In the middle of the posterior edge of the musculus sterno- 
 cleido-mastoid., the nerve comes into view, passes across the muscle 
 obliquely forwards and upwards, and divides into two branches : the 
 anterior ramus auricularis, and the posterior ramus mastoid. The latter 
 accompanies the arteria auric, post, and radiates in the integument of 
 the mastoid process and of the upper part of the auricle. The 
 anterior branch passes on to the posterior surface of the lobe of the 
 ear, and there gives off the cutaneous twigs for the posterior and (by 
 means of perforating branches) the anterior surface of the lower half 
 of the auricle, as well as for the external meatus. The inferior portion 
 
PREPARATION OF THE NERVUS AURICULO-TEMPORALIS. 141 
 
 of the nervus auricul. magn. is covered by the platysma, and therefore 
 does not become visible until this is removed. 
 
 PREPARATION OF THE TEMPORAL BRANCHES OF THE NERVUS 
 AURICULO-TEMPORALIS. 
 
 The preparation of this nerve may be commenced either with that 
 of the peripheral branches on the external region of the ear, or with 
 the laying bare of the central portion of the nerve. In the former 
 case a vertical incision is made in the skin in front of the tragus, and 
 from here the integument of the temple is dissected off, leaving the 
 subcutaneous connective tissue in position. Thus the branch of the 
 auriculo-temporalis, ascending above the zygomatic arch, may be 
 exposed, and its smaller branches, ramifying in the integument of the 
 auricle and towards the external meatus, may be followed. The 
 anastomoses of the nervus auriculo-temporalis with the nervus facialis 
 are met with after dissecting away the upper part of the parotid 
 gland, in the deeper layers between the maxillary joint and the 
 anterior wall of the meatus. 
 
 PREPARATION OF THE ORIGIN OF THE NERVUS AURICULO-TEMPORALIS 
 AND OF THE CHORDA TYMPANL 
 
 In order to find the origin of the nervus auriculo-temporalis, the 
 same proceeding is followed as in laying bare the arteria masill. int. 
 and the art. auric, prof., passing off from it. After removal of the 
 musculus pterygoid, ext., together with the upper half of the ramus of 
 the inferior maxilla, the third branch of the trigeminus, at its exit from 
 the foramen ovale, is exposed. Immediately below this are found the 
 two peduncular roots of the nervus auriculo-temporalis, which have 
 between them the arteria mening. media before its entrance into the 
 foram. spinos. and which, laterally from here, unite in a sino-le trunk 
 passing outwards through the upper part of the parotid gland, and 
 ascending, between the maxillary joint and the anterior wall of the 
 meatus, above the zygomatic arch to the temple. 
 
 The chorda tymp. may be prepared along with the origin of the 
 nervus auriculo-temporalis. Should it be desired to exjDose the nerve 
 from the outside, it may be found at its exit from the Glaserian 
 fissure immediately behind the fossa glenoidalis, or, what is easier, it 
 may be traced from its junction with the trunk of the nervus 
 lingualis upwards and backwards as far as the fissura Glaseri. In 
 the same manner the preparation of the chorda tymp. can be efi'ected, 
 together with that of the otic ganglion, in following it, as shown in 
 
142 PREPARATION OF THE GANGLION OTICUM, ETC. 
 
 Fig. 108, from its anastomosis with the lingual nerve as far as the 
 tympanic cavity, and thence into the facial canal. 
 
 PREPARATION OF THE GANGLION OTICUM. 
 
 The representation of the otic ganglion is one of the most difficult 
 preparations. It is made from within, on a skull cut vertically into 
 halves, as the ganglion is situated on the medial side of the third 
 branch of the trigeminus (Fig. 108, go.). 
 
 In order to make the principal trunk of this branch accessible, the 
 body of the sphenoid bone, together with the basilar portion of the 
 occipital bone, and the cartilaginous Eustachian tube with the levator 
 palati mollis, are removed ; the tensor palati, however, in its greater 
 part, is retained. The principal trunk of the third division of the 
 fifth nerve having thus been laid bare, the exposure of the ganglion 
 may now begin. For this purpose, the nervus pterygoideus internus 
 must be looked for, as it forms an important guide for finding it. 
 With this object, after cutting away the remainder of the tongue, the 
 inner side of the musculus pterygoideus is dissected clean, and the 
 nerve sought for where it enters at the upper margin of that muscle, 
 following it in a central direction towards the principal trunk. By 
 this proceeding, the ganglion cannot escape the notice of the dissector, 
 since the central termination of the nervus pterygoideus internus, 
 entering the main trunk of the nerve, pierces the ganglion. The 
 preparation will make it plain that the latter lies immediately below 
 the foramen ovale, and is surrounded by vascular cellular tissue. In 
 dissecting this away, beginners, taking it for adipose tissue, are apt to 
 remove the ganglion along with it, which makes it advisable to practise 
 at first on objects hardened in alcohol. The preparatory work is carried 
 out as far as the excision of the body of the sphenoid, of the pars 
 basilaris, and of the Eustachian tube ; the nervus pterygoideus internus 
 remains to be exposed. After this the object is first well steeped in 
 water (one to two days), next hardened in alcohol, and not until then 
 should the preparation of the ganglion be commenced. 
 
 The branches of the ganglion radiate from its anterior and posterior 
 pole. Of the two posterior nerves, the inferior belongs to the tensor 
 tympani ; the superior is termed nervus petrosus superficialis minor. 
 The anterior branches supply the tensor palati mollis. 
 
 The preparation of the nervus petrosus superficialis minor is effected 
 from its origin at the otic ganglion through the fissura spheno-petrosa. 
 Having passed through the latter, it runs laterally and parallel to_the 
 nervus petrosus superficialis major through the canaliculus tymp., at 
 the superior opening of which it enters the tympanic cavity to anasto- 
 mose with Jacobson's nerve. 
 
PREPARATION OF THE RAMUS AURIC. VAGI. 
 
 143 
 
 PREPARATION OF THE RAMUS AURICULARIS VAGI. 
 
 The preparation of the ramus auricularis vagi is best commenced 
 by exposing its peripheral portion. For this purpose, the posterior 
 surface of the auricle is carefully dissected away from its insertion at 
 the mastoid process, in order to find the peripheral portion, which 
 runs in the stratum of connective tissue between the auricle and the 
 
 Fig. 108. — Preparation of the otic ganglion and the nerve branches issuing from it. — tr = 
 nervus trigeminus with the ganglion Gasseri ; go = ganglion oticum ; nt' = nervus tens, 
 palat. moll. ; nl = nervus levat. palat. moll. ; pe = nervus pterygoid, exb. ; pi = nervus 
 pterygoid, int. ; tp = muse. tens. tymp. ; mt — nervus tens, tympani ; pm = nervus 
 petrosus superf, minor ; m = nervus mandibularis ; ch = chorda tymp. : 1 = nervus 
 lingualis and its anastomosis with the chorda tymp., forming an acute angle ; a = nervus 
 auriculo-tempor. ; f = nervus facialis ; mt = inner surface of the membrana tympani ; 
 ma = proc. mast. ; si — sinus transvers. ; mp = musculus pterygoid, int. After a pre- 
 paration in the anatomical museum of Vienna. 
 
 opening of the canaliculus mastoid., and enters the fissura tympanico- 
 mastoidea. 
 
 To prepare the nerve from its origin, the pars condyloidea of the 
 occiput is removed, the nervus vagus then followed into the fossa 
 jugularis, where the ganglion jugulare is laid bare, when the ramus 
 
144< PREPARATION OF NERVUS ACUSTICUS AND NERVUS FACIALIS. 
 
 auricularis vagi, passing off from behind the latter, can be searched 
 for. 
 
 The most difficult part of the preparation of this nerve is to follow. 
 It consists in opening with the chisel the canaliculus mastoid, from 
 the posterior part of the fossa jugularis to the canalis Fallopii, in 
 which the nerve anastomoses with the facial nerve, and from here to 
 its opening at the fissura tympanico-mastoidea. The preparation of 
 this nerve in its whole extent is rarely successful, even after repeated 
 attempts, and it is therefore advisable first to open the canaliculus 
 mastoid, on the macerated temporal bone. 
 
 PREPARATION OF THE NERVUS ACUSTICUS AND NERVUS FACIALIS. 
 
 To represent the nervus acusticus in its whole length, after removal 
 of the cerebrum and dividing the tentorium cerebelli at the edge of 
 
 Fig. 109. — View of the tympanLc cavity after the removal of the tegmen tymp. (Right 
 ear. ) — ha = malleo-incudal articulation ; t — muse. tens. tymp. ; s = tendon of the muse, 
 tens. tymp. , passing across the tympanum ; f = nerv. facialis ; g = genu nervi facialis ; 
 n = nerv. petros. superf. major ; a =: nerv. acusticus ; an = antrum mast. After a 
 preparation in my collection. 
 
 the pyramid, the cerebellum, together with the medulla, is raised up a 
 little, and the acoustic nerve cut through, close to its point of exit 
 at the side of the medulla oblongata, along with the neighbouring 
 facial nerve. Next, the upper wall of the internal meatus is removed 
 with chisel and forceps as far as its floor, then the fibrous lining of 
 the canal, a continuation of the dura mater, is split, and the acoustic 
 nerve, running in company with the facial, will be exposed. The 
 latter, recognisable by its firmer consistence (portio dura), lies above 
 the acusticus. This nerve, somewhat softer (portio mollis), divides, at 
 the bottom of the meatus, into an anterior branch which enters the 
 modiolus and the lower convolution of the cochlea (ramus cochleas), 
 and a posterior branch, penetrating the bone between the cochlea and 
 vestibule, and passing into the latter (ramus vestibuli); before its 
 
PEEPARATION OF THE NERVUS ACUSTICUS AND NERVUS FACIALIS. 145 
 
 entrance it shows a slight swelHng (intumescentia ganglioformiy 
 Scarpse), and a small branch passes from it to the inferior ampulla. 
 
 The preparation of the nervus facialis is carried out along with that 
 of the acoustic nerve. The upper wall of the internal meatus having 
 been removed, and the trunks of the two nerves exposed, as far as the 
 fundus, the object is fixed in the vice, and the osseous mass situated 
 above the vestibule and the cochlea cut away with the chisel (4-5 mm. in 
 front of the superior semicircular canal), and that portion of the facial 
 nerve, which passes transversely from within outwards through the 
 petrous bone, is laid bare up to the genu nervi facialis at the boundary 
 of the inner wall of the tympanic cavity. In order to prepare the 
 nerve in its further course in the tympanic cavity, the pars tympanica 
 et squamosa must be separated from the pyramid and the mastoid 
 portion in such a manner that the posterior lower part of the pars 
 tymp., lying within the foramen stylomast., remains connected with 
 the pars petrosa. The preparation of the nerve, from the genu to the 
 descending portion of the facial canal, is the easiest part of the work, 
 as this part of the canal, with its thin, at times dehiscent osseous wall, 
 projects above the niche of the fenestra ovalis as an elevation, descend- 
 ing obliquely in a direction backwards and downwards, and a slight 
 pressure with a broad graver will be sufficient to remove the thin 
 osseous lamella. 
 
 Somewhat more elaborate is the exposure of the descending 
 portion of the facial nerve, because it is covered by a thicker layer of 
 bone, the removal of which with the chisel requires more time. The 
 direction in which the preparation must be proceeded with is given by 
 the point at the posterior tympanic wall, where the horizontal meets 
 the descending portion at an obtuse angle, and by the exit of the 
 nerve from the foramen stylo- mastoideum. 
 
 The representation of the course of the facial nerve is materially 
 facilitated on decalcified petrous bones. Here it suffices to remove in 
 layers, with a scalpel, the superior wall of the internal meatus, 
 simultaneously with the bone on the upper surface of the pars petrosa, 
 covering the facialis, to speedily come upon the nerve. In a like 
 manner its horizontal and descending piece in the tympanic cavity 
 is also quickly brought to view. Such preparations, preserved in 
 spirits of wine, are specially adapted for purposes of demonstration. 
 
 Among the nerves communicating with the nervus facialis, the 
 nervus petros. superf. major may be mentioned. Its preparation is 
 very easy, since it occupies a groove in the dura mater, and runs, as 
 described on p. 28, from the anterior angle of the temporal bone to 
 the hiat. canal. Fallop. on the upper surface of the pars petrosa ; its 
 course as far as the genu can, therefore, be represented with pincette 
 
 10 
 
146 PKEPARATION OF THE NERVUS ACUSTICUS AND NERVUS FACIALIS. 
 
 and scalpel without further manipulation on the bone. The direction 
 of its course corresponds, as the accompanying illustration (Fig. 109) 
 shows, with that of the musculus tensor tymp. 
 
 The question as to how the anastomosis of the nervus petr. sup. 
 major with the facialis takes place, has been decided by Friihwald 
 (Sitzungsber. d. kais. Acad. d. Wiss. in Wien, 3876, Bd. 74), who has 
 shown that the facial nerve gives off fibres to the nervus petr. sup. 
 major, but that, on the other hand, it receives fibres from the nervus 
 petr. major. As the method of examination suggested by Friihwald 
 may also be employed to demonstrate the course of other nerve 
 bundles, it shall be briefly described here : The nerve to be placed in 
 95^ alcohol, until it loses its natural softness, and then saturated in 
 oil of turpentine. In order to destroy the connective tissue, the pre- 
 paration is heated on a water-bath in 50 ccm. of a concentrated 
 solution of chlorate of potash and 3h ccm. of fuming nitric acid, 
 until the nerve becomes soft again. After boiling, it is to be placed 
 for one or two days in distilled water, and after that in equal parts of 
 a concentrated solution of tartaric acid and glycerine, which clears up 
 the remaining connective tissue, leaving, however, the nerve fibres 
 white. The latter are examined on a black ground of wax. 
 
 The exposure of that portion of the chorda tympani, which runs in 
 the canaliculus chordae on the posterior tympanic wall as far as the 
 facial canal, is difficult, on account of the narrowness of the small 
 furrow, and its variable position in the osseous mass behind the 
 membrana tympani, especially if it be desired to show both nerve and 
 chorda in their continuity. In opening the narrow canal with the 
 chisel, injury to the thread-like chorda can scarcely be avoided, and 
 it is therefore laid bare more rapidly on decalcified preparations. 
 
 In addition, a method of opening the entire facial canal on the 
 macerated temporal bone, as suggested by Kiesselbach, may be 
 noted. He commences the cut in a line which unites the middle of 
 the hiatus aqused. vestib. on the posterior surface of the pyramid and 
 the posterior edge of the foram, stylo-mastoid., and meets the proc. 
 mastoideus. The cut then passes towards the posterior margin of the 
 internal meatus, and after that in a plane, which lies through the 
 opening at the commencement of the facial canal and the spina supra 
 meat.; it next turns towards the upper edge of the genu facial., 
 and thence in any direction through the cochlea. The surface 
 of the cut anteriorly shows, besides the whole of the canalis Fallop., 
 the lower part of the vestibule with the foram. ovale and the 
 commencement of the cochlea ; posteriorly, the position of the antr. 
 mast, and the upper portion of the vestibule with the semicircular 
 canals. 
 
TOPOGKAPHICAL SECTIONS OF THE ORGAN OF HEARING. 147 
 
 14. MAKING TOPOGRAPHICAL SECTIONS OF THE ORGAN OF HEARING 
 FOR INSTRUCTION PURPOSES. 
 
 For the study of the topography of the organ of hearing, in 
 addition to the previously described preparations, a series of sections 
 of the entire temporal bone is required, the most important of which 
 shall here be discussed. 
 
 The topographical preparations of the ear in my collection are 
 divided into : 1, sections of common preparations of the temporal 
 bone, preserved in spirits of wine ; 2, sections of decalcified temporal 
 bones ; 3, topographical sections on dry preparations. 
 
 (a) Topographical Sections of the Temporal Bone prepared for 
 Preservation in Spirits of Wine. 
 
 The technical proceeding in making topographical preparations ol 
 the ear, which are to be preserved in spirits of wine, is the following 
 On a specimen which has been soaked in water and sufficientl} 
 hardened in alcohol, the external soft parts, auricle, and cartilaginous 
 meatus, are first divided by means of a sharp scalpel, in the direction 
 in which the cut is to be made, if possible at one sweep down to the 
 periosteum, the cut being continued through the bone in the same 
 direction with a fret-saw. On preparations where it passes through 
 the membrani tympani, the latter must be divided with a small 
 pointed knife from the external meatus (under illumination with the 
 mirror), and exactly in the direction of the saw-cut. 
 
 A more exact representation of the topographical position of 
 the external soft parts, in their relationship to the cavities in the 
 temporal bone, is obtained by sections on frozen specimens. These 
 admit of dividing the soft parts and bone with the saw in any 
 direction without great difiiculty, while the displacement of the 
 tissues, frequently occurring in ordinary spirit preparations, is avoided. 
 The freezing of the preparation may be effected either by exposing it 
 to the open air during frosty weather, or by artificial means. In the 
 latter case the object, simply wrapped in a piece of linen, is surrounded 
 by a mixture of two-thirds snow or pounded ice, and one-third 
 common salt, and allowed to stand for two or three hours in the cold 
 open air, or in a cool place. The frozen sections are quickly washed, 
 and immediately placed in concentrated spirit, which must be changed 
 after twenty-four hours, whereby the soft parts retain their firmness 
 and original positions. 
 
 The topographical preparations of this kind most important for the 
 purposes of instruction are the following : 
 
 1. A horizontal section through the entire temporal bone, so 
 
 10—2 
 
148 HORIZONTAL SECTION THROUGH THE ORGAN OF HEARING. 
 
 carried through the auricle that the plane of the cut coincides with 
 that part of the antrum mastoid, which is situated behind the cavum. 
 tymp. (Fig. 110). 
 
 In order to fix accurately the direction of the cut, we first remove 
 the tegmen tymp. and mastoid, from a temporal bone, sawn out 
 in the regular way, and with the auricle in situ, so as to obtain a 
 view into the antrum mastoid. Then, placing the point of one leg 
 of a pair of compasses in the antrum, and the other on a correspond- 
 ing place on the concha, the spot is determined through which the 
 horizontal cut is to be carried. Now, this spot on the anterior surface 
 of the auricle is either in the portion of the concha bordering on the 
 mastoid process, behind the upper margin of the external orifice, or 
 somewhat higher up, above the transverse ridge of the concha, formed 
 
 Fig. 110. — Horizontal section through the temporal bone at the level of the antrum mastoid. 
 — a = insertion of the posterior surface of the auricle at the mastoid process ; me = 
 meatus audit, ext. ; kn = section of the tragus and of the anterior cartilaginous wall of 
 the meatus ; ca = cavum tympani with the ossicles ; an = antrum mastoid. ; si = sinus 
 transversus. After a preparation in my collection. 
 
 by the continuation of the antihelix. In making such sections, 
 numerous exceptions are met with, due partly to the strong arching 
 forwards and outwards of the sinus transversus, partly to an 
 abnormally high or low position of the auricle. 
 
 To make these horizontal sections, the auricle is divided, at a point 
 determined by the compasses, with a sharp scalpel, down to the bone 
 (on frozen preparations it is sawn through). It will now be better to 
 saw the bone through in the direction of the incision in the soft parts 
 from behind forwards, whereby a horizontal section is obtained, on 
 which, as the accompanying illustration shows, the relative positions 
 of the external and middle ear come clearly into view. To avoid 
 injuring the malleus and incus while proceeding with the section, the 
 
FRONTAL SECTION THROUGH THE ORGAN OF HEARING. 
 
 149 
 
 plane of the cut must, at the point where the antrum passes into the 
 tympanic cavity, lie a little higher. 
 
 The horizontal section through the temporal bone here described 
 is suitable for studying the external meatus in its course from the 
 orifice to the tympanic membrane. A complete representation of the 
 angular curvatures of the canal is, however, only to be obtained by 
 placing side by side horizontal and frontal sections (Figs. 110 and 111). 
 These further show the mode of apposition of the posterior carti- 
 laginous wall of the meatus to the anterior surface of the mastoid 
 process, the relationship of the anterior wall of the meatus to the 
 maxillary joint, as well as that of the attachment of the posterior 
 
 Fig. 111. — Frontal section through the temporal bone. — k = upper portion of the cartilage 
 of the auricle ; a = insertion of the auricle in the temporal region ; 1 = lobulus ; kn = 
 sections of the lower portion of the auricle and of the inferior cartilaginous wall of the 
 meatus ; o = superior, u = inferior, wall of the osseous meatus ; t = membrana tymp. ; 
 ct = cavum tyrap. ; co = cochlea. 
 
 surface of the auricle to the mastoid process, which is of importance 
 in the surgical opening of the latter. It is only by the examination 
 of such preparations that we recognise the necessity of a partial 
 detachment of the auricle from its insertion, in order, during operative 
 interference, to reach the antrum mastoid, by the shortest way. 
 
 2. A frontal section through the auricle, external meatus, membrana 
 tympani, tympanic cavity, and labyrinth. 
 
 The cut takes such a direction as to pass through the middle of the 
 outer opening of the ear and through the anterior portion of the lobe. 
 After dividing the auricle, fascioQ, and temporal muscle down to the 
 bone, the incision is continued with a small scalpel through the upper 
 
150 
 
 SAGITTAL SECTIONS THROUGH THE EXTERNAL MEATUS. 
 
 and lower cartilagino-membranous walls of the meatus to the union 
 with its osseous portion. After this the cut is carried farther with a 
 fret-saw through the upper and lower walls of the osseous meatus to 
 the vicinity of the membrana tympani. To protect the latter from 
 being torn by the saw, it is, under sufficient illumination of the ex- 
 ternal meatus, cut through with a small knife close in front of the 
 manubrium from above downwards, and the saw-cut continued in such 
 a manner that it passes in front of the malleus towards the tympanic 
 cavity and labyrinth. 
 
 Such frontal sections (Fig. Ill) of the organ of hearing demon- 
 strate the mode of apposition of the upper parts of the auricle (k) 
 to the temporal muscle, the relation of the superior membranous wall 
 
 ma S 
 
 Fig. 112. — Sagittal section through the temporal bone, 2 mm. inwardly from the external 
 orifice of the ear. — g = section of the cartilagino-membranous meatus ; ca = section of 
 the lower wall of the cartilaginous groo%'e ; ma = mastoid cells; s = sinus transvers., 
 opened ; c = section of the outer extremity of the proc. condyloid, of the inferior maxilla. 
 
 of the meatus to the horizontal part of the squama, the direction of 
 the course of the external meatus in the frontal plane, and the relation- 
 ship of its lower wall to the parotis. 
 
 3. A series of sagittal sections through the external meatus, mastoid 
 process, and maxillary joint. 
 
 It is best to use for this purpose firmly-frozen preparations, on 
 which the auricle and cartilaginous meatus, as well as the ascending 
 ramus of the inferior maxilla, have been left intact in situ. The first 
 cut (Fig. 112), 2 mm. inwardly from the external orifice, is carried 
 through the cartilagino-membranous meatus (g), the outer part of the 
 mastoid process (ma), and meets the outermost end of the proc. con- 
 dyloideus of the ramus of the inferior maxilla (c). This section shows, 
 
SAGITTAL SECTIONS THROUGH THE EXTERNAL MEATUS. 
 
 151 
 
 in addition to the relative position of the maxillary joint to the meatus, 
 the mode of apposition of the cartilagino-membranous meatus to the 
 
 ^.s fin I 
 
 Pig. 113.— Sagittal section through the temporal bone, 4 mm. medially from the previous 
 one. — g = lumen of the osseous meatus; vo = its anterior wall ; ma = mastoid cells • 
 s = sinus trans vers., opened ; c = section of the proc. condyloid, of the inferior maxilla • 
 me = meniscus of the maxillary articulation ; fm = fossa mandibularis. 
 
 anterior surface of the mastoid process. If the sinus trans versus 
 (s) be strongly arched outwards, it will be exposed by this cut. 
 
 A second sagittal cut (Fig. 113), made 4 mm. medially, divides the 
 
 A 
 
 Fig. 114. — Sagittal section through the temporal bone at the inner end of the osseous 
 meatus. — g = osseous meatus ; am = antrum mast. ; c = section of the medial extremity 
 of the proc. condyloid, of the ramus of the inferior maxilla ; me = meniscus ; fm = fossa 
 mandibularis. 
 
 osseous meatus (g), the articular fossa of the lower jaw (fm), the entire 
 condyle (c), and its meniscus (me). The space between the maxillary 
 
152 FRONTAL SECTION THROUGH BASE OF SKULL AND EUST. TUBES. 
 
 joint, the auditory meatus, and mastoid process is occupied by parotis 
 and adipose tissue. Besides the exceedingly variable number of the 
 mastoid cells, there are frequently found on this section the outermost 
 space of the antr. mastoid, (ma), and a considerable gap in the sinus 
 transversus. 
 
 Lastly, a third sagittal section through the osseous meatus, imme- 
 diately in front of the upper pole of the membrana tympani (Fig. 114), 
 shows, besides the elliptical opening of the section of the osseous 
 meatus (g), the transverse section of the inner extremity of the proc. 
 condyloideus of the inferior maxilla, with the articular fossa (fm), the 
 meniscus (me), and, behind, the transverse section of the antr. mas- 
 toid, (am) in its greatest extent. 
 
 4. A frontal section through the skull, to show the relative posi- 
 tion of the two cartilaginous Eustachian tubes at the base of the 
 skull. 
 
 Most suitable for this is a firmly frozen head, which, while in the 
 normal position, is sawn through in a frontal plane, passing through 
 both oval windows. The posterior view of this section (Fig. 115) 
 shows the middle portion of the naso-pharyngeal space (R), on the 
 lateral wall of which the medial plate of the cartilage of the tube (t), 
 is symmetrically placed. The latter, standing obliquely to the base of 
 the skull, and connected with the basilar fibre- car tillage (f), is bent in 
 an upward direction, and forms the lateral cartilage hook (h h'), which 
 roofs over the slit of the tube (sp sp'), directed almost perpendicularly 
 downwards. In addition to this view of the Eustachian tubes, the 
 section shows the topographical position of the tensor (ts) and levator 
 (1) palati mollis, of the m. pterygoid, int. (pi) et ext. (pe). As a 
 matter of course the aspect of this section of the tube and the size of 
 the slit will var}' according to whether the plane of the cut approaches 
 the ostium pharyng. or the ost. tymp. 
 
 In order, therefore, to obtain a clear representation of the section 
 of the tube, it is advisable to carry at least three parallel frontal cuts 
 through the base of the skull, so that the first falls immediately behind 
 the ostium pharyng. tubse, while the second passes through the 
 cartilaginous tubes in the plane of the foramen ovale, and the third, 
 4-5 mm. further back, in a frontal direction through the osseous tubes. 
 
 5. A frontal section through the entire skull and brain in the 
 frontal plane of the two external auditory canals. 
 
 The favourable results recently obtained by Thomas Barr and 
 William McEwen, of Glasgow, in their operative treatment of otitic 
 cerebral abscesses, must be regarded as a fresh and most important 
 advance in dealing with dangerous affections of the ear. 
 
 For such operations, an accurate knowledge of the topographical 
 
FEONTAL SECTION THROUGH BRAIN ABOVE AUDITORY APPARATUS. 153 
 
 relations of those parts of the brain, which are situated above the 
 external meatus and the middle ear, is therefore of the greatest 
 importance. 
 
 With the object of ascertaining the extent and size of the temporal 
 lobe, in which cerebral abscesses most frequently have their seat, the 
 whole skull and brain must be so divided in a frontal direction that 
 the plane of the section passes on both sides through the external 
 meatus and the tegmen tymp. For this purpose it is preferable to 
 use the entire head of a middle-aged individual, which, if there be no 
 
 Fig. 115.— Frontal section through a frozen skull at the level of the twoforam. oval. (Two- 
 thirds of its natural size. )— f = fibro-cartilago basilaris ; p = section of the medial cartilage 
 plate ; h = lateral cartilage hook of the Eustachian tube ; s = slit-like opening of the 
 tube ; 1 = section of the muse, levat. palat. mollis ; t = section of the muse, tensor, palat. 
 mollis ; pe = muse, pterygoid, extern. ; pi pi' = muse, pterygoid, intern. ; v = palat. 
 moUe ; z = tongue. 
 
 frost, is made to freeze in a mixture consisting of two-thirds snow or 
 pounded ice, and one-third common salt. In from eight to ten hours 
 the whole head will be so firmly frozen that it can be sawn through 
 with an ordinary joiner's saw, while the brain retains its original 
 position in the skull. In order not to miss the direction of the cut, it 
 is well to mark it on the vertex of the head, after the hair has been 
 
154 FRONTAL SECTION THROUGH BRAIN ABOVE AUDITORY APPARATUS. 
 
 removed, by a frontal incision passing from the outer opening of one 
 ear to that of the other. 
 
 When this cut has been made, a second one is carried through the 
 skull 2-2 1 cm. behind, and parallel to the, first, for the purpose of 
 reducing the bulk of the object for preservation. The bone-dust 
 adhering to the surface is scraped off with a long knife, the preparation 
 quickly washed in iced water, and immediately placed in concentrated 
 alcohol. After twenty- four hours it is transferred to fresh concen- 
 trated spirit, in which the object, now quite freed from water, retains 
 its firm consistency. Commonly, this method of preparation results 
 in the shrinking of the brain in toto, caused by the action of the 
 alcohol. As, thereby, its various parts are drawn somewhat towards 
 the middle, this should be taken into account when estimating the 
 topographical position of the different portions of the temporal lobe as 
 regards their relationship to the organ of hearing. 
 
 Topographical sections of the brain may also be made on heads 
 hardened in alcohol, the use of the saw, however, being inadmissible. 
 The proceeding is the following : As in the anatomical opening of the 
 cranial cavity, the roof of the skull is sawn through from one auricle 
 to the other, in the plane before mentioned, down to the dura mater ; 
 this is then divided in the direction of the saw- cut with a long, thin, 
 and sharp knife from above downwards to the base of the skull, and 
 finally the cut completed through the latter with a tine saw. 
 
 A clear representation of the more exact topographical relations 
 of the temporal lobe to the temporal bone is obtained by making 
 several parallel frontal cuts through the entire skull, the most anterior 
 of which passes through the apex of the pyramid, the middle one 
 through the tympanic cavity, and the posterior one through the 
 antrum mastoid. The accompanying illustration (Fig. 116) is taken 
 from a preparation in which, on the left side, the external meatus and 
 tympanic cavity, on the right side the antrum mastoid, and the 
 posterior portion of the vestibule with the semicircular canals, were 
 met. We notice in this section, above the osseous meatus, the gyrus 
 inferior (gi) of the temporal lobe, which is conspicuous at the transition 
 of the squama into the horizontal portion of the middle cranial fossa, 
 by a strongly-marked impressio digitata. Farther inwards, corre- 
 sponding to the tympanic cavity (t), are situated the most anterior 
 portions of the gyrus fusiformis (the gyrus lying between gi and fh), 
 which in part extends beyond the labyrinth and receives a deep 
 impression (impressio petrosa) through the eminentia arcuata of the 
 upper surface of the pyramid. Finally, with the medial and most 
 anterior portion of the pyramid corresponds the gyrus hippocampi (ghj, 
 which laterally adjoins the tentorium cerebelli. 
 
FRONTAL SECTION THROUGH BRAIN ABOVE AUDITORY APPA RATUS. 155 
 
 To reach otitic cerebral abscesses by operation, it is of importance 
 to know the diameters of the temporal lobe above the middle ear, and 
 measurements noted by me on several preparations are given below. 
 According to these, the transverse diameter of the temporal lobe 
 immediately above the external meatus, that is, from the lateral edge 
 of the cerebral hemisphere to the medial border of the gyrus hippo- 
 
 Fig. 116. — Frontal section through the frozen skull and brain : on the left through the 
 vertical plane of the external meatus and of the tympanum ; on the right through the 
 mastoid antrum. — On the left : e = meat. aud. extern. ; o = upper wall of the osseous 
 meatus ; c = cavum tympani ; t = tegmen tymp. ; co = cochlea. On the right : a = 
 antrum mastoid. ; v = vestibule with portions of the superior and horizontal semicircular 
 canals ; T = temporal lobe ; S = parietal lobe ; f = falx durte matris ; s s' = lateral ven- 
 tricle ; V = third ventricle ; B = pons ; pd = pedunciilus cerebri ; fi = fissura Sylvii ; 
 st = sulcus temp, super. ; sm = sulcus temp. med. ; si = sulcus temp, infer. ; gi = gyrus 
 temp. inf. ; gi-fh = gyrus fusiformis ; fh = fissura hippocampi ; gh =: gyrus hippocampi ; 
 u = inferior cornu. 
 
 campi, amounts to 5 cm. The breadth of a section of the brain made 
 4 cm. higher, namely, on a level with the fissur. temper, sup. from the 
 external surface of the temporal lobe to the third ventricle, measures 
 
156 SECTIONS OF THE ORGAN OF HEARING 
 
 6-6^ cm. The transverse diameter of the hemisphere on a level with 
 the fissura Sylvii to the lateral ventricle amounts to 5 cm. The height 
 of the temporal lobe above the tympanic cavity measures 4-4| cm., 
 that of the temporo-parietal lobe 7-7^ cm. 
 
 (b) Topographical Sections of the Organ of Hearing on Decalcified 
 
 Temporal Bones. 
 
 This method of preparation offers such great advantages for the 
 study of the topography of the organ of hearing, as to make it a 
 matter of surprise that, up to the present, it has not been in use to a 
 greater extent in the anatomical institutions. For the decalcification 
 of the entire temporal bone, either 5-10% hydrochloric acid, or a 
 mixture consisting of 100 parts water, 3|% nitric acid, and |% common 
 salt may be used. The quantity of the fluid necessary for uniform 
 decalcification of one or two temporal bones varies from 1-1| litres, 
 and must be renewed at least every second day. The process, which 
 occupies two to three weeks, may be considered complete if a needle, 
 thrust into the pyramid behind and below the porus acust. int., does 
 not meet with any resistance (Moos). The decalcified preparation, 
 when freed from any acid remaining in it, either by placing it for 
 several hours under a stream of water, or in a weak alkaline solution, 
 is finally soaked for several weeks in 50-60% alcohol for the purpose 
 of hardening it. If placed in rectified spirit, the decalcified bone 
 becomes, after a short time, so hard that it can only be cut through 
 imperfectly and with great difficulty. 
 
 Sections may now be made, without any further preparation, on 
 decalcified objects taken direct out of the spirit, or on such as have 
 been decalcified and saturated with celloidin. The latter method (see 
 ' Celloidin Embedding ' in the Histological part) is especially suitable 
 when, on the topographical section, the vestibular saccules, the 
 ampul Ise, semicircular canals, and merabranous cochlea are to be 
 retained in their positions. Where the celloidin, on a section, inter- 
 feres with the clearness of the details, it may be dissolved by placing 
 it in a mixture of alcohol and ether. With careful handling, the 
 structures of the labyrinth do not suffer thereby any change of 
 position, particularly if, before decalcification, the preparation had 
 been placed in a suitable fixing and hardening fluid. (Compare the 
 section ' Preparatory Methods ' in the Histological part.) 
 
 In making sections on decalcified temporal bones, a long, narrow, 
 flat knife is used, with which, if the cut is to be made in one 
 plane only, the incision, where possible, is carried through the pre- 
 paration at one sweep, the direction of the cut having been previously 
 
ON DECALCIFIED TEMPOKAL BONES. 157 
 
 marked. On preparations, however, where various parts of the organ 
 not lying in one plane are to be brought into view, the cut must be 
 made at intervals. 
 
 It would lead too far to enumerate all the sections that micfht 
 possibly be made on decalcified temporal bones. It need here onl}^ 
 be noted that, both on frontal and horizontal sections through the 
 entire temporal bone, the topographical position of the various parts 
 of the auditory organ can, in many respects, be brought much more 
 clearly into view than on frozen preparations. Thus, while in the 
 sawing through of temporal bones which have not been decalcified, 
 the membrana tympani may frequently be injured, the ossicula dis- 
 located, and the labyrinthine structures destroyed, the cut can, on 
 decalcified preparations, be made in any plane passing through the 
 tympanic membrane, ossicles and labyrinth, without running the risk of 
 injuring important structures, and thus spoiling the anatomical picture. 
 As especially instructive preparations of this kind we here mention : 
 
 1. Three horizontal sections through the temporal bone, the first 
 of which passes through the upper wall of the osseous meatus, the 
 upper tympanic space, the malleo-incudal articulation, the upper 
 periphery of the cochlea, and the superior semicircular canal. The 
 second, somewhat lower, passes through the external meatus, imme- 
 diately below its superior osseous wall, divides the malleus above its 
 short process and above the insertion of the tendon of the tensor 
 tymp., meets the cochlea in its greatest diameter, and" opens the upper 
 part of the vestibule. The third cut, lower still, lies in the axis of the 
 osseous meatus, divides the inferior extremity of the manubrium, the 
 incudo-stapedial connection, and the foot-plate of the stapes in the 
 fenestra ovalis, meets the lower segment of the cochlea, and lays bare 
 the vestibule in its greatest circumference. 
 
 2. Two or three frontal sections, the most anterior of which passes 
 through the front of the tympanic cavity, immediately behind the 
 ostium tympanicum tubse, and divides the cochlea nearly in its axis. 
 The second, lying 3-4 mm. behind, is best made at that spot where 
 the umbo of the tympanic membrane approaches most closely the 
 wall of the promontory. Particularly instructive is the frontal cut 
 made in this region, if it passes exactly through the longitudinal axis 
 of the malleus, which is thus divided from its head to the umbo into 
 halves. Such sections give a general idea of the height and breadth of 
 the tympanic cavity, the relative curvature of the membrana tympani 
 and of the promontorial wall, as well as of the position of the ossicula 
 in the tympanic space. A third frontal cut, 2-2i mm. behind the 
 second, meets the posterior segment of the tympanic membrane, the 
 body of the incus and its long process, crosses the niches of the oval 
 
158 TOPOGRAPHICAL PREPARATIONS OF THE ORGAN OF 
 
 and round windows, and exposes the posterior wall of the vestibule in 
 its entire extent. 
 
