Учебники / Middle Ear Surgery
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Contents |
XI |
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15 Mastoid Cavity |
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H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 73 |
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Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 73 |
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Definition of Open and Closed Techniques . . . . . . . . . . . . . . . . . . . . . . . |
. . 73 |
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Open Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 75 |
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Surgical Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 76 |
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Reduction of Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 80 |
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Meatoplasty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 81 |
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Closed Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 81 |
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Intact Canal Wall Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 81 |
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Surgical Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 82 |
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Obliteration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 88 |
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Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 91 |
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Fistulas of the Semicircular Canals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 92 |
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Packing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 93 |
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16 Specific Infections |
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H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 94 |
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17 Complications |
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J. Lautermann, H. Sudhoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 95 |
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Labyrinthitis and Facial Palsy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 95 |
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Extradural Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 96 |
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Intracranial Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 97 |
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18 Tympanosclerosis |
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H. Sudhoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. . 98 |
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19 The Atelectatic Ear
H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
20 Revision Surgery
H. Hildmann, H. Sudhoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Early Revisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Late Revisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Special Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
21 Facial Nerve Surgery
O. Guntinas-Lichius, H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . 103 Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Facial Nerve Palsy After Temporal Bone Fracture and Other Traumas . . . 105 Approaches for Facial Nerve Exploration and Decompression . . . . . . . . . 106 Techniques of Facial Nerve Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . 107 Iatrogenic Lesions During Ear Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Postoperative Complete Palsy After Ear Surgery in Patients with Normal
Preoperative Facial Nerve Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
XII Contents
Facial Nerve Palsy in Patients with Chronic Inflammatory Disease . . . . . 110 Postoperative Adjuvant Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
22 Stapes Surgery
H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Floating Footplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Abnormal Course of the Facial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Malleovestibulopexy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
23 Laser Stapedotomy
S. Jovanovic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Laser Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
CO2 Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Micromanipulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Scanner System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Safe and Effective Energy Parameters for CO2 Laser Stapedotomy . . . . . . 121 Surgical Technique of CO2 Laser Stapedotomy . . . . . . . . . . . . . . . . . . . . . . . 123 Special Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Obliterative Otosclerosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Overhanging Facial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Overhanging Promontory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Inaccessible Footplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Floating Footplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Problems in Revision Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Surgical Technique of CO2 Laser Revision Stapedotomy . . . . . . . . . . . . . . . 128 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
24 Stapes Revision Surgery
S. Dazert, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Early Revisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Late Revisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Displacement of the Prosthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Complete Destruction of the Incus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Reclosure of the Oval Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Fixation of Incus or Malleus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Schuknecht’s Prosthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Perilymphatic Fistula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Vertigo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
25 Middle Ear Trauma
H. Hildmann, H. Sudhoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Traumatic Tympanic Membrane Perforation . . . . . . . . . . . . . . . . . . . . . . . . 134
Ossicular Chain Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Perilymph Fistula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Contents XIII