 3. A frontal section through the membrana tympani in its con- 
 nection with the malleus and incus, but detached from the pyramid 
 for the demonstration of the relative positions of Shrapn ell's mem- 
 brane, of the system of cavities, situated between the malleus and 
 incus and the lateral niche of the external tympanic wall, as well as 
 of the ligamentous apparatus of the malleus and incus (see Fig. 69, 
 p. 86). (For the more detailed method of preparation of this region 
 see pp. 86 and 87.) 
 
 Two horizontal sections, the first of which divides the malleus and 
 incus in a plane Ij'ing through the short process of the incus and the 
 ligamentum mallei anterius, the second, somewhat lower, meeting the 
 malleus and incus above the short process of the former, are indispen- 
 sable as supplementary preparations for the study of the anatomical 
 relations of this, in a pathological respect, so important region. 
 
 4. A series of horizontal and vertical sections through the pyramid, 
 first decalcified, then dehydrated in alcohol, and embedded in celloidin, 
 in order to show the topographical positions of the saccules, ampullae, 
 and semicircular canals, as well as of the membranous cochlea. As 
 regards the direction to be observed while making these cuts, we 
 refer to the former chapter, ' Preparation of the Membranous Laby- 
 rinth,' p. 127. 
 
 (c) Preparation of Topographical Sections of the Organ of Hearing 
 
 by the Dry Process. 
 
 To make dry preparations of the organ of hearing, specimens pre- 
 served in spirits of wine are made use of, which are dried at an 
 ordinary temperature in a drying apparatus, provided with several air- 
 holes and protected from dust. This applies only to those prepara- 
 tions from which, with the exception of the membrana tympani, the 
 intra-tympanic muscles, and the labyrinthine fenestrse, all the soft 
 parts have been removed. Since, by the drying of the object, the 
 membrana tympani becomes very easily fissured, it should, while still 
 moist, be brushed over with a mixture of sublimate glycerine (3 parts 
 glycerine, 7 parts water, 0.01 corrosive sublimate). By this means the 
 membrane retains its pliancy, and by the addition of the sublimate it 
 is preserved from being destroyed by the larvae of insects. 
 
 With objects, however, where the soft parts — cartilage of the ear, 
 cartilaginous meatus, Eustachian tube with its muscles, and the dura 
 mater— are to be retained on the preparation, it should, after Professor 
 Laskowski's excellent method, be saturated in a 5% solution of car- 
 bolized glycerine, then dried and sawn. 
 
HEARING AFTER THE DRY PROCESS. 
 
 151) 
 
 Of the topographical preparations of the organ of hearing the 
 following sections are suitable for the purposes of study and demon- 
 stration : 
 
 1. A preparation on which the external surface of the membrana 
 tympani, the anterior aspect of the tympanic cavity with the ossicular 
 chain and the tendon of the tensor tymp., the vestibule, and internal 
 auditory meatus are represented (Fig. 117). The mode of preparing 
 is as follows : 
 
 After removal of the anterior, and in part also of the inferior osseous 
 wall of the meatus, according to the method already described 
 (p. 58), a frontal cut is made by means of the fret-saw through the 
 middle of the superior wall of the osseous meatus, up to the vicinity 
 of the tympanic membrane. Here the cut turns forwards and slightly 
 
 Fig. 118. — Frontal section through the external 
 meatus, tympanic membrane and tympanum. 
 (Right ear.) — a = cell spaces in the upper 
 tympanic wall, communicating with the 
 middle ear ; b = roof, c = lower wall of 
 the tympanum ; e = tympanic membrane ; 
 f = head of the malleus ; g = manubrium ; 
 h = incus ; i = stapes ; k = canalis Fallopii ; 
 1 = fossa jugularis ; m = openings of glands 
 in the external meatus. 
 
 Fig. 117. — Frontal section through the 
 external meatus, tympanum and the 
 labyrinth of an adult. The annulus 
 tymp. a.nd the tympanic membrane are 
 preserved intact. (Left ear.) — me = 
 meat, audit, extern. ; ot = cavum tymp 
 with the tympanic membrane, the ossi- 
 cular chain and the tensor tendon • 
 tg = tegmen tymp. ; v = vestibule [ 
 mi = meat, audit, intern. After a pre- 
 paration in my collection. 
 
 downwards, and encircles the anterior periphery of the membrane 
 1-1^ mm. m front of the sulcus tymp., as far as the inferior wall of the 
 tympanic cavity. By removing this piece of the external wall of the 
 osseous Eustachian tube only an imperfect view into the tympanum is 
 obtained. To lay bare its middle portion, together with the ossicular 
 Cham, the tegmen tymp. (tg) is cut through in a frontal direction im- 
 mediately m front of the tendon of the tensor tymp., stretched trans- 
 
160 
 
 TOPOGRAPHICAL DRY PREPARATIONS. 
 
 versely, and the saw-cut continued from here in front of the fenestra 
 ovalis, through the vestibule (v) and the internal meatus (mi). 
 
 2. Equally instructive, especially for studying the mutual relations 
 of the curvature of the membrana tympani and of the promontory, 
 are preparations on which (Fig, 118), after frontally dividing the 
 superior and inferior osseous walls of the meatus, the tympanic mem- 
 fa de' 
 
 Fig. 119. — Horizontal section through the organ of hearing. — a = anterior wall of the 
 osseous meatus ; b = its posterior wall ; c = section of the tympanic membrane, of the 
 manubrium, and of the posterior pouch ; d = promontory ; e — ostium tymp. tubse ; f = 
 stapes, in connection with the lower extremity of the long crus of the incus and the 
 tendon of the stapedius ; g = mastoid process ; h = cochlea ; i — vestibule ; k = canalis 
 caroticus. 
 
 brane is cut with a narrow, sharp knife immediately in front of the 
 handle of the malleus down to its lower periphery, the course of the 
 cut taking the same direction through the tympanic cavity and the 
 labyrinth as in the preceding case. 
 
 3. A horizontal cut through the external meatus, tympanic cavity 
 
 V 
 
 Tig. 120. View into the tympanic cavity from below.— t = membrana tymp. ; st - 
 
 with the tendon of the muse, stapedius ; v = vestibulum ; mi = meat, audit. 
 After a preparation in my collection. 
 
 stapes, 
 intern. 
 
 and labyrinth (Fig. 119). It runs in the external meatus just above 
 its axis, meets the tympanic membrane (c) 2 mm. above the umbo, 
 separates the manubrium and the lowest extremity of the long process 
 of the incus, and proceeds through the labyrinth so as to open the 
 vestibule (v) above the fenestra ovalis, and to expose the cochlea (h) 
 with the modiolus and the membrana spiralis. 
 
TOPOGRAPHICAL DRY PREPARATIONS. 
 
 161 
 
 4. A horizontal section, on which the tympanic cavity and the 
 labyrinth are laid bare from below (Fig. 120). After exposing the 
 external surface of the tympanic membrane by removal of the anterior 
 and lower walls of the meatus, the anterior wall and the floor of the 
 tympanum are carefully broken away with the forceps ; a cut is then 
 made with the finest fret-saw round the lower and anterior periphery 
 of the osseous frame of the tympanic membrane, the outer and inner 
 surfaces of which become thus open to unobstructed examination. 
 After this the pyramid is divided by a horizontal cut, which com- 
 mences at the lower wall of the internal meatus, and terminates im- 
 mediately below the fenestra ovalis at the inner wall of the tympanic 
 cavity. By taking away the lower half of the pyramid, a general view 
 
 me ma 
 
 Fig. 121. — Frontal section throusjh the innermost portion of the external meatus and the 
 posterior part of the tympanic membrane. — me = meat, audit, ext. ; mt = membran. 
 tymp. ; ha = malleo-incudal articulation, sawn through ; a = surface of the saw-cut 
 through the body of the incus ; st = stapes ; an = antrum mastoid. ; si = sinus transv. ; 
 ma = proc. mastoid. After a preparation in my collection. 
 
 is obtained of the relative positions of the ossicles in the tympanic 
 cavity, especially of the curvature of the membrana tympani, of the 
 inclination of the lower extremity of the manubrium towards the inner 
 tympanic wall, and of the incudo-stapedial connection. 
 
 5. A frontal cut, which meets the innermost portion of the osseous 
 meatus, the posterior part of the membrana tympani and of the tym- 
 panic cavity (Fig. 121). Such sections show, on their posterior surface, 
 the position of the antrum mastoid, (an) in relation to the posterior 
 superior wall of the meatus, and on their anterior surface the relative 
 position of the membrana tympani and the inner portion of the 
 osseous meatus. They, moreover, enable us to obtain a clear view 
 into the tympanum from behind, in which the topographical position 
 of the ossicular chain, and the niches of the oval and round windows 
 may be noticed. 
 
 Sections of dry preparations, in which the membrana tympani and 
 
 11 
 
162 
 
 TOPOGKAPHICAL DRY PREPARATIONS. 
 
 the ossicula are cut through, must be made with the finest saws, on 
 objects which have been hardened in alcohol, and afterwards 
 thoroughly dried. I possess a number of preparations of this class, 
 in some of which the malleus and incus, others in which the mem- 
 brana tympani, the manubrium and the long process of the incus, 
 have been sawn through without the slightest dislocation of the small 
 bones. On wet preparations, or such as were saturated with glycerine, 
 the ossicles are nearly always dislocated in the sawing. 
 
 6. A horizontal section, on which the external surface of the 
 membrana tympani, the tympanic cavity with the ossicula, the 
 tendon of the tensor tympani, the vestibule, superior semicircular 
 canal (cs), the cochlea (co), and the internal meatus, come clearly 
 into view (Fig. 122). 
 
 The proceeding is as follows : First the tympanic membrane with 
 its osseous frame is laid bare in the way indicated sub 1. of this 
 section ; then the tegmen tymp. is broken away with the forceps, and 
 the cavity of the labyrinth opened with a fine fret-saw in the follow- 
 
 FiG. 122.— Topography of the tympanic cavity and of the labyrinth, after a preparation in 
 my collection. — t = membrana tymp. with the malleus and incus ; an = antr. mastoid. ; 
 CO = cochlea ; cs = canalis semicircul. super., with the vestibulum ; na = nervus acusticus, 
 
 ing manner: the cut commences at a point vertically above the 
 eminentia arcuata, and takes a frontal direction corresponding to the 
 superior semicircular canal, advances downwards, with a very slight 
 curve forward, to the level of the internal meatus and the tendon of 
 the tensor tymp. Here it passes at nearly a right angle forward, to 
 divide the pyramid horizontally up to its apex. With some practice 
 it is possible, by these combined cuts, to represent the whole of the 
 superior semicircular canal (cs) with its ampuUary dilatation, the 
 vestibule, the internal meatus with the nervus acusticus (na) and the 
 cochlea (co). 
 
 An instructive topographical preparation is obtained if, after laying 
 bare the membrana tympani and ossicula in the manner already de- 
 scribed (sub 1 and 6), the pyramid be cut through in a perpendicular 
 direction corresponding to its long axis. If the cut be carried parallel 
 
TOPOGRAPHICAL DRY PREPARATIONS. 
 
 163 
 
 with the inner wall of the tympanic cavity through the middle of the 
 vestibule, the lateral surface of the section presents the already de- 
 scribed aspect of the external wall of the labyrinth, together with the 
 inner surface of the footplate of the stapes, the commencing portion of 
 the lamina spiralis, and, towards the front, the cochlea divided perpen- 
 dicularly to its axis. 
 
 7. Very instructive for the topography of the organ of hearing are 
 preparations on which, as the accompanying illustration (Fig. 123) 
 shows, the membrana tympani, the ossicular chain with the tensor 
 tendon, and the osseous labyrinth have been prepared out in one 
 piece. The preparation of such objects is most difficult, as special 
 manual dexterity and practice are required in order to cut out from 
 
 Fig. 123. — Topographical preparation, on which the tympanic cavity and the osseous laby- 
 rinth have been prepared out in connection. (Enlarged to double its size.) — t = tympanic 
 membrane ; o = superior semicircular canal ; s = posterior semicircular canal : h = 
 horizontal semicircular canal ; co — cochlea ; mi = internal auditory canal. After a pre- 
 paration in my collection. 
 
 the hard mass of the temporal bone of an adult the osseous semi- 
 circular canals and the capsule of the cochlea, without injuring at the 
 same time the ossicles and the tympanic membrane. Working at the 
 rate of two hours per day, it requires about a fortnight to complete 
 one of these preparations. 
 
 A detailed description of the proceeding appears superfluous after 
 what has been previously stated, since the preparation of the membrana 
 tympani and tympanic cavity is the same as that described sub 5 
 and 6. This applies also to the preparation of the osseous labyrinth, 
 respecting which we refer to the section under that heading (p. 11.5). 
 The greatest difficulty is met with in laying bare the horizontal semi- 
 circular canal and the posterior portion of the cochlear convolutions, as 
 
 11—2 
 
164 TOPOGRAPHICAL PREPARATIONS OF TYMPANIC MEMBRANE, ETC. 
 
 the work on the exceedingly brittle bone has to be carried out with 
 gravers and files, constantly moving backwards and forwards in close 
 proximity to the tympanic membrane, which will be destroyed by the 
 least slipping of the instruments. 
 
 8. Topographical preparations to shoAV the inclination of the 
 membrana tympani and the relative position of the Eustachian 
 tubes. 
 
 On a skull from which the calvaria and the brain have been 
 removed, the two pyramids are prepared out from the base of the 
 skull in the manner described at p. 15, the tendon of the tensor 
 tympani and the incudo-stapedial articulation having previously been 
 divided from the upper tympanic space. The view of the inner 
 surfaces of both tympanic membranes, now exposed on either side, 
 gives a clear idea of their strong inclination to the horizontal. With 
 the object of representing in the same preparation the position of the 
 Eustachian tubes in the skull, and their relation to the tympanic 
 cavity, those portions of the great wing of the sphenoid bone covering 
 the cartilaginous Eustachian tubes, and the proc. pterygoid, are re- 
 moved with chisel and forceps after the manner described on pp. 71 
 and 72, and the canal of the tube is then split longitudinally (p. 104). 
 
 Another method of demonstrating the position of the Eustachian 
 tube in the skull consists in cutting the latter into halves in 
 a sagittal direction, removing the inferior maxilla while leaving the 
 septum narium intact ; after which the tympanic membrane is laid 
 bare by taking away the anterior lower wall of the meatus. The 
 cartilagino-membranous tube is then prepared out of the surrounding 
 parts in the following manner: A wooden cone, 3-4 cm. long, and 
 running to a point, is pushed forward through the ost. pharyng. tubce 
 towards the narrowest part of the canal, in order, during the work of 
 preparation, to allow the position of the latter to be recognised, and to 
 avoid injuring its membranous portion. Leaving now the membranous 
 tube in connection with the lateral choanal wall, all the adipose and 
 muscular tissue lying round it, as also part of the basilar fibro- 
 cartilage, are cut away with scalpel and scissors up to its union with 
 the osseous tube, the whole tube being thereby exposed on all 
 .sides. 
 
 Mention might here be made of the mode of preparing some 
 .anatomical objects which are of importance for otoscopy. 
 
 1. A preparation, on which the osseous meatus in connection 
 with the membrani tympani is prepared out of the temporal bone in the 
 form of a tube. For this purpose the tympanic membrane is cut out 
 with a fine fret-saw from the pars tympanica et squamosa on a moist 
 ■or dry preparation which, after the removal of its soft parts, has been 
 
VIEW IN PROJECTION OF THE INNER TYMPANIC WALL. 1G5 
 
 thoroughly washed and then dehydrated by immersing it in alcohol. 
 As the thin anterior wall of the meatus is merely bounded by soft 
 structures, the saw- cut need only be carried round the upper posterior 
 and lower wall of the meatus. Such preparations serve for the 
 superficial representation of the inclination of the membrana tympani 
 to the axis of the osseous meatus, both for purposes of instruction, 
 and for the study of the relationship of the different walls of the 
 auditory canal to the tympanic membrane, which have to be considered 
 when foreign bodies are to be removed from it. 
 
 2. An entire temporal bone, on which the soft parts are removed 
 by maceration, the membrana tympani being retained intact. For 
 this purpose, the fresh temporal bone, as it is taken from the body, 
 according to the method recommended by Schwabach,* is placed in a 
 
 -t> * 
 
 rj", i^ 
 
 Fig. 124. — View, in projection, of the inner tympanic wall, showing its relation to the mem- 
 brana tympani. — vo = anterior superior quadrant ; vu = anterior inferior quadrant ; 
 ho = posterior superior quadrant ; hu = posterior inferior quadrant ; r = niche of the 
 fenestra rotunda. 
 
 5-8% solution of caustic potash (Partsch's method of maceration), and 
 the fluid, at first, renewed daily. In the ordinary temperature of a 
 room the whole of the soft parts on the bone are in a short space of 
 time destroyed by maceration,- while the membrana tympani resists 
 the action of the potash in the degree of concentration above 
 mentioned, and remains intact on the macerated temporal bone. On 
 specimens thus dried the membrane appears almost exactly as during 
 life, and is, therefore, specially suitable for purposes of demonstration, 
 previous to practising the examination of the membrane in the living 
 subject. 
 
 3. A preparation to represent the topographical relationship of the 
 membrana tympani to the inner wall of the tympanic cavity. 
 
 The process consists simply in cutting out the membrane, without 
 at the same time dislocatinof the malleus and incus. With sufficient 
 illumination from the reflecting mirror, the upper periphery of the 
 membrane is first detached from its insertionby means of a sharp-pointed 
 knife; then two incisions are made in front of, and below the 
 
 * Centralblatt f iir medicinische Wissensch. 1885, Nr. 39. 
 
166 TOPOGRAPHICAL SECTIONS OF PATHOLOGICO-ANATOMICAL PREP. 
 
 manubrium down to its lower extremity, and finally a cut is carried 
 round its entire periphery. Any portions of the membrane left 
 behind are singed off with a red-hot piece of wire (Fig. 124). A 
 glance into the tympanic cavity shows, in projection, the image of the 
 inner wall, in its relation to the membrana tympani, acquaintance 
 with which is of such importance, both in estimating the pathological 
 appearance of the membrane, and when operating on this part, or in 
 the tympanum. In order to obtain a general idea of the position of 
 the various portions of the membrane in relation to the inner 
 tympanic wall, the plane of the former is divided into four segments, 
 by continuing the line of direction of the manubrium downwards, 
 this line being crossed by another horizontal one, which touches the 
 lower extremity of the handle. 
 
 Examining the membrane while the head is in the normal position 
 we find, corresponding to the anterior superior quadrant (vo) of the 
 membrane, the anterior superior portion of the inner tympanic wall 
 bordering on the ostium tymp. tuba3 (rarely only is part of the 
 canalis pro tensore tymp. visible) ; corresponding to the anterior 
 inferior quadrant (vu), the anterior inferior portion of the inner 
 tympanic wall bordering on the ost. tymp. tuba3, and part of the 
 ridged lower and anterior tympanic wall ; corresponding to the 
 posterior superior quadrant (ho), above, the incudo-stapedial articula- 
 tion, and behind this the apex of the eminentia staped., with the 
 tendon of the stapes ; below that, the major part of the upper portion 
 of the niche of the fenestra rotunda (r) ; and corresponding to the 
 posterior inferior quadrant (hu), above, the minor inferior portion of 
 the niche of the round window (r), and below, part of the ridged lower 
 wall of the tympanum. 
 
 As regards the making of topographical sections on pathologico- 
 anatomical preparations we must, in order to avoid repetition, refer to 
 the methods of preparing such specimens of the organ of hearing de- 
 scribed on p. 51 and following. It should, however, be observed that 
 the practice, still in use in many anatomical institutions, of sawing the 
 temporal bone through, in all cases of fatal middle ear suppurations 
 without previous careful examination of the external and middle ear, 
 is altogether objectionable, because, in doing so, not only are the soft 
 structures destroyed, but the examination of the labyrinth, on account 
 of its being filled with bone dust, is rendered impossible. Only in 
 rare cases, particularly in necrosis of the pyramid, does it appear 
 advisable to lay bare, by a corresponding cut with the saw, the breach 
 in the bone leading from the temporal bone into the cranial cavity, 
 whereby the extent of the disease in the interior of the petrous bone 
 will be more clearly noticed. In caries and necrosis of the temporal 
 
CORROSION PREPARATIONS OF THE ORGAN OF HEARING. 167 
 
 bone a tolerably good idea, as to the extent of the morbid process, 
 may be formed from macerated preparations, on which it is possible to 
 recognise how far the bone is affected from its worm-eaten, eroded, 
 and porous appearance, and from the osteophytic formations, of 
 frequent occurrence in the neighbourhood of the seat of the disease. 
 Maceration of the carious-necrotic temporal bone should, however, 
 only be decided upon when the soft parts of the external meatus, the 
 membrana tympani, the lining membrane of the middle ear, the 
 labyrinth and dura mater have been minutely examined, and the 
 changes found there present nothing requiring the preparation to be 
 preserved in spirits of wine. 
 
 Though I have, on the grounds above mentioned, pronounced 
 against the representation of topographical sections on pathological 
 preparations, I must, on the other hand, lay stress on the importance 
 of such sections in certain cases. These are the extensive adhesions 
 between membrana tympani and inner tympanic wall, the connective- 
 tissue proliferations enveloping the ossicula in the upper tympanic 
 space, etc., the outlines and topographical position of which come out 
 more clearly on a section than on an ordinary preparation. In these 
 cases one ousfht, however, not to make use of the saw, which would 
 destroy the soft parts, but the preparation should be decalcified after 
 the method described on p, 156, and the section made with the 
 knife. 
 
 y. 
 
 MAKING PREPARATIONS OF THE ORGAN OF HEARING BY CORROSION. 
 
 Preparations of the organ of hearing by corrosion form a material 
 aid for the study of its anatomy. The three divisions being made up 
 of cavities of more or less complicated shape, we obtain, by corrosion 
 preparations, a far more precise notion of the actual form and extent 
 of the external, middle, and internal ear than on sections carried 
 in various directions through the macerated or unmacerated temporal 
 bone. Of still greater importance is this method of preparation for the 
 study of the topographical positions of the various parts of the organ 
 of hearing, and of their relationship to one another. A good view 
 as to the extent, especially of the pneumatic cavities of the middle 
 ear, of their connection with one another, and their relationship to 
 the external and inner ear and to the large neighbouring vessels, etc., 
 can in general only be gained in this way. It is only by representing 
 these spaces in the solid that the significance of their so frequently 
 occurring inflammatory affections can be brought into the full light. 
 Historical. — The first attempts to produce preparations of the ear 
 
168 CORROSION PREPARATIONS OF THE ORGAN OF HEARING. 
 
 by corrosion were limited to the internal ear, and date from the second 
 decennium of our century. According to Bezold, the first casts in 
 wax of the osseous labyrinth appear to have been made by the 
 veterinary surgeon Gerber at A. Meckel's suggestion * Hyrtl {Medi- 
 cinische Jahrhucher, 1873) saw in Meckel's museum at Halle and at 
 Valentin's in Berne casts of the labyrinth. Also Ilg gives in his work 
 on the structure of the cochlea an illustration of a metal cast of it. 
 But it was Hyrtl who first employed the method of corrosion on a 
 large scale for the study of the comparative anatomy of the osseous 
 labyrinth of vertebrate animals, the results of which he has 
 embodied in his celebrated work, copiously illustrated, * Vergleichend- 
 anatomische Untersuchungen iiber das innere Gehororgan ; Prag, 
 1845.^ Kiidinger, too, in his atlas of the organ of hearing, has 
 illustrations of casts of the labyrinth. According to Sapolini (III. 
 Otological Congress at Bale, 1884), there are in the Anatomical 
 Museum of Turin very fine metallic casts of the labyrinth, the work 
 of Professor Tommasi. 
 
 Interest for this method of preparation of the external and middle 
 ear does not seem to have been awakened among anatomists until 
 later. For although Sommering in 1806, in his anatomical illus- 
 trations of the organ of hearing, shows a cast of the auricle and 
 external meatus, the first preparations of the middle ear by corrosion 
 are to be found in Hyrtl's work, 'Die Corrosionsanatomie und ihre 
 Ergebnisse, 1873,' in which he gives a description, accompanied by 
 several illustrations, of corrosion preparations of the middle ear. 
 
 To Bezold belongs the merit of having elaborated this method 
 in all its directions, and of having, in his treatise 'Die Corrosions- 
 anatomie des Ohres, mit 6 Tafeln in Lichtdruck, Miinchen, 1882,' 
 utilized it for the study of anatomy and for practical otology. 
 Referring, as regards the description of the anatomical details 
 obtained through this method, to the excellent work alluded to, we 
 here propose to discuss merely its technical side. 
 
 Preparations of the ear by corrosion are made either on macerated 
 temporal bones (dry corrosion) or on fresh preparations (soft-part 
 preparations). 
 
 For the purpose of anatomical study, both kinds of representation 
 are indispensable. Soft-part corrosion preparations allow us to see 
 at one glance the upper spaces of the middle ear, the cartilaginous 
 and osseous Eustachian tube, tympanic cavity, aditus ad antrum, 
 antrum, as well as the commencement of the pneumatic cells, and, 
 by simultaneous representation of the external ear, the relative 
 position of the one to the other. Preparations of the bone by 
 
 * Archiv fiir Anatomie und Physiologie von Meckel, Jahrgang 1827. 
 
BONE CORROSION PREPARATIONS. 169 
 
 corrosion, on the other hand, bring into representation the entire 
 system of pneumatic spaces in connection not only with the osseous 
 meatus auditor, ext., but also with the labyrinth, the aquceducts, and 
 the large vessels. 
 
 1. BONE-CORROSION PREPARATIONS. 
 
 To prepare the macerated temporal bone by corrosion, a thoroughly 
 dried specimen, free from all remains of soft parts, should be chosen. 
 In order to destroy any portions of tissue still remaining behind in 
 the inner spaces of the temporal bone, and which often prove an 
 obstacle to successful corrosion, the bone is left for several hours in 
 a 5% solution of caustic potash heated to 60° ; it is then washed in 
 clean water and thoroughly dried, after a vigorous use of the syringe. 
 
 Before placing the temporal bone in the corrosion medium, a 
 needle is pushed through the internal meatus, the vestibule, and 
 fenestra ovalis, as far as the external meatus, for the purpose of 
 keeping the various portions of the cavities in the temporal bone in 
 close connection, two short needles being so inserted as to pass from 
 the sulcus transversus through the mastoid cells. When the substance 
 has hardened, these needles are cut level with it, but not removed, in 
 order to preserve the connection between the cast of the sulcus trans- 
 versus and that of the inner cavities of the temporal bone. To 
 facilitate the escape of air from the labyrinthine cavity, it is 
 recommended to make a small opening in the superior semicircular 
 canal. 
 
 (a) Corrosion Preparations by the Medium of a Compound of Wax 
 
 and Resin, 
 
 The perfectly-dried temporal bones are boiled in a melted mass 
 consisting of four parts of resin and one part of wax, until the air 
 has escaped from all the cavities. To uniformly colour the corrosion 
 substance, either ultramarine, minium, or any other pigment is added, 
 which has been previously triturated with a small quantity of copaiba 
 balsam (Kudinger). By the addition of the latter the mass also loses 
 some of its brittleness. 
 
 The liquid having hardened, the wax covering the outer surface 
 of the preparation is removed by scraping it with a heated knife, and 
 the object placed in concentrated hydrochloric acid, in which the 
 bone is more or less rapidly destroyed. 
 
 To retain the aquasductus vestibuli, a bridge of the medium is 
 left between its orifice at the posterior wall of the pyramid (Fig. 105, 
 p. 131) and the mass lying in the sulcus transversus. It is also 
 advisable to leave a quantity of the corrosion medium adhering to the 
 
170 COEROSION PREPARATIONS BY THE WAX AND RESIN PROCESS. 
 
 lower wall of the pyramid, which, during the work of preparation, 
 serves as a firm and convenient handle. 
 
 Temporal bones of new-born infants, or of children during the 
 first year of life, are corroded in 6-8 days, while bones of adults 
 must be exposed for two or three weeks longer, to the action of 
 the hydrochloric acid, to destroy any portion of bone adhering to the 
 preparation. 
 
 When the maceration is completed, friable bits of the destroyed 
 bone will be found in the depressions of the preparation. If an 
 attempt be made to remove them with pincettes or needles, the more 
 delicate parts of the specimen are broken off, whereby its scientific 
 value is diminished. In order, therefore, to obtain an object as 
 perfect as possible, the hydrochloric acid is carefully poured off, and 
 
 f S C 
 
 Tig. 125. — Corrosion preparation of the macerated temporal bone of an adult, made accord- 
 ing to the wax and resin process ; outer aspect, seen from the front, (Left ear. )— su = 
 external meatus, with the sulcus tymp. ; c = cavum tymp. and antr. mastoid. ; w w' = 
 mastoid cells ; t = cast of the canalis pro tens. tymp. ; f = canalis facialis ; s = canalis 
 semicircul. super. ; co = cochlea ; mi — meat, audit, int. After a preparation in my 
 collection. 
 
 the preparation lying at the bottom of the vessel is washed with 
 the ball syringe, or with the more powerful stream of an ordinary 
 syringe. 
 
 The moss-like impressions of the cavities of the spongy substance 
 surrounding the corrosion cast on all sides must be removed with 
 care. In the vicinity of the pneumatic spaces of the external meatus 
 this is very easily done, but greater difiiculty is encountered in the 
 neighbourhood of the labyrinth and aquseducts, where some practice 
 and intimate acquaintance with the relative positions of the parts 
 concerned are needed. The spongy masses of the cast at the apex of 
 the pyramid are so compact that they can> in most cases, only be 
 separated with a narrow, sharp knife. \ 
 
 The cast of the macerated temporal bone (Fig. 125) when com- 
 pleted shows, in a more general manner than is possible with sections 
 through the bone, the relations of the spaces of the osseous meatus 
 in its various divisions, the length of its different walls from the 
 
DETAILS OF THE CORROSION CAST. 171 
 
 external orifice to the sulcus tymp., the form of its transverse section, 
 varying from without inwards, the relative curvature of its walls, as 
 well as the direction of its course up to the membrana tympani. At 
 the boundary between the meatus and middle ear the impression of 
 the sulcus tymp. stands out at the lower and lateral periphery, in the 
 form of a sharply-defined ledge. The cast of the tympanic cavity is, 
 corresponding to its upper recess, found to project beyond that of 
 the external meatus. From above, the cast appears at times smooth, 
 at others, again, in accordance with the ridged condition of the upper 
 tympanic wall, irregularly furrowed ; one groove in particular, running 
 in the transverse diameter of the tympanum, is to be regarded as 
 constant, and corresponds, according to Bezold, to the constant 
 transverse ledge on the upper tympanic wall (crista transversa 
 tympani, see p. 29). Besides, there are found on some preparations 
 of this kind, in great variety and to a large extent, the impressions 
 of the pneumatic spaces, which enter into close relationship, externally, 
 
 ca i c q p si 
 
 Fig. 126.— "Wax and resin corrosion preparation of the temporal bone. View of the inner 
 side, with the cast of the labyrinth.— i = meat, audit, intern. ; s = canal, semicircul. 
 super. ; p = canal, semicirc. post. ; q = aquseduct. vestibuli ; c = aqueduct, cochleae ; 
 f = canal, facialis ; ca = canal, caroticus ; si = sinus transversus. (After Bezold.) 
 
 with the upper wall of the outer meatus, internally, with the air 
 spaces in the pyramid. On the inferior surface of the cast it is, 
 from the position of the irregular cellular spaces of the lower tympanic 
 wall, much easier to demonstrate than on frontal sections of the 
 temporal bone, by how much the floor of the tympanic cavity is more 
 deeply situated than the lower periphery of the membrana tympani, 
 or the floor of the osseous meatus. 
 
 The upper and inner surface of a perfect cast (Fig. 126) bring 
 under observation the three semicircular canals— the cochlea, the 
 internal meatus (i), and the facial canal (f). The latter may, in cor- 
 respondence with its anatomical position in the temporal bone, be 
 traced with all its windings through the entire cast as far as the 
 foramen stylo-mastoid. In addition is seen the aquffiductus vesti- 
 buli (q), proceeding from the inner wall of the labyrinth as a fine 
 
172 GALVANO-PLASTIC COATING OF THE COEROSION CAST. 
 
 threadlike loop, tlie lower, broader end of which corresponds to the 
 hiatus aquseductus vestibuli on the posterior surface of the pyramid. 
 More frequently still we see the cast of the aquseductus cochlese (c), 
 which, corresponding to the posterior lower edge of the pyramid 
 below the commencing portion of the internal meatus, is connected, 
 in the form of a short cone running upwards to a point, with the 
 commencing part of the lowest convolution of the cochlea. 
 
 Objects prepared by the medium of the wax and resin compound 
 must, on account of the brittleness and fragility of the corrosion 
 substance, be handled and preserved with the greatest care. In order 
 to render them more capable of resistance, Hyrtl recommends that 
 the preparation be repeatedly coated with a solution of isinglass. 
 
 Experiments which I have lately made to cover preparations of 
 
 Fig. 127. 
 
 this kind with a galvano-plastic layer of copper have had satisfactory 
 results. 
 
 I use for this purpose a small galvano-plastic apparatus, con- 
 taining about 1 litre of liquid, such as is used by amateurs for 
 making galvano-plastic copies of ancient coins. The apparatus 
 (Fig. 127) consists of a glass jar closed by a wooden hd (d), and 
 holding about 1| htre of fluid. Fixed to the lid is a porous pot (c), 
 into which dips a grooved zinc rod, attached to a copper support. 
 The holder of the copper support bearing the zinc rod is fixed in 
 the wooden Hd, passes through it into the glass vessel, and terminates 
 in a round copper disc (r) with a bright upper surface. This, as well 
 as the zinc rod in the porous pot, can be raised and lowered by 
 adjusting-screws (s s'). The apparatus forms a galvanic element, 
 
GALVANO-PLASTIC COATING OF THE CORROSION CAST, 173 
 
 having the zinc rod for its negative, and the copper disc in the glass 
 for its positive pole. The outer vessel is filled up to two-thirds of 
 its height Avith distilled water, wherein 250 g. sulphate of iron and 
 50 g. bisulphate of potash are dissolved. 
 
 The glass jar having been filled, its lid, together with the copper 
 support and the zinc rod are put in position. Distilled water, with 
 10 g. of common salt dissolved in it, is poured into the porous pot 
 up to the level of the liquid in the glass, after which the apparatus 
 will be ready for immediate use. 
 
 In order to coat the cast with a galvanic Isijer of copper, its entire 
 surface, even to the least depression, must, by repeated brushing, be 
 first covered with a layer of finely triturated Siberian graphite. The 
 object is then placed upon the copper disc (r), and, by means of the 
 adjusting-screw (s'), brought within 1-2 cm. of the lower surface of 
 the porous pot. If, at the end of several hours, the surface of the 
 
 f h b a i 
 Fig. 128. — Cast of the osseous labyrinth. — a = fenestra ovalis ; b = fenestra rotunda ; c = 
 superior semicircular canal ; d = its ampulla ; e = posterior semicircular canal ; f = am- 
 pulla of the same ; g = horizontal semicircular canal ; h = its ampulla ; i = cochlea. 
 
 preparation, which is turned upwards, appear copper coloured, it is 
 turned, and left for several hours longer in the apparatus. When 
 coated with a deposit of copper, the preparation is washed in water 
 and cleaned with a soft brush. The thin layer of copper gives a 
 sufficient degree of firmness to the preparation without materially 
 altering the form. To prevent the copper oxidising, such casts may, 
 at small cost, be silvered or gilt. 
 
 For the corrosion of the labyrinth alone, by the wax-resin process, 
 well-macerated pyramids from temporal bones of adults are the most 
 suitable. It is more difficult to obtain casts of the labyrinth from 
 petrous bones of new-born infants, because here the corrosion medium 
 penetrates into the porous bone up to the immediate vicinity of the 
 capsule, and the cast can only with difficulty be separated from the 
 net-like masses which surround it on all sides. The filling of the 
 labyrinthine cavity with the corrosion mass is effected, either by 
 boiling in the wax and resin, or by injecting it with a heated glass 
 tube. The cast is the more successful if the capsule be so far cleared 
 from the surrounding bone, that at the highest point of convexity of 
 each semicircular canal, and at the anterior edge of the lower convo- 
 
174 METALLIC COREOSION PREPARATIONS OF THE ORGAN OF HEARING 
 
 lution of the cochlea, an aperture of the size of a pin's head can be 
 made, which allows the escape of air from the labyrinthine cavity, and 
 permits the wax to completely fill it. Casts of the labyrinth may also 
 be made in a space where the air has been rarefied, a method which is 
 to be discussed more in detail in the description of metal corrosion 
 apparatuses. 
 
 Should the preparation, after setting of the corrosion medium, be 
 sufficiently warmed as to allow part of it to flow again from the laby- 
 rinthine cavity, a cast is obtained after corrosion which, as Hyrtl 
 asserts, may be mistaken for the natural osseous labyrinth. 
 
 (6) Representation of Metallic Corrosion Preparations of the Organ of 
 
 Hearing. 
 
 Metallic corrosion preparations are, on account of their durability, 
 eminently adapted for the purposes of instruction. The alloy when 
 melted reaches the minutest canals of the petrous bone as readily as 
 the wax and resin compound does. But while, with the latter, the 
 casts of the finest channels break, even during corrosion, they are pre- 
 served perfect in the metallic casts.* 
 
 For making metallic corrosion preparations, various kinds of alloys 
 are made use of, which are fusible at a relatively low temperature. 
 Most suitable are found to be : 1st, Metal d'Arcet, consisting of 1 
 part lead, 2 parts tin, and 2 parts bismuth; 2nd, Rose's Metal, 
 consisting of 2 parts bismuth, 1 part lead, and 1 part tin ; 3rd, Wood's 
 Alloy, consisting of 8 parts lead, 4 parts tin, 16 parts bismuth, and 3 
 parts cadmium. The latter is adapted, on account of its ready fusibility, 
 especially for casts of the labyrinth. 
 
 The proceeding in making metallic casts of the temporal bone 
 differs materially from that observed with wax -resin corrosions. 
 Pluno-ing the temporal bone into the molten alloy nearly always 
 results in imperfect casts. Simply pouring the alloy into the external 
 meatus does not, however, yield the desired result, because the metal 
 escapes through the numerous openings in the temporal bone, which 
 are in communication with each other. 
 
 For the production of metallic casts of the temporal bone, special 
 methods are therefore recommended, a brief description of which we 
 give in the following : | 
 
 Professor v. Brunn, of Rostock, showed, at a meeting of German 
 naturalists and medical men held in Berlin in 1886, a series of success- 
 ful metallic casts of the temporal bone, which were produced by the 
 foUowino- method, for the communication of which we are indebted to 
 Dr. Lemcke : 
 
 * Passage altered at the request of the author. — G. S. ' 
 
ACCORDING TO V. BRUNN AND SIEBENMANN. 175 
 
 To make perfect metallic casts of the external, middle, and internal 
 ear on macerated temporal bones, the external meatus is closed by a 
 cork, the porus acust, int. pasted over with a small piece of paper, and 
 then the entire temporal bone covered with gypsum, so that only the 
 opening of the osseous tube remains free. The whole is then placed 
 in the heating apparatus, and left there for three or four hours at a 
 temperature of about 100° C. After this the metal is poured in 
 through the opening, and by repeatedly shaking the object, made to 
 penetrate into every cavity. Generally all the spaces of the temporal 
 bone are completely filled. 
 
 The preparation having cooled, the plaster is removed, the bone 
 transferred into 8°/^ caustic potash, and the vessel placed in the 
 heating apparatus (50° C). In a few days any remains of bone 
 are washed away by a stream of water, and the cast will be found 
 perfect. 
 
 At the Otological Congress at Brussels, Dr. Siebenmann demon- 
 strated a series of perfect metallic casts of the organ of hearing made 
 after a method of his own, which in several respects differs materially 
 from that of Professor v. Brunn. We here propose to give a short 
 description of this method. 
 
 To make casts of macerated temporal bones, it is, on the whole, 
 better to select such as are not too heavy, and have been carefully 
 macerated. Before the casting is proceeded with, the following pre- 
 liminary preparations have to be attended to : the canaliculi carotico- 
 tympanici are widened with a needle, and from the canaliculus 
 caroticus an opening is made in the tube. The superior semicircular 
 canal is slightly opened with a file behind the crista. The sulcus 
 transversus and, in connection with it, the base of the petrous bone, 
 are spread over with strips of linen in order that they may subse- 
 quently be covered with a thicker layer of metal. In the same 
 manner a canal bridged over is to be made from the external opening 
 of the aquseduct. vestibuli down to the sinus, ' so as to give to the 
 cast of the canalis aqused, a firmer support, and the openings of the 
 meatus extern, et intern, must be closed with linen. On the apex of 
 the pyramid a cardboard funnel, not too narrow at its lower end, is 
 introduced into the canalis caroticus and likewise firmly glued on with 
 paper or linen strips. 
 
 When the casting is to commence, the bone thus prepared should 
 first be well warmed ; it is, moreover, indispensable that the object 
 should be firmly covered on all sides by a material which, though 
 giving free passage to the air, does not allow the metal to escape. 
 This was done, in the production of the specimens demonstrated at 
 Brussels, by heating the bone in a covered pan, quickly wrapping it 
 
176 METALLIC COEROSIONS OF THE OEGAN OF HEARING. 
 
 first in linen cloth, then in wadding, and finally surrounding it, 
 with the exception of the funnel, on all sides with moulding clay to 
 the depth of 5 cm. By vigorous kneading with both hands this was 
 shaped into a firm ball. 
 
 Extremely good casts are obtained by the following method, which 
 has of late been universally employed : the bone, provided with linen 
 bridges, as indicated above, is covered with plaster of Paris as far as 
 the edge of the funnel, which is turned upwards, and then left to stand 
 for several days in a moderate temperature with the funnel turned 
 downwards. The filling of the block should not be proceeded with 
 until it is thoroughly dry, and while allowing the air to escape freely, 
 it should not show any cracks in the heating, which must necessarily 
 precede the casting. 
 
 If the object has been well cleaned and sufficiently heated, 
 metal poured in through the funnel will fill up any, even the minutest 
 cavity from the squama to the apex of the pyramid. In the prepara- 
 tions which were made last, not only the canals of the two aquseducts, 
 but also those of the veins accompanying them, were represented in 
 the most perfect manner. 
 
 While pouring the molten metal in a continuous stream, and in as 
 large a quantity as possible, through the funnel, it is well to gently 
 knock the bottom of the block of plaster against the table. The 
 pouring in of the metal is only to cease when its level no longer sinks 
 in the funnel ; after waiting a few minutes, the block is placed upright 
 in water. On the following day the plaster is broken away, the bone 
 cleaned with a brush, and the metal removed with the chisel or a 
 red-hot blade of a knife, on those spots where it is not required. 
 
 The petrous bones are next corroded in 10-30% caustic potash (or 
 caustic soda), at a temperature of 40-50° C. At the end of a month 
 they are soaked for 24 hours in water, and then placed in dilute (1 : 6) 
 pure hydrochloric acid. After a few hours the last remains of the 
 adhering portions of bone (labyrinthine capsule, etc.) are dissolved, so 
 that nothing further remains to be done but to free the preparation 
 from the acid by placing it in distilled water. During the entire pro- 
 cess of corroding, the preparation never comes under a stream of 
 water, which is rather an advantage over other corroding methods in 
 use. 
 
 For further preservation, and for purposes of demonstration, the 
 specimen is fixed on a forked stand with heavy supports. The 
 branches of the fork are, with this object, forced when red-hot into 
 the thick metal plate on the lower surface of the preparation in such 
 a way, that, when fixed, it has as nearly as possible the natural posi- 
 tion of the petrous bone in the upright skull. 
 
METALLIC CORROSIONS OF THE EAR ACCORDING TO SIEBENMANN. 177 
 
 In order to make such casts more serviceable for study, it is 
 advisable to brush over the various parts with a thin layer of paint 
 (or varnish), e.g., the meatus bone-yellow, the nerve canals bright 
 yellow, middle ear bright rose-colour, labyrinth greenish-yellow, the 
 carotid artery crimson, sinus bulbus jugul. and veins of the aquieduct 
 light blue, diploe brownish. On preparations which are intended to give 
 a general view of the organ the spongiosa is first broken away. Prepara- 
 tions which are not to be painted over are lacquered with ' Fixative.' 
 
 The proceeding in the making of metallic corrosions of soft-part 
 preparations (casts of the middle ear), after Siebenmann's method, is 
 identical with that of Bezold (making use of the wax and resin com- 
 pound). For the purpose of more thoroughly heating the moist 
 temporal bones, and of more surely fixing the cartilaginous tube, 
 Siebenmann also uses gypsum ; only the opening of the tube and the 
 artificial gap in the proc. mastoid, are left free. But the plaster 
 block, having been hardened, is immediately heated, and the casting 
 proceeded with. The syringe to be employed must be one of steel or 
 brass, and should be well heated before using it. The air-tight closure 
 between the syringe and the gap in the mastoid process is simply 
 effected by fastening on the nozzle of the syringe a short piece of 
 drainage tube with thick walls but of small calibre, in such a way 
 that the nozzle projects only about 3 mm. beyond it. The selection 
 of suitable bones, the further preparatory arrangements, and the in- 
 jection are the same as in Bezold's process. For corrosion, however, 
 the well-cleaned bone is merely placed in 20% caustic potash, where, 
 especially under temperatures of 40-50° C, the destruction of the tem- 
 poral bone is so rapidly effected, that in two, at most three or four, 
 weeks the bright metallic preparation can be removed from the lye. 
 For the corrosion of the moist temporal bones of children, only a few 
 days are required. 
 
 Instructive preparations may be obtained by immersing such bones 
 when charged with metal for a few days in a very weak solution of 
 the caustic, until the soft parts and the diploe can be easily removed. 
 At this stage the bones are again soaked for a day or two in water 
 and cleared of the soft parts, care being taken not to injure the tube. 
 Now the outer osseous plate of the lateral surface of the petrous bone 
 is removed ; the air-spaces of the anterior and posterior surfaces of 
 the pyramid must be carefully exposed and freed from the surround- 
 ing spongy tissue ; the outer anterior wall of the tubal canal is broken 
 away in its entire length, and in some preparations also the inner 
 half of the anterior lower wall of the meatus. If the bone has 
 been corroded too far, it is, after the filling of the middle ear has 
 been chiselled away or dug out, to be dipped once more into thin 
 
 12 
 
178 METALLIC CORROSIONS OF THE EAR ACCORDING TO THE AUTHOR. 
 
 liquid glue or gelatine, to restore its firmness, and to prevent tlie metal 
 falling out. 
 
 Several good metallic corrosions of the temporal bone I obtained 
 by the following simple procedure : on a well-dried, markedly pneu- 
 matic temporal bone, a small hole is bored ^-1 cm. behind the ex- 
 ternal orifice of the ear. After this the anterior opening of the osseous 
 Eustachian tube, and the hiatus canalis Fallopii are stopped up with 
 glazier's putty, and the preparation is embedded in heated dry sand, 
 so that only the external opening of the osseous meatus and the drill 
 hole in the mastoid process turned upwards, remain free from the 
 sand. A small quantity of the molten alloy is now poured into the 
 auditory canal by means of a pointed spoon, in such a way that the 
 metal penetrates through the round and oval windows into the 
 cavity of the labyrinth ; the tympanic cavity and the external 
 meatus are then filled, until the alloy runs out from the bore-hole in 
 the mastoid process. Experiments which I have lately made to pro- 
 duce metallic corrosions by injecting the alloy through the internal 
 meatus have yielded a favourable result. With this object the 
 osseous lamella, separating the floor of the internal meatus from the 
 cavity of the labyrinth, is pierced with a pointed instrument, and 
 another hole made on the processus mastoid, behind the external 
 meatus. Then the preparation is covered over with gypsum, so as to 
 leave only the external and internal meatus, and the bore-hole in the 
 mastoid free. The injection of the alloy from below upwards is 
 effected by means of a heated metal syringe, the nozzle of which, 
 covered with a piece of india-rubber tube, fits air-tight into the in- 
 ternal meatus. The injection is continued until the mass flows from 
 the bore-hole in the mastoid process. 
 
 Metallic casts of the labyrinth may be made simply by injecting the 
 alloy through the fenestra ovalis, or by making the injection in a space 
 where the air has been rarefied according to Gottfried's method. This 
 proceeding, of the excellence of which I had the opportunity of con- 
 vincing myself from the perfectly successful preparations of the laby- 
 rinth made by Dr. Dalla Kosa, consists in placing the pyramid, reduced 
 down to the capsule of the labyrinth, together with several small pieces 
 of Wood's metal, in a spacious eprouvette. The latter is stopped by 
 means of an india-rubber plug with a hole in it, through which a short 
 glass tube is passed. Now, in order to rarefy, as much as possible, the 
 air in the Eprouvette, and to facilitate the penetrating of the molten 
 metal into the labyrinthine cavity, water is made to boil in a retort, 
 provided with a forked tube, over the flame of a spirit-lamp, until the 
 steam escapes with some force at the openings of the tube. If then 
 the mouth of one of the branches be connected by means of an india- 
 
CORROSION PREPARATIONS OF THE AURICLE AND EXTERNAL MEATUS. 179 
 
 rubber tube with tliat of the eprouvette, the steam can only escape by 
 the other branch, whereby the air in the eprouvette becomes so raiu- 
 fied that the metal, which is melted at the same time over a spirit- 
 lamp, penetrates into all the canals of the labyrinth. 
 
 The maceration of the objects with caustic potash requires the 
 same precautions to be taken as with Siebenmann's method. 
 
 2. CORROSION PREPARATIONS OF SOFT PARTS. 
 
 On corrosion preparations of the soft parts of the temporal bone, 
 only the air-containing spaces of the external and middle ear can be 
 represented. The procedure differs, according to whether a cast of 
 the auricle and external meatus, or one of the middle ear (tympanic 
 cavity, mastoid cells, and Eustachian tube), or finally, one of the 
 external and middle ear in connection, is to be obtained. 
 
 The easiest to represent are casts which show the depressions of 
 the auricle, the length and direction of the external meatus, and the 
 curvature of the outer surface of the membrana tympani. For this 
 purpose a normal organ is made use of, the external meatus of which 
 has been thoroughly cleansed from ceruminal and epidermic masses 
 by syringing, and where the tympanic membrane, upon examination 
 with a mirror, is found to be in a perfectly normal condition. Before 
 pouring in the corrosion mass, the preparation must be warmed 
 in hot water, and after it has been taken out, the meatus should 
 be well dried by repeatedly forcing air into it from a heated metal 
 syringe. As a corrosion mass, either that of wax and resin, before 
 described, or one of the alloys mentioned, may be used (Lowenberg). 
 These latter, according to Professor Brunn, should not be poured in 
 too hot, otherwise the cutis of the external meatus, and the membrana 
 tympani might be burned or shrunk, and the casts, in consequence, 
 turn out shapeless and thin. When pouring in the metal, special 
 care should be taken that the meatus and auricle be kept in their 
 normal positions, lest by traction on the latter, the relationship of one 
 to the other might be altered. "When using metallic alloys, the 
 angular incurvations of the meatus stand out in too pronounced 
 a manner in the cast, owing to the weight of the metal filling the 
 auricle, while the impression of the membrana tympani is less 
 distinct. 
 
 After the wax and resin compound has hardened, the preparation 
 is placed in concentrated hydrochloric acid, and the corrosion pro- 
 ceeded with in the same manner as with macerated temporal bones. 
 With metallic casts, after cooling of the molten alloy, the auricle and 
 cartilaginous meatus are cut away, and, according to Prof. Brunn, 
 the cast may then be taken out. If this cannot be done the pars 
 
 12—2 
 
180 
 
 CORROSION CASTS OF THE MIDDLE EAR. 
 
 tympanica must be removed with the chisel, or destroyed by 8% 
 caustic potash. 
 
 Somewhat more difficult is the procedure with corrosions of the 
 middle ear. The object selected must be taken from the skull in such 
 a manner that, towards the front, the Eustachian tube remains intact, 
 while the posterior cut through the bone is so directed that the cells 
 of the mastoid process are not opened thereby. The injection into the 
 spaces of the middle ear is best effected, according to Bezold, from 
 an opening made in the incisura mastoid., since, especially in pneumatic 
 temporal bones, there frequently exist, in the neighbourhood of this 
 incisura, one or several large cavities which communicate with the 
 mastoid antrum. Having introduced the canula air-tight into this 
 opening, warm air is made to pass through the middle ear by means 
 
 Fig. 129. — Corrosion cast of the auricle and of the external auditory canal. (After Bezold.) 
 — s = fossa scaphoidea ; i = fossa intercruralis, c = upper, c' = lower portion of the 
 concha ; u — second bend of the external meatus ; t = border of the tympanic membrane ; 
 um = umbo ; b = depression of the membr. Shrapnelli, and of the proc. brevis. 
 
 of a large, well-heated metal syringe. If, while this is being done, 
 air escapes from the ostium pharyng. tubse, it may be assumed that 
 the cavities in the mastoid process communicate with the rest of the 
 spaces in the middle ear. 
 
 Previous to injecting the corrosion mass into the middle ear, an 
 insect pin is pushed through the tubal canal into the tympanic 
 cavity, so that when the injection is completed, the pin will be sur- 
 rounded by the corrosion substance, and the breaking of the cast of 
 
COKROSION CASTS OF THE MIDDLE EAR. 
 
 181 
 
 the tube at the isthmus tubse will be prevented. The heated corrosion 
 medium is now injected with some force through the canula at the 
 incisura mastoid., until it flows out freely, and without air-bubbles, from 
 the ostium pharyng. tubas which is directed upwards. The preparation 
 is kept in this position until the corrosion mass has hardened, and 
 must afterwards be immersed, for the purpose of corroding it, in 
 concentrated hydrochloric acid (where alloys are used, in caustic 
 potash). If, on corrosion preparations of soft parts, the external and 
 middle ear are to be represented in connection, several strong insect 
 pins are pushed from the meatus through the membrana tympani. 
 The injection of the spaces of the middle ear is effected after the 
 method previously described. When the corrosion medium has 
 cooled in the spaces of the middle ear, the preparation is so placed, 
 that the external meatus is directed vertically upwards, and then the 
 latter and the auricle are likewise filled with the liquid mass. The 
 
 Fig. 130. — Corrosion cast of the middle ear. (After Bezold.) — o = ost. pharyng. tubs ; 
 i — isthmus tubse ; ct — ost. tymp. tubse ; u = lower tympanic space ; t = tympanic 
 membrane, with the groove of the malleus, and the umbo ; h = depression for the body of 
 the malleus and incus ; a = posterior end of the mastoid antrum ; e = transition cell ; 
 te = terminal cell. 
 
 connection between the spaces of the external and middle ear is pre- 
 served by means of pins thrust through the tympanic membrane. 
 
 The cast of the soft parts of the middle ear differs in many respects 
 from the middle-ear cast of the macerated temporal bone. With the 
 former we obtain an exact impression of the inner surface of the 
 tympanic membrane, which on bone corrosions must of course be 
 wanting. On soft-part corrosions we also find, besides the hollow 
 spaces, which have been left behind after the corrosion of the 
 malleus and incus and of the stapes, the canal formed by the tendon 
 of the tensor tympani, passing transversely through the cast of the 
 tympanum, as well as the furrows which the larger mucous membrane 
 folds leave in the corrosion mass. All these details are missing in 
 bone corrosion, though we obtain by it the impression of the facial 
 
182 CORROSION CASTS BY MEANS OF CELLOIDIN AND PARAFFIN. 
 
 canal, while in the cast of the soft parts this impression, as well as 
 those of the small osseous canals of the temporal bone, are wanting. 
 In the mastoid process, only the pneumatic spaces appear on the soft- 
 part cast ; on the cast of the macerated bone we have also those of the 
 diploetic spaces. Finally, we obtain on the macerated temporal bone 
 only the cast of the osseous Eustachian tube, on the cast of the soft 
 parts the entire tube. The cast of the latter does not correspond to 
 the actual capacity of the tubal canal in a state of rest, but during its 
 maximal dilatation. 
 
 Professor Steinbriigge recommends, for corrosion preparations of 
 the labyrinth, celloidin, which of late has been so much used for 
 embedding microscopical preparations.* 
 
 He opens the tympanic cavity from the roof, divides the muse, 
 tensor tymp. and the incudo-stapedial articulation, and then, sawing 
 through the antrum mastoid., separates the labyrinthine portion from 
 the outer wall of the middle ear. The stapes is next carefully 
 removed from the fenestra ovalis, and the bone then, for forty-eight 
 hours, immersed in equal parts of ether and absolute alcohol, and 
 afterwards placed in a thin-fluid solution of celloidin, v/hich, after 
 having been left for eight days in action, is allowed to evaporate by 
 removing the lid of the vessel. The bones embedded in celloidin are left 
 for fully three days in 50% alcohol ; they are then freed from the 
 superfluous celloidin by scraping, and placed in pure hydrochloric 
 acid. After the lapse of three days the macerated tissues can be 
 removed from the casts by means of a gentle stream of water. In 
 this manner Steinbriigge obtained very good preparations of the 
 perilymphatic spaces of the labyrinth, including the membranous 
 structures ; but his attempts to represent the latter in their connection 
 by dissolving the celloidin again have hitherto not been successful. 
 
 Another method of obtaining preparations by the process of corro- 
 sion was suggested by Earth. -f- 
 
 In his various experiments to embed the ear he hit upon a plan of 
 making casts of the spaces of the labyrinth, retaining the soft parts. 
 The undecalcified and unopened petrous bone, after being hardened 
 and stained (osmic acid), is placed first in dilute, then in absolute 
 alcohol, and finally in chloroform. In each of these it is allowed to 
 remain for several days. After that, paraffin is melted at as low a 
 temperature as possible, the preparation quickly taken direct from the 
 chloroform into the melted paraffin, and left there until the chloro- 
 form ceases to give off vapours, which is, with a human petrous bone, 
 from five to six hours. After allowing the paraffin to cool rapidly, the 
 
 * Zur Corrosionsanatomie des Ohres. (Centralbl. f. d. med. Wissenschaft, 1885, Nr. 31). 
 t Beitrage zur Anatomic des Ohres, Z. f. O., Bd. XVII. s. 261-266. 
 
CORROSION CASTS BY MEANS OF CELLOIDIN AND PARAFFIN. 183 
 
 preparation is cut out, a small block of paraffin being left standing for 
 subsequent attachment to the meatus auditorius internus, or to the 
 fenestra ovalis et rotunda. In the latter case the stapes must, of 
 course, be removed before immersion in the medium, and the mem- 
 brana tympani secundaria pierced. The superfluous paraffin is scraped 
 off down to the bone. Now the petrous bone is transferred to con- 
 centrated or nearly concentrated common hydrochloric acid, in which 
 it remains, according to its bulk, for eight to fourteen days. The pre- 
 paration, on which a considerable portion of the cast of the inner ear 
 is already visible, is then to be carefully placed in water, and what 
 remains of the tissue still adhering to it is washed off by means of a 
 syringe provided with a long nozzle. 
 
 Thus a cast of the whole of the internal ear is obtained, which 
 includes the soft parts, sometimes with, sometimes without, preserva- 
 tion of the periosteum of the scalse. It shows everything that is to be 
 noticed on a cast of the osseous labyrinth, and in addition, though 
 only faintly shining through, the position of the n. facialis in its rela- 
 tionship to the acusticus, the origin of the nerve-trunks and their 
 ramifications on the ampullse, the radiation of the r. cochleae, the 
 course of the ductus cochlearis, as well as that of the membranous 
 semicircular canals within the osseous. With organs of children, up 
 to the age of about ten years, the internal ear is obtained in tolerably 
 close connection with the nerve-trunks. The preparation being com- 
 pleted, may, for preservation, find a suitable place beside the cast of 
 the internal meatus. In adults the nerve-passages to the internal ear 
 have, through gradual ossification, become so narrow that the pre- 
 paration must be very carefully handled to avoid breaking the cast. 
 Earth's attempts to clear the preparation in the paraffin embedding — 
 i.e., to render it quite transparent — have hitherto not been successful ; 
 but it gains somewhat in firmness, even against moderate heat, if it be 
 placed for some time in soluble glass and dried, any defective places 
 being subsequently brushed over with the same substance. In further 
 experiments it is recommended to try careful painting over with resin 
 dissolved in chloroform. For microscopic examination these pre- 
 parations are unsuitable, although the pillars of Corti's organ, as well 
 as cells and nuclei, are for the most part plainly recognisable ; but the 
 membranous labyrinth may be demonstrated by dissolving and re- 
 moving the paraffin. This manipulation — dissolving in chloroform, 
 gradual removal into ether, alcohol, glycerine — must be very carefully 
 carried out, lest there occur disfiguring shrinkings and displacements, 
 or even rents in the vestibular structures, or, what is more likely still, 
 in the canals. Tolerably good preparations may, however, be obtained, 
 which afterwards can be stained, to make them stand out more dis- 
 
184 ANATOMICAL AND PATHOLOGICAL PEEPARATIONS. 
 
 tinctly in glycerine. Earth considers this method better suited for 
 the examination of other cavities. Celloidin casts become more 
 resistant if the pyramid be placed in oil, or in resin dissolved in 
 alcohol. 
 
 VI. 
 
 Mounting and Peeserving Anatomical and Pathological 
 Preparations of the Organ of Hearing. 
 
 preparatory methods. 
 
 1. Soaking the Preparations in Water. 
 
 All preparations intended for preservation in an anatomical collection 
 must, in a fresh state, either before or after preparing them, be soaked 
 in clean water, which is frequently to be changed so as to get rid of 
 the blood which has been left behind in the bone and soft parts. The 
 space of time within which the blood may be removed from the tem- 
 poral bone varies from one to three days. It is effected the more 
 rapidly the oftener the water is changed, and frequently one day will 
 be sufficient if the object be placed in a stream of water. The latter 
 is advisable to prevent rapid putrefaction setting in, especially during 
 the warmer season of the year. 
 
 When the object is quite freed from blood — which will be seen if, 
 after repeatedly changing the water, the latter no longer shows any 
 reddish tint — it is, for the purpose of dehydration, steeped in ordinary 
 spirit, from which it may be taken at any time when required for pre- 
 paration. This, however, is only to be recommended in cases where 
 normal organs of hearing are to be dissected. Pathological objects, 
 on the other hand, should always be prepared in the fresh state, as 
 the new formations of tissue, the result of the morbid process in the 
 ear, undergo alterations when soaked in water. If intended for pre- 
 servation as macroscopic objects, they must also be steeped in water 
 after their preparation is completed, and a note made of their appear- 
 ances ; they are then placed in spirits of wine. Alcohol preparations, 
 if not quite free from blood, show the details less sharply. 
 
 2. Bleaching of Preparations of the Ear intended for 
 Preservation. 
 
 Macerated temporal bones are, under favourable conditions, best 
 bleached in the sun. Frequently, however, one meets with temporal 
 bones which contain such quantities of fat that, even after long 
 exposure to the rays of the sun, they do not lose their yellow colour. 
 The best bleaching substance for such objects is benzoline. The 
 
MOUNTING OF SPIRIT PREPARATIONS. 185 
 
 manipulation requires, however, a special apparatus. This consists in 
 a correspondingly large, hermetically closed metallic case in which, 
 close to the bottom, a piece of wire netting is fixed for the temporal 
 bones to rest on. If, now, a quantity of benzoline be poured on the 
 floor of the case, the latter being well closed, the fat is extracted from 
 the bone by the vapours arising, and the objects are completely 
 bleached. 
 
 Another simpler method of bleaching yellow bones is to immerse 
 them in a 10% aqueous solution of ammonia ; the bones must, how- 
 ever, be exposed for several weeks to the action of the liquid, which 
 should be frequently changed. The bleaching of temporal bones in 
 chlorine water or in a solution of chlorinated lime is certainly more 
 expeditiously accomplished ; but the osseous tissue, particularly in 
 young individuals, is too strongly affected by the destructive action of 
 the chlorine and the hydrochloric acid. Smaller bones, such as the 
 osseous labyrinth, the tympanic membrane with its osseous frame, and 
 the ossicles, may be bleached in as dark a place as possible, either in 
 a mixture of sulphuric ether and alcohol, or in a 6% solution of per- 
 oxide of hydrogen, with the addition of a few drops of ammonia. 
 
 With regard to the bleaching of unmacerated preparations of the 
 ear, in the majority of cases thorough soaking in water and subsequent 
 immersion in alcohol will suffice to whiten the bone. Only with ex- 
 ceptionally yellow or yellowish-brown bones may a bleaching medium 
 be used. One of the best modes is to immerse the preparation in 
 water slightly acidulated with nitric acid (|- 1,000). 
 
 MOUNTING OF THE PREPARATIONS. 
 
 In mounting anatomical and pathologico-anatomical preparations 
 of the auditory organ regard should be had, in the first instance, 
 that the important details on each object be clearly and fully brought 
 under observation. There is a distinction in the mode of mounting 
 spirit preparations and dry preparations. 
 
 1. Mounting of Spirit Preparations. 
 
 Preparations preserved in spirit must, for the study of the 
 anatomical details, almost invariably be taken out of the vessel where 
 they are kept. It is, however, advisable, when placing the object 
 in spirit, to give it such a position that the principal detail may 
 be easily seen through the glass without there being any need of 
 opening the vessel. The glass intended for keeping the preparation 
 should, therefore, be only of a diameter corresponding to the size of 
 the object, to minimize the changes of its position, which would 
 
186 MOUNTING OF PATHOLOGICO-ANATOMICAL 
 
 interfere with the proper examination. Such changes frequently 
 happen when the vessels are too wide. 
 
 The greater number of the anatomical and pathologico-anatomical 
 preparations in my collection are preserved in glass jars, provided 
 with well-fitting glass stoppers ; they measure 9 cm. in height, 6 cm. 
 in width, and 4 cm. at the mouth. All these are preparations on 
 which the opened osseous meatus, the outer surface of the membrana 
 tympani, the tympanic cavity and the pyramid in connection, are re- 
 presented in sections of the most varied kinds. Preparations on 
 which, in addition to the above-mentioned parts of the ear, the 
 auricle, mastoid process, and the Eustachian tube are retained, must 
 be placed in larger vessels, having a height of 12 cm. and a width of 
 7 cm. 
 
 More bulky preparations, such as half the skull with the organ 
 of hearing ready prepared, both organs in connection, frontal sections 
 through the entire skull and ear, must, of course, be put into 
 correspondingly capacious glasses. Best adapted for these are 
 longish oval shallow ones, 16 cm. long, 7 cm. wide, and 18 cm. high, 
 which can be closed by a well-fitting glass lid (by means of glazier's 
 putty). 
 
 Flat sections of the entire organ, particularly horizontal and 
 frontal ones of decalcified preparations, on which the details appear 
 more sharply marked in the spirit than when taken out of the liquid 
 for inspection, are kept in commoner glasses, measuring 6^ cm. in 
 height, and 5 cm in width ; these may be covered with a glass disc 
 and hermetically closed with glazier's putty. 
 
 Thin sections of decalcified organs which, on account of their 
 pliancy, curl up in the glass are fixed on uncoloured or coloured 
 (blue, yellow, black) glass slips of suitable size. The most durable 
 fixing material, which is not soluble in alcohol, is ichthyocoUa or 
 dissolved glue gelatine. A few drops of the strongly condensed 
 solution, applied to the upper and lower edges of the preparation, 
 which for a short time previously must have been lying in water, 
 will be sufficient to fix it on the slip, and if the whole be carefully 
 placed in spirit, the preparation will remain fixed in its position. 
 
 It would lead too far to enumerate all the preparations and 
 sections of the organ of hearing it might be possible to make, and 
 which might be found suitable for preservation in spirit for instruction 
 purposes. Besides, this appears to me superfluous, inasmuch as, 
 from the description of the anatomical preparations hitherto given, it 
 may be readily gathered which of them are required for study and 
 demonstration. It need here only be pointed out in a general way 
 that for such purposes spirit preparations and dry preparations 
 
PREPAEATIONS OF THE ORGAN OF HEARING. 187 
 
 supplement one another, as some details appear more strongly marked 
 in the former than in the latter. To demonstrate the soft parts, in 
 particular, of the auditory apparatus, it is advisable to keep in 
 every anatomical collection a considerable number of spirit prepara- 
 tions, on which should be represented, in their mutual relationship : 
 the auricle, the cartilaginous meatus, the tympanic membrane with 
 its pouches, and the chorda tymp., the lining membrane and ligaments 
 of the middle ear, the intra-tympanic muscles, the Eustachian tube 
 with its muscular apparatus, the membranous labyrinth and the 
 acoustic and facial nerves. For pathologico-anatomical preparations 
 preserving in spirit is, in the majority of cases, preferable to dry 
 mounting. Certain changes, such as opacities of the tympanic 
 membrane, non-adherent cicatrices, and atrophic depressions, almost 
 completely disappear when the objects are dried. On the other 
 hand, calcareous deposits on the membrana tympani appear more 
 sharply defined in dry than in spirit preparations ; this applies also 
 to adhesion bridges between the membrane, inner tympanic wall, and 
 the ossicula. 
 
 Smaller preparations, intended for demonstration, are best kept 
 in small, specially manufactured glasses such are shown in their 
 actual size on p. 191, Figs. IV. and YI. Among these preparations are 
 to be mentioned : transverse sections of the cartilagino-membranous 
 meatus, the membrana tympani, with the annulus tymp. ; the 
 membrane, prepared out of the sulcus and dissected into its various 
 layers; sections through the longitudinal axis of the decalcified 
 malleus and of the membrana tympani, with the view of Shrapnell's 
 membrane and of Prussak's space in profile ; longitudinal, and trans- 
 verse sections of the isolated Eustachian tube, the malleus, with 
 the m. tens. tymp. dissected out ; the stapes, with the m. stapedius, 
 that portion of the inner tympanic wall on which the stapes with 
 the m. staped., the fenestra rotunda and the n. facialis have been pre- 
 pared out ; likewise the external wall of the labyrinth, with the foot- 
 plate of the stapes, and the commencing portion of the lamina 
 spiralis, the sacculus with the membranous semicircular canals, the 
 membranous cochlea, sections of hardened and decalcified petrous 
 bones, etc. Especially clear and beautiful appear stained sections of 
 the tympanic cavity, with the transverse section of the malleo-incudal 
 articulation, of the longitudinal section of the malleus, with the view 
 of Shrapnell's membrane and Prussak's space in profile, of the 
 cochlea and vestibule, with the transverse sections of the saccules 
 and ampullae. Microscopical sections of those structures which have 
 turned out too thick for histological examination form, when pre- 
 served in small glasses, and examined with a lens in a good light. 
 
188 MOUNTING OF DRY PREPARATIONS. 
 
 very beautiful and instructive objects for lecturing purposes. In 
 order to mount such sections on an even surface, they are fastened at 
 both ends by means of a drop of fluid gelatine to a small coloured 
 (yellow or blue) glass slip, and after a few minutes placed in a 
 small glass containing common spirit. 
 
 Of pathological preparations to be preserved in smaller glass 
 vessels we may mention : calcareous deposits, perforation, cicatrices, 
 granulations and polypoid formations on the tympanic membrane,*' 
 polypi, carious ossicles, the labyrinthine capsule wholly or partially 
 exfoliated by necrosis, the extruded cochlea, etc. 
 
 For a preservative fluid I use the ordinary 50% spirit, in ex- 
 ceptional cases, for small objects (membranous cochlea, semicircular 
 canals, membrana tympani, etc.), Laskowski's carbolized glycerine 
 
 It is of great importance, when forming an anatomical collection, 
 to have well-fitting covers for the preparation glasses, because many 
 objects, after the evaporation of the alcohol, dry up so as to become 
 useless. Glasses closed with imperfectly fitting stoppers, and which, 
 on being turned upside down, allow the liquid to escape, if only in 
 drops, must be rejected and replaced by others. To ensure air-tight 
 closure, the circumference of the glass stoppers is brushed over with 
 a mixture of stearine and ceresine. The evaporation of the preserva- 
 tive fluid is best prevented by making use of glazier's putty, which 
 can, however, only be done (see p. 186) with preparations which do 
 not always require to be taken out of the vessel for demonstration. 
 Preparations which, for want of attention, dry up through evaporation 
 of the alcohol, are made to expand again by placing them for one or 
 two days in water, strongly acidulated with nitric acid (2-3%), after 
 which they are replaced in alcohol. When the preservative fluid 
 is found to have turned brown or thick, it must of course be renewed. 
 
 2, Mounting of Dry Preparations. 
 
 The mounting and arranging of dry preparations is of the greatest 
 importance if they are to be kept in a perfect condition. Special care 
 should be taken in fixing them^ that those portions of the object 
 which are to be brought under notice should present themselves 
 freely and clearly to view. Preparations of the tympanic cavity and 
 labyrinth, in particular, must be mounted in such a way that their 
 respective cavities be open to unobstructed inspection. It is 
 scarcely necessary to say that, while mounting preparations of the 
 auditory organ in a manner most suitable for their particular purpose, 
 
 * Compare the figure in my text-book of Diseases of the Ear, second edition, p. 188. 
 
MOUNTING OF DRY PREPARATIONS. 389 
 
 regard should also be liad to their tasteful grouping, in order to show 
 them to greater advantage. 
 
 Smaller preparations, such as the outer and inner surfaces of the 
 membrana tympani stretched out in the sulc. tymp., the ossicles, 
 sections through the vestibule and cochlea, are best fixed with a drop 
 of glue on small black slips of wood measuring 4 cm, by 2 cm. Glass 
 slips (reduced to the proper size) have the advantage of allowing 
 the objects fixed upon them to be examined on both sides. In 
 order to protect the preparation from dust and insects, the slip is 
 fastened on a round stand, which has a diameter of 4 cm., and is 
 covered with a glass shade 5 cm. (high p. 191, Figs. I. and III. in the 
 actual size). 
 
 In a like manner, smaller objects may be mounted in a round cap- 
 sule resting on a stand, and closed in front with a watch-glass fitted 
 in (p. 191, Fig. II.). A still more simple method of mounting consists, 
 as shown in Fig. VII., in fixing the preparation with a drop of glue on 
 a small, black polished or varnished slip of wood, measuring 8 cm. by 
 4^ cm., covering it afterwards by means of a watch-glass in such a 
 way that the edges of the latter firmly adhere to the slip. 
 