Rupture of the Round Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Traumatic Stenosis or Atresia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Fractures of the Temporal Bone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
26 Endolymphatic Sac Surgery
H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Surgical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Anatomical Position of the Endolymphatic Sac . . . . . . . . . . . . . . . . . . . . . 138
27 Malformation Surgery
H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Surgery of Middle Ear Malformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Minor Malformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Small Tympanic Membrane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Chain Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Major Malformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Timing of Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Surgical Steps and Landmarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
28 Cochlear Implantation
S. Dazert, H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Surgical Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Raising of the Flaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Preparation of the Implant Bed for the Receiver . . . . . . . . . . . . . . . . . . . . 148
Mastoid Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Posterior Tympanotomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Cochleostomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Placement of the Receiver and Electrode Insertion . . . . . . . . . . . . . . . . . . . 150 Closure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Mastoiditis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
29 Revision Surgery After Cochlear Implantation
J. Müller, H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Revision Surgery Can Become Necessary for Several Reasons . . . . . . . . . . 153 Medical Reasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Electronic Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Electrode Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Soft Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
30 Labyrinthectomy
H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Surgical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
XIV Contents
31 Vestibular Neurectomy – Translabyrinthine Approach
H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Contraindications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Surgical Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
32 Vestibular Neurectomy – Transtemporal Approach
H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Contraindications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Surgical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
33 Retrosigmoidal Approach
M. Scholz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Surgical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Skin Incision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Preparation of Subcutaneous Tissue and Nuchal Muscles . . . . . . . . . . . . 170
Trephination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Fine Work with the Drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Withdrawal of Cerebrospinal Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Opening of the Dura . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Intracranial Part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Closing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
34 Otological Instruments
J. Lautermann, H. Sudhoff, H. Hildmann . . . . . . . . . . . . . . . . . . . . . . . 175
Special Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Operating Room Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
181 |
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
182 |
Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
189 |
Contributors
Prof. Dr. med. Manuel Bernal-Sprekelsen
Servicio de Otorrinolaringolog´ıa, Hospital Clinic, Villarroel, 170 08036 Barcelona, Spain
Prof. Dr. med. Stefan Dazert
Hals-Nasen-Ohren-Klinik der Ruhr-Universität Bochum
St. Elisabeth-Hospital, Bleichstr. 15, D-44787 Bochum, Germany
PD Dr. med. Orlando Guntinas-Lichius
Universitätsklinik und Poliklinik für Hals-Nasen-Ohren-Heilkunde-, Kopfund Hals-Chirurgie sowie plast. rekonstr. Kopf-Hals-Operationen Kerpener Str. 62, D-50937 Köln, Germany
Dr. med. Andre Gurr
Hals-Nasen-Ohren-Klinik der Ruhr-Universität Bochum
St. Elisabeth-Hospital, Bleichstr. 15, D-44787 Bochum, Germany
Prof. Dr. med. Sergije Jovanovic
Universitätsklinikum Benjamin Franklin, Hals-Nasen-Ohrenklinik mit Polikliniken, Hindenburgdamm 30, D-12200 Berlin, Germany
PD Dr. med. Jürgen Lautermann
Hals-Nasen-Ohrenklinik und Poliklinik, Universitätsklinikum Essen Hufelandstr. 55, D-45122 Essen, Germany
PD Dr. med. Joachim Müller
Klinik und Poliklinik für Hals-, Nasenund Ohrenkranke der Universität Würzburg, Josef-Schneider-Str. 11, D-97080 Würzburg, Germany
Prof. Dr. med. Alexander Rauchfuss
Caritas-Kliniken St. Theresia Rastpfuhl, Klinik für HNO-Heilkunde Kopfund Hals-Chirurgie, Plast. Operationen, Phoniatrie/Pädaudiologie Rheinstr. 2, D-66113 Saarbrücken, Germany
PD Dr. med. Martin Scholz
Neurochirurgische Klinik des Knappschafts-Krankenhauses Bochum-Langendreer, Ruhr-Universität Bochum, In der Schornau 23 – 25 D-44892 Bochum, Germany
Matthew Yung, MD, PhD, FRCS
Ear, Nose and Throat Department, Ipswich Hospital NHS Trust, Heath Road Ipswich, Suffolk, IP5 4PD, UK
Chapter 1 |
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1 Surgical Anatomy
Alexander Rauchfuss
The temporal bone presents a very complex anatomy. Therefore this overview is restricted to some major points from the viewpoint of surgical anatomy. For more detailed information see “Suggested Reading”.
The temporal bone according to its developmental anatomy is divisible into four parts: the squamous, mastoid, petrous, and tympanic portions. Points of topographical reference on the lateral surface are the external acoustic meatus with its suprameatal spine, the temporal line, and the mastoid process.
The base of the zygoma extends as a crest posteriorly and slightly upward, forming the supramastoid crest or temporal line. The temporal line as a landmark corresponds to the base of the medial cranial fossa/tegmen tympani, which in most cases of surgery can easily be identified. In combination with the radiological anatomy in a Schüller view it allows adequate planning of the surgical approach to the antrum via the mastoid.