 Larger dry preparations I mount for my collection in two ways. 
 If the object has been so prepared that the parts intended to be shown 
 can only be seen on one side, such as the view of the cavum tymp. 
 from above or below, and horizontal sections of the entire organ, 
 etc., holes are drilled through the preparation at its two opposite ex- 
 tremities, or at any other suitable point ; it is then fastened by means of 
 metal tacks to a small, black slip of wood, which may be polished or 
 varnished. It is hardly necessary to say that the holes drilled in the 
 object for fixing it should not be made in any part which is anatomi- 
 cally of importance, but, if possible, in places where the tacks are out 
 of sight. To avoid their being noticed at all, a tack li-2 cm. lone is 
 driven half-way into the wooden slip, and the free portion of it having 
 been brushed over with glue is inserted into a bore-hole drilled on 
 the lower surface of the preparation. These slips vary in size, accord- 
 ing to the bulk of the object, from 9 cm. by 6 cm. to 14 cm. by 
 8 cm.; for small objects slips of 6 cm. by 4 cm. are sufficient. In- 
 stead of small wooden slips, square or oblong glass plates may be 
 used, on which the preparations are fixed by means of glue or glass 
 cement (syndektikon). To protect the objects from dust and insects, 
 from four to eight specimens are kept in correspondingl}^ large cases, 
 the lids of which may be partly of glass so as to render inspection 
 more convenient. It is absolutely necessary that these cases should 
 be made as air-tight as possible, especially for dry preparations, the 
 soft parts of which have been impregnated with Laskowski's pre- 
 
190 PROTECTION OF DRY PREPARATIONS AGAINST DESTRUCTION BY INSECTS. 
 
 servative fluid (glycerine lOO'O, acid, carbolic. 5'0, acid, boric. I'O), 
 because such objects, if not sufficiently protected, become in tlie 
 course of time so soiled, that it is scarcely possible to again perfectly 
 clean them. 
 
 Preparations that require to be examined on all sides, such as the 
 membrana tympani, with the ossicular chain and the labyrinth, pre- 
 pared out in one piece, are mounted, as shown in Fig. V., p. 191, on a 
 stand which may be covered with a bell glass of corresponding size. 
 The diameter of the round stand measures 10 cm,, the height of the 
 upright piece supporting the preparation 4 cm., and that of the shade 
 fitting into a groove in the stand 8-9 cm.^ This mode of mounting, 
 on account of its rendering it possible to inspect the object on all 
 sides, is also to be recommended for those corrosion preparations 
 which have been treated by the wax and resin process, and require to 
 be covered with a glass shade to protect them from dust and mechani- 
 cal influences. 
 
 Small dry preparations, tympanic membranes, ossicula, casts of 
 the labyrinth, may also be mounted on black slips of wood under glass 
 and frame. A model collection of preparations of the ear is that 
 which represents the comparative anatomy of the ossicles and osseous 
 labyrinth, and which has been mounted on two tablets by Hyrtl's 
 master-hand. 
 
 PROTECTION OF DRY PREPARATIONS AGAINST DESTRUCTION BY 
 
 INSECTS. 
 
 All dry preparations intended for preservation must, in order to 
 protect them against destruction by the larvae of insects, be brushed 
 over with a solution of glycerine sublimate (3 parts glycerine, 7 
 parts water, O'Ol sublimate of mercury). Instead of jthe sublimate, 
 arsenious acid (O'l) may be employed. The painting over of the soft 
 parts (not the bones) is done with a fine camel's-hair brush. Especi- 
 ally the outer and inner surfaces of the membrana tympani, which is 
 most frequently destroyed by the larvse, should be carefully pencilled 
 over, so as to become impregnated with the fluid. In order to pre- 
 serve the pliancy of the membrane, and to prevent it from cracking, 
 it is advisable to repeat the pencilling over after the lapse of 3-4 
 years. Tympanic membranes on preparations which have been 
 saturated with Laskowski's preservative fluid (5% carbolized glycerine, 
 with the addition of 1% boracic acid), and which, as a rule, are not 
 attacked by the larvse of insects, should, for greater safety, be treated 
 in the same manner. 
 
 * In this way I have mounted a collection consisting of sixty preparations, which were 
 purchased in 1876 for the Museum of the College of Physicians in Philadelphia. 
 
me. 
 
192 PROTECTION OF DRY PREPARATIONS AGAINST DESTRUCTION BY INSECTS. 
 
 In spite of these precautions for protecting the preparations from 
 destruction, I consider it advisable at the beginning of the warm 
 season to provide the various cases of the anatomical collection with 
 pieces of camphor wrapped in gauze, thus preventing their being in- 
 fested with insects. 
 
 Preparations showing the presence of insects by such traces as 
 brownish-gray granules, must either be entirely separated from the 
 collection, or, for the purpose of destroying the larvae, be put in 
 sublimate spirit (1:300). If several specimens of the collection 
 show signs of being affected, all the dry preparations should be 
 placed in an air-tight box in order to destroy the larvge by ex- 
 posing them for five or six hours to the fumes of carbon bi-sulphide. 
 
SECOND PART. 
 
 THE HISTOLOGICAL EXAMINATION OF THE ORGAN OF HEARING IN 
 ITS NORMAL AND PATHOLOGICAL CONDITION. 
 
 Introduction. 
 
 The histological examination of tlie tissues of the auditory apparatus 
 forms an essential part in the dissection of the ear. For although, by 
 dissecting pathological organs as macroscopic objects, we frequently 
 enough gain information as to the anatomical cause of the disturbance 
 of hearing, yet in many cases it is only the histological examination 
 which will throw sufficient light on those functional impairments 
 which originate from the finer structural alterations in the auditory 
 apparatus, and which it would be impossible to recognise with the 
 naked eye. 
 
 The histology of the organ of hearing is beset with far greater 
 difficulties than that of other organs. This is due to the fact that it 
 is made up of tissues with greatly varying peculiarities. Thus we see 
 the sound- conducting apparatus and the delicate terminal structures 
 of the acoustic nerve in the labyrinth surrounded on all sides by 
 exceedingly dense osseous envelopes, which admit of a pathologico- 
 histological or a topographico-anatomical investigation only when, by 
 proper methods of decalcification and embedding, all the tissues are 
 rendered fit for sectioning. These preparatory methods, however, 
 require the greatest care and circumspection, in order to prevent the 
 delicate structures of the connective tissue, of the epithelium, and of 
 the nerves in the middle and inner ear from being altered and injured 
 by the action of the decalcifying fluids. 
 
 In nearly all cases, therefore, must organs of hearing, intended for 
 microscopical examination in their normal as well as their pathological 
 state, be treated with certain chemical agents in order to preserve, as 
 far as possible, the natural structure of their cells and tissues (fixing) ; 
 to prevent the setting in of decomposition, which might have a 
 destructive influence on their delicate texture (preservation) ; and to 
 give their dissimilar tissues a homogeneous consistence, so as to render 
 them fit for sectioning (hardening, decalcification). Where it is merely 
 
 13 
 
194 HISTOLOGICAL EXAMINATION OF THE ORGAN OF HEARING. 
 
 a question of examining the soft structures of tlie ear (tympanic mem- 
 brane, lining membrane of the meatus and middle ear, Eustachian 
 tube, membranous labyrinth), it is generally possible to comply with 
 all the above-mentioned conditions by making use of a suitable pre- 
 servative fluid (chromates, alcohol), which effects both hardening and 
 fixing, and prevents putrefaction. In some cases, however, where 
 special forms of organization (cell-nuclei, nerve-fibres, etc.) are to be 
 examined, it is necessary to have recourse to a combination of fixing 
 and preserving methods. It is, of course, understood that, in cases 
 where a topographico-histological examination of the organ is intended, 
 the parts selected, or even the entire apparatus, with its osseous 
 envelopes, must be decalcified before being submitted in toto to 
 microscopical examination. 
 
 Preparatory Methods. 
 1. fixing and hardening. 
 
 The object of fixing is the perfect preservation of the natural cell- 
 structure. The normal histology of the ear, especially the complicated 
 anatomical relations of the membranous labyrinth, cannot be success- 
 fully studied without previously fixing the object. Particularly where 
 the chief aim is to give prominence to special protoplasmic cell-forma- 
 tions in the microscopical image the finest methods of histological 
 treatment must be employed, in order to demonstrate not only the 
 microscopic structure of the exceedingly delicate portions of the 
 auditory apparatus, but also to bring under observation those of the 
 more important protoplasmic formations therein which may be chosen 
 for the purpose. Besides the usual methods of fixing the preparations, 
 the impregnation of the objects with metallic salts (osmium, gold) is 
 largely employed, whereby — especially the nerve-elements of the in- 
 ternal ear — the cellular terminal expansions of the acoustic nerve, by 
 virtue of their peculiar chemical reaction upon these substances, 
 present themselves in a distinct form and colour. 
 
 The fresher the object, the more natural are the representations 
 obtained by the fixing. Successful metallic impregnations, in par- 
 ticular, can only be obtained on perfectly fresh organs. The gilding 
 methods used in neuro-histology (Freud) can only be employed to a 
 limited extent in oto-histology, because the decalcification of the 
 object, which must necessarily precede, commonly deprives the cell- 
 protoplasm of its reducing power. 
 
 It must be accepted as a general rule that the organs of hearing 
 under treatment, after removal of any superfluous portions still 
 .attached to them, are to be immersed in the liquid direct, wi'thout 
 
FIXING AND HARDENING. 195 
 
 having previously been washed. Most of the substances here employed 
 being equally suitable as hardening, preservative, and even decalcifying 
 media, the organ under preparation should be kept in the solution 
 until sufficient hardening or decalcification of the soft parts has been 
 effected. 
 
 1. Chromic Acid and its Salts. — Chromic acid in 0.1-1% 
 aqueous solution has fixing, hardening, preserving and decalcifying 
 properties, and forms therefore an excellent medium for our purposes. 
 The only disadvantage it has, though only Avhen kept in action too 
 long, is that the preparations frequently assume an intense dark-green 
 colour, throusrh the reduction of the oxide of chromium, in con- 
 sequence of which the soft parts of the organ are rendered unfit for 
 staining with carmine, htematoxylin, and aniline dyes. 
 
 Most in use as fixing media are potassium and ammonium 
 bichromicum in a 2% solution, and Miiller's fluid, a mixture of 2 
 parts bichromate of potash, 1 part sulphate of soda, and 100 parts 
 water. If these solutions be used in sufficient quantity and changed 
 every day, we succeed in durably fixing the tissue structures of the 
 ear in from one to three weeks, sometimes even in a few days, after 
 which the decalcification can be proceeded with. 
 
 2. An exceptional reputation in oto-histology has Tafani's fixing 
 fluid. It consists of 80 parts of a 0.4% aqueous solution of bichromate 
 of potash and 20 parts of a 1% aqueous solution of hyperosmic acid. 
 The two solutions are only to be mixed immediately before use. 
 Leaving the preparations in the solution for twenty-four hours is 
 sufficient to fix them, and to reduce the osmic acid. 
 
 3. Good results are also obtained by employing Vlakovic's less 
 costly chrom-alcohol fixing fluid, which I frequently use for fix- 
 ing pathological preparations ; it consists of one part of a 5% 
 aqueous solution of chromic acid, and 16 parts of 90% alcohol, and 
 effects sufficient fixation in twenty-four hours. After-hardening in 
 alcohol. 
 
 A fixing fluid which is greatly to be recommended for normal 
 and pathological organs is that of Urban Pritchard : acid, chromicum 
 cryst. 1 g., aqu. dest. 20 g., alcohol 90° 180 g., in which the object is left 
 for seven to eight days. 
 
 4. For pathologico-histological investigations, especially where it 
 is intended to study pathological cell-proliferations, Flemming's fixing 
 method, now generally employed to show nucleus segmentation, is 
 specially to be recommended. This solution consists of 15 parts 
 of 1% chromic acid, 4 parts of 2% osmic acid, and 1 part of glacial 
 acetic acid. The tissues, which should be as fresh as possible, are left 
 for two or three days in the solution, and having been well washed, 
 
 13—2 
 
196 IMPREGNATION OF PREPARATIONS OF THE EAR WITH GOLD. 
 
 they are decalcified, then hardened in alcohol, sectioned, and 
 coloured with nucleus-staining aniline dyes (see Staining Methods). 
 
 5. Good results are also obtained from the 3% nitric acid medium, 
 recommended by Altmann, which, on account of its excellent 
 decalcifying properties, is well suited for oto-histological purposes. 
 (The subsequent staining is to be effected with hsematoxylin.) 
 
 6. Ir)xpregnation with Metallic Salts. — For oto-histological pur- 
 poses the treatment with gold and osmium is to be preferred. By 
 the action of the gold and osmium compounds on the tissue, not only 
 an excellent fixing of the structural elements is obtained, but, what is 
 of special value for the histological examination of the nervous 
 and sound-conducting apparatus, the metal, owing to the reducing 
 properties of certain tissue elements (nerves, epithelial cells, etc.), 
 is precipitated in a fine granular form, while these elements them- 
 selves appear sharply differentiated m the microscopical image. 
 Metallic impregnations are, therefore, chiefly employed for the re- 
 presentation of the vessels and nerves of the membrana tympani, of 
 the lining membrane of the tympanic cavity, and of the Eustachian 
 tube, as well as of the nerve terminations in the saccules, ampullse, 
 and in Corti's organ. Those portions of tissue which are to undergo 
 metallic impregnation should, in as fresh a state as possible, and 
 without previous treatment in any other way (alcohol, chromium, etc.), 
 be immersed in the fixing fluid, which must be kept in a brown bottle, 
 and not exposed to the influence of the light. 
 
 I. Gilding. — The re-agent exclusively used is chloride of gold in a 
 -|-1^ aqueous solution. The action of the metallic salt solution 
 having taken effect, a weak solution of an organic acid (formic or 
 acetic acid) is employed to accelerate reduction. 
 
 The peculiar effect of the chloride of gold is that the axis- 
 cylinders of the nerves and nerve terminations in the labyrinth 
 assume a colour from dark violet to deep dark-red. The vessels 
 and nerves of the tympanic membrane, and of the lining membrane of 
 the middle ear, the cell protoplasm of the various epi- and endothelia 
 (mucous membrane, tympanic membrane, membranous labyrinth, 
 etc.), show the same colour, but only when examined in a perfectly 
 fresh state. 
 
 Methods for gilding : (a) The fresh organs, or portions of them, 
 are first of all placed in a 0.5% solution of chloride of gold. The 
 length of time they are to remain therein depends on the kind of 
 tissue • under treatment, and on the bulk of the preparation. 
 Membranes, drumhead, lining membrane of the tympanum and of the 
 Eustachian tube, saccules, and semicircular canals are left in it 
 for a quarter of an hour, while more bulky tissues, tuba Eustach., 
 
AND OSMIC ACID FOR HISTOLOGICAL PURPOSES, 197 
 
 tympanum, and the pyramid, require from half an hour to an hour. 
 Then the gold preparations are exposed to the light, and for twenty- 
 four hours kept in a fluid which contains 10 drops of formic acid for 
 every 10 g. of water. With tissues containing much calcareous 
 matter, the gold solution must be taken stronger ; for Corti's organ, of 
 about 5%. The objects assume on the surface a deep dark- violet 
 colour. 
 
 (6) Another method is to place the parts of fresh organs in a 
 0.5% solution of chloride of gold, to which is added a minute 
 quantity of acetic acid, and to leave them in it for a quarter of an hour 
 to an hour, until they acquire a straw colour. They are then washed 
 in distilled water acidulated with acetic acid, and kept for twenty-four 
 to forty-eight hours standing in a light place, until reduction has fully 
 set in. The colour of the preparations has then become deep bluish-red, 
 violet, blue, or dark gray. After-hardening in alcohol. 
 
 (c) Dr. E. Berger, of Paris, gilds after the following method, which 
 
 1 have employed with advantage on Corti's organs, taken from young 
 animals immediately after they had been killed. The objects are 
 immersed in a solution the composition of which is as follows : 1% 
 chloride of gold, 1% hydrochloric acid, 23% glycerine, and 75% 
 distilled water. In this the preparations remain six to eight hours, 
 until they become of a dark-blue colour ; then, washing in water, and 
 after-hardening in alcohol. For decalcification I used a saturated 
 solution of picric acid. 
 
 {d) Good reduction is also obtained by the use of amylic alcohol 
 (1 drop to 10 g. water), which, after impregnation of the object with 
 gold, is used either alone or combined with acetic or formic acid as a 
 reducing agent. 
 
 Stohr boils 8 ccm. of a 1% solution of chloride of gold with 
 
 2 ccm. of formic acid in a test-tube, and then allows it to cool. In 
 this mixture the object remains for an hour in the dark ; it is then 
 washed in distilled water and immersed in a mixture of 10 ccm. 
 formic acid and 40 ccm. distilled water, and exposed to the air. 
 Reduction is effected in twenty-four to forty-eight hours. The pre- 
 paration to be kept for eight days in the dark in 70%, then 90%, 
 alcohol. 
 
 Impregnations with gold or with osmium prove effectual only in 
 the superficial layers, since the chemical changes resulting from the 
 peculiar reaction in the tissues prevent the metallic salt solutions 
 from penetrating deeper. To obtain successful representations, care 
 should above all be taken to brinsf the tissues which are to be 
 gilded into sufficient contact with the chloride of gold solution. 
 When examining the lining membrane of the tympanum, and the 
 
198 OSMIUM TREATMENT. 
 
 membranous structures of the labyrinth, these cavities must be 
 opened in a suitable manner without doing injury to important parts. 
 For the tympanic cavity this is done at the tegmen tymp. ; for the 
 labyrinth, at the superior semicircular canal, or else by piercing the 
 membrane of the fenestra rotunda. 
 
 If it be merely intended to gild the tympanic membrane or the 
 lining membrane of the tympanum and of the Eustachian tube 
 separately, it is necessary, in order to insure direct action of the 
 metallic solution, to remove any accumulated secretion and epithelial 
 deposit from their exposed surfaces, by brushing them over with a 
 solution of common salt (0.6%). 
 
 The after-hardening is effected in alcohol, decalcification in the 
 case of petrous bones of slight consistence (young animals, embryos) 
 by picric acid ; with consistent ones, by an alcoholic solution of 
 hydrochloric acid or nitric acid (see Methods of Decalcification). 
 
 II. Osmium Treatment. Osmic acid in a 0.5-2% solution for 
 fixing and reducing fresh tissues of the organ of hearing is made 
 use of, where it is intended to represent bloodvessels, meduUated 
 nerve fibres, and pathological fatty degeneration in cellular elements. 
 As the red blood corpuscles become dark brown under the action of 
 osmic acid, the vessels filled with them stand out as strongly marked, 
 deep, blackish-brown strands from the rest of the tissues. All fat- 
 containing tissues assume under osmium reduction a blue-black 
 colour, so that the nerve medulla and fat-cells can be made easily 
 distinguishable. Like the treatment with chloride of gold, osmium 
 reduction is limited chietiy to the surface of the preparations, which 
 makes it necessary to use all the precautions observed in gilding. 
 The staining caused by the osmium reaction shows better on fresh 
 preparations than on those previously hardened, especially when 
 treated with alcohol, because the latter deprives the tissues of part of 
 their fat. 
 
 Directions. — Structures of this kind which are to be examined in 
 part or as a whole must, according to their bulk, be placed in a small 
 quantity (1-8 ccm.) of a 1-2% aqueous solution of osmic acid, and 
 left in a dark place, until they are hardened and have assumed a 
 blue colour (1-24 hours). After this, repeated thorough washing for 
 several hours in distilled water, which is to be frequently changed, and 
 to which a few drops of acetic acid should be added ; then washing, 
 for a like space of time, in a 0.6% solution of common salt. Soft 
 parts are to be preserved in alcohol, which should be gradually in- 
 creased in strength ; bone must be decalcified according to one of the 
 methods to be described further on. 
 
 III. Chloride of palladium acts on the nerves and protoplasms in a 
 
METHODS OF DECALCIFICATION. 199 
 
 similar manner to that of chloride of gold. A combined osmium- 
 palladium method for fixing, and colour reduction of the membranous 
 labyrinth, we owe to Dr. Schonlein, of Halle, the directions for which 
 are here given : The cochlea having been prepared out, after removal 
 of the stapes from the fenestra ovalis, is placed in a ^% solution of 
 osmic acid, and left in it for twenty -four hours. The preparation is then 
 washed and immersed in a 0.1% solution of chloride of palladium, to 
 which ten drops of hydrochloric acid are to be added. This solution 
 serves also for decalcification. It must be well shaken several times a 
 day, and one drop of hydrochloric acid added each day until the 
 decalcification is complete. The process requires from three to six 
 weeks, according to the hardness of the bone. Then follows thorough 
 washing, after- hardening in absolute alcohol, embedding in celloidin, 
 and sectioning. 
 
 The chromates, described in detail at the commencement of this 
 chapter, effect also the hardening of the soft parts of the organ of 
 hearing to that degree of consistence which is necessary to render 
 them fit for cutting. The greater the quantity of fluid used, and 
 the oftener it is changed, the more perfect will be the hardening. 
 Owing to the drawback of frequently occurring coagulation images, 
 the rapid method of hardening with absolute alcohol, which, if 
 changed two or three times in the course of the day, will render the 
 preparations perfectly hard and fit for cutting, is rarely used in oto- 
 histology. 
 
 When sufficiently hard, the object is thoroughly washed in dis- 
 tilled water ; for perfect hardening and further preservation it is 
 placed either in alcohol gradually increased in strength, or, for the 
 purpose of decalcifying it, in a suitable fluid (see Decalcification). 
 
 2. DECALCIFICATION. 
 
 To decalcify the osseous structures of the ear, aqueous solutions 
 of different mineral acids in various degrees of concentration are 
 exclusively used. 
 
 There are two methods of decalcification, one which occupies more 
 time and is more preservative, and another (the so-called rapid 
 method) which requires the acids to be used in a higher degree of 
 concentration. Each of these two methods has its advantages and 
 disadvantages, which shall be duly considered in connection with the 
 description of the various methods of decalcification. 
 
 Every object which is to be decalcified, after having previously 
 been subjected to a suitable process of fixation, is, before its immersion 
 in the decalcifying fluid, washed in fresh water until the latter ceases 
 to be coloured. Next, the osseous portion of the object is, as far as 
 
200 SLOW DECALCIFICATION. 
 
 possible, freed from adherent soft parts, the dura mater in particular to 
 be stripped off from the petrous bone, so as to allow the decalcifying 
 fluid to act directly on the bone. The preparation must, by removal 
 of all superfluous osseous parts with saw and bone forceps, be reduced 
 to the smallest possible bulk, and placed in a sufficient quantity 
 of fluid, since decalcification is the more uniform and rapid the 
 smaller the object, and the greater the quantity of the medium used 
 in the process. 
 
 The proceeding must be continued until the preparation has 
 become soft throughout, and thus fit for cutting. The best test for 
 this is to thrust a fine preparing needle at various points into the 
 petrous bone. If this can readily be done in many places, and if, 
 especially in the osseous mass behind the porus acust. internus, no 
 hardness be found (Moos), it may be assumed that the petrous bone is 
 in such a condition as to be ready for cutting. If, however, on the 
 needle being pushed in, resistance should be encountered in the 
 deeper parts, this would show that there are still undecalcified 
 portions, and the preparation must be left to the action of the fluid 
 until perfectly decalcified. 
 
 Methods of Decalcification. 
 
 1. Miiller's fluid, which has been repeatedly mentioned, and the 
 excellent qualities of which, for fixing and hardening -tissue, have 
 already been pointed out, may, on account of its containing free 
 chromic acid, be advantageously used as a decalcifying fluid, but 
 only for small osseous structures (ossicula), or comparatively soft 
 temporal bones (of embryos, new-born infants, young animals, etc.). 
 For the decalcification of petrous bones of adults it is not suitable, as 
 the quantity of free chromic acid which it contains is only trifling. 
 Even with small bones, or those containing little calcareous matter, 
 it is necessary to use the liquid in abundant quantities, and to 
 frequently change it (at first every day, later every third or fourth 
 day). Five to ten drops of concentrated nitric acid, added at the 
 end of the first week to half a litre of Miiller's fluid every time it is 
 changed, will, without causing any injury, considerably shorten the 
 process, which, even with petrous bones of slight consistence, such 
 as those of very young individuals, takes weeks to complete. 
 
 For the histological investigation of organs of hearing taken from 
 embryos, children, or young animals, this method has its advantages, 
 because it preserves the elements of the connective tissue and nerve- 
 structures in a perfect condition, and the nerve-elements of the sound - 
 perceiving apparatus in the labyrinth admit, when decalcification has 
 
NITRIC ACID DECALCIFICATION. 201 
 
 been completed, of staining after one of the usual nerve-staining 
 methods (Weigert's hseraatoxylin,). 
 
 2. Chromic Acid Method {Wcddeyer, Gottstein, Moos) .—¥ov decalci- 
 fying the petrous bone Waldeyer recommends an aqueous solution of 
 chromic acid, with the following directions : The superfluous soft parts 
 and osseous portions having been removed, the object is first placed 
 in a weak solution of chromic acid (1 :G00), remains there for several 
 days, is then transferred to another solution of the same acid of 1 : 400 
 water, and after a similar interval to a stronger solution of 1 : 200 
 water. This solution is now used as the decalcifying fluid proper, and 
 is to be renewed every Ave or six days, when, to shorten the process, 
 2 g. of oflicinal concentrated nitric acid are added to every 100 g. of 
 the fluid. After perfect decalcification, which with petrous bones of 
 adults takes three months to complete, the preparation is quickly 
 washed in water and placed for a few hours in spirit. Only then 
 is it thoroughly washed and freed from acid by placing it for some 
 hours under a stream of water until the latter flows ofl" quite colourless. 
 The further proceeding is to immerse the object in spirits of wine, the 
 strength of which is to be gradually increased, absolute alcohol being 
 used a few hours before sectioning. 
 
 As a rule good results are obtainable by this method, as it has an 
 additional advantage, the chromium being an excellent hardening 
 agent for the soft parts. It has, however, one drawback, viz. : that in 
 the vicinity of the internal meatus there frequently remain undecalci- 
 fied portions of bone (Moos) which, when the rest of the preparation is 
 already soft, cannot be got rid of without injury to the entire object, 
 an exact histological examination thus becoming impossible. That the 
 chromic and nitric acid decalcification frequently causes alterations in 
 the labyrinth, in Corti's and Deiters's cells, in the tunnel fibres, and 
 Reissner's membrane (Katz), which may easily be mistaken for patho- 
 logical changes, will be confirmed by those who have been making use 
 of this method for some time. Besides, through want of sufiicient 
 care in the proceeding, it may happen that the objects become too soft 
 and crumble away into a useless mass. 
 
 3. Picric acid in a saturated aqueous solution is well suited for the 
 decalcification of the petrous bones and ossicula of embryos and 
 children. When the study of the normal histological structures of the 
 labyrinth is intended, the decalcification by picric acid may be pre- 
 ceded by the gilding of these parts. To decalcify the hard petrous 
 bones of adults picric acid is not to be recommended, on account of its 
 comparatively slow action. 
 
 4. Nitric Acid Decalcification. — The fluid used in the process is 
 made up of 100 parts water, 3i parts nitric acid, and f of ^ 
 
202 HYDROCHLORIC ACID DECALCIFICATION. 
 
 part chloride of sodium. The solution, which is to be used in large 
 quantities, is at first changed every day. Normal organs, on which 
 the mucous membrane of the middle ear or labyrinth are to be 
 examined, must before decalcification be fixed in Miiller's fluid or in a 
 solution of osmic acid. In pathological cases I allow, as a rule, fix- 
 ation in yiakovic's solution to precede decalcification by nitric acid 
 (see p. 195). But for the examination of the external and middle 
 ear it is'often sufficient to place the object in the medium direct, as a 
 8% solution of nitric acid alone is an excellent means of hardening, 
 and often used for histological purposes. Decalcification and softening 
 are effected by this method in a perfectly safe and uniform manner 
 without detriment to the soft parts of the organ. For the study of the 
 pathological condition of the ear the nitric acid method is of special 
 value, as by the action of the acid the karyokinetic figures are 
 rendered visible. The decalcification of a human temporal bone is 
 completed by this method in twenty to twenty-five days. The pre- 
 parations are then well washed and preserved in 50% alcohol. By 
 rectified or absolute alcohol the decalcified bone is hardened to 
 such a degree that it must be placed in warm water, or in warm 
 dilute alcohol, to restore its consistence sufficiently to render it fit for 
 cutting. 
 
 5. HydrocJiloric Acid Decalcification. — For decalcifying the organ 
 of hearing, hydrochloric acid should not be used in an aqueous, but in 
 an alcoholic solution, on account of its causing the soft parts to swell 
 out. Besides, it is advisable to add a small quantity of chloride of 
 sodium to the acid solution. For the histological examination of the 
 labyrinth the hydrochloric acid method is not to be recommended, 
 because of its injurious action upon the labyrinthine structures, the 
 macul. acustica^, and Corti's organ, but as a rapid method when 
 making topographical sections of the entire organ. We employ for 
 our purpose a mixture consisting of 5 to 15 parts of concentrated 
 hydrochloric acid, 1,000 parts rectified spirit, 200 parts water, and 
 5 parts common salt. The latter counteracts the swelling out of the 
 connective tissue caused by the hydrochloric acid. Large quantities 
 of the liquid, and its renewal from day to day, are absolutely necessary 
 if rapid and good results are to be obtained The washing and pre- 
 serving of the decalcified organs to be carried out as in the previous 
 method. 
 
 3. EMBEDDING AND SECTIONING. 
 
 When, by the proceeding explained above, the tissue-elements 
 have been fixed and hardened, and the entire organ has been reduced, 
 by the decalcification of its osseous parts, to a consistence which admits 
 
EMBEDDING OF PREPARATIONS FOR HISTOLOGICAL PURPOSES. 203 
 
 of cutting, the preparation must be embedded in the regular way, so 
 that, during sectioning, the dehcate structures of the middle ear and 
 of the labyrinth may be retained in situ. Embedding is indispensable, 
 not only when making sections of the tympanic membrane, of tlie 
 articulations of the ossicula, and of the labyrinth, but also where it is 
 intended to cut the entire organ into serial sections for topographico- 
 histological and pathologico- anatomical purposes. It is obvious that 
 the sound-conducting and sound-perceiving organs, suspended m the 
 cavities of the temporal bone (tympanic membrane, ossicula and their 
 articular connections, membranous labyrinth, saccules, ampullae, 
 membranous semicircular canals, Corti's organ, can only be per- 
 fectly preserved in situ on sections, if these cavities have been pre- 
 viously filled with some medium which, at first fluid, but stiffening 
 afterwards, will retain all the parts in their natural positions. If this 
 is not done, some of the structures only loosely connected with the 
 osseous walls of the middle ear or of the labyrinth might fall out of 
 the section. Besides, these delicate structures are so liable to injury 
 that, in order to prevent their being torn, it is requisite to entirely fill 
 up the cavities with a medium which, though sufficiently firm, will 
 admit of cutting, and allow, even in sections, all parts to remain m 
 their normal connection and position. 
 
 The older embedding masses— among which we mention mucilage 
 (hardening in alcohol), glycerine glue (fluid when hot, firm at room 
 temperature), paraffin (5 parts paraffin, 2 parts spermaceti, 1 part 
 pure hog's lard), the mixture of oil and wax, the white of an egg 
 —are, with the exception of paraffin, which is still made use of m 
 some cases, of little value in oto-histology, since we have been 
 made acquainted by Schielferdecker and Duval with celloidin, an 
 embedding medium which answers the purpose in every respect. 
 
 Celloidin, a substance resembling collodion, is procurable in the 
 trade as white transparent cakes, and has the property, when mixed 
 with ether and absolute alcohol (in equal parts), of gradually dis- 
 solving into a syrupy fluid, which, however, again solidifies as soon 
 as the dissolving medium is allowed to evaporate, or if dilute alcohol 
 be added. 
 
 1. Formula for the celloidin solution. 
 
 For oto-histological purposes, three solutions in different degrees 
 of concentration should always be kept in readiness : one thin-fluid, 
 another somewhat stiffer, and a thick-fluid one. The first is prepared 
 by placing 30 g. of chemically pure celloidin, cut into small cubes, 
 in a vessel hermetically closed by a glass stopper, and containing a 
 mixture of 30 g. absolute alcohol and 30 g. sulphuric ether. 
 
 The second solution is obtained from a mixture of equal parts 
 
204 METHOD OF CELLOIDIN EMBEDDING. 
 
 (25 g.) of alcohol and ether, in which 30 g. of celloidin are dissolved. 
 Finally, the most concentrated solution is made by dissolving 30 g. of 
 celloidin in alcohol and ether (20 g. of each). With frequent shaking 
 of the mixture, the solutions of the required consistence (oil or thick 
 syrup) will be ready in a few days, and are to be used according to 
 the directions which shall be given later on. 
 
 2. Preparation of the structures of the ear for celloidin em- 
 bedding. 
 
 (a) The completely decalcified objects are first thoroughly washed 
 in distilled water, which must be frequently changed, until they are 
 perfectly freed from the acid. 
 
 After this the tympanic cavity, semicircular canals, and cochlea 
 should be opened according to the methods described, so as to allow 
 the embedding substance to penetrate into the cavities of the temporal 
 bone. 
 
 (b) Then the preparation must be thoroughly dehydrated, because 
 the celloidin could not enter any tissues, or tissue spaces, containing 
 water. For this purpose the object is placed for twenty-four hours in 
 dilute, and afterwards from one to two hours in concentrated, alcohol. 
 When structures of the external and middle ear are under examina- 
 tion, the specimen may be transferred direct from the absolute alcohol 
 to the celloidin solution. In the case of the labyrinth, however, 
 where it is absolutely necessary that all the spaces should be com- 
 pletely filled with the medium, the preparation is taken from the 
 alcohol into a mixture of 6 parts sulphuric ether and 1 part absolute 
 alcohol, where it is to remain for at least twelve hours. 
 
 (c) After this the preparation is placed in a weak solution of 
 celloidin, where it remains from one to three days, according to the 
 size of the object. Preparations of the external and middle ear may 
 be transferred from this solution direct to the thick-fluid celloidin 
 mass. Those of the labyrinth, however, in order that the embedding 
 may be the more successful, are taken from the weak solution into a 
 more concentrated one, and from this into the thick fluid. 
 
 3. The organs, permeated with the celloidin solution, are taken 
 out at the end of twenty-four to thirty-six hours, and placed in a 
 small paper case of corresponding size, which has been previously 
 filled to about one-third with partially-set celloidin. Then the most 
 concentrated solution of the medium is quickly poured over the 
 preparation, and left for two to three hours under a bell-glass to allow 
 it to thicken by evaporation. After that the embedded object is 
 transferred to 80%, and at the end of five to six hours to 70%, alcohol, 
 where, in the course of twenty-four to forty-eight hours, the whole 
 mass will set, and become fit for cuttinsf. 
 
MAKING MICROSCOPICAL SECTIONS OF ORGAN OF HEARING. 205 
 
 Before embedding the preparations it must be determined whether 
 they have not been over-hardened by the absolute alcohol, in which 
 case they must be softened again in warm dilute alcohol. This 
 proceeding should also be observed when the object has become over- 
 hardened by the celloidin embedding itself, which frequently happens 
 with preparations decalcified in the nitric acid and salt solution. 
 
 In order not to miss the direction of the cut when making sections 
 on embedded preparations, that surface which in the microtome comes 
 to lie upwards is, before embedding, brushed over with carmine, which 
 shines through the transparent medium. 
 
 If the embedding is perfect, the celloidin, when set, must in the 
 microscopic section completely surround all the tissues, and retain 
 them in situ. The medium being quite transparent in thin sections, 
 it in no way interferes with the microscopical examination. The 
 celloidin may easily be removed from the sections by placing them 
 in a mixture of alcohol and ether for a quarter of an hour, clearing 
 up being effected with oil of cloves. This should, however, not be 
 done under any circumstances, when it is intended to examine those 
 structures of the middle ear (ossicula, bridges of connective tissue) 
 and in the labyrinth (saccules, ampullse, semicircular canals, and 
 cochlear membranes) which are only loosely connected with the 
 osseous walls, because by dissolving the fixing medium these 
 structures would fall out of the section. On the other hand, where 
 the various parts of the organ are to remain in situ, care ought to 
 be taken in any proceeding with the sections that the fixing substance 
 be preserved. When sectioning the preparations, the blade of the 
 knife must, therefore, not be moistened with absolute alcohol, but 
 common spirit should be employed. 
 
 Fhotoxylin, which in recent years has been recommended as a 
 substitute for celloidin for embedding purposes, has, in my own oto- 
 histological investigations, not proved so useful. It certainly possesses 
 the advantage of dissolving in a few minutes in alcohol and ether, but 
 it has the great drawback that, during dehydration of microscopical 
 sections in absolute alcohol, the photoxylin layer easily dissolves, and 
 the preparation falls in pieces. 
 
 Mention might here be made of the rather complicated method 
 of paraffin embedding, as practised in the laboratory of Professor 
 Klebs, of which I myself have no experience, but which, according 
 to the statements of Dr. Rohrer, of Zurich, offers many advantao-es 
 for special examinations of the membrana tympani and of the laby- 
 rinth. 
 
 (1) The previously fixed and decalcified preparation is, for the 
 purpose of dehydration, placed in absolute alcohol. 
 
206 CUTTING AND STAINING OF THE MICROSCOPICAL SECTIONS. 
 
 (2) From the alcohol the preparation is transferred to pure aniUne 
 oil, in which it remains at a constant temperature of 40^ to 60° for 
 twenty-four to thirty-six hours, until the object becomes of a glassy 
 transparency. 
 
 (3) After this the specimen is placed for twenty -four to thirty-six 
 hours in xylol, which during that time must be twice renewed, until 
 the aniline oil has been completely got rid of. 
 
 (4) Next the preparation is transferred to xylol, slightly mixed 
 with paraffin ; and finally 
 
 (5) Into pure melted paraffin of 56° C, under which temperature 
 it is to remain for forty-eight hours. 
 
 • When the paraffin mass has become cold and set, the preparation 
 is taken out and cut in the microtome. 
 
 The sectioning is carried out in the usual way. On the whole, 
 cutting with a well-constructed sliding microtome is for our purpose 
 much to be preferred to all other methods, especially on account of 
 the evenness obtainable in the sections and there being no loss of 
 material, while the whole manipulation is more expeditious. Where 
 serial sections are required, this method is altogether indispensable. 
 For several years I have been using the automatic sliding microtome 
 of Reichert of Vienna ; on rare occasions one of his hand-microtomes, 
 which for small objects and for less minute examinations are quite 
 sufficient. 
 
 The decalcified osseous tissue offering greater resistance to the 
 knife of the microtome than hardened soft parts, most preparations 
 must, during the sectioning, be fixed in clamps, because fastening them 
 simply upon cork with celloidin, as was formerly done, does not give 
 the object sufficient firmness. 
 
 4. STAINING OF THE SECTIONS. 
 
 We employ for oto-histological purposes principally the following 
 dyes and staining methods : 
 
 1. Carmine Staining. — Carminate of ammonia and Beale's carmine 
 are specially adapted for staining decalcified bones and cell-proto- 
 plasms, without colouring the nuclei. By leaving the specimens for 
 twelve to twenty-four hours in a greatly diluted rose-coloured carmine 
 solution (slow carmine staining), the sections take a beautiful colour 
 (Stohr). 
 
 Picro-carmine* is chiefly employed for pathologico-histological 
 examinations of the organ of hearing (pathological ossifications, de- 
 
 * Carmini, Amnion, pur. lisf. . aa 0.50, Aq. dest. 25.0 ; cui digerendo adde Acidi picrin. 
 cone, puri 75.0 etfiltra. Dein adde Phenoli puri gtts. dnas. 
 
STAINING OF THE MICROSCOPICAL SECTIONS. 207 
 
 structive and tuberculous osseous processes in the temporal bone, 
 round-cell proliferation). It stains the osseous tissue brick-red ; the 
 medulla and cell-protoplasm, as' well as the muscular fibres, take a 
 diffuse yellow colour ; while the cell-nuclei appear cherry-red. 
 
 Staining for five minutes, then immersion for half an hour in a 
 hydrochloric solution of glycerine (1 : 100), then washing in water and 
 alcohol. 
 
 For rapid and durable nucleus-staining, alum-carmine* is also 
 to be recommended (Grenacher), as it offers the additional advantage 
 that the sections, even when left for a considerable time in it, do not 
 become over-stained. Five to ten minutes are sufficient to give a 
 perfectly distinct colour. 
 
 2. Eosin in a 5% solution, poured drop by drop into a watch-glass 
 filled with distilled water or alcohol in which the sections have been 
 placed, gives in a few minutes a bright-red colour, without differen- 
 tiating nuclei and cells (rapid staining). We therefore employ it as a 
 ground-colour, to be followed by a suitable differentiating dye for the 
 nuclei. This is effected, after thorough washing of the sections in 
 alcohol, by after-staining in hsematoxylin, methylene blue, or gentian 
 violet. 
 
 3. Hcematoxylin. — We prefer the hsematoxylin-alum stain (hsema- 
 toxylin 2.0, alcohol absol. 100.0, aq. destill. 100.0, glycerin, pur. 2.0, 
 alum. pulv. 2.0), as mentioned in Friedlander's microscopic technique. 
 To be filtered every time before it is used. Does not stain well until a 
 week after it has been prepared. In a few minutes the sections are 
 ■coloured brown, but change to blue in distilled water, in which 
 they must be washed for a quarter of an hour to two hours. The 
 dye gives the nuclei, the decalcified bone, and its vessels a beautiful 
 blue. 
 
 Bacteria- Staining on Sections. 
 
 To show the presence of micro-organisms on sections of the 
 auditory organ, after it has been preserved in absolute alcohol and 
 decalcified by nitric or hydrochloric acid (see Decalcification), Ave 
 recommend Lofller's ' universal bacteria-staining ' method. When 
 perfectly free from acid, the sections are left for five to ten minutes in 
 an alkaline solution of methylene blue (30 ccm. concent, alcoholic 
 methylene blue solution to 100 ccm. 0.01% solution of caustic j^otash). 
 Wash for a few seconds in 1% acetic acid, then place in alcohol, clear 
 up with cedar-oil, and mount in Canada balsam. All schizomycetes, 
 especially diphtheric micro-organisms and pyogenic cocci, as well as 
 the mycelia of mould-fungi (aspergillus), take a beautiful blue. 
 
 * Carmini 1.0. Alumin. pulv. 5.0. Aq. dest. 95.0 leni calore solvet et filtret. 
 
208 CLEARING AND MOUNTING OF THE SECTIONS, 
 
 Bacteria may also be stained separately by Gram's method. Staining 
 in aniline-gentian ; decolorization by alcoholic solution of iodine. 
 
 For the demonstration of tubercle-bacilli in sections of carious 
 portions of the temporal bone, we particularly recommend the staining 
 method suggested by Ziehl-Neelsen. The solution employed is the so- 
 called carbol-fuchsin,* in which the sections remain fifteen to twenty 
 minutes. Decolorization with 25% sulphuric acid, washing in rectified 
 alcohol ; after- staining (three minutes) in a watery solution of methy- 
 lene blue. Bacilli red, cells and tissues blue. 
 
 5. CLEARING AND MOUNTING OF THE SECTIONS. 
 
 The further treatment of the sections after staining, up to their 
 mounting under glass, is carried out after the following well-known 
 methods : (1) Dehydration of the sections in absolute alcohol, according 
 to their size and thickness, for five to fifteen minutes. (2) Careful 
 liftincy out of the sections from the alcohol by means of a metal 
 spatula bent at a right angle to the handle, and drying with fine 
 blottino'-paper. (3) Clearing of the section. With preparations 
 embedded in celloidin, this must be done either by steeping in 
 orio-anum oil of the finest quality, or in aniline oil, ol. thy mi., cedar 
 oil. On the other hand, the use of oil of turpentine and oil of cloves 
 must be avoided, as these, through dissolving the celloidin, cause a 
 milky cloudiness of the object, and dislocation of the more delicate 
 structures. With paraffin embedding, however, the last-named oils are 
 of great service, in so far as the preparations are not only cleared, but 
 the paraflin is also dissolved, without the transparency of the sections 
 being thereby diminished. (4) Transferring the preparation with the 
 metal spatula on to the glass slip, where, after mopping up the ethereal 
 oil with blotting-paper, the sections are mounted in Canada balsam. 
 Thick, not sufficiently transparent sections are cleared by adding a 
 drop of xylol to the balsam ; generally, however, xylol (only to be 
 employed in paraffin embedding) renders the objects too transparent, 
 which sometimes makes the differentiation of the tissues a matter of 
 greater difficulty. 
 
 Sections which are to be preserved in glycerine are first of 
 all washed in distilled water, then mounted in somewhat diluted 
 "■lycerine, and the edges of the cover-glass cemented with black japan 
 or white Frankfort lac. Celloidin sections do not alter in glycerine, 
 but those embedded in paraffin cannot be mounted in that medium. 
 Sections are now generally mounted in Canada balsam or Dammar, 
 less frequently in glycerine. For the study of pathological changes in 
 
 * Rp. Fuchsin 1.0, Alcohol, absol. 10.0, Aq. carbol. 5% 100.0. 
 
MAKING SERIAL SECTIONS OF THE ORGAN OF HEARING. 209 
 
 the structures, however, it is recommended to mount a few sections of 
 a preparation in glycerine also, because some details stand out more 
 clearly in that medium than in Canada balsam or Dammar. 
 
 6. SERIAL SECTIONS. 
 
 For the making of serial sections, particularly of the smaller 
 structures — cochlea, semicircular canals, transverse sections of the 
 membrana tympani, malleo-incudal articulation, system of cavities 
 between malleus and incus and external tympanic wall, mucous 
 lining of the tympanum, etc., where it is of importance to deduce 
 from the series of sections the topography of the parts concerned — it 
 is advisable to make use of the following method, practised at the 
 zoological stations for the study of the smaller animals, and for the 
 details of which I am indebted to Dr. KoUer. 
 
 Staining in toto (1) in Ranvier's picro-carmine solution, (2) alco- 
 holic hsematoxylin solution, or (3) in borax-carmine. 
 
 The piece of tissue is transferred direct from the alcohol to the 
 staining fluid, and left there, according to its size, for two to four 
 days (in borax-carmine, one to two days). It is then washed (de- 
 colorized) in 70% alcohol (if borax-carmine be used, in acid alcohol). 
 Duration of the decolorization, from a quarter of an hour to an 
 hour. 
 
 Then the preparation is, for the purpose of dehydration, placed 
 for several hours in absolute alcohol. It is next soaked in turpentine, 
 after that removed to a mixture of turpentine and paraffin (on a water 
 bath of 60°), is left there for several hours, and for a like space of time 
 in pure (hard) paraffin. 
 
 After the embedding, the melted paraffin is made to set rapidly, 
 by dipping in cold water, so as to give it a glassy, not white, snowy 
 appearance. 
 
 The glass slip is painted over with as thin a layer as possible of 
 equal parts of collodion and oil of cloves ; the sections are placed upon 
 it, and exposed for ten to fifteen minutes to a temperature of 60°, to 
 allow the paraffin to melt and the oil of cloves to pass off. Thus, the 
 section is firmly fixed upon the glass, which is then laid in a saucer 
 containing turpentine, to extract the paraffin. The mounting in 
 Canada balsam or Dammar is the same as with the other methods. 
 
 For making serial sections of some particular parts of the organ 
 of hearing, a method* devised by Dr. Ignazio Dionisio, of Turin, is 
 recommended, a description of which is here given. The microscopic 
 sections are arranged in their order on the slip, and covered with a 
 
 * From the laboratory of Prof. Schenk in Vienna. 
 
 14 
 
210 MAKING SERIAL SECTIONS OF THE ORGAN OF HEARING. 
 
 fine metallic net prepared for the purpose. By a special contrivance 
 the net is fastened at both ends of the slip with two clamps, so that 
 all the sections are fixed alike, none of them being pressed too hard. 
 The whole of the preparations can be subjected to the usual treat- 
 ment of microscopic sections, by placing the slip, still fixed in the 
 apparatus, in the staining fluid, then alcohol, and, lastly, in oil of 
 xjloves or origanum oil. When the preparations have been sufficiently 
 cleared in one of the last-mentioned oils, any superfluous oil is 
 soaked up by gently pressing blotting-paper upon the net; this 
 is then removed, and the sections are mounted in Canada balsam or 
 Dammar. 
 
 This method has the advantage that even the thinnest sections do 
 not curl up during treatment in the various liquids, and that the pro- 
 cedure of staining and clearing up, which with most of these methods 
 takes a considerable time, is materially shortened. 
 
 Some special methods of the microscopic technique, in particular 
 those employed in the examination of Corti's organ and the central 
 course of the acoustic nerve, will be discussed in the following part 
 of the work, having for its object the description of the histological ex- 
 amination of the various portions of the organ of hearing. 
 
SPECIAL PART. 
 
 I. 
 
 The Histological Examination of the Auricle and of the 
 Cartilaginous Meatus. 
 
 For hardening and preserving the auricle and cartilaginous meatus, 
 Miiller's fluid (p. 195) is best adapted. The preparation, having been 
 left for two to three weeks to the action of the medium, is washed 
 for an hour or two in distilled water, and hardened for three to four 
 days in alcohol, which is to be gradually increased in strength. The 
 parts to be examined are embedded either in celloidin or in paraffin, 
 or sectioned between elder-pith, stained with carmine, eosin, picro- 
 carmine or hsematoxylin, after which the sections are mounted, some 
 in Dammar, others in glycerine. 
 
 Sections of the normal auricle show: (1) The diameter (1-2 mm.) 
 and the structure of the elastic cartilage, which proves to be fibro- 
 cartilage. (2) The thickness of the perichondrium, the elastic fibres 
 of which are connected, on the one side, with those of the auricular 
 cartilage, and with those of the subcutaneous connective tissue on 
 the other. (3) The structure of the integument, which shows all the 
 elements of the cutis, with this difference, that on the convex side, 
 particularly on the concha, the papillae are very low, and that the 
 numerous sebaceous follicles, with greatly dilated excretory ducts, 
 empty themselves on the surface, while the sweat glands are here 
 almost entirely wanting. Successful capillary injections of the cutis 
 with carmine glue or Berlin blue yield beautiful representations of 
 the arrangement of the bloodvessels, which may be traced from the 
 cutis into the perichondrium. 
 
 The histological examination of the cartilaginous meatus is best 
 conducted on sections made perpendicularly to its long axis. For 
 this purpose the cartilagino-membranous portion of the meatus is 
 carefully dissected away from the osseous, then either embedded in 
 celloidin or filled with paraffin, and sectioned in the microtome in a 
 vertical direction to its long axis. The ring-shaped sections bring 
 
 14—2 
 
212 HISTOLOGICAL EXAM. OF CARTILAGINO-MEMBRANOUS MEATUS. 
 
 into view the relationship of the circumference of the cartilaginous 
 to the membranous portion of the meatus, and, with suitable staining, 
 yield a clear representation of the position of the hair-follicles, of the 
 acinose sebaceous glands, and of the ceruminous glands in the cutis 
 (Fig. 131). The sebaceous glands (o o') discharge for the most part 
 laterally into the hair-follicles (h h'), less frequently on the surface of 
 the cutis. Below the layer of the hair-follicles there lie, in the sub- 
 cutaneous connective tissue, rolled up like a ball, the ceruminous- 
 
 
 Tig. 131.— Section through the cutis of the cartilaginous meatus of a new-born infant, 
 h h' - hair-follicles ; m = opening of ji hair-follicle on the surface of the cutis ; o o' =' 
 sebaceous glands, discharging laterally into the hair-follicle ; c c' = section through the 
 coil of_ ceruminous glands in the deeper layers of the cutis ; gg' = excretory duct of the 
 ceruminous gland ; s = lateral discharge of this duct into the hair-follicle. After a 
 preparation of Dr. Gompertz. 
 
 glands (c c'), resembling the sweat glands. The diameter of the 
 glandular tube measures, according to Schwalbe, 0.1 mm., that of 
 the glandular body, 0.2-1..5 mm. Their excretory ducts (g g') are 
 narrow (0.01 mm.), and open, according to Stohr, in children laterally 
 
HISTOLOGICAL EXAMINATION OF LINING OF OSSEOUS MEATUS, 213 
 
 into the hair-follicles (s), in adults on the surface of the meatus, close 
 to the hair-follicles. Their brownish-yellow colour is often retained, 
 even on stained sections. If the vessels are successfully injected, the 
 fine capillary network with which the ceruminous glands and hair- 
 follicles are enclosed may be beautifully demonstrated. 
 
 In order to become acquainted with the arrangement of the hair- 
 follicles and glandular elements of the cutis, and its epithelial lining, 
 a series of cuts should be carried through the cutis, parallel to the 
 surface of the meatus, consequently vertically to the long axis of the 
 follicles and ceruminous glands. These have a cubical epithelium 
 of a single layer (Stohr), to which, externally, a layer of smooth 
 muscular fibres and a membrana propria succeed. The epithelium is 
 covered internally by a cuticular seam, which is especially distinct in 
 adults. 
 
 Pathological preparations of the auricle and cartilaginous meatus 
 intended for microscopical examination are subjected to the same 
 treatment. But objects hardened merely in alcohol also yield useful 
 sections. Suitable for simple alcohol hardening are especially : retro- 
 gressive changes in the auricle (age metamorphoses), and those 
 peculiar connective - tissue proliferations and lacuna -formations as 
 described by Pareidt and J. PoUak ; also the deposit of lime salts, 
 gouty concretions, thickenings of the perichondrium, ossifications 
 (Bochdalek, J. PoUak), etc. On the other hand, carcinomatous 
 degeneration of the auricle, inflammatory infiltration of the cutis, 
 abscesses in the cartilaginous meatus, ruptures and fistulous tracts 
 in the incisures Santorini, and changes in the glandular elements of 
 the cutis should always be fixed and hardened with chromic salt 
 solutions, or Miiller's fluid. It is to be understood that in those cases 
 where sections are examined for the presence of micro-organisms, the 
 method described on p. 207 must be followed to demonstrate them. 
 
 II. 
 
 The Histological Examination of the Lining of the 
 Osseous Meatus. 
 
 As the lining of the osseous meatus is intimately connected with 
 the periosteum, its histological relations are best examined on temporal 
 bones that have been previously treated with Miiller's fluid and sub- 
 sequently decalcified, and from which the osseous meatus is cut out, 
 along with its cuticular lining. 
 
 The cutis and the periosteum of the osseous meatus are in close 
 connection. With the exception of that triangular space before 
 
214- HISTOLOGICAL EXAMINATION OF THE MEMBRANA TYMPANI. 
 
 mentioned (p. 56), wliicli extends on the posterior superior wall^ 
 from the cartilaginous into the osseous meatus, the glandular elements 
 are entirely wanting in the pars ossea. But the lining shows a spirally 
 arranged ledge-shaped fold of the cutis (Kaufmann), which, on sections 
 made vertically to the direction of the fold, shows a papillary arrange- 
 ment. Besides, there are found, especially at the inner portion, in the 
 vicinity of the tympanic membrane, vascular papillae which, particu- 
 larly in the foetus and new-born infant, are strongly developed, and 
 can be followed up to the peripheral part of the membrane (Moos). 
 On injected preparations the entrance of the bloodvessels, accompanied 
 by processes of the periosteum, can be traced from the cutis into the 
 osseous walls of the meatus, and from here, not infrequently, into the 
 mastoid process and the cavum tymp. These anastomoses explain 
 the strong injection of the cutis in inflammations of the tympanic 
 cavity and of the mastoid process. 
 
 To demonstrate the relation of the dermic layer of the meatus to 
 the membrana tympani, sections are made on decalcified preparations, 
 in which the meatus has been left in connection with the tympanic 
 membrane, the cuts being carried in the long axis of the meatus, 
 some in a frontal, others in a horizontal direction. Very instructive 
 are those frontal sections which show the transition of the cutis and 
 its bloodvessels from the superior wall of the meatus on to the tym- 
 panic membrane. 
 
 In like manner the osseous meatus is histologically examined in 
 pathological cases, where it is a question of becoming acquainted with 
 the changes in the inflammatorily infiltrated cutis, or papillae, and 
 polypous proliferations thereon, carcinomatous infiltration of the 
 lining spreading from the cartilaginous meatus or from the parotid 
 gland ; the histological condition of membranous and osseous stric- 
 tures and atresise of the meatus, and the simultaneous alterations in 
 its osseous walls. 
 
 HI. 
 
 Histological Examination of the Membrana Tympani. 
 
 The tympanic membrane, loosened from the sulcus tymp. (p. 75), 
 may be subjected to histological examination by several methods. 
 
 (a) Histological Examination on ^Surface Preparations. 
 
 This is proceeded with in various ways. 
 
 1. In the fresh state, by the dissection of the membrane into three 
 layers. For this purpose two fine pincettes are used, with which^ 
 starting from the annulus tendinosus, and proceeding towards the 
 
HISTOLOGICAL EXAMINATION OF THE MEMBRANA TYMPANI. 215 
 
 handle of the malleus, the dermic layer is first separated from the 
 radiating fibrous layer, and then the latter from the circular fibrous 
 layer (Toynbee, Von Troltsch). The work of preparing is the easier, 
 as these layers of the tympanic membrane are only connected by a 
 few bundles of connective tissue. The circular fibrous layer and the 
 mucous membrane lamina, on the other hand, are so intimately united 
 that their anatomical separation is impossible. The membrana 
 tympani, dissected into three layers, and suspended in a small glass 
 vessel by means of a thread fastened to the neck of the malleus (plate, 
 p. 191, Fig. VI.), furnishes an instructive object for demonstration. For 
 microscopical examination the separated layers are cut off with a fine 
 pair of scissors from the manubrium, then stained and mounted after 
 the methods already described. 
 
 2. After removal of the handle of the malleus, without dissecting 
 the tyvipanic membrane into its various layers. With this object, 
 after the membrane has been loosened from the sulcus, the tympanic 
 layer covering the inner edge of the manubrium is slit length-wise 
 with a small sharp knife, then slightly drawn back from the lateral 
 surfaces of the handle, and after that the entire hammer is carefully 
 detached from the membrana tympani with a fine pincette. After 
 pencilling over both surfaces of the membrane, it is either treated 
 with hyperosmic acid (p. 198) or placed in MUller's fluid (p. 195). In 
 the former case the preparation being coloured brown by the process 
 of fixation, dehydrated in alcohol and cleared, shows, besides the 
 direction of the fibres of the substantia propria, frequently also the 
 bloodvessels of the cutis and mucous membrane layer, as well as the 
 nerve plexus of the cutis. The last-mentioned differentiate well under 
 gold treatment (Kessel). By fixation in Miiller's fluid, the direction 
 of the fibres in the tympanic membrane will only stand out strongly 
 marked after staining with eosin, alum-carmine, or hsematosylin. To 
 examine both surfaces of the membrane, it is divided with a flue 
 pair of scissors into several triangular segments directed towards 
 the lower extremity of the manubrium ; they are mounted, some 
 with the surface of the mucous membrane, others with that of the 
 cutis, upwards. 
 
 The examination of the outer side of the tympanic membrane 
 displays, on surface preparations behind the manubrium, after careful 
 brushing over of the epidermic layer, a band-like stria passing at an 
 acute angle to the lower end of the handle, so that there remains 
 between it and the manubrium a transparent space in the shape of a 
 triangle, directed downwards (cutis strand of Von Troltsch, Prussak's 
 descending fibres). This fibrous band, radiating starlike at the lower 
 extremity of the handle, is the continuation of a cutaneous stria 
 
216 RADIATING AND CIRCULAR FIBROUS LAYER OF MEMBRANA TYMPANI. 
 
 passing from the upper wall of the meatus to the tympanic membrane, 
 and gives passage to the bloodvessels and nerves which cross from 
 the external meatus on to the membrane. The radiating vascular 
 ramifications of the dermic layer, as well as the peripheral corona 
 vascularis of the membrana tympani, and the vascular plexus behind 
 the manubrium, appear especially clear on the membrane of the new- 
 born infant, if the vessels be macroscopically strongly injected, and if 
 the object be treated in a perfectly fresh state with osmic acid. 
 Kessel asserts that he has also demonstrated the presence of a 
 fine network of lymphatic vessels in the dermic layer of the tympanic 
 membrane. 
 
 Although the direction of the fibres of the substantia propria, par- 
 
 
 Fig. 132. — Segment of the lower portion of the tympanic membrane. — h = handle of the 
 malleus ; r — layer of radiating fibres ; c = layer of circular fibres. 
 
 ticularly that of the radiating fibrous layer, can also be examined on 
 successful surface preparations from the dermic side, it is best demon- 
 strated from the inner side of the membrane (Fig. 132). The radiating 
 fibres, which arise from the tendinous ring, and in places unite at an 
 acute angle, converge in the lower segment towards the inferior 
 extremity of the manubrium to become attached to its spatula-shaped 
 expansion (h). In the vicinity of this place of attachment there arises, 
 partly through condensation of the radiating fibres meeting there, 
 partly through deposition of small cartilage - cells, the so-called 
 umbilical opacity of the membrana tympani (yellow spot, Trautmann). 
 In the upper segment, the radiating fibres attach themselves to the 
 anterior edge of the handle, and appear sharply defined at the 
 boundary of Shrapnell's membrane. The inner circular fibrous layer 
 
MICROSCOPIC DETAILS ON INNER SURFACE OF TYMPANIC MEMBRANE. 217 
 
 (c) does not reacli up to the outer periphery of the membrane. It 
 appears most dense in the neighbourhood of the tendinous ring, while 
 towards the centre it diminishes in density, and is lost close to the 
 extremity of the manubrium. It is attached, with the greater mass 
 of its fibres in the upper segment of the membrane, to the external 
 surface of the handle, especially at the short process. 
 
 On the inner surface of the membrana tympani there is an incon- 
 stant, greatly varying, fibrous framework (Fig. 133), which belongs to 
 its mucous membrane, and is most strongly marked on the posterior 
 segment. This framework, being spread over, sometimes smaller, at 
 other times larger spaces, is interrupted by roundish-oval interstices 
 of varying size. The processes of the framework radiate towards the 
 
 Fig. 133. — Fibrous trabecular structure in the posterior segment of the inner surface of the 
 tympanic membrane in the adult. — a = large interspace in the trabecular structure ; b = 
 small interspace, through which a thin process passes. 
 
 tendinous ring and the manubrium, and in part become closely united 
 with the fibres of the substantia propria. This trabecular structure, 
 which has been described by Gruber as a dendritic formation of the 
 membrana tympani, but which, in my opinion, is identical with 
 the inconstant fibrous processes in the mucous lining of the tympanic 
 ■cavity may be demonstrated under a low magnifj'ing power, even on 
 fresh preparations, after brushing away the epithelium of the mucous 
 layer ; but it stands out more sharply on preparations stained with 
 oarmine or ha^matoxjdin, and on such as have been treated with gold 
 or osmium. 
 
 On the tympanic membrane of the new-born infant there are found, 
 
218 HISTOLOGICAL EXAM. OF TYMPANIC MEMBRANE ON SECTIONS. 
 
 on surface preparations of the inner side, chiefly towards the periphery, 
 those papillae first described by Gerlach, covered with pavement 
 epithelium, and containing vascular loops which may be as readily 
 found on fresh preparations as on those which have been preserved in 
 MuUer's fluid. 
 
 The vascular network of the inner surface of the tympanic mem- 
 brane is best demonstrated on the new-born infant by injecting the 
 bloodvessels from the aorta, or common carotid, with liquid glue 
 coloured with carmine or Berlin blue (Moos). Beautiful specimens of 
 it may also sometimes be obtained on osmium preparations, par- 
 ticularly if the membrane, in the fresh state, be already naturally 
 injected. The closely meshed capillary network is developed out of 
 an artery which runs parallel to the handle of the malleus. 
 
 The fine, non-medullated nerve-fibres of the surface of the mucous 
 lining, described by Gerlach, may sometimes be seen on gold or 
 osmium preparations, and form, according to Kessel, a plexus, from 
 which nerve filaments penetrate into the epithelium. Kessel has also 
 succeeded, by treatment with nitrate of silver, in demonstrating a 
 system of lymphatics in the mucous covering of the tympanic mem- 
 brane. 
 
 (h) Histological Examination of the Memhrana Tympami on 
 
 Sections. 
 
 The structure of the tympanic membrane, especially its relation to 
 the manubrium, can only be represented on sections made on one 
 preparation, at a right angle to the long axis of the handle, and on 
 another through the entire length of the malleus and of the mem- 
 brane. For these examinations it is best to use a tympanic membrane, 
 which has been left in connection with the annulus tymp. These 
 sections offer the advantage of representing, at the same time, the 
 relationship of the annulus tendinosus, and of allowing the various 
 parts of the preparation to retain their relative positions better than 
 would be the case if the membrane were loosened out of the sulcus 
 tymp. 
 
 As a matter of course, in all cases where the memhrana tympani, 
 together with its osseous frame and the manubrium, are to be sub- 
 jected to microscopic examination, the slow decalcification of the 
 osseous portions in picric acid, or in the nitric acid and chloride of 
 sodium solution (p. 201), must always follow the fixing of the pre- 
 paration in Miiller's fluid or Vlakovic's solution (p. 195), which 
 requires eight to ten days. Embedding in celloidin or paraffin. In 
 embedding with celloidin, staining with alum-carmine or hsematoxylin 
 
HISTOLOGICAL EXAM. OF TYMPANIC MEMBRANE ON SECTIONS. 
 
 21» 
 
 must be avoided, because by over-staining the embedding medium 
 the clearness of the microscopic image suffers. 
 
 The appearance of the tympanic membrane on horizontal sections 
 shall first be discussed. In making serial sections in a horizontal 
 direction through the membrane, it is best to begin with the upper- 
 most part of the malleo-incudal articulation, and to continue the 
 sectioning to below the extremity of the manubrium. This mode of 
 proceeding has the advantage of affording information as to the ana- 
 tomical details of the malleo-incudal articulation and the relationship of 
 the space between the body of the malleus and incus, and the lateral 
 wall of the niche. In the examination of pathological preparations 
 this is of great importance, especially in those suppurative processes 
 
 Fig, 134. — Section through the tympanic membrane of an infant.— a = epidermic layer ;. 
 b = cutis layer ; c = layer of radiating fibres, with the ramified interstitial spaces ; d = 
 layer of circular fibres ; e = mucous layer. 
 
 which run their course in this space, and which are accompanied by 
 perforation of Shrapnell's membrane. Referring, as regards the 
 anatomical relations of this region, to a future chapter, we will here 
 first discuss the structure of the tympanic membrane on transverse 
 sections, the relations of the annulus tendinosus to the membrane, 
 and those of the latter to the handle of the malleus. 
 
 On microscopic sections of the tympanic membrane the following 
 details may be distinguished from without inwards (Fig. 134) : (1) 
 The epidermic layer, consisting of stratified pavement epithelium, 
 with its rete Malpighii (a) composed of cylindrical cells. (2) The con- 
 nective-tissue stratum of the cutis layer, with its bloodvessels and 
 nerves (b). This layer appears most strongly developed at and behind 
 the place of apposition of the manubrium to the tympanic membrane ; 
 it here attains a thickness of 0.4 mm. (Schwalbe), and in the upper 
 
220 EXAMINATION OF THE TYMPANIC MEMBRANE ON SECTIONS. 
 
 segment shows small papillary elevations. (3) The substantia propria, 
 having outwardly the layer of radiating fibres (c), inwardly the 
 circular fibrous layer (d), and between the fibre bundles the inter- 
 spaces and lymph channels (Troltsch's corpuscles), which on trans- 
 verse sections appear star-shaped, on longitudinal sections spindle- 
 shaped, and have a lining of endothelial cells. (4) The mucous 
 membrane layer (e), consisting of connective tissue, interspersed with 
 elastic filaments, conveying a capillary network of bloodvessels, and 
 covered by a non-ciliated pavement epithelium. 
 
 The bloodvessels and nerves of the various layers of the mem- 
 brane are examined on sections taken from preparations treated after 
 
 
 Fig. 135.— Section through the annulus tendinosus, embedded in the sulcus tymp., and 
 through the peripheral portion of the tympanic membrane.— su = sulcus tymp., with the 
 annulus tendinosus, the fibres of which merge, in an upward direction, into the r = layer 
 of radiating fibres of the tympanic membrane ; cu' = cutis of the lower wall of the external 
 meatus, continuous with the cu = cutis layer of the membrana tympani ; c = section of 
 the peripheral layer of radiating fibres of the tympanic membrane ; s = mucous layer of 
 the tympanic membrane and of the tympanum with its epithelial covering. After a pre- 
 
 ■ paration in my collection. 
 
 the gilding or osmic acid process ; the bloodvessels alone, also on 
 membranes where the capillary injection has been successful. The 
 largest transverse sections of the vessels and nerves of the cutis are 
 seen on its thickened portion behind the manubrium. The peri- 
 pheral vascular zone shows in sections numerous anastomotic con- 
 nections of vessels, passing through the interspaces of the peripheral 
 part of the membrane to the mucosa. On the intermediate zone, 
 lying between the manubrium and the periphery, some capillaries run 
 
HISTOLOGICAL EXAMINATION OF THE ANNULUS TENDINOSUS. 221 
 
 from the cutis into the substantia propria. From the nerve plexus of 
 the cutis Kessel saw small knotty filaments penetrating into the 
 epithelium. 
 
 Sections made through the decalcified osseous frame of the tym- 
 panic membrane are adapted for the examination of the structure of 
 the annulus tendinosus, and its relation to the membrane on the one 
 side, and to the cutis of the external meatus and the mucous lining of 
 the tympanum on the other. The tendinous ring (Fig. 135) appears 
 on sections in the form of a triangle, the serrated base of which is 
 inserted in the rough surface of the sulcus tymp. (su). At the apex 
 of the triangle the fibres of the annulus tendinosus pass over into the 
 radiating fibrous layer of the tympanic membrane (r), but some of the 
 
 tr 
 
 Fig. 136. — Section through the malleus and the posterior tympanic pouch at the level of the 
 short process of the malleus. — h = malleus ; br = cartilaginous portion of its short process ; 
 tr = posterior portion of the tympanic membrane ; fa = posterior fold of the tympanic 
 membrane ; ta = posterior pouch of Von Troltsch ; s = mucous lining of the tympanic 
 cavity. 
 
 fibrous bundles of the tendinous ring may also be traced up to the 
 periosteum of the osseous meatus, and to the mucous membrane of 
 the cavum tymp. The texture of the ring consists of connective- 
 tissue fibrillse, interspersed with elastic fibres, which cross each other 
 frequently, but contains, according to Schwalbe's and the author's in- 
 vestigations, no cartilage-cells. 
 
 As regards the anatomical relations of the tympanic membrane to 
 the handle of the malleus, the uppermost sections, made through 
 Shrapnell's membrane and the neck of the malleus, show the topo- 
 graphical relations between this membrane and the neck of the 
 
222 SERIAL SECTIONS THROUGH THE HEAD OF THE MALLEUS. 
 
 hammer, and, on successful preparations, the anterior and posterior 
 boundaries of Prussak's space. For an accurate knowledge of the 
 limits of this cavity, however, vertical sections, corresponding to the 
 long axis of the malleus, are required, to which we shall refer again 
 later on. 
 
 The horizontal series of sections, from the short process of the 
 malleus to the lower spatula-shaped extremity of the manubrium, 
 yields the following representations : 
 
 1. The section passing through the tip of the short process of the 
 malleus and through the upper part of the posterior tympanic pouch 
 shows (Fig. 136) the short process of the malleus (br), covered by a 
 thick layer of cartilage-cells, which is intimately connected with the 
 osseous substance of the malleus, and which is to be regarded, not as 
 a peculiar cartilaginous formation of the tympanic membrane 
 (Gruber), but as the residuum of the embryonic cartilaginous 
 hammer.^ Between the short process (br) and the osseous frame 
 of the tympanic membrane (kn), the section of the posterior superior 
 segment of the membrane (tr) appears covered, externally by the 
 cutis, internally by the mucous lining of the middle ear. Medially 
 from the membrane, the inner tympanic fold (fa) is stretched from an 
 osseous ridge near the sulcus tymp. to the handle of the malleus, 
 and forms, with the surface of the membrane opposite, the posterior 
 pouch of Von Troltsch (ta). The fibres of this fold are very similar 
 to those of the substantia propria of the membrana tympani (Von 
 Troltsch). On sections of the anterior tympanic pouch, it is not in- 
 frequently possible to follow the tense fibrous band of the ligamentum 
 mallei ant. entering the Glaserian fissure, the chorda tymp., and, in 
 the new-born infant, the longitudinal section of the long process of 
 the malleus (processus Folianus). The mucous covering of the tym- 
 panum (s) and the lining of the two tympanic pouches, which, in the 
 adult, are thin and present only few transverse sections of vessels, 
 appear in the new-born infant strongly tumefied, and show numerous, 
 often very wide, bloodvessels. 
 
 2. On a section made somewhat deeper (Fig. 137), the osseous 
 ridge (c), from which the inner tympanic fold (f) arises, appears more 
 strongly marked, and the space of the pouch (t) larger. On sections 
 made in this plane, we sometimes find this fold divided in the vicinity 
 of the manubrium into two laminae ("compare p. 77), the outer of 
 which is inserted on the posterior surface of the handle (v), while the 
 anterior (a duplicatare of the mucous membrane) passes to the 
 
 * Heinrich Miiller (Zeitsehrift flir wissenschaftl. Zoologie, Bd. ix.) proved, as early as 
 1858, the existence of layers of cartilage -cells ia the manubrium of the new-born infant and 
 of the adult. 
 
SERIAL SECTIONS THROUGH THE HEAD OF THE MALLEUS. 223 
 
 truncated part of the inner and posterior edge (1). At the same time 
 we notice the cross-section of the chorda tymp. (ch) in its connection 
 with the inner tympanic fold, and sometimes also inconstant filaments 
 and fibrous fasciculi stretched between the membrane and the fold. 
 3. The somewhat deeper section of the manubrium (Fig. 138), 
 
 ^'U£:;^::r;:3;:x3ss!k''a:csai:w^'« 
 
 ■^x-3B^- 
 
 je A f 
 
 
 Fig. 137. — Section through the upper part of the manubrium and of the posterior pouch of 
 the tympanic membrane, somewhat deeper than the previous one. — h = inner surface of 
 the handle of the malleus ; b = its outer edge ; p = section of the posterior superior 
 segment of membrana tympani ; v' = its insertion in the uppermost portion of the sulcus 
 tymp. ; a = piece of the anterior portion of the tympanic membrane ; f = inner posterior 
 fold of the membrane ; c = insertion of this fold on a sharp osseous ledge, situated within 
 the sulcus tymp. ; v = insertion of the inner fold of the tympanic membrane at the 
 posterior surface of the manubrium ; 1 = mucous membrane lamella of the fold passing to 
 the inner surface of the handle ; t = posterior pouch of Von Troltsch ; ch =; section of 
 the chorda tymp. After a preparation in my collection. 
 