All figures show the anatomy of a left ear.
2 1 Surgical Anatomy
Figs. 1.1 – 1.5. Temporal bone and sigmoid sinus
Fig. 1.1. Temporal bone. The degree of pneumatization is inconstant. The extent and arrangement of air cells varies considerably from a minimal air cell system in the surroundings of the antrum to involvement of most of the temporal bone. Pneumatization usually begins in late fetal life, progressing until the end of childhood. The pneumatization process starts from the antrum. In most cases one can describe the topography of the cells as follows: periantral, sinodural, perisinual, perifacial and mastoid tip cells. According to the extension of the cells, there is only one rule: the further from the antrum, the bigger the cells
Fig. 1.2. Schüller view of the left ear. The bony shell of the sigmoid sinus, the base of the middle cranial fossa/tegmen tympani, and the external auditory canal can easily be identified
Fig. 1.3. The temporal line, the position of the sigmoid sinus as identified in the Schüller view, and the margin of the posterior wall of the external auditory canal form a triangle which represents a safe approach to the antrum via the mastoid (......). The sigmoid sulcus housing the sigmoid sinus is a deep groove on the medial surface of the mastoid. Following the ancient Greek anatomical terminology, the sigmoid sulcus describes an S-shaped figure, curving from the transverse sinus downward, terminating in the bulb of the internal jugular vein
Fig. 1.4. A prominent suprameatal spine is an indicator of normal topography of the sigmoid sinus in most cases. The superior petrosal sulcus is a dual venous channel along the superior angle of the pyramid ending in the transverse sinus. The inferior petrosal sulcus follows the posterior angle and ends in the jugular bulb. The jugular fossa is situated on the inferior surface of the temporal bone posteromedial to the carotid foramen. During surgery one should always be aware that the fossa jugularis sometimes is separated from the posterior cranial fossa by only a thin plate of bone. When the roof of the fossa is dehiscent, the bulbous vein protrudes into the tympanic cavity covered with nothing more substantial than the middle ear mucosa
Fig. 1.5. In the case of a narrow or absent suprameatal spine one should be aware of a protruding sigmoid sinus
1 Surgical Anatomy |
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Fig. 1.1 |
fissura tympanomastoidea |
Fig. 1.2
Fig. 1.3
Fig. 1.5
Fig. 1.4
4 1 Surgical Anatomy
Figs. 1.6 – 1.7. The antrum and the topography of the posterior approach to the middle ear
Fig. 1.6. The antrum is an aperture in the upper part of the posterior wall of the epitympanic recess, positioned above, behind, and lateral to the tympanic cavity. It varies exceedingly in size. The lumen and the extent of the antrum into the mastoid depend on the individual’s age. In the newborn it is almost cranial to the external auditory canal. During the process of aging and pneumatization it exfoliates stepwise into the mastoid
Fig. 1.7. Sketch of the mastoid topography
newborn infant
twelve years old
Fig. 1.6
posterior semicircular canal
digastric ridge
Fig. 1.7
1 Surgical Anatomy |
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Figs. 1.8 – 1.10. Stepwise exposure of the middle ear via the posterior approach
Fig. 1.8. Identification of the short process of the incus in the antrum just over the bony coverage of the lateral semicircular canal. The digastric ridge can be helpful as a landmark and a guideline for identification of the facial nerve in cases of difficult topography
Fig. 1.9. Posterior approach to the middle ear. The buttress (“Brücke” in the
German surgical literature) is still intact
Fig. 1.10. The buttress is removed and part of the bony coverage of the facial canal is taken away. The posterior tympanic artery, which lies in close contact with the nerval sheath, is a reliable landmark with which to identify the facial nerve
Fig. 1.8 |
Fig. 1.9 |
Fig. 1.10