 Pig. 138. — Section througli the manubrium 
 on a level with the place of attachment of 
 the tendon of the tensor tymp. — a = 
 anterior portion of the tympanic mem- 
 brane ; p = its posterior portion ; b = 
 slanting bridge, forming the connection 
 between tympanic membrane and manu- 
 brium ; t = attachment of the tendon of 
 the tensor tjanp. After a preparation in 
 my collection. 
 
 Fig. 139. — Section through the manubrium 
 below the previous one. — a = anterior 
 portion of the tympanic membrane ; p — 
 its posterior portion ; b = slanting bridge, 
 connecting tympanic membrane and manu- 
 brium ; h = posterior edge of the handle 
 of the malleus. After a preparation in 
 my collection. 
 
 which passes through the tendon of the tensor tympani, is no longer 
 triangular like the sections made higher up, but shows the outlines of 
 an ellipsis, the long axis of which stands vertical to the plane of the 
 
224 SERIAL SECTIONS THROUGH THE HEAD OF THE MALLEUS. 
 
 membrane. While in the region of the short process, between the 
 handle of the malleus and the tympanic membrane, there is close 
 contact, the section through the middle portions of the manubrium 
 appears connected with the membrane only by a narrow bridge, which 
 passes, not from the outer edge of the handle, but laterally from it in 
 a slanting direction towards the posterior portion of the membrane. 
 Similar in appearance are the next following sections of the manu- 
 brium (Fig. 139) lying below the tensor tendon. 
 
 4. On sections of the lower third of the handle, its edge is more 
 closely in contact with the membrane, and the connecting surface 
 appears broader (Fig. 140). The closest contact between membrane 
 and handle exists, however, at the lower spatula-shaped extremity of 
 
 Fig. 140. — Section through the middle 
 portion of the manubrium, below the pre- 
 vious one. The apposition of the handle 
 of the malleus to the tympanic membrane 
 is here broader and closer than in the upper 
 portions. — a = anterior portion of the 
 membtana tympani ; p = its posterior 
 portion ; h = inner border of the manu- 
 brium. 
 
 Fig. 141. — Section through the inferior 
 spatula-shaped extremity of the handle of 
 the malleus. — a = anterior portion of the 
 tympanic membrane ; p = its posterior 
 portion ; v v' = condensation of the tissue 
 of the membrane at the lateral portions 
 of the manubrium ; h = inner border of 
 the latter. 
 
 the latter (Fig. 141), this flattened portion of the hammer being sur- 
 rounded on all sides by the here very dense tissue of the tympanic 
 membrane. 
 
 The mode of attachment of the radiating and circular fibres at the 
 manubrium is, notwithstanding the investigations hitherto made, not 
 yet quite clear. That the radiating layer is attached with the 
 greatest mass of its fibres to the lower part of the handle, while the 
 circular fibres are inserted at the upper portion in the region of the 
 short process, may be taken as an established fact. The statements 
 as to the relationship of the fibres of the substantia propria to the 
 middle portion of the handle, on the other hand, require rectification. 
 That the radiating fibres in the middle portion of the manubrium 
 pass, as some suppose, everywhere crossed over to its surface, I could 
 not quite convince myself. So far as it is possible to form an opinion 
 from sections, I was able to see, even with a low magnifying power, 
 that in the upper as well as the middle portions of the manubrium 
 
VERTICAL SECTIONS THROUGH TYMP. MEMBRANE AND MANUBRIUM. 225 
 
 (compare Figs. 138 and 139), chiefly the fibres of the posterior superior 
 segment of the membrane (p), pass over to the handle, and unite with the 
 periosteum of its surfaces, directed towards the tympanic cavity ; that, 
 however, the fibres of the anterior superior segment, running along 
 the edge of the manubrium, meet the fibres of the posterior segment. 
 Only in the lower third of the handle (Figs. 140 and 141) does there 
 seem to be a crossing of the fibres on their passing from both sides to 
 the edffe of the manubrium. 
 
 The study of horizontal sections should be supplemented by a 
 series of vertical sections of the tympanic membrane. Those passing 
 through the anterior portion of the osseous frame vertically to the 
 
 Fig. 142. — Vertical section through the malleus, Shrapnell's membrane and the malleo-in- 
 cudal niche. — a = head of the malleus ; h = processus brevia mallei ; g = membrana 
 Shrapnelli ; e = margo tympanicus ; c = Prussak's space ; b = ligamentum mallei exfc. ; 
 f = inconstant framework between the membrana ShtapnelU and the ligamentum mallei 
 ext. ; d d = inconstant bridges of mucous membrane in the malleo-incudal niche. After 
 a preparation in my collection. 
 
 Glaserian fissure allow, on successful preparations, the sections of the 
 ligament, mallei ant., of the chorda tymp., of the art. tymp., and, in 
 the new-born infant, the section of the proc. Folianus, to be dis- 
 tinguished. 
 
 The most important vertical sections of the tympanic membrane 
 are those made through the entire malleus, Shrapnell's membrane, and 
 the malleo-incudal niche. To guard against useless slanting sections, 
 the embedded preparation must be so fastened in the microtome that 
 the cut passes exactly through the long axis of the malleus. The 
 transparent celloidin, in which the hammer shines through, is, for this 
 purpose, an indispensable embedding medium. The relationship of 
 Shrapnell's membrane to the malleus having been previously discussed 
 (see pp. 84 and following) it need here only be observed that Prussak's 
 space, situated above the short process of the malleus, as also 
 
 15 
 
226 HISTOLOGICAL EXAM. OF MEMB. TYMP. IN PATHOLOGICAL CASES. 
 
 the malleo-incudal niclie (Fig. 142), show numerous varieties, and 
 that the ligam. mallei extern., passing from the crista capit. mallei 
 to the incisura Rivini, is, in the majority of preparations, inserted 
 only on the anterior portion of the incisura; that, however, the 
 posterior part of the ligament, below the tapering incisura (margo 
 tymp.), unites with Shrapnell's membrane. 
 
 The methods of histological examination of the normal tympanic 
 membrane are generally employed in pathological cases also. Whether 
 in any special case the examination is to be made on surface prepara- 
 tions or on sections will always depend upon the nature of the morbid 
 changes present. With atrophic membranes, or where cicatrices and 
 thin calcareous deposits are found, surface preparations are preferable 
 to sections, if the object be to represent clearly the extent of the 
 pathological change on the surface, the partial or total absence of the 
 fibres of the substantia propria, the disposition of the epithelium, and 
 the course of the bloodvessels. The two methods may, however, be 
 combined with one and the same preparation, one piece of it being 
 used as a surface preparation, the other for sections. The latter 
 method is especially to be recommended in cicatrix formations on 
 the tympanic membrane, where it is to be ascertained from which of 
 its layers the cicatricial tissue has grown, and what is the relation 
 of the thickness of the membrane as compared with that of the 
 cicatrix. 
 
 On the other hand, when the membrane, through inflammatory 
 infiltration or connective-tissue proliferation on its dermic and mucous 
 layers, through polypous hypertrophy, calcification, or ossification, 
 has increased to several times its normal thickness, the preparations 
 can only be histologically examined on sections. Where information 
 is to be gained as to the relation of the pathologically altered mem- 
 brane to the manubrium, it is necessary, after previous fixation, to 
 soften the handle by slow decalcification, the same as with normal" 
 preparations (see p. 200). This also applies to markedly calcareous 
 and partially ossified membranes. As, however, these become con- 
 siderably altered through decalcification, it is advisable to examine 
 some pieces of the morbidly changed membrane undecalcified. 
 
 In the histological examination of the various morbid forms of 
 the tympanic membrane it is necessary, according to the results of 
 previous research, to consider the following changes : 
 
 1. In the epidermic portion of the cutis layer, considerable pro- 
 liferation and superposition of the epithelium, pigmentation of the 
 same, formation of small bead-like globules, with epithelial (Urbant- 
 schitsch) or cholesterine contents, cone-shaped proliferations of the 
 deeper epithelial strata into the cutis layer (Moos). 
 
HISTOLOGICAL EXAMINATION OF LINING OF TYMPANUM. 227 
 
 2. In the cutis layer proper : serous, purulent, and htumorrhagic 
 infiltration of the connective-tissue stratum, dilatation of the blood- 
 vessels, hypertrophy of the cutis through cell-proliferation, new for- 
 mation of connective tissue and of bloodvessels, the springing up of 
 granulations, polypi and villous excrescences on the surface, fibrous 
 tissue thickening of the cutis layer; finally ulceration, destruction, 
 cicatrices, and partial atrophy. 
 
 3. In the substantia propria : serous and purulent infiltration, 
 thickening through connective-tissue new growth, atrophy, calcareous 
 and osseous deposits, fatty degeneration, and pigmentation. 
 
 4. On the mucous membrane layer : hypersemia, swelling, hyper- 
 trophy through round- cell proliferation and connective-tissue neo- 
 plasm, polypous formation, pigmentation, perforation, and cicatriza- 
 tion. 
 
 IV. 
 
 Histological Examination of the Lining Membrane of the 
 
 Tympanic Cavity. 
 
 The knowledge of the normal structure of the mucous membrane 
 of the tympanum is of great importance for forming an estimate of 
 the pathological changes therein, because it is here that those morbid 
 processes, which so frequently are the cause of disturbances of hearing, 
 run their course. 
 
 The normal mucous lining of the tympanic cavity is subjected to 
 histological examination on surface preparations and on sections. 
 
 1. Examination on Surface Preparations. 
 
 The most beautiful surface preparations are obtained from the 
 promontory, from which part the mucosa may be detached in larger 
 pieces without disturbing its continuity. This is done simply by 
 means of a small knife rounded off at the point, with which the 
 mucous membrane is pressed away from the inner wall of the ost. 
 tymp. tubse, backwards up to the vicinity of the two labyrinthine 
 fenestrte. Particular care must be taken while manipulating in the 
 neighbourhood of Jacobson's nerve, because here the mucous mem- 
 brane is most intimately connected with the subjacent bone. 
 
 Far more difficult is it to obtain surface preparations from the 
 other walls of the tympanum. One may certainly succeed in loosen- 
 ing small portions of the membrane from the smooth malleo-incudal 
 niche, from the posterior wall of the tympanum, the lateral osseous 
 wall of the Eustachian tube, and from the sinus tymp. (Steinbriigge) ; 
 but from the other parts of the cavity, especially from the ridgy 
 
 15—2 
 
228 HISTOLOGICAL EXAMINATION OF LINING OF TYMPANUM. 
 
 inferior and upper walls, where the mucous membrane either sinks 
 into the irregular depressions, or bridges them over, only small par- 
 ticles can be stripped off, which are not of much use for examination. 
 
 The normal lining membrane of the tympanic cavity in the fresh 
 state is little adapted for histological examination. The best surface 
 preparations are obtained if the entire organ of hearing, or even the 
 detached pyramid, be first placed in Miiller's fluid, or else in Ylako- 
 vic's or Urban Pritchard's solution (p. 195), the loosening of the 
 membrane being only proceeded with after the preparation has been 
 fixed and soaked in water. By staining with eosin or alum-carmine 
 the various tissue-elements become so clearly differentiated that in 
 the microscopical examination, of surface preparations which have 
 been mounted in Canada balsam or in glycerine, it is possible to 
 recognise the contours and nuclei of the epithelium, and, by deeper 
 focussing, the disposition of the fibrous filaments in the connective- 
 tissue layer, and not infrequently also the course of the larger vessels 
 and nerve-trunks. 
 
 In order to examine, on surface preparations, the blood- and 
 lymphatic vessels in the periosteal layer, the detached lining mem- 
 brane must be mounted with its periosteal surface directed upwards. 
 
 The network of bloodvessels in the mucous membrane of the 
 tympanum is rendered visible for microscopical examination in 
 various ways : 1. By injecting the arterial vessels from the common 
 carotid, or from the aorta by means of carmine glue or Berlin blue. 
 But even when this is most carefully done, it is only seldom that 
 perfectly successful -injections of the capillaries are obtained, 2. By 
 the action of 2% hyperosmic acid (p. 198), through which the red 
 corpuscles in the finest capillaries are stained brown, so that the 
 bloodvessels appear in the microscopical image as dark wavy lines. 
 
 If the pyramid, separated from a fresh preparation, be subjected 
 to osmium treatment, the dark vascular network of the lining mem- 
 brane on the promontory may be recognised, even with an ordinary 
 magnifying lens. In addition, there are seen on the surface of the 
 mucous membrane minute black dots in varying numbers, which, 
 according to my investigations, are to be regarded as the points of 
 entrance of larger bloodvessels of the membrane into the osseous 
 wall of the promontory. For a more detailed histological examina- 
 tion, the lining membrane on such preparations is detached from the 
 bone after the manner already described, and the preparations are 
 mounted, some with their epithelial, others with their periosteal, side 
 upwards. 
 
 Less reliable for the representation of the bloodvessels of the 
 mucous membrane of the tympanum is the gilding method (p. 196). 
 
HISTOLOGICAL EXAMINATION OF LINING OF TYMPANUM. 22f) 
 
 But the nerve-trunks and the finer ramifications of the nerves are 
 most beautifully shown in successful gold preparations, while the 
 finest and most delicate nerve-plexuses, which wind round the blood- 
 vessels of the mucous membrane of the promontory and of the tube, 
 appear markedly differentiated in the microscopical image. 
 
 On osmic acid preparations also, not infrequently, in addition to 
 the bloodvessels, the nerve-trunks and their ramifications in the 
 mucous membrane are brought clearly into view. On successful 
 osmium preparations I have often seen in the vicinity of the larger 
 nerve-trunks ganglion cells arranged in groups, and especially fre- 
 quently near Jacobson's nerve, and in the angular spaces which the 
 branches of that nerve form with the nerve -trunk. 
 
 The examination of the pathologically altered lining membrane 
 of the tympanum on surface preparations is also advisable where 
 there is a slight degree of thickening of the mucosa, allowing such 
 clearing up of the tissues as will be necessary for histological pur- 
 poses. In hypertrophy of the membrane through round- cell proli- 
 feration developed in the course of chronic middle-ear suppurations, 
 or in polypous hypertrophy, the examination on surface preparations 
 is impossible, and the alteration of the structures can only be repre- 
 sented on sections. Very instructive surface-preparations are, how- 
 ever, obtained in those middle-ear suppurations which have run their 
 course, where the mucous membrane is pale, smooth, and only very 
 slightly tumefied. Tliese, when fixed in Miiller's fluid or in Vlako- 
 vic's solution, show, on the side of the epithelium, the sharp contours 
 of the latter, here and there varicose veins and cyst-like spaces, and 
 on the periosteal surface the varicose expansions and club-like rami- 
 fications of lymph vessels (Fig. 143), first described by me,* and, 
 besides these, well-defined cyst-spaces lined with epithelium. 
 
 2, Examination of the Lining Membrane of tJie Tym2Janic Cavity 
 
 on Sections. 
 
 This method makes us acquainted with the structure of the lining 
 membrane of the tympanum in the superficial and deeper layers, and 
 the relative position of the bloodvessels and nerves therein. The 
 lining membrane, when detached from the bone, not being suitable 
 for sections, on accoimt of its thinness, it is advisable to cut it in 
 connection with the decalcified bone. This has the advantage that 
 the mucous membrane is retained in situ on the section by the decal- 
 cified bone, and the bloodvessels of the membrane in their relationship 
 to those of the adjoining osseous wall, and an}^ consecutive patho- 
 logical changes in the bone itself, are represented simultaneously. 
 
 * Lehrbuch d. Ohrenheilk. 2. Aufl. S. 287. 
 
230 EXAMINATION OF LINING OF TYMPANUM ON SECTIONS. 
 
 The fixing of the tissue-elements, the decalcification and subse- 
 quent microscopico-technical procedures are the same as before 
 described. The bloodvessels and nerves are examined on prepara- 
 tions treated with hyperosmic acid and chloride of gold. 
 
 The lining membrane of the tympanum shows, on sections of the 
 different walls of the latter, a varying degree of thickness. The 
 epithelium of the membrane on the promontory (Fig. 144) is a 
 simple pavement epithelium, but on the other walls, according to the 
 investigations of Kolliker, a ciliated columnar epithelium, which, 
 according to Brunner, shows tapering basal cells ; according to Kessel, 
 also goblet cells. The connective-tissue stratum consists of fibrillar, 
 
 Fig. 143. — Dilated network of lymphatic vessels in the deeper layers of the covering of the 
 promontory in a phthisical individual, 27 years old, who had otorrhoea since childhood, 
 (liight ear.) Hartnack Obj. 7. 
 
 reticulated filaments, while in the layer corresponding to the perios- 
 teum the dense prolongations of connective tissue are placed parallel. 
 
 On microscopic sections of the mucous membrane of the tym- 
 panum in decalcified preparations, which have been injected or 
 treated with hyperosmic acid, it is easy to determine the relationship 
 of the bloodvessels in the superficial and deeper layers of the mucosa. 
 The superficial vascular network reaches as far as the epithelial layer, 
 and in the new-born infant vascular loops are seen to enter the villi 
 (Moos) and papillae (Lucse). 
 
 The bloodvessels in the deeper layers, accompanied by the con- 
 nective-tissue processes of the periosteal layer (Fig. 144), penetrate 
 
KELATION OF BLOODVESSELS TO THE LINING OF TYMPANUM. 231 
 
 into the bone covered by the membrane, to become connected with 
 the bloodvessels of the same. On some preparations I have also 
 found bloodvessels passing in a spiral course from the surface of the 
 mucosa into these fissures in the bone (c'). On the promontory it is 
 possible, as I was the first to point out,* to demonstrate, on successful 
 osmic acid preparations, anastomotic communications of the blood- 
 vessels in the mucous membrane of the middle ear with those of the 
 lining of the labyrinth, by means of vessels running in the osseous 
 wall. 
 
 Glandular elements are found in greatly varying numbers only in 
 the anterior portion of the tympanum, corresponding to the ost. tymp. 
 tubse. In the middle and posterior part of the cavity they are wanting, 
 or occur but seldom, and then only isolated. Wendt, by boiling the 
 membrane in acetic acid, has demonstrated the presence of mucous 
 glands on the promontory. 
 
 d f d 
 
 Fig. 144 -Section throudi the mucous membrane of the promontory (decalcified osmic acid 
 preparation).-a = epithelium ; b = section of a bloodvessel in the connective-tissue layer, 
 a branch of which penetrates into the funnel-shaped depression of the bone ; c - Diooa- 
 vessel, passing from the surface of the lining into the bone ; d d = osseous wall ; e e 
 funnel-shaped depressions in the bone, where the periosteal layer of t^.e mucous n.ng 
 enters ; f = section of a large nerve trunk in the connective-tissue layer with the mucous 
 lining. 
 
 The already-mentioned (pp. 165 and 112) inconstant folds and fila- 
 ments stretched in the tympanum consist of a connective-tissue base, 
 which is covered with an epithelium, and the fibrous bundles of which 
 radiate in the form of a fan. By the side of and between these^ folds, 
 knotty filaments are stretched both in the tympanic cavity and in the 
 antrum mast., which, as I was the first to demonstratef (Fig. 14.5), 
 prove in the microscopical examination to be oval or angular stalked 
 formations with a stratified, bulb -like structure. The stalk (a), 
 
 * Wiener med. Wochenschrift, 1876, u. Arch. f. Ohrenheilk., Bd. XI. 
 j Ibid., 1869, 20 Nov., u. Arch. Ohrenheilk., Bd. V. 
 
232 EXAM. OF PATHOLOGICAL CHANGES IN LABYKINTHINE FENESTRiE. 
 
 entering the rounded extremity, passes sharply defined through the 
 structure, and emerges at the opposite end, to become attached to the 
 prolongation of a fold, or to the osseous wall. For the examination 
 of these small bodies, which may attain a size of 0.1 — 0.9 mm., organs 
 are suitable in which, after removal of the tegm. tymp. et mast., the 
 folds of mucous membrane and filaments alluded to will be found in 
 considerable numbers. If this frequently web-like spreading network 
 be loosened with a fine pincette, then removed, stained with eosin or 
 alum-carmine and placed on the slide, a number of these stalked 
 formations will commonly be discovered between its fan - shaped 
 fibrous processes. 
 
 Eor the study of the pathologico-anatomical changes in the lining 
 membrane of the tympanic cavity, the examination on sections is 
 indispensable. This is especially the case in hypertrophies of the 
 membrane caused by chronic catarrhs and suppurative processes, 
 where sections alone will enable us to examine the changes of the 
 epithelium, the superposition of its layers, the degree of round-cell 
 
 c 
 
 Tig. 145. — Pedunculated formation from the tympanic cavity of an adult. 
 
 and connective -tissue neoplasms, the presence of papillary and 
 polypous excrescences on the surface of the lining and cystic spaces 
 therein, the changes in its blood- and lymphatic vessels, and in the 
 osseous wall covered by the membrane. But even with a not 
 markedly hypertrophic membrane — e.g., in some forms of middle- 
 ear sclerosis — the examination on section preparations cannot be 
 dispensed with, when it is a question of ascertaining the finer 
 structural changes in the mucous lining. 
 
 THE HISTOLOGICAL EXAMINATION OF THE PATHOLOGICAL CHANGES IN 
 THE TWO LABYEINTHINE FENESTRiE. 
 
 The technical proceeding in the histological examination of the 
 morbid changes in the two fenestrse and in their niches requires, 
 considering the physiological importance of this region of the 
 tympanum, a more detailed discussion. 
 
 First, as regards the changes in the fenestra ovalis and its niche, 
 the direction of the cut will have to vary according to whether the 
 pathological alterations in the niche alone, or, at the same time, also 
 those at the ligamentum orbiculare stapedis, are to be brought under 
 
HISTOLOGICAL EXAMINATION OF CHANGES IN FENESTRA OVALIS. 
 
 233 
 
 examination. In the first case, the cuts are made parallel to the 
 inner tympanic wall through the decalcified pyramid, previously 
 reduced down to the capsule of the labyrinth. Such sections 
 (Fig. 146) show the circumference of the niche of the fenestra ovalis, 
 its mucous lining, and the relationship of the semilunar sections of 
 the crura of the stapes. Sections made in this direction through the 
 normal ear show the disposition of the connective-tissue bridges and 
 filaments, stretched in varying numbers between the crura of the 
 stapes and the wall of the niche. These narrow bridges form, on the 
 setting in of an inflammatory process, a predisposing cause for the 
 commencement of anchylosis of the crura of the stapes. In patho- 
 
 Fig. 146.— Anchylosis of the crura of the stapes with the lower wall of the pelvis_ ovalis, 
 from the left ear of a woman 48 years of age, who, while suffering from constant tinnitus, 
 had gradually become deaf (20 years on the left, 10 years on the right side), and who died 
 in one of the charities. Microscopic section through the pelvis ovalis and the crura of the 
 stapes. — p = pelvis ovalis ; o = upper wall of the niche of the fenestra ; n = mucous 
 lining of the lower wall of the niche, which has become changed into sclerosed tissue ; 
 St st = sections of the anchylosed crura of the stapes, enveloped in dense sclerosed con- 
 nective tissue. 
 
 logical investigations such parallel sections prove especially instructive 
 for the study of anchylosis of the crura of the stapes with the lower 
 wall of the niche (Fig. 146), and for the purpose of showing the 
 relationship of the crura in those excessive connective-tissue pro- 
 liferations which, wholly or in part, fill up the niche, and envelop the 
 stapes on all sides.* 
 
 A second mode of sectioning, in order to represent the normal 
 and pathological relations in the fenestra ovalis, consists in carrying 
 horizontal cuts parallel to the two crura of the stapes in such a way 
 
 * Compare A. Politzer: Sur les changements pathologiques dans la fent'tre ovale et dans 
 la fenetre ronde, qui es produisent chez les affections de I'oreille moyenne. Comptes'rendus 
 du IVme Congrfes otologique a Bruxelles, 1S8S. Publie par le Dr. Ch. Delstanclie, 1SS9. 
 
234 
 
 EXAMINATION OF CHANGES IN THE FENESTRA OVALIS. 
 
 that several cuts meet the greatest longitudinal diameter of the foot- 
 plate, the two crura^ and the capitulum (Fig. 147). These sections 
 offer the advantage that not only the connective- tissue and osseous 
 adhesions occurring between the crura and the walls of the niche 
 become clearly visible, but also the histological changes in the fibrous 
 ligament of the oval window, and in the cartilaginous covering of the 
 stapedio-vestibular articulation. The number of serviceable sections 
 obtainable by this method is, however, limited to two or three at 
 most, because all those made above and below the greatest diameter 
 of the fenestra must meet the stapedio-vestibular articulation in a 
 slanting direction ; and, if the cut pass beyond the margin of the fenestra 
 ovalis or of the stapes, they will prove of little use for examination. 
 
 Fig. 147. — Horizontal sect'on through the stapes and the niche of the fenestra ovalis. — 
 c = capitulum stapedis ; b = basis stapedis ; o o' = section of the border of the fenestra 
 ovalis, covered with cartilage ; n n' = niche of the fenestra ovalis ; s s = section of the 
 ligamentum orbiculare stapedis ; 1 = normal rnucous-membrane bridge between the niche 
 of the fenestra ovalis and the crus of the stapes. After a preparation in my collection. 
 
 The direction of the cuts here described corresponds to the 
 course of that piece of the facial nerve which passes above the 
 fenestra ovalis. If, therefore, they are to meet both the capitulum 
 and the two crura, the preparation should be so embedded that the 
 knife of the microtome may move parallel to that piece of the nerve. 
 
 A third mode of making microscopical sections through the 
 labyrinthine fenestrse is the frontal. It offers the advantage of 
 allowing the changes in the oval and round windows to be examined 
 at the same time (Fig. 148). 
 
 For making frontal sections, the preparation must be so fastened 
 in the microtome that the posterior extremity of the pyramid is 
 directed upwards. If it be intended to examine the two fenestras, 
 together with the labyrinth, the cuts carried in this direction will first 
 
EXAMINATION OF MEMBRANE AND NICHE OF THE FEN. ROT. 
 
 235 
 
 bring the transverse sections of the semicircular canals into view. 
 Should these show nothing abnormal, the entire portion of the 
 pyramid lying behind the fenestra} may, to save time, be removed, 
 and the sectioning through the fenestra3 at once proceeded with. 
 
 As the frontal cuts fall perpendicularly to the long axis of the 
 oval window, a greater number of useful serial sections for the 
 examination of the histological changes in the stapedio-vestibular 
 articulation is obtained than by carrying the cuts horizontally. On 
 the other hand, the more exact anatomical relations of the crura of 
 
 
 .^P 
 
 
 Fig. liS.-^Frontal section of the inner tympanic wall through the two labyrinthine fenestrae. 
 — s = basis stapedis ; n = niche of the fenestra ovalis with a portion of the crus of the 
 stapes, which has been divided obliquely ; o = upper, u = lower wall of the niche ; pr = 
 section of the promontory with its mucous covering ; m = membr. fenestras rotundas ; 
 nr = niche of the fenestra rotunda ; p = lamina spiralis secundaria ; f = section of the 
 n. facialis ; v — vestibule. After a preparation in my collection. 
 
 the stapes to the walls of the niche will not be visible on frontal 
 sections. 
 
 The anatomical relations of the membrane of the fenestra rotunda, 
 and the normal and pathological formations occurring in its niche, 
 present themselves most clearly in sections of this kind. Here we see 
 in the normal organ of hearing (Fig. 148), the insertion of the mem- 
 brana fenestras rotundse (m) in the groove, its thickness and structure, 
 
286 EXAMINATION OF THE MALLEO-INCUDAL ARTICULATION. 
 
 the mucous covering of its outer surface, its relationship to the lamina 
 spiral, secundaria (p), and sometimes, in the niche of the fenestra (nr), 
 a trabecular structure of connective tissue stretched in exceedingly 
 varying form between the walls of the niche. It is evident that, in 
 acute inflammations of the lining membrane of the middle ear, the 
 exudation secreted in the niche of the round window is retained in 
 the spaces of this structure, and that pressure upon the membrane 
 ^must cause disturbance of hearing to a high degree. There is also no 
 doubt that in chronic inflammatory processes, particularly in middle- 
 ear suppurations, the normal folds and bridges in this niche supply 
 the foundation of excessive round-cell and connective-tissue prolifera- 
 tions, which fill up the niche and adhere to the membrane of the 
 fenestra. The formation of such connective-tissue plugs, which block 
 the niche, may, however, also proceed from its inflamed mucous 
 membrane. 
 
 The frontal cuts through the two labyrinthine fenestra?, moreover, 
 offer a special advantage, as they yield a perfect section of the pro- 
 montorial wall (Fig. 148, pr), and of its mucous lining, as well as of 
 the covering of the labyrinth, which will enable us to examine the 
 morbid changes occurring there, and their relations to the vessels of 
 the osseous wall of the promontory. In addition to this, such cuts 
 render it possible to examine any alterations in the section of the 
 facial nerve (f ), in the vestibule (v), and in the commencing portion 
 of the cochlea. In pathological cases where, simultaneously with the 
 changes in the niches of the fenestrse, the morbid processes developing 
 in the labyrinth are also to be investigated, it is advisable to cut the 
 entire pyramid, from the anterior end of the cochlea to the posterior 
 extremity of the horizontal semicircular canal, into serial sections, on 
 which^ in addition to the pathological appearance in the mucous 
 membrane of the inner tympanic wall, the structural changes in the 
 cochlea, vestibule, semicircular canals, and in the trunk of the acoustic 
 nerve, can be represented. 
 
 V. 
 
 The Histological Examination of the Ossicula. 
 
 For the histological examination of the ossicula and their articular 
 connections, only decalcified preparations can be employed. 
 
 1. Malleo-Incudal Articulation. 
 
 To obtain serial sections of the malleo-incudal articulation, after 
 dividing the tensor tendon and the incudo-stapedial joint, the pars 
 tymp., with the tympanic membrane and the malleo-incudal connec- 
 
EXAMINATION OF THE INCUDO-STAPEDIAL ARTICULATION. 2'^j7 
 
 tion, are separated from the pyramid and fixed in one of the before- 
 enumerated sohitions (p. 195), or in hyperosmic acid, and slowly 
 decalcified (picric acid or nitric acid). The preparation, embedded in 
 celloidin, is cut perpendicularly to the long axis of the malleus and 
 incus — that is, parallel to the rotation axis of the malleo-incudal 
 joint. The objects, fixed in the chromic acid solutions, are subjected 
 to double staining in alum- carmine or eosin, or in eosin and hosma- 
 toxylin. Osmic acid preparations require no further staining. The 
 same method is also employed in the examination of the other 
 articular connections of the ossicles. 
 
 In the horizontal section of the malleo-incudal joint (Fig. 149) the 
 two small bones are connected by means of a capsular ligament (c), 
 which is attached to the depressed margins of the articular surfaces, 
 and permits ample mutual displacement of the bones. A connective- 
 
 FiG. 149. — Section through the malleo-incudal articulation.- — a = malleus ; b = incus ; c = 
 capsular ligament with the wedge-shaped meniscus. Preparation treated with hyperosmic 
 acid. 
 
 tissue cartilage, first observed by Pappenheim (I.e.), and accurately 
 described by Kiidinger, is seen projecting, in the form of a wedge- 
 shaped meniscus, from the inner wall of the capsule into the cavity of 
 the joint, and adapting itself closely to the cartilaginous surfaces of 
 the malleus and incus. 
 
 2. Incudo-Stapedial Articulation. 
 
 On a decalcified organ, after removal of the tegmen tymp., the 
 tendon of the m. stapedius, the crura of the stapes, and the long 
 process of the incus are divided with a small pair of scissors, and 
 the incudo-stapedial connection, thus loosened, is lifted out. The 
 embedding and cutting (horizontal) require great care, on account of 
 the smallness of the object. Successful sections of this joint are 
 occasionally obtained when sectioning the entire organ in horizontal 
 series. 
 
 The incudo-stapedial joint (Fig. 150) is formed by the concave 
 
238 
 
 HISTOLOGICAL EXAMINATION OF 
 
 articular surface of the capitulum stapedis (g) and tlie corresponding 
 convex surface of the ossicul. lenticulare Sylvii (o). Both surfaces are 
 covered with a thin layer of hyaline cartilage. The fibrous capsular 
 ligament, which connects the extremities of the joint, allows ample 
 lateral displacement of the same. The articulation is not an amphi- 
 arthrosis (Brunner), but a true joint, provided with a cavity (Eisell), 
 the hollow of which is divided into two clefts by a meniscus of fibrous 
 tissue (Kiidinger). 
 
 3. Stapedio-Vestibular Connection. 
 
 In order to examine the normal relations of this joint, the 
 separated pyramid, after previous fixing in chromic acid solutions or 
 
 c k 
 
 St 
 
 Fig, 150. — Section through the incudo-stapedial articulation. — a = terminal piece of the 
 long crus of the incus, and, connected with it by fibrous tissue o = ossicul. lentic. Sylvii ; 
 st = capitulum stapedis ; g = articular fossa with the meniscus ; c c' = hyaline cartilage 
 covering of the articular surfaces ; k k' = articular capsule ; m — tendon of the muse, 
 stapedis. 
 
 in hyperosmic acid, is slowly decalcified and embedded in celloidin or 
 paraffin. The celloidin embedding has the advantage of allowing the 
 stapes to shine through, so that the direction of the horizontal or 
 frontal cut (p. 233) through the fenestra ovalis can be accurately 
 determined. This is very important, as slanting sections, which give 
 indistinct images, are to be avoided. 
 
 The margin of the fenestra ovalis (Fig, 151, a) and the foot-plate of 
 the stapes (b) are covered by a layer of hyaline cartilage (Toynbee, 
 Magnus), which is continuous over the whole of the foot-plate (Eisell). 
 This cartilage layer is to be regarded as the residue of that part of the 
 foot-plate which is derived from the labyrinthine capsule (Gradenigo). 
 
THE STAPEDIO-VESTIBULAR CONNECTION. 
 
 289 
 
 According to my investigations, this layer of cartilage is very thin on 
 the vestibular surface of the stapes — at times, howevei', so thick that 
 in some places it reaches as far as the tympanal side of the stapes. 
 At the margin of the fenestra ovalis it sometimes descends deeply into 
 the osseous tissue, and occasionally I have seen it extending outwards 
 towards the wall of the niche — i.e., to a spot which lies outside the 
 stapedio-vestibular connection. 
 
 The fenestra ovalis and the edge of the foot-plate are connected 
 through a fibrous elastic ligament (c), the radially disposed fibres of 
 which are intimately united with the perichondrium. 
 
 The histological examination of the articular connections of the 
 ossicula in pathological cases is made according to the same methods 
 observed with normal preparations. Considering the physiological 
 importance of the ossicular chain, it is hardly necessary to enter more 
 fully into details to show the value of these examinations for the 
 
 Fig. 151. — Section through the stapedio-vestibular connection. — a = border of the fenestra 
 ovalis, covered with a layer of cartilage ; b = edge of the foot-plate of the stapes, 
 covered with cartilage ; c c = section of the ligament, orbic. stapedis. 
 
 pathology of the organ of hearing. In anchylosis of the malleo- 
 incudal articulation, in caries of the malleus and incus, with con- 
 nective-tissue masses in the upper tympanic space, by which these 
 bones are enveloped, the microscopic sectioning of the joint must be 
 effected in a horizontal direction. In anchylosis of the hammer-head 
 with the tegmen tymp., again, in all cases where the relations of the 
 malleus and incus to Shrapnell's membrane, and to pathological 
 processes occurring in the malleo-incudal niche, are to be clearly 
 shown, sectioning in a frontal (vertical) direction will have to be 
 decided upon. The incudo-stapedial articulation is always cut hori- 
 zontally. Of the pathologico-histological changes in this part little 
 is as yet known. The cuts through the stapedio-vestibular connection 
 are carried in a horizontal or frontal direction (p. 234), in case the 
 relationship of the crura of the stapes to any simultaneous processes 
 in the pelvis ovalis is to be taken into consideration : in the micro- 
 scopical examination attention must be directed to the structural 
 
240 EXAMINATION OF THE INTRA-TYMPANIC MUSCLES. 
 
 changes in trie cartilage layer (calcareous incrustations, atrophy, 
 fusion), in the ligam. orbiculare staped. (shrinking, calcification, 
 ossification, destruction), and at the foot-plate (thickening of the 
 periosteum of the surface of the labyrinth, hyperostosis, wearing 
 away, etc.). 
 
 YI. 
 
 Histological Examination of the Intra-Tympanic Muscles of 
 
 THE Ear. 
 
 The disposition of the muscular fasciculi in the osseous canals 
 enclosing them (p. 98), and the relations of the two intra- tympanic 
 muscles to the tendons, are examined on decalcified organs, both on 
 horizontal and transverse sections. 
 
 1. Musculus Tensor Tympani. 
 
 Microscopical sections in the long direction of this muscle are 
 made by carrying a series of cuts horizontally through the entire 
 decalcified organ. In order to obtain specimens which, in addition to 
 the muscle, show also the longitudinal section of the tensor tendon 
 and its attachment to the handle of the malleus, the tegmen tymp. is 
 so far removed as to allow the tendon to become visible ; it will then 
 be possible to fasten the embedded preparation in the microtome in 
 such a way that the knife passes simultaneously through muscle, 
 tendon, and manubrium. On transverse sections of the muscle, 
 obtained by sectioning the entire organ in frontal series, it is possible 
 to demonstrate the varying form of the outline of the muscle, and 
 the marked tapering of its anterior extremity springing from the 
 cartilaginous tube. 
 
 The muscular fasciculi of the tens. tymp. arise, according to 
 Helmholtz, from the periosteum of the upper surface of the canal ; the 
 tendon of the muscle can be followed for some distance into the canal, 
 
 2. Musculus Stapedius. 
 
 On the pyramid, which after separation from the pars tymp. has 
 been decalcified, the muscle is sectioned longitudinally correspond- 
 ino- to the direction, elongated backwards and downwards, of its 
 tendon. Successful sections show the pyriform shape of the pennate 
 muscle, the exit of its tendon at the apex of the eminentia pyra- 
 midalis, and the insertion of the tendon below the capitul. stapedis. 
 On transverse sections the muscle appears, according to my exami- 
 nations, triangularly prismatic. The statement of Zuckerkandl, 
 that between the muscular bundles of the m. tensor tymp. and 
 
HISTOLOGICAL EXAM. OF CARTILAGINO -MEMBRANOUS EUST. TUBE. 241 
 
 m. Stapedius, adipose tissue is here and there deposited, I can confirm 
 from my own preparations. 
 
 Transverse sections of the m. stapedius meet also the descending 
 portion of the nerv. facialis, which allows the topographical relations 
 of these two to be represented. In the new-born infant one finds a 
 more or less constant communication between the eminentia stapedii 
 and the canal, facialis, so that the muscle and the nerve come into im- 
 mediate contact ; in the adult the separation of the two spaces is more 
 complete^ but here, too, one very often meets gaps of various sizes on the 
 posterior portion of the eminentia stapedii* adjoining the facial canal. 
 
 The examination of the intra-tympanic muscles in pathological 
 cases has already been discussed (p. 100). 
 
 VII. 
 
 Histological Examination of the Eustachian Tube. 
 
 The structure of the Eustachian tube, the relations of its cartilaginous 
 and membranous portions, as regards form, the position of the mucous 
 glands and their discharge into the canal, the mode of insertion of the 
 tubal muscles, are most comprehensively illustrated by sections made 
 transversely to the long axis of its canal. Longitudinal sections are 
 only made use of to represent microscopically the union between the 
 cartilaginous and osseous portions. 
 
 For the purpose of making transverse sections of the cartilagino- 
 membranous portion, the tube is prepared out, together with the 
 muscles inserted therein, according to the method described on p. 104 
 Fixing, hardening, and embedding are effected after the general 
 methods, details of which have been given before (p. 194). Where the 
 relationship of the Eustachian tube to the basilar fibro-cartilage and 
 to the neighbouring vessels and nerves is also to be examined, the tube, 
 with the corresponding piece of the basis cranii, is sawn out, and, after 
 sufficient fixing, decalcified in chromic acid solutions. Best adapted 
 for this purpose, because less bulky and more quickly decalcified, are 
 organs of new-born infants. 
 
 On transverse sections of the cartilagino-membranous tube (Fig. 
 152) the medial cartilaginous plate (a) appears bent over at the upper 
 edge in the form of a hook (b). 
 
 Close to the insertion of the cartilagino-membranous part in 
 the osseous portion of the tube, the medial cartilaginous plate is 
 narrower than where it is bent laterally. Lower down, however, the 
 breadth of this plate rapidly increases, while the lateral part (b), which 
 
 * Compare A. Politzer, Ueber das Verhaltniss des Muse, stapedius zum Nerv. facialis. 
 Arch. f. Ohrenheilk., Bd. ix. 
 
 16 
 
242 HISTOLOGICAL EXAM. OF CARTILAGINO-MEMBEANOUS EUST. TUBE. 
 
 is turned in, forms, along the whole tube, a narrow strip, which roofs 
 over the tubal canal. 
 
 At the convoluted extremity of the cartilage hook is inserted 
 the pars membranacea of the Eustachian tube, which passes below 
 into the fascia salpingo-pharyngea, forming, with the cartilage hook, 
 the lateral wall (i) and the floor (d) of the tube. In the vicinity of 
 the hook the pars membranacea is thinner than in the lower portion, 
 and its thickness increases from the ost. pharyng. tubse towards the 
 upper portions, being strengthened by the addition of fibrous tissue 
 from the spina angularis of the sphenoid bone, and by a small rod of 
 cartilage pushed into this tissue (Zuckerkandl). 
 
 The relations of the space (c), formed by the cartilage hook (b) 
 below the spot where it is twisted, vary in the several sections of 
 
 Fig. 152. — Transverse section through the cartilaginous Eustachian tube. — a = medial 
 cartilage plate ; i — membranous plate ; b = cartilage hook ; c = space below the same ; 
 d = floor of the Eustachian tube ; e e' = folds of mucous membrane ; f =: cylindrical 
 epithelium ; g — muse, tensor palat. mollis ; h = muse, levator palat. mollis. 
 
 the tube. In the portions lying near the osseous part of the tube, 
 there is no contact of the walls of this small space, while in the 
 middle portion the contact of the medial and lateral walls is com- 
 plete. 
 
 The mucous membrane, which has numerous folds, especially in the 
 lower part of the tube, shows a ciliated cylindrical epithelium, 
 with basal and goblet cells (Schultze). The greater mass of the 
 strongly developed acinose mucous glands lies in the mucous mem- 
 brane covering the medial cartilaginous plate. On successful sections, 
 the excretory ducts of these glands may be followed as far as their 
 lateral discharge into the tubal canal. The glandular layer reaches 
 
HISTOLOGICAL EXAM. OF THE OSSEOUS EUSTACHIAN TUBE. 243 
 
 up to the perichondrium ; not infrequently, however, single glands 
 extend through the inconstant fissures of the tubal cartilage, as far as 
 the connective tissue outside the Eustachian tube. In addition to the 
 mucous glands there are found, from the ost. pharyng. tuba3 to the 
 osseous Eustachian tube, numerous follicular glands (Gerlach), and in 
 the lower portion of the tube in the adult scanty adenoid tissue. 
 Finally, the transverse sections here sketched throw light on the 
 relationship of the tubal muscles to the cartilagino- membranous part 
 of the tube. The bundles of the tensor palat. mollis (g) (abducto. 
 tubfe, Von Troltsch) arising from the cartilage hook, correspond in 
 their course with the longitudinal direction of the muscle, while those 
 of the m. levator palati mollis (h), passing along the floor of the mem- 
 branous tube, appear in the transverse section. 
 
 Transverse sections of the osseous part of the Eustachian tube 
 show the outline of the canal to be, anteriorly, that of an irregular 
 triangle; posteriorly, that of a quadrangle. (Compare pp. 39 and follow- 
 ing.) The mucous membrane contains glands, though fewer than the 
 cartilaginous portion. At the ost. tymp. tubse we find on the medial 
 and lower walls papillary elevations of the mucous membrane. 
 
 The structural changes in the Eustachian tube in pathological 
 cases are also examined on transverse sections. The most strikinef 
 alterations in the tube are met with in chronic diffuse catarrhs, and 
 chronic suppurations of the middle ear. The epithelium is frequently 
 cast off, or transformed into one of several layers, permeated with fat- 
 globules and pigment. The mucous glands are either hypertrophic, 
 the acini and excretory ducts dilated, or wasted by atrophy. The 
 submucous connective tissue is either traversed by round cells, or 
 thickened, condensed, and shrunken by new formations of connective 
 tissue, whereby the tubal canal may be narrowed in various degrees. 
 Adhesions in the canal are of rare occurrence : most frequently they 
 are caused in chronic middle-ear suppurations, through the formation 
 of granulations at the ost. tymp. tubc^. The tubal cartilage shows, in 
 pathological cases, either a normal state, or atrophy, fatty degeneration, 
 calcareous deposits, and pigmentation. 
 
 Addenda. — For the histological examination of the processus 
 mastoid, in the normal organ of hearing, frontal sections of decalcified 
 preparations are best adapted. These sections show the outlines of 
 the antrum mastoid., the shape and arrangement of the pneumatic 
 cell-spaces of the mastoid process, and their relative position to the 
 antrum, the section of the very delicate mucous-membrane lining of 
 the latter, and of the pneumatic cells, and, not infrequently, of the 
 ramified trabecular structure of connective tissue, stretched out in 
 the antrum, with the already- described (p. 232) pedunculated and 
 
 16—2 
 
244 HISTOLOGICAL EXAMINATION OF THE LABYRINTH. 
 
 stratified corpuscles. Besides, on sections of partly diploetic mastoid 
 processes (p. 106), the characteristic differences between pneumatic 
 cells and the diploetic spaces can easily be determined. If the cut 
 through the mastoid process meets also the sinus transversus, not in- 
 frequently the openings of the veins of the mastoid, passing along the 
 osseous wall of the sinus into the sinus transversus, may be observed. 
 
 In pathological cases, microscopical sections through the de- 
 calcified mastoid process are prepared chiefly when the pneumatic 
 spaces are filled up with new-formation of connective tissue, in 
 eburnation of the mastoid process, and in cholesteatomatous formation 
 therein, exceptionally only, in carious or necrotic processes. It will 
 depend on where the seat and extent of the pathological change in the 
 mastoid process may be found, whether, in a given case, the section is 
 to be made horizontally or frontally. 
 
 VIII. 
 
 Histological Examination of the Labyeinth. 
 
 The histological examination of the membranous labyrinth is one 
 of the most difficult tasks. This will be understood if we consider 
 the complicated relations of the membranous labyrinth, the peculiar 
 way in which it is fixed in the osseous capsule, and the extreme 
 delicacy of the terminal organs of the acoustic nerve apparatus, which 
 are displaced on the slightest mechanical interference. 
 
 Notwithstanding the unusual interest which, since the epoch- 
 making discovery of Corti, prominent anatomists such as KoUiker, 
 Max Schultze, Deiters, Bottcher, Waldeyer, Gottstein, Hasse, Lowen- 
 berg, Ranvier, Retzius, Kuhn, Urban Pritchard, Winiwarter, Nuel 
 and others have directed to the investigation of the histological rela- 
 tions of the labyrinth, the microscopical dissection of its structures 
 remained up to recent times imperfect, and it is only of late years, 
 especially through the perfection of the methods of decalcifying 
 and embedding, that material progress has been made in the further 
 development of the normal and pathological histology of the 
 labyrinth. 
 
 For the study of the histology of the normal labyrinth, the 
 majority of the above-mentioned anatomists used organs of newly 
 killed animals, most frequently of guinea-pigs and cats. Indeed, cir- 
 cumstances are less favourable for obtaining perfect microscopical 
 preparations of the labyrinth in the human subject than in animals, 
 where, immediately after death, the organ can be placed in one of 
 those chemical fluids which effect differentiation of the tissue- 
 
HISTOLOGICAL EXAMINATION OF THE LABYRINTH. 245 
 
 elements of the labyrinth only, when the objects are perfectly 
 fresh. 
 
 In the human subject, on the contrary, where the post-mortem 
 examination is, by law, not allowed to be undertaken until twenty- 
 four hours after death, the labyrinth undergoes, in consequence of 
 decomposition setting in, changes which interfere with the histological 
 examination. To this must be added that in chronic disease of any 
 organ, or in general disease ending fatally, the tissue changes develop- 
 ing in the whole organism must also affect the auditory apparatus, 
 and alter the tissue-elements of the labyrinth to such a degree as to 
 render the histological examination very difficult. This fact must be 
 reckoned with when examining pathological labyrinths, if errors re- 
 specting their condition are to be avoided. 
 
 To obtain serviceable preparations of the human labyrinth, organs 
 of younger individuals should be selected where death ensued after 
 acute diseases, which had run their course rapidly, or where it 
 occurred suddenly through apoplexy, paralysis of the heart, or 
 through suicide, etc. As, however, the microscopic preparation of the 
 labyrinth requires considerable experience, it is advisable to practise 
 by making microscopical sections of the labyrinths of young guinea- 
 pigs and cats. 
 
 The most beautiful microscopic representations of the normal 
 membranous labyrinth are obtained by the treatment of fresh organs 
 with hyperosmic acid (p. 198), with the solution of Tafani (p. 195), 
 or with chloride of gold (p. 196). The latter is chiefly employed in 
 the preparation of Corti's organ, for the purpose of showing the con- 
 nections of the nerve-filaments of the acusticus with the hair-cells. 
 While referring, for the respective details of the work of preparing to 
 the methods previously described, we will, in addition, give a method 
 employed by Dr. Katz, of Berlin, for the representation of Corti's 
 organ, which, to judge from the preparations kindly sent to me, 
 yields excellent results. 
 
 The preparation, in as fresh a state as possible, is first placed in a 
 -i% solution of osmic acid (30 ccm. of fluid), and left in it for about 
 ten hours. To this Hquid is to be added four times the quantity 
 of a mixture of chromic and acetic acid (4% chromic acid, and 1% 
 glacial acetic acid). After three to four days, only the quantity men- 
 tioned 'of the chromic and acetic acid solution is renewed, and the 
 preparation again left therein for about four days. Next follows the 
 decalcification of the petrous bone in a 3 to 5% solution of nitric 
 acid, according to the size and consistence of the object. After com- 
 plete decalcification, the bone is, for the purpose of hardening, 
 dehydrated in alcohol, and embedded in celloidin. 
 
246 HISTOLOGICAL EXAMINATION OF VESTIBULAR STRUCTURES 
 
 The embedding is tlie more successful if tlie superior semicircular 
 canal be opened with a file, and the preparation placed first in the 
 thin, and then in the thick-fluid celloidin solution (see ' Celloidin 
 Embedding,' p. 203). 
 
 The addition of the acetic acid in this proceeding is very im- 
 portant, as it causes the chromic acid to penetrate into the tissue 
 better and more quickly. With very dense human petrous bones, 
 Katz employs, for the purpose of decalcification, hydrochloric acid 
 and chloride of palladium (Waldeyer), which is frequently more effec- 
 tive and rapid in its action. 
 
 Kegular fixing of the tissue-elements, slow and careful decalcifica- 
 tion, and complete filling up of the labyrinthine cavity with celloidin, 
 are, therefore, the principal conditions for obtaming successful sections 
 of the labyrinth. 
 
 The sections intended for the examination of the labyrinthine 
 structures are made in a horizontal or frontal direction ; for the study 
 of the anatomical and topographical relations of the membranous 
 labyrinth both methods of sectioning are indispensable. 
 
 1. .Histological Examination of the Structures of the Vestibule 
 on Horizontal and Frontal Sections. 
 
 Series of horizontal and frontal sections of the pyramid in the 
 new-born infant will give a general view of the topographical position 
 of the two vestibular saccules and of the ampuUse. The horizontal 
 sections are made parallel to the upper surface of the pyramid. The 
 uppermost portion of the vestibule shows the roundish section of the 
 sinus utriculi super., which is, at its entire circumference, in con- 
 nection with the vestibular wall by means of a finely-meshed con- 
 nective tissue. On sections lying somewhat deeper there appears, 
 behind the utriculus, the section of the ampulla superior with its 
 crista ampullaris, and if the cut has been in the right direction, also 
 the discharge of this ampulla into the utriculus. In a still lower 
 section passing above the fenestra ovalis (Fig. 153), the utriculus (s), 
 into which the ampulla extern, (a) discharges, shows an oval form ; 
 its diameter appears here smaller than that of the upper part of the 
 sacculus (r), called by Retzius sinus utricularis sacculi. Here, too, 
 the saccules are nearly everywhere attached to the wall of the vesti- 
 bule by a delicate network of connective tissue, the interstices of 
 which are filled with perilymphatic fluid. Where the anterior wall of 
 the utricle is in direct contact with the posterior wall of the saccule 
 (septum vestibuli), we find the 2 — 4 mm. broad macula acustica 
 utriculi (na), with which the utricular branch (n) of the ramus vesti- 
 
ON HORIZONTAL SECTIONS. 
 
 247 
 
 bull of the acoustic nerve becomes connected, and the more detailed 
 description of which remains to be given. The macula acustica 
 sacculi (na'), lying on the anterior wall of the saccule, to which a 
 separate nerve branch (n') of the ramus vestibuli passes, is narrower 
 (1.5 mm. Schwalbe). According to my examinations,* there exist 
 anastomotic communications between the ramulus utriculi et 
 sacculi. 
 
 On the deeper sections, falling in the region of the fenestra ovalis 
 and below it, the diameter of the utricle appears greater than that of 
 the saccule, which, diminishing downwards, passes over into the canalis 
 reunions Hensenii. 
 
 The utricle is attached, in and below the projection of the fenestra 
 
 Fig. 153. — Horizontal section through the vestibule above the fenestra ovalis of a new- 
 born infant. — s = utriculus ; a = ampulla ext. and crista ampullaris discharging into it ; 
 r — upper space of the sacculus ; n = nerve bundles of the ramus vestibuli, passing to the 
 utriculus and the macula acust. utric. ; p p" = adherent wall of the sacculus ; p" = 
 anterior wall of the sacculus ; n" = nerve bundles passing to the macul. acust. sacculi ; 
 an = nerve anastomoses running from the bundle n to n". After a preparation in my 
 collection. 
 
 ovalis, to the medial wall of the vestibule, while, between the free 
 lateral side of the saccule and the lateral vestibular wall, there exists a 
 considerable perilymphatic space (Steinbrligge), which is named by 
 Retzius cisterna perilymphatica. To become accurately acquainted 
 with this space, which, below and in front, merges into the scala vestib. 
 of the cochlea, and with the topographical position of the utriculus, 
 
 * Lehrbuch der Ohrenheilkunde, 2. Aufl., 1887, S. 459. 
 
248 EXAM. OF VESTIBULAR STEUCTURES ON FRONTAL SECTIONS. 
 
 both must be examined together on serial sections, made in a frontal 
 direction through the pyramid. Karely only does one succeed in 
 finding, on horizontal and frontal sections, either the discharge of the 
 ductus endolymphaticus from the medial wall of the vestibule into the 
 two saccules (as represented by Bbttcher, I.e. Plate IV.)* or the con- 
 nection between these by the canalis utriculo-saccularis. 
 
 The saccules of the vestibule consist of a fibrillar layer of con- 
 nective tissue, with a structureless homogeneous hyaline membrane, 
 and of an epithelial layer ; the former of these layers is most strongly 
 developed near the maculae acust. (according to Retzius 150 — 200 yu.) ; 
 
 Fig. 154. — Frontal section through the vestibule and the fenestra ovalis of a new-born 
 infant. — u = utriculus, attached to the medial and upper walls of the vestibule; ma = 
 free, lateral wall of the utriculus ; st = fenestra ovalis and stapes ; c — cisterna perilym- 
 phatica ; n, n' n" = nerve bundles of the ramus vestibuli passing to the utriculus and 
 ampullae ; a = ampulla inferior ; ca = crista ampuUaris ; f = nervus facialis. After a 
 preparation in my collection. 
 
 the latter is formed by a simple layer of pavement epithelium. At 
 the maculae acust. this passes over into a neuro-epithelium (Urban 
 Pritchard), which is made up of the auditory cells, and the filiform 
 cells (Hasse's isolation cells)— (Fig. 155). The auditory cells are 
 bottle-shaped, have a bulging in the middle, and a process at the free 
 surface (Urban Pritchard). The latter formations, which have been 
 termed auditory hairs, consist, according to Retzius, of 10 to 15 fila- 
 
EXAMINATION OF THE MACULE ACUSTICVE. 
 
 249 
 
 merits which have a length of 20 — 25 jx. The eniptically-shaped 
 nucleus lies in the bulging portion of the cell. The cylindrical filiform 
 cells have a roundish nucleus placed near the base. The expansion 
 of the ramus vestibuli on the saccules takes place, according to the 
 investigations of Urban Pritchard (' The Termination of the Nerves of 
 the Vestibular and Semicircular Canals,' Quar. for med. Science, 1876), 
 
 Tig. 155. 
 
 in such a manner that the meduUated nerve-fibres spread, under 
 numerous anastomoses, in the connective-tissue layer of the maculae 
 acusticse, whence isolated non-medullated nerve filaments penetrate the 
 hyaline membrane, pass into the epithelium, and enter into contact 
 with the base of the auditory cells (Retzius). The nerve epithelium 
 of the maculae acusticse is covered by a clear, transparent semi-fluid 
 
 Fig. 156. 
 
 substance (Steinbriigge), which after death coagulates, and, as a 
 membrane, envelops the otoliths or otoconia (1 — 15 fi), consisting of 
 small hexagonal crystals of carbonate of lime (Fig. 156). In the 
 middle of the otoliths Schwalbe found small vacuoles. 
 
250 
 
 EXAMINATION OF AMPULLA AND MEMBRANOUS CANALS. 
 
 2. Examination of the Ampullce and Membranous Semicircular 
 
 Canals. 
 
 The best sections of the ampulla super, et horizontalis are obtained 
 by horizontal cuts through the upper portion of the vestibule (Fig. 
 153a), but of the ampulla inferior, on frontal sections (Fig. 154a). If 
 the longitudinal cut meet the ampulla in such a way as to expose its 
 embouchure into the utricle and into the semicircular canal (Fig. 153), 
 we first notice a dark stria (a) which crosses the ampulla, and, passing 
 from a slight constriction on the outer surface of the latter, rapidly 
 diminishes towards the middle. This is the point of entrance of the 
 ramus ampullaris, corresponding to which the crista ampullaris arises 
 
 Fig. 157. — Section through the osseous and membranous semicircular canal. — a = osseous 
 semicircular canal ; b = place of attachment of the membranous semicircular canal ; c = 
 elevations on the inner surface of the membranous semicircular canal ; d = vascular bands 
 of connective tissue. 
 
 from the inner surface of the ampulla. This crista divides the ampuUary 
 space into two unequal portions, the shorter of which, directed 
 towards the utricle, is described by Steifensand as the sinus portion, 
 the longer being known as the tubular portion. The epithelium, 
 which in the ampullae appears in part flattened, in part cylindrical, 
 shows, on the border of the crista (planum semilun., Steifensand), high 
 cylindrical cells and a neuro-epithelium analogous to that on the maculae 
 acusticse of the saccules. Especially beautiful is the appearance 
 of the structure of the crista ampullaris and of its epithelium in 
 
HISTOLOGICAL EXAMINATION OF THE COCHLEA. 251 
 
 transverse sections of the ampulla on preparations treated with 
 hyperosmic acid. 
 
 Best adapted for the study of the structure of the membranous 
 semicircular canals, and their relation to the osseous, are transverse 
 sections made perpendicularly to the long axis of the canals. The 
 horizontal and posterior semicircular canals are examined on frontal 
 serial sections, which commence at the posterior extremity of the 
 pyramid, while the superior canal is examined on horizontal sections 
 through the same. 
 
 The membranous canals, whose diameter measures about one-third 
 of that of the osseous, are, as shown in the accompanying illustration 
 (Fig. 157), attached with part of their walls to the convex side of the 
 osseous canal (b) (Kolliker, Riidinger, comp. p. 127), while on the 
 opposite side they are free and bathed by the perilymphatic fluid. 
 From the free part of the membranous canal there pass through 
 its perilymphatic space, which is lined with endothelium, many 
 vascular processes of connective tissue (d) (ligaments) to the peri- 
 osteum of the osseous canal. Especially numerous are these pro- 
 cesses in the new-born infant. They are to be regarded as the 
 residue of the gelatinous connective tissue which fills up the peri- 
 lymphatic space of the semicircular canals in foetal life. On the 
 inner surface of the canals arise numerous capillary elevations (c) 
 covered with epithelium, which are wanting on the adherent portion 
 of the canal (b), and at the embouchure of the semicircular canals 
 into the utriculus (Riidinger). Through these the inner superficial 
 space of the canals is considerably increased. They are covered with a 
 polygonal epithelium which, on the band (raphe) lying on the concave 
 side of the canal, and extending into the ampulla, assumes a more 
 cylindrical form. Nerve-elements have not been proved to exist in the 
 semicircular canals. 
 
 3. Histological Exa'mination of the Membranous Structures and of 
 the Terminal Apparatus in the Cochlea. 
 
 The histological examination of the cochlea is most frequently made 
 on sections carried parallel to the long axis of the modiolus, either in 
 a frontal or in a horizontal direction through the pyramid. Most 
 instructive are those which pass through the modiolus in its entire 
 length from base to apex, because, on them, not only all the convolu- 
 tions are met in their greatest extent, but also the course of the 
 ramus cochleae in the modiolus, the disposition of the ganglion 
 spirale, and the entrance of the twigs of the cochlear nerve into 
 the lamin. spiralis, and from here into Corti's organ, are brought most 
 clearly under observation. We ought, however, not to omit to extend 
 
252 
 
 TOPOGRAPHY OF THE COCHLEAR SPACE. 
 
 our investigations, also to transverse sections directed vertically to 
 tlie long axis of the modiolus, in order to gain a clear knowledge 
 of the arrangement of the nerve bundles and bloodvessels in its 
 osseous canals, as well as of the relations of these bundles to the spiral 
 ganglion. Since, in sections made parallel to the long axis of the 
 cochlea, Corti's organ is only represented in profile, it should also 
 be examined on surface preparations, these being the only ones on 
 which it is possible to study the dentate projecting borders of the 
 crista spiralis, the arrangement of Corti's pillars, the formation of the 
 lamina reticularis, etc. Especially suitable for this purpose are 
 labyrinths which have been fixed in osmic acid or chloride of gold, and' 
 on which, after sufficient hardening in alcohol, the cochlear capsule is 
 broken open, the lamina spiral, ossea et membranacea carefully 
 detached with a needle, and placed upon the glass slip to be examined 
 after the usual methods. 
 
 Fie. 158. — Section through the lower convolution of the cochlea of a new-born infant. — 
 Sc. V = scala vestibuli ; Sc. t = scala tymp. ; k = lamina spiral, ossea ; b = lamina 
 basilaris ; 1 =: ligamentum triangulare ; E, = membrana Reissneri ; Cc = canalis coch- 
 learis ; o = Corti's organ ; m = Corti's membrane ; n = fasciculus of the ramus cochleae ; 
 gs — ganglion spirale. After a preparation in my collection. 
 
 The study of the details of the complicated cochlear structures 
 must be preceded by a general superficial examination under low 
 magnifying power. A section of one of the coils, enlarged forty to 
 fifty times, is sufficient to see the extent and position of both scalse 
 (Sc. v., Sc. t.) of the canal, cochlearis (Cc), with the terminal apparatus 
 of the acoustic nerve, and the ganglion spirale (gs). To make the 
 subject clearer, we here give a short description of the section of one 
 of the cochlear convolutions. The cavity of the cochlea (Fig. 158) is 
 divided by the lamina spiralis (k, b) into the scala vestibuli (Sc. v.) and 
 the scala tymp. (Sc. t.). The scala vestib. leads immediately into the 
 
CORTl'S ORGAN. 253 
 
 vestibule ; the scala tymp. is closed at the lowest convolution by the 
 membrana fenestrn3 rotundiu. The two scalte are in communication 
 at the apex of the cochlea. The osseous portion of the spiral lamina 
 (k), a plate of bone springing horizontally from the outer surface of 
 the modiolus, consists of two lamellse connected by vertical bridges, 
 which enclose the nerve bundles, passing from the ganglion spirale 
 (gs). From the free border of the lam. spiral, ossea arises the mem- 
 branous plate (b), which is attached to the projecting triangular 
 ligam. spirale (1) . On the membranous spiral plate three portions are 
 distinguished : the inner, which is perforated by numerous openings 
 for the passage of the fibres of the nerv. cochl. (zona perforata, p) ; the 
 middle portion, supporting the organ of Corti (zona arcuata) ; and the 
 outer finely-striated portion (zona pectinata). 
 
 The scala vestibuli again is divided by Keissner's membrane (K), 
 passing obliquely from the crista spiralis to the outer wall of the 
 cochlea, into two parts, of which the one, formed by the membrana 
 basilaris, the external cochlear wall (stria vascularis), and Keissner's 
 membrane, is termed the canalis s. duct, cochlearis (Cc), This canal, 
 which is lined with epithelium, contains the terminal apparatus 
 proper, is filled with endolymph, and, communicating below through 
 the canalis reuniens Hensenii with the sacculus, ends in a cul-de-sac 
 at the cupola of the cochlea. 
 
 When we have become acquainted with the position of the various 
 structures in the interior of the cochlea by slightly magnifying them, 
 we pass on to the examination of the details of Corti's organ, and of 
 the cochlear membranes, using a higher magnifying power. 
 
 The situation of Corti's organ is best demonstrated by profile 
 views of a greater number of microscopic frontal sections. We see 
 (Fig. 159) on such sections, at the upper surface of the outer portion 
 of the osseous spiral plate, a tuberosity (H — crista spiralis, Huschke), 
 which is caused by the thickening of the periosteum, and, with its 
 dentate edge, somewhat resembles a cock's comb. It roofs over a 
 spiral canal (sulcus spiralis int.), lined with cubical epithelium (k). 
 The upper sharp edge of the crist. spiral, is known as the labium 
 vestibulare ; the lower, which passes into the membr. basilar., as the 
 labium tympanicum. 
 
 Externally from the sulcus spiralis lies Corti's organ proper. 
 This consists of a row of inner (C), and a row of outer (C), slightly- 
 curved rods (fibres of Corti), which rest with their lower extremities 
 upon the membrana basilar., while their upper ends have a joint-like 
 connection. These two rows of rods form Corti's arch. In the lower 
 angles formed by the rods and the lam. basil, lie two rows of roundish 
 nucleated cells (floor cells). 
 
254 
 
 CORTI'S ORGAN. 
 
 The rods of the outer row have, at their upper extremities, 
 lamelliform processes, directed outwards, to which is attached a net- 
 Hke fenestrated membrane, the lamina reticularis (r). It roofs over 
 the outer row of Corti's fibres, and the so-called cells of Corti, or 
 outer hair-cells (ah). These structures (Z) are, in the human subject, 
 arranged in four or five parallel rows (Gottstein), and connected 
 with the terminal fibres of the acusticus through small nerve pro- 
 cesses. With their lower attenuated ends (Gottstein's basal process), 
 which, according to Bottcher and Baginsky, do not belong to Deiters's 
 cells, they are fastened to the membrana basilar., while their upper 
 broader extremities, provided with auditory hairs, project through 
 the openings of the lam. reticularis. A row of inner hair-cells (ih) is 
 placed before the sulcus spiral, int., immediately in front of Corti's 
 inner pillar. With Corti's cells are connected those named after 
 Deiters (D), the broader ends of which are directed downwards. Ex- 
 
 Fig. 159. — Terminal apparatus of the ramus cochleae, with Corti's organ, in the human sub- 
 ject. — o = lamin. spiral, ossea, with the nerve bundle of the ramus cochl. ; pi = lamin. 
 spir. membr. ; H = tooth of Huschke (crista spiral. ) ; c = inner pillar of Corti ; c' = 
 outer pillar of Corti ; r = lamina reticularis ; Z = Corti's cells ; D = Deiters's cells ; 
 ih = inner hair-cell ; ah = four outer hair-cells ; e = radial tunnel fibres of the ramus 
 cochl. passing to the cells of Corti ; k = cells of the sulcus spiralis int.; CI = Hansen's 
 supporting cells ; cm = Corti's membrane ; vs = vas spirale. After Retzius. 
 
 ternally to the last row of Corti's cells lie the supporting cells (CI) of 
 Hensen, which pass into the epithelium of the outer wall of the 
 ductus cochlearis. 
 
 Corti's organ is roofed over by the firm striated membrane (cm) of 
 Corti. It arises near Reissner's membrane from the crista spiralis, 
 and terminates, as is generally supposed, at the outer boundary of the 
 sensory cells of Corti's organ ; it is, according to Bottcher (A. f. 0., 
 Bd. xxiv.), attached to the surface of the terminal apparatus of the 
 acusticus. 
 
 Reissner's membrane presents a homogeneous structure inter- 
 spersed with spindle-shaped cells. The side turned towards the canal, 
 cochlearis is covered by a flattened epithelium, the upper side by an 
 endothelium. 
 
EXAMINATION OF THE INTERNAL MEATUS AND N. ACUSTICUS. 255 
 
 The histological examination of the labyrinth in pathological cases, 
 on the importance of which we laid due stress in the introduction 
 to this work, is made according to the methods observed with the 
 normal labyrinth; only the mode of fixation of the tissue-elements 
 differs in a slight degree, since in the examination of pathological 
 labyrinths we mostly use chromic acid and its salts (the fixing fluids 
 of Vlakovic, Urban Pritchard, and Mliller's solution, p. 195), rarely 
 only hyperosmic acid and chloride of gold. 
 
 By cutting the labyrinth into microscopic serial sections we not 
 only gain information as to the structural changes in its various 
 portions, but, through the successive sections, also a representation of 
 the extent of the morbid process. We employ, by preference, frontal 
 sections made through the pyramid, from the apex of the cochlea to 
 the posterior extremity of the horizontal semicircular canal, because 
 this direction of the cut is more favourable for simultaneous examina- 
 tion of the two labyrinthine fenestrge. Yet there are cases where 
 horizontal sections are preferable, especially when the continuity of 
 pathological products in the vestibule and in the cochlea are to be 
 brought under notice in one section. 
 
 The histological dissection of the labyrinth is always to be 
 undertaken where, during life, symptoms of an affection of the 
 auditory nerve had existed, no matter whether it appeared primarily, 
 or complicated with middle-ear disease. It is true the examination 
 often gives a negative result, but much more frequently than is 
 generally supposed, one finds more or less strongly pronounced 
 pathological changes in the labyrinth, which are recognised as the 
 cause of the impairment of hearing during life. We need only refer 
 to the haemorrhages and purulent exudations in the labyrinth, to 
 the new-formations of connective tissue and bone, to the retro- 
 gressive changes in the ganglion cells of the gangl. spirale, in the 
 terminal expansion of the ramus cochleae in the cochlea, in Corti's 
 organ, and in the macul. acust. of the vestibular saccules. 
 
 HISTOLOGICAL EXAMINATION OF THE INTERNAL AUDITORY MEATUS AND 
 OF THE ACOUSTIC NERVE, 
 
 The internal meatus and the acoustic nerve are histologically ex- 
 amined on longitudinal and on transverse sections. On lonofitudinal 
 sections, which pass horizontally through the decalcified pyramid 
 and expose, besides the internal meatus, also the vestibule and 
 cochlea, the direction of the course of the acoustic nerve in the 
 pyramid, the division of the nerve trunk into the posterior upper 
 ramus vestibuli and the anterior lower ramus cochleae, appear sharply 
 
256 EXAMINATION OF THE INTERNAL MEATUS AND N. ACUSTICUS. 
 
 marked (comp. Figs. 100 and 101, p. 127). The vestibular branch 
 shows, in the neighbourhood of the infundibulum of the internal 
 meatus, a grayish-red swelling, which contains numerous ganglion 
 cells, the intumescentia ganglioformis Scarpse. The upper portion of 
 the ramus vestibuli runs in an outward direction in the osseous 
 mass between the cochlea and the vestibule, and, describing a 
 slight curve backwards, enters through the maculae cribrosse of the 
 recess, hemiellipt. into the vestibule, to give off small twigs to 
 the recess, utriculi and to the ampullae of the superior and horizontal 
 semicircular canals. The lower portion of the ram. vestibuli (the 
 ramus medius of Schwalbe) divides into two small branches, the 
 upper of which also runs forward in the osseous mass between the 
 cochlea and vestibule, enters the latter and proceeds to the neuro- 
 epithelium of the macula acust. sacculi ; while the lower branch 
 passes separately to the crista ampullar, of the inferior ampulla. 
 The bundles of the ramus cochleae pass through the openings of the 
 tract, spiral, foraminul., in part directly to the first convolution 
 of the cochlea, in part to the nerve-canals of the modiolus, and 
 from here to the lam. spiral, ossea. Between the fibrous bundles 
 of the modiolus and the lamina spiralis we find, on the periphery 
 of the former, an extensive ganglion layer (zona ganglionaris) in- 
 terposed (Fig. 158), which lies in the sharply defined canal of 
 Rosenthal, and appears oval in the section (Fig. 160). Into the 
 lower portion of this ganglion layer the nerve bundles n n' n" enter at 
 various spots, and pass, after numerous connections with the ganglion 
 cells at the upper extremity of Rosenthal's canal, into the lam. 
 spiralis. 
 
 In the spiral plate, the nerve bundles, which are through numer- 
 ous cross anastomoses, in plexiform connection, run with their 
 non - meduUated fibres between the two osseous lamellsG to the 
 habenula perforat. of the lower surface of the basilar membrane, 
 pass from here through numerous openings on the upper surface of 
 the same to the ductus cochlearis, and dividing, according to the in- 
 vestigations of Waldeyer and Gottstein, into very fine, in places ' 
 knotty terminal fibres, become connected with the inner hair- cells, 
 and, through the gaps of Corti's arch, with Corti's cells, or outer hair- 
 cells. 
 
 For the purpose of making transverse sections of the internal 
 meatus, of the acoustic nerve and n. facialis, the pyramid, after having 
 been subjected to one of the usual methods of fixation, and then 
 carefully decalcified, is embedded in celloidin, whereby alone sections 
 of [the nerve can be kept in situ in the preparation. Through 
 such serial sections, extending from the entrance of the porus acust. 
 
GANGLION SPIRALE. 
 
 257 
 
 int. to the floor of tlie internal meatus, we obtain a correct idea as 
 to the topographical position of the n. aciist. to the n. facialis in the 
 various portions of the internal meatus, and of the normal relationship 
 of the transverse sections of the nerve fibres with their sharply defined 
 axis-cylinders. Such knowledge is all the more important, as it enables 
 us to judge of the altered appearance of the acusticus in pathological 
 thickening, connective-tissue proliferation, atrophy, adipose and colloid 
 degeneration ; also of the relations of any neoplasms in the internal 
 meatus and auditory nerve ; of the localization of purulent inflam- 
 
 b"- 
 
 ¥ia. 160. — Section of Rosenthal's canal and of the ganglion spirale.— a = ganglion cells of 
 the gangl. spir., lying in Rosenthars canal ; b b' b" = three separate nerve bundles of the 
 ram. cochl., entering the gangl. spir. ; c = nerve bundle passing out of the upper pole of 
 the gangl. spir. ; d = entrance of this bundle into the lam. spir. ossea. After a prepara- 
 tion in my collection. 
 
 mations in the internal auditory canal (Gradenigo) ; of thickenings 
 and calcifications of its lining membrane ; of exostoses, etc. 
 
 THE HISTOLOGICAL EXAMINATION OF THE AQUEDUCTS OF THE 
 
 LABYRINTH. 
 
 The histological examination of the aqueducts is not attended with 
 any special difficulty if the sections be made in a perpendicular direc- 
 tion to the long axis of the canals. For obtaining transverse sections 
 of the intradural sac of the aquceductus vestibuli, the pyramid, on a 
 decalcified preparation, with the dura mater in connection, is divided 
 
 17 
 
258 HISTOLOGICAL EXAMINATION OF THE AQUEDUCTS. 
 
 into two parts by a sagittal longitudinal cut ; the inner half is then 
 embedded in celloidin, and the preparation, from the lower portion of 
 the sinus transversus as far as the vicinity of the porus acusticus 
 intern, (p. 132), sliced in serial sections, which are carried nearly 
 vertically to the long axis of the pyramid. The same mode of trans- 
 verse sectioning is also employed in the examination of the narrow 
 intratemporal part of the aquseductus vestibuli, which, as we have 
 seen (p. 130), describes, in the osseous mass situated in front of the 
 sagittal semicircular canal, a slight curve from the apertura extern, 
 aquseductus vestibuli up to the embouchure into the vestibule. It is 
 only seldom possible to obtain by frontal cuts through the petrous 
 bone a longitudinal section of the entire intratemporal portion of the 
 aquseductus vestibuli. 
 
 To make transverse sections of the aquseductus cochlear on a 
 decalcified pyramid, the funnel-shaped dilatation of the aqueduct is 
 to be looked for at the inner border on the inferior wall (see p. 134), 
 and from here the short canal is divided in a series of sections up to 
 its opening into the scala tympani. On frontal serial sections of the 
 cochlea I succeeded several times in obtaining the entire longitudinal 
 section of the aquseductus cochlese. 
 
 Of the pathological changes in the aqueducts of the labyrinth little 
 is as yet known. 
 
 TOPOGRAPHICAL SERIAL SECTIONS OF NORMAL AND PATHOLOGICAL 
 ORGANS OF HEARING. 
 
 When making topographical serial sections of the organ of hearing, 
 it is best to employ, for fixing the tissue-elements, Miiller's fluid or 
 yiakovic's solution (chromic acid and alcohol hardening, p. 195) ; for 
 decalcification, the solution of nitric acid and chloride of sodium 
 (p. 201) ; and for embedding, celloidin. As the bulk of the object to 
 be examined is considerable, it should be exposed longer to the action 
 both of the fixing- and decalcify ing-fluids than smaller objects. Kapid 
 decalcification especially must be guarded against, on account of the 
 bone nuclei, which it is difficult to get rid of After decalcification, 
 the preparation is freed from acid by irrigating in a stream of pure 
 water for several hours ; it is then placed in dilute alcohol, and only a 
 few hours before embedding in celloidin must it be immersed in 
 absolute alcohol. To allow the celloidin to completely fill up all the 
 cavities of the temporal bone, the tegmen antri mastoid, is broken 
 open, and an aperture filed in the superior semicircular canal. Not 
 until the preparation has been for several days in the thin-fluid 
 celloidin solution should it be transferred to a more concentrated 
 
TOPOGRAPHICAL SERIAL SECTIONS OF NORMAL ORGANS. 259 
 
 one, and after two to three days more to the syrupy solution, where it 
 is to be embedded. 
 
 For the purpose of obtaining topographical serial sections of the 
 auditory organ, it is cut either in a horizontal or a frontal direction 
 by means of the microtome. For the study of the normal relations 
 both methods recommend themselves, as their results supplement one 
 another. 
 
 Information as to the topographical representations which are to 
 be obtained from horizontal and frontal serial sections of the ear may 
 be gathered from the previous description of the sections through the 
 temporal bone (p. 33), and from the topographical sections of the organ 
 (p. 147), so that a detailed account may here be dispensed with. It is 
 sufficient to remark that the diameter of the tympanic cavity in the 
 horizontal and frontal planes, the topographical position of the ossicula, 
 the arrangement of their ligaments, and the relative position of the 
 middle ear to the labyrinth and its membranous structures, can by no 
 other method be so accurately and instructively demonstrated as by 
 these serial sections of the entire auditory apparatus. But as this 
 presents in the new-born infant peculiarities differing in some respects 
 from those in the adult, it is recommended, for purposes of com- 
 parative study, and for estimating pathological serial sections, to 
 prepare organs of both kinds. The great value of these sections 
 requires, after what has been said, no further proof. 
 
 For demonstrating microscopical sections as preparations to be 
 examined with the magnifying lens, a method may here be mentioned 
 which I make use of before large classes. With a sharp knife or a 
 fret-saw two or three square holes are cut side by side in the upper 
 third of the wooden lid of a common cigar-box (22 cm. by 13 cm.). 
 The diameter of these openings measures about 2 cm., so that they 
 are a little larger than an ordinary cover-glass. As they are cut 
 according to the width of the board, there is a distance of 2 cm. 
 between them. The front of the lid is covered with dark-coloured 
 embossed paper, the back with smooth black paper, and in this 
 covering holes are cut which correspond to those in the wood. 
 
 The preparation to be examined is now fastened on the board in 
 the following manner : The slide, with its cover-glass directed towards 
 the front, is so placed against the back of the wood that the circum- 
 ference of the cover corresponds to the square aperture in the board. 
 After this, the slide is pasted over with a piece of black glazed 
 paper which has been gummed and cut out to correspond with the 
 square openings in the board in such a way that the edges of the 
 paper overlap those of the slide. By this means two or three prepara- 
 tions can be fixed side by side on one board, so that, if held against 
 
 17—2 
 
260 EXAMINATION OF THE CENTEAL COURSE OF THE N. ACUSTICUS. 
 
 the light and examined with a lens, they show the exact anatomical 
 and pathologico-anatomical details in their rough outlines. In order 
 to avoid inconvenience while the preparations are being passed from 
 hand to hand in the class, each board should be provided with a lens 
 fastened with a piece of cord about a foot long. A short written 
 description, or an enlarged drawing of the objects, gummed below the 
 apertures, will be of assistance. 
 
 IX. 
 
 Histological Examination of the Centkal Course of the 
 Acoustic Nerve. 
 
 The histological examination of the medulla oblongata on transverse 
 sections is, for the study of the topographical relations of the acusticus 
 and its nuclei, so far of importance to the otologist, as it is only by the 
 knowledge of the complicated relations of the central course of the 
 nerve that he will be enabled to judge of the congenital anomalies and 
 arrest of development in the region of the central origin of this nerve, 
 and of the primary and secondary pathological changes occurring 
 therein. 
 
 For the investigation of the central origin of the auditory nerve in 
 the medulla oblongata, of the intra-cerebral course of the fibres of the 
 acusticus and of the acoustic cortical areas in the temporal lobe, the 
 chrome-hardening and fixing methods are best adapted. Most fre- 
 quently Miiller's fluid (kal. bichromici 2.0, natr. sulfurici 1.0, aqu, dest. 
 100.0) and Erlitzki's solution (kal. bichromici 2,5^ cupri sulfurici 0.50, 
 aqu. dest. 100.0) come into use. 
 
 Perfect hardening of these central organs in Miiller's fluid is a very 
 slow process, and often takes weeks and months to accomplish. 
 Frequent changing of the fluid is the safest means of insuring 
 homogeneous and rapid hardening of the parts of the brain. This 
 is, according to Weigert, materially shortened in the drying ap- 
 paratus, under a temperature of 30-40° C. Erlitzki's method effects 
 more rapid hardening. To guard against the formation of mould, and 
 to better preserve the preparations, it is well to add a little camphor 
 to the above-mentioned fluids. 
 
 The examination of the nuclei of the acusticus, and of the course 
 of its fibres in the central organ, requires special staining methods, of 
 which especially those recommended by Weigert and Pal have been 
 found to yield excellent results.* 
 
 * Compare Heinrich Obersteiner's excellent work : ' Anleitung beim Studium des Baues 
 dernervosen Centralorgane im gesunden und kranken Zustande.' — Leipzig und Wien, 1888, 
 S. 13 u. 15. 
 
nuclki and roots of the n. acusticus. 261 
 
 1. weigert's method. 
 
 The organs, hardened in Muller's fluid, are, without being washed, 
 placed in alcohol, then in a solution of acetic oxide of copper (two 
 days), then again in alcohol; after that, cutting. Staining in hsema- 
 toxylin 1.0,* alcohol 10.0, aqu. dest. 90, hthium carb. cone, solut. 1.0 
 two to four hours, until the whole is stained black; decolorization in 
 borax 2.0, ferridcyankal, 2.50, aqu. dest. 200.0. Washing in water, 
 etc. 
 
 The medullated fibres appear deep blackish-blue, axis- cylinders, 
 ganglion cells and nuclei bright yellow, almost colourless. Gray sub- 
 stance shows yellowish- white, white substance black. 
 
 2. pal's method. 
 
 A method for the investigation of the central nerve-system, which 
 has of late been frequently employed, and which in some respects 
 differs from Weigert's, is that of Pal, a short description of which is 
 here given. 
 
 1. The object is hardened in Muller's fluid, which must be fre- 
 quently renewed. 
 
 2. The hardened preparation is cut under alcohol instead of under 
 water, which is to be avoided. 
 
 3. The sections are stained in the following solution: Rp. hema- 
 toxylin 1, alcohol 10, water 90, The hematoxylin solution must be 
 an older one. If fresh, it should have a small quantity of lithium 
 carbonicum added to it. 
 
 4. The sections remain for one day in the cold staining medium, 
 and for an hour in one heated to 35-75° C. 
 
 5. Washing of the sections in water, and transferring them to a 
 solution of permanganate of potash (0.25 : 100), where they rema'n 
 until differentiation of the tissues begins to be noticed. 
 
 6. Washing of the sections in 1 part kalium sulphurosum, 1 part 
 oxalic acid, 200 parts water, until the brown colour of the preparations 
 has disappeared. 
 
 7. Washing in alcohol 1 part, xylol 3 parts, and carbolic acid 
 3 parts. 
 
 8. Clearing up in oil of cloves, and mounting in Canada balsam. 
 As regards the position of the auditory nuclei and the central 
 
 course of the n. acusticus, we shall here follow in our description the 
 excellent work of S. Freud, ' Ueber den Ursprung des N. acusticus,' 
 M. f. O., 18SG, Nr. 8 u. 9, of which notice was taken in my Lehrbuch, 
 2 Aufl., 1887. 
 
 "■•" Rp. hsematoxylini 1.0, alcohol ab. 100.0, aqu. dest. 100.0, glycerini 2.0, alumin. pulv. 
 2.0. To be filtered every time it is used. Stains well only after eight days. 
 
262 
 
 NUCLEI AND ROOTS OF THE N. ACUSTICUS. 
 
 A tranverse section through the medulla oblongata in the lowest 
 planes of the acusticus (Fig. 161), through the tip of the great olivary 
 body, shows that this nerve occupies the outer area of the oblongata, 
 which extends to the great ascending root of the trigeminus (V), and 
 contains the section of the restiform body (Cr). Internally and 
 superiorly (dorsal) from the latter lies, beautifully marked against the 
 gray mass, an area (I)k) which has been described as the inner portion 
 of the pedunculus cerebelli, but assigned by Freud to the acusticus, 
 and which is known as Deiters's nucleus. In the outer central corner 
 of the section lies a large nucleus of the auditory nerve, the anterior 
 or external nucleus (8e). 
 
 On transverse sections made a little higher, we meet with bundles 
 of the acusticus, which cross the restiform body (VIIIo) and have led to 
 
 Fig. 162. — Higher preparation from the 
 saroe series of sections, showing also the 
 nucleus of the facialis 7, and the fibres of 
 the root of this nerve VII, passing to its 
 knee ; VIIIj =: the second portion of the 
 acoustic nerve, passing round and 
 through the restiform body ; oO = the 
 superior olive. The rest of the letters as 
 in Fig. 161. 
 
 Fig. 161. — Section through the lowest planes 
 
 of the place of exit of the acoustic nerve, 
 
 from a human fcEtus of 6 lunar months. 
 
 Treatment with Weigert's hsematoxylin. 
 
 — VIIIj = first portion of the acoustic 
 
 nerve ; 8e = outer, 8i = inner nucleus of 
 
 the acoustic nerve ; DK = nucleus of 
 ' Deiters ; V = section of the fifth nerve ; 
 
 Cr = corpus restiforme ; Oz = interoli- 
 
 vary layer ; 1 = acoustic nerve-filaments 
 
 round the restiform body : 2 = fibres from 
 
 8i to the raphe ; Ctrp = corpus trapezoides. 
 
 the supposition that the nerve arose out of that fibrous mass. Other 
 portions (VIIIJ of the nerve, which occupy the space between the 
 anterior nucleus and the section of the great root of the trigeminus 
 (V), pass over direct into the lateral region of the gray floor (8i). 
 These fibres, the most medial portions of the nerve, do not belong to 
 the acusticus, but to the vestibular nerve, which is connected with it. 
 The planes, in which the course of the vestibular nerve is to be seen, 
 are the lowest ones of the pons. The medulla oblongata here appears 
 
NUCLEI AND ROOTS OF THE N. ACUSTICUS. 
 
 263 
 
 connected, through the brachiam pontis, with the cerebellum; the 
 roots of the n. facialis (Figs. 163 and 164, VII) and of the n. abducens 
 (Fig. 164) occupy the inner areas of the oblongata. The nucleus of 
 Deiters (Figs. 102 and 163 DK), or the inner portion of the pedunculus 
 cerebelli, can here no longer be demonstrated. The fibres which it 
 contained have curved over into the acusticus (Fig. 103, Villa, 
 Roller). The boundary between the tegmental region and that of the 
 pons is given by a large cross bundle, the corpus trapezoides (Figs. 163 
 and 164, Ctrp), which, while lying free in animals, can also be plainly 
 distinguished in the human subject, although covered over by the 
 fibres of the pons. It arises from the anterior auditory nucleus, is 
 therefore an indirect continuation of the acoustic nerve proper, and 
 passes beyond the middle line. It terminates, at least in part, in a gray 
 
 >RBtt 
 
 ^IG. 163. — Transition of the third portion 
 of the acusticus VIII.j into the fibres of 
 Deiters's nucleus. Lettering as in Fig. 
 162. 
 
 Fig. 164. — Section through the planes of the 
 fourth portion of the acusticus and of the 
 nucleus of the abducens (6). — VI = the n. 
 abducens ; hL = the posterior longitudinal 
 bundles ; Vllk = genu of the facialis ; 
 Ctr' — portion of the corpus trajiezoides, 
 which passes to the superior olive of the 
 same side ; oOSt — peduncle of the supe- 
 rior olive. The other letters are the same 
 as in Fis;. 161. 
 
 mass lying above it, the superior olivary bod}^ (Figs. 163 and 164, oO), 
 which manifests itself, through its connections, as the reflex ganglion 
 of the acusticus (Freud, Bechterew). Other central connections of 
 the acoustic and vestibular nerves pass, as curved fibres (fibr^e 
 arcuatffi), beyond the raphe. Among these, special attention has 
 always been directed to the so-called striaB acusticiB, which are visible, 
 with varying distinctness, on the floor of the sinus rhomboideus. 
 They have, however, not the significance of auditory roots, but of 
 central continuations, probably from the anterior nucleus. As to the 
 
264 ORIGIN AND CENTEAL CONTINUATIONS OF THE N. ACUSTICUS. 
 
 origin and the central continuations of the n. acusticus, the following 
 is known, according to the investigations of S. Freud. 
 
 The n. acusticus (labyrinthine and vestibular nerve) arises from 
 the already described gray substance of the medulla oblongata, and 
 displays the typical relationship of a posterior spinal root. Its 
 central continuations pass mostly beyond the raphe of the oblongata. 
 The outermost and most posterior portion of the nerve (Villi), the 
 acusticus proper, terminates in the great anterior nucleus (Fig. 161, 
 8e). Its continuation from here is to be found partly in bundles 
 (Fig. 161), which pass round the restiform body, then backwards 
 towards the raphe, and whose further course is not quite known 
 (striae acusticse, connections with the inner nucleus), partly in the 
 large cross bundle of *he corpus trapezoides (Ctrp). This mass of 
 fibres is composed of several constituents ; one part of them connects, 
 according to Flechsig, the anterior auditory nuclei of both sides with one 
 another, a second bundle runs to the superior olive of the same side 
 (Fig. 164, Ctrp), a larger bundle to the crossed superior olivary body. 
 It is supposed that other bundles pass out of the corpus trapezoides 
 into the interolivary layer, and descend towards the spine (Freud). 
 The superior olivary body appears to be the glanglion for the reflex of 
 auditory impressions on the movements of the eyes, as it is connected 
 with the nucleus of the n. abducens through its so-called peduncle 
 (Fig. 164, oOSt), and with the posterior corpus quadrigemina through 
 the ' lateral loop.' The latter connection was first recognised by 
 Flechsig and Bechterew, and demonstrated by Baginsky through 
 experimental degeneration. The further course of the acusticus, 
 from the posterior corpus quadrigemina into the inner capsule, requires 
 investigation. 
 
 A second portion (Fig. 163, VIIL) of the n. acusticus unites with 
 those fibres which pass through and arise from the nucleus of Deiters 
 (DK). This portion is morphologically quite intelligible, as it 
 represents an ascending root (Roller, Freud), such as are also met 
 with in other nerves (trigeminus, vagus). But of its physiological 
 significance nothing is known. 
 
 A third portion (Fig. 164, VIII^) — the medial and uppermost 
 fibres — constitutes the nerve of the semicircular canals. It runs 
 partly through the restiform body, partly inwards from the same, and 
 terminates in the inner acoustic nucleus, which, after disappearance 
 of the nucleus of Deiters, occupies its space (large-celled nucleus). 
 Other connections of the vestibular nerve known are : curved fibres to 
 the nucleus of the abducens (Fig. 164, o) and beyond the raphe, 
 occasioning the reflex movements of the eyes in vertigo (the fibres 
 beyond the raphe possibly represent the central continuation in the 
 
EXAM. OF CENTRES OF N.^ACUSTICUS IN PATHOLOGICAL CASES. 205 
 
 cerebellum) ; a fasciculus to the interolivary layer, descending towards 
 the spine ; and curved bundles, which pass round the lateral wall of 
 the ventricle, to the crossed central ganglion of the cerebellum (roof- 
 nucleus, spheroidal nucleus, nucleus emboliformis) . 
 
 Macroscopical preparations of the medulla oblongata for the demon- 
 stration of the strise acustic^e on the floor of the sinus rhomboideus, 
 and of the exit of the trunk of the n, acusticus from the med. obi., are 
 to be placed for several hours in a weak solution of chloride of zinc 
 (2%)' ^^d then soaked in pure glycerine for ten to fourteen days. The 
 morbidly changed oblongata (tumours, etc.) may be subjected to the 
 same method of preservation. If the preparation be placed in a 
 shallow glass dish and covered with a glass shade in such a way that 
 no dust can penetrate into the enclosed space, the object will retain 
 for years its normal shape and colour. 
 
 The microscopical dissection of the medulla oblongata and of the 
 temporal lobe in pathological cases is always advisable whenever the 
 examination on the living subject pointed to a central affection of 
 the acusticus, or where, during life, a high degree of deafness had 
 existed which was not accounted for by the result of the autopsy. 
 Especially with deaf-mutes should the examination of the med. 
 oblong, not be omitted, no matter whether the deafness was congenital 
 or brought on after birth by serious diseases of the middle ear 
 (diphtheritis scarlat.) and of the labyrinth (parotitis), or lastly, by 
 meningitis, cerebro-spinal meningitis and hydrocephalus. In the 
 adult, the examination must be extended to the medulla oblongata 
 and the temporal lobe, if, during life, the disturbance of hearing was 
 complicated with cerebral symptoms, or with aphasia ; also with deaf- 
 ness the result of meningitis, hydrocephalus, apoplexy, and tumours 
 of the brain. But also in deafness of many years' standing, caused by 
 carious-necrotic destruction of the labyrinth, by obliteration and 
 ossification of the labyrinthine cavity, the oblongata must be subjected 
 to microscopical examination, because, as we have seen (p. 264), 
 destruction of the labyrinth in animals (Baginsky) leads to microscopi- 
 cally perceptible secondary changes in the nuclei of the acusticus. 
 
LITERATURE. 
 
 Gahrielis Fallopii medici mutinensis Observationes anatomicae. 
 Coloniae 1562. — Bartholomdus Eustachius : Epistola de organis au- 
 ditus. In eius opusculis anatomicis. Venetiis 1563. — Hieronhnus 
 Fahricius ah Aquapendente : Tractatus anatomicus triplex de oculo, 
 aure et larynge. 1614. — J. Mery : Description exacte de Toreille. 
 Paris 1677. — Duverney : Traite de I'organe de I'ouie. Paris 1683. — 
 B. Vieussens : Traite de la structure de I'oreille. Toulouse 1714. — 
 Duverney : Traitd de I'organe de I'ouie. Leide L731. — Joannes 
 Fridericus Cassebohm : Tractatus quatuor anatomic! de aure liumana. 
 Halae 1737. — Antonius Maria Valsalva : Tractatus de aure liumana. 
 Venetiis 1740. — Dominici Cotunnii: De aquaeductibus auris 
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 Leonhard Fischer : Anweisung zur praktischen Zergliederungskunst. 
 Die Zubereitung der Sinneswerkzeuge und Eingeweide. Leipzig 
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 Nlirnberg 1800. — Joan. Hieronym. Kniephof: De praeparatione 
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 p. 228. — Samuel Thomas Sommering : Abbildungen des mensch- 
 lichen Gehororgans. Frankfurt a. M. 1806. — J". Cunningham 
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 Georg Ilg : Einige anatomische Beobachtungen vom Bau der Schnecke 
 des menschlichen Gehororgans. Prag 1821. — John Shaw: A 
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 anatomy and their application to pathology and surgery. London 
 1820. 8. edit. 3. 1822. — David Tod: The Anatomy and Physiology 
 of the Organ of Hearing. London 1832. -if. Gilbert Breschet: 
 Etudes anatomiques et physiologiques sur I'organe de I'ouie et sur 
 I'audition. Paris 1833. — Ed. Hagenbach : Disquisitiones anatomicae 
 
LITERATURE, 
 
 267 
 
 'circa musculos auris internae hominis, etc. Basileae 1838. — E. Alex. 
 Lauth : Neues Handbuch der praktischen Anatomie oder Beschrei- 
 bung aller Theile des menschlichen Korpers, mit besonderer Riick- 
 ■sicht aiif ihre gegenseitige Lage, nebst Angabe iiber die Art., dieselbc 
 -zu zergliedern und anatomische Priiparate zu verfertigen. Band I. 
 Stuttgart 1835. S. 351 u. f. — Eduarcl Hagenbach : Die Paukenhbhle 
 ■der Saugethiere. Leipzig 1835. — G. Breschet: Eecherches anato- 
 raiques et physiologiques sur I'organe de I'ome et sur I'audition dans 
 I'homme et les animaux vertdbres. Paris 1836. — Arnold : Icones 
 organorum sensuum. Turici 1839. — S. Pappenheim : Die specielle 
 'Gewebelehre des Gehororgans nach Structur, Entwicklung, Krank- 
 heit. Breslau 1840. — Josef Hyrtl : Vergleichend - anatomische 
 Untersucbungen liber das innere Gehororgan. Prag 1845. — Corti : 
 Recherches sur I'organe de I'ouie des mammiferes. Zeitschr. fiir 
 wissensch. Zool. III. 1851. — Kolliker : Mikroskopische Anatomie. 
 II. 2. 1852. — J. Toynbee : On the structure of the ear. London 
 185S.—Toynbee : Transactions of the Pathol. Soc. 1853. Vol. lY. — 
 ■Joseph Toynbee : Descriptive catalogue of preparations illustrative of 
 the Diseases of the Ear, p. 121. London 1857. — J. Gerlach : Mikros- 
 kopische Studien auf dem Gebiete der menschlichen Morphologic. 
 Erlangen 1858. — Troltsch : Die Untersuchung des Gehororgans an 
 derLeiche. Virch. Arch. Bd. XIII. S. 513. 1858. — O^to Deiters : 
 Untersucbungen iiber die Lamina spiralis membranacea. Bonn 1860. 
 — A. V. Troltsch: Die Anatomie des Ohres. Wiirzburg 1861. ■ — R. 
 VoUolini : Die Zerlegung und Untersuchung des Gehororgans an der 
 Leiche. Inaug.-Dissert. Breslau 1862. — V. Hensen : Studien liber 
 das Gehororgan der Decapoden. Leipzig 1863. — August Lucae : 
 Anatomisch-physiologische Beitrage zur Ohrenheilkunde. Virchow's 
 Archiv. Bd. 29. Berlin ]863. — Carl Bogislaus Beichert : Beitrag zur 
 feineren Anatomie der Gehorschnecke des Menschen und der Sauge- 
 thiere. Berlin 1864. — B. Lowenberg : Etudes sur les membranes et 
 les canaux du lima9on. Paris 1864. — Rildinger : Ein Beitrag zur 
 Anatomie und Histologie der Tuba Eustachii. Sep.-Abdr. a. d. 
 Aerztl. Intell.-Blatt. Nr. 37. Mlinchen 1865. — Ludwig Mayer: 
 Studien iiber die Anatomie des Canalis Eustachii. Mlinchen 1866. — 
 Rildinger : Ueber das hautige Labyrinth im menschlichen Ohre. 
 Aerztl. Intell.-Blatt. Mlinchen 1866. — L. Joseph : Osteologischer 
 Beitrag liber das Schlafebein und den in ihm enthaltenen Gehorap- 
 parat. Zeitschr. f. rat. Medicin. Bd. 28. 1866. — E. Zaufal : Die 
 pathologisch-anatomische Untersuchung der Gehororgane. Wien. 
 medic. Wochenschrift. Jahrgang 16. Nr. 62 — 65. 1866. — M. V. 
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 Sep.-Abdr. a. M Schultze's Arch. f. mikr. Anat. Bd. III. 1867. — 
 
268 LITERATURE. 
 
 Gruher : Beitrage zur Anatomie des Trommelfells. Woclienbl. d. 
 Ges. d. Aerzte in Wien. I. 21. 1867. — Prussak : Ueber die anato- 
 mischen Verhaltnisse des Tommelfells zum Hammer. Sep.-Abdr. a. 
 (1. Centralblatt f. d. med. Wissensch, 1867. Nr. 15. — Rudinger : 
 Atlas des menschl. Gehororgans. Mllnchen 1867. — Luschka: Der 
 Schlundkopf des Menschen. Tubingen 1868. — Arthur Bottcher : 
 Ueber Entwicklung und Bau des Gehorlabyrinths nach Unter- 
 suchimgen an Saugethieren. Dorpat 1869. — HelmhoUz : Die 
 Mechanik der Gehorknochelchen und des Trommelfells. Pfiiigers 
 ArcMv. I, 1869. — Kessel: Nerven und Lymphgefasse des mensch- 
 lichen Trommelfells. Medic. Centralbl. Nr. 23 u. 24. 1869. — J.. 
 Politzer : Ueber gestielte Gebilde im Mittelohre des menschlichen 
 Gehororgans. Vorlaufige Mittheilung. Wiener med. Wochenschrift. 
 Nr. 93. 20. Nov. 1869 u. Arch, fur Ohrenheilk. Bd. 5. 1870. — /. 
 Kessel : Beitrag zum Bau der Paukenhohlenschleimhaut des Hundes 
 und der Katze. Centralbl. f. die med. Wissensch. 1870. Nr. 6. — 
 Wendt : Ueber schlauchformige Driisen der Schleimhaut der Pauken- 
 hohle. Leipz. Arch, f Heilk. Bd. 11. 1870. — v. Winiiuarter: 
 Untersuchungen iiber die Gehorschnecke der Saugethiere a. d. 61. 
 Sitzungsber. d. Acad. d. Wissensch. Mai 1870. — J. Gottstein: Ueber 
 den feineren Bau und die Entwicklung der Gehorschnecke beim 
 Menschen und den Saugethieren. Dissert. Bonn 1871. — Magnus : 
 Ueber die Gestalt des Gehororgans bei Thieren und Menschen. 
 Yirchow-Holtzendorff's Sammlg. Nr. 130. 1871. — Nuel : Beitrao' zar 
 Kenntniss der Saugethierschnecke. 1871. — H. Burnett : Ueber das 
 Vorkommen von Gefasschlingen im Trommelfelle einiger niederer 
 Thiere. Monatsschr. f. Ohrenheilk. Nr. 2. 1872. — Rudinger: Das 
 hautige Labyrinth. Strieker's Handb. d. Lehre von den Geweben. II. 
 
 1872. — Josef Hyrtl : Die Corrosions- Anatomie und ihre Ergebnisse. 
 Wien 1873. — if 2//^Z: Lehrb. der Anatomie. XI. Aufl. S. 307. — J.. 
 Politzer: Zur mikroskopischen Anatomie des Mittelohrs. Arch. f. 
 Ohrenheilk. Bd. 6. 1873. — Burnett : Bloodvessels in the Membrana 
 Tympani. Kepr. fr. the ' Amer. Journ. of Med. Sciences.' Philad. 
 
 1873. — C. Basse : Die vergleichende Morphologic und Histologic des 
 hautigen Gehororgans der Wirbelthiere. Leipzig 1873. — A. Politzer: 
 Zehn Wandtafeln zur Anatomie des Gehororgans. Wien 1873. — *S'.. 
 Moos : Beitrage zur Anatomie und Physiologie der Eustachischen 
 Rohre. Wiesbaden 1874. — Urbantschitsch : Beitrage zur Anatomie 
 der Paukenhohle. Archiv f. Ohrenheilkunde. Bd. 2. 1874. Wiener 
 med. Presse. Bd. 14. 1873. — Gerlach : Zur Morphologic der Tuba Eust. 
 Sitz.-Ber. d. phys.-med. Soc. in Erlangen. 8. Marz 1875. — Rudinger: 
 Beitrage zur Anatomie des Gehororgans, etc. .Mllnchen 1876. ■ — 
 Weher-Liel : Die Membrana tympani secundaria. Monatsschrift f 
 
LITERATURE. 269 
 
 Ohrenheilk. Nr. 1. 4. 5, 1876. — E. Zuckerkandl : Ueber die 
 Vorhofswasserleitung des Menschen. Sep.-Abdr. a. d. Monatsschr. f. 
 Ohrenheilk. Nr. 6. 1876. — >Sf. Moos: Die Blutgeftisse und der 
 Blutgefilsskreislauf des Trommelfells und HammergrifFs. Sep.-Abdr. a. 
 d. Arch. f. Aug.- u. Ohrenheilk. Bd. VI. 1877. — Ch. H. Burnett : The 
 Ear, its Anatomy, Physiology, and Diseases. Philadelphia 1877. — 
 Schalle : Eine neue Sectionsmethode fiir die Nasen-, Rachen- und 
 Gehororgane. Yirchow's Archiv. Bd. 71. Berlin 1877. — A. v. 
 Troltsch : Lehrbuch der Ohrenheilkunde. YI. Aufl. Leipzig 1877. — 
 H. Schwartze : Pathologische Anatomie des Ohres. Halle-Berlin 
 1878. — E. Zuckerkandl : Zur Anatomie des Warzenfortsatzes. M. f. 
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INDEX OF AUTHORS. 
 
 Arnold, 31 
 Altmann, 196 
 
 Baginsky, 254, 264, 265 
 
 Barr, Thomas, 152 
 
 Earth, 126, 182 
 
 Bechterew, 263 
 
 Berger, 197 
 
 Bezold, 35, 43, 44, 46, 47, 73, 94, 168, 171, 
 
 177 
 Bischofif, 269 
 Bochdalek, 213 
 
 Bottcher, 129, 134, 244, 248, 254 
 Breschet, 266 
 van den Broek, 129 
 Brun, 7 
 
 V. Brunn, 174, 175, 179 
 Brunner, 230, 238 
 Burckhardt-Merian, 3 
 Burnett, 269 
 
 Caldani, 266 
 
 Cassebohm, 266 
 
 Comparetti, 266 
 
 Corti, 244 
 
 Cotugno Domenico, 128, 133 
 
 Dalla Rosa, 178 
 Deiters, 244 
 Dionisio, 209 
 Duval, 203 
 Duverney, 32 
 
 Eisell, 238 
 Eitelberg, 73 
 Erlitzky, 260 
 Eustachius, 266 
 
 Eabricius ab Aquapendente, 266 
 
 Fallopius, 266 
 
 Fischer, 266 
 
 Flechsig, 264 
 
 Flemming, 195 
 
 Freud, 194, 261, 263, 264 
 
 Friedlander, 207 
 
 Friihwald, 146 
 
 Gerber, 168 
 
 Gerlach, 218, 243 
 
 Gompertz, 212 
 
 Gottfried, 178 
 
 Gottstein, 201, 244, 254, 255 
 
 Gradenigo, 238, 257 
 
 Gram, 208 
 Grenadier, 207 
 Gruber, 217, 222 
 
 Hagenbach, 266 
 
 Hasse, C, 129, 244, 248 
 
 Helmholtz, 76, 79, 81, 82, 95, 99, 240 
 
 Henle, 25, 44, 46, 79, 81, 105 
 
 Hensen, 267 
 
 Hrubesch, 70 
 
 Huschke, 253 
 
 Hyrtl, 35, 44, 114, 129, 168, 172, 190 
 
 Ilg, 114, 119, 131, 168 
 Ingrassias, Ph., 266 
 
 Joseph, 267 
 
 Katz, 126, 201, 245 
 
 Kaufmann, 214 
 
 Kessel, 215, 216, 218, 221, 230 
 
 Kiesselbach, 146 
 
 Kirchner, 27, 44, 105 
 
 Klebs, 205 
 
 Kniephof, 266 
 
 Koller, 209 
 
 KoUiker, 230, 244, 251 
 
 Kretschmann, 85 
 
 Kuhn, 244 
 
 Laskowski, 158, 188 
 Lauth, 267 
 Luschka, 26, 100 
 Lemcke, 174 
 Loffler, 207 
 Lowenberg, 179 
 LucEe, 21, 70, 230 
 
 McEwen, W., 152 
 
 Magnus, 238 
 
 Mayer, L., 98 
 
 Meckel, 129, 168 
 
 Mery, J., 266 
 
 Moos, 94, 156, 200, 201, 214, 218, 226. 
 
 230 
 Morpurgo, 63, 87 
 MuUer, H., 222 
 
 Nuel, 244 
 Nussbaum, 6 
 
 Obersteiner, 260 
 Odenius, 267 
 
272 
 
 INDEX OF AUTHORS. 
 
 Pal, 260, 261 
 
 Pappenheim, 237 
 
 Parreidt, 56, 213 
 
 Partsch, 165 
 
 Politzer, 66, 94, 229, 233 
 
 Pollak, 213 
 
 Pritchard, Urban, 195, 244, 248, 249 
 
 Prussak, 78, 79, 215 
 
 Ranvier, 209, 244 
 Reichert, 206 
 
 Retzius, 244, 246, 247, 248, 249 
 Rohrer, 205 
 Roller, 263, 264 
 Ruge, 57 
 
 Riidinger, 6, 99, 125, 129, 133, 168, 169,237, 
 238, 239, 251 
 
 Sappey, 35 
 
 Sapolini, 168 
 
 Saunders, 266 
 
 Scarpa, 266 
 
 Schalle, 11 
 
 Schenk, 209 
 
 Schiefferdecker, 203 
 
 Schonlein, 199 
 
 Schultze, 242, 244 
 
 Schwabach, 165 
 
 Schwalbe, 32, 43, 55, 56, 64, 79, 82, 105, 
 
 212, 219, 221, 247, 249, 256 
 Shaw, 266 
 
 Siebenmann, 175, 177 
 Sommering, 56, 83, 168 
 Steifensand, 250 
 Steinbrligge, 125, 182, 227, 247, 249 
 
 Stohr, 197, 206, 212, 213 
 
 Tod, David, 266 
 
 Tafani, 195 
 
 Teichmann, 136 
 
 Toldt, 269 
 
 Tommasi, 168 
 
 Toynbee, 66, 71, 93, 94, 215, 238 
 
 Trautmann, 113, 216 
 
 V. Troltsch, 21, 31, 35, 43,46, 56, 66, 71, 73, 
 
 77, 94, 103, 104, 215, 220, 222, 243 
 Tschudi, 16 
 
 Urbantschitsch, 84, 226 
 
 Valentin, 168 
 Valsalva, 266 
 Vieussens, 266 
 Virchow, 6, 10 
 Voltolini, 67, 122 
 Vlakovic, 195 
 
 Wagenhauser, 28 
 Waldeyer, 201, 244, 246, 256 
 Weber-Liel, 129, 133, 134, 135 
 Weigert, 201, 260, 261 
 Wendt, 10, 231 
 Winiwarter, 244 
 Wywodzew, 6 
 Wolf, K., 36 
 
 Zaufal, 83 
 Ziehl-Neelsen, 208 
 
 Zuckerkandl, 25, 26, 31, 106, 129, 133, 134, 
 240, 242 
 
 THE END. 
 
 liailliere, Tindall dk Cox, 20 cfc 21, King Wiliiam iStriet Strand. 
 
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