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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4501_Библиотеки_им_академика_М_И_Перельмана
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230 ■ ANATOMY OF THE TEMPORAL BONE WITH SURGICAL IMPLICATIONS
Figure 14
A blue line has been made on the superior canal.
Making blue lines is not part of any surgical
procedure, but as a dissection exercise it
improves drilling skills and knowledge of the
anatomic relationships of the canals to adjacent
structures.
Figure 13
The posterior tympanotomy has been extended
by sacrifice of the chorda tympani nerve
to expose the round window niche and
hypotympanum. This approach is also used for
insertion of cochlear implants. While creating the
cochleostomy (the opening into the cochlea), the
bur should be held at such an angle as to avoid
contact with the facial nerve lying medially.
CHAPTER 8: STEREOSCOPIC VIEWS OF THE TEMPORAL BONE ■ 231
Figure 15
This overall view shows the anatomic relationships between the semicircular canals, facial
nerve, ossicles, mastoid cavity, and middle ear.
The exenteration, approximately as shown, is
known as intact-canal-wall tympanomastoidectomy.
Figure 16
The posterior wall of the external auditory canal
(EAC) has been removed, exposing the tympanic membrane and the anterior wall of the
EAC. The subarcuate cell tract is evident, and
the posterosuperior cell tract has been opened.
The jugular bulb will be found medial to the
facial nerve, and may rise as high as the level of
the posterior canal.
232 ■ ANATOMY OF THE TEMPORAL BONE WITH SURGICAL IMPLICATIONS
Figure 18
The convexity of the anterior wall of the external
auditory canal has been removed to afford easy
surgical access to the anterior aspect of the middle ear. The dissection shown here, exclusive of
the facial nerve exposure, is the approximate
extent of a modified radical (Bondy) mastoidectomy
in which diseased tissue is removed from the
mastoid and middle ear but the ossicles and
tympanic membrane, or what remains of them,
are left undisturbed.
Figure 17
The skin of the external auditory canal (EAC)
has been elevated as a laterally based, pedicled
flap in preparation for thinning the anterior wall
to reduce its convexity. Overzealous bone
removal can allow posterior prolapse of the soft
tissue contents of the temporomandibular joint.
CHAPTER 8: STEREOSCOPIC VIEWS OF THE TEMPORAL BONE ■ 233
Figure 19
This is a high power view of the middle ear area
seen in Figure 18.
Figure 20
The tympanic membrane, including its annulus,
has been removed to expose the anterior part of
the mesotympanum, the protympanum, and the
tympanic orifice of the eustachian tube.
234 ■ ANATOMY OF THE TEMPORAL BONE WITH SURGICAL IMPLICATIONS
Figure 22
The tensor tympani tendon is severed with scissors preparatory to removal of the malleus. The
tympanic sulcus can be seen.
Figure 21
This view is the same as that shown in Figure 20,
but at a lower magnification.
CHAPTER 8: STEREOSCOPIC VIEWS OF THE TEMPORAL BONE ■ 235
Figure 23
The malleus and incus have been removed,
revealing the cochleariform process and tensor
tympani tendon. The anterior part of the lateral
epitympanic wall and adjacent canal wall have
been drilled away, opening the anterior epitympanum widely into the mesotympanum. The
exenteration to this stage (exclusive of the facial
nerve exposure) is approximately that of a radical
mastoidectomy.
Figure 24
The facial nerve has been lifted from its canal.
During the surgical removal of extensive
cholesteatomas or neoplasms, it may be necessary to remove the nerve from its canal either
temporarily or permanently, a procedure known
as transposition of the facial nerve. The greater
superficial petrosal nerve is visible as it exits
anteriorly from the geniculate ganglion.
236 ■ ANATOMY OF THE TEMPORAL BONE WITH SURGICAL IMPLICATIONS
Figure 26
The semicircular canals have been opened.
Mid-size diamond burs work well here, and
have less of a tendency to “skip” than do cutting
burs.
Figure 25
The internal carotid artery has been exposed by
removing overlying bone with a diamond bur.
The jugular bulb is seen in the hypotympanum.
CHAPTER 8: STEREOSCOPIC VIEWS OF THE TEMPORAL BONE ■ 237
Figure 27
Surgical removal of the semicircular canals leads
to the vestibule and internal auditory canal
(IAC). This procedure is known as the
translabyrinthine approach to the internal auditory
canal and is used for removal of neoplasms of
the canal and cerebellopontine angle. Sectioning
of the greater superficial petrosal nerve allows
for posterior displacement of the facial nerve
along with removal of the cochlea, as in the
transcochlear approach to lesions located anterior
to the internal auditory canal.
Figure 28
The tensor tympani muscle and cochleariform
process have been removed. The underlying
basal and middle turns of the cochlea have been
opened to expose the scalae and osseous spiral
lamina.
238 ■ ANATOMY OF THE TEMPORAL BONE WITH SURGICAL IMPLICATIONS
Figure 29
Vestibular schwannoma (acoustic neurinoma).
This person had an 18-yr history of left-sided
hearing loss and tinnitis; there was no history of
vertigo or dysequilibrium. In the left ear there is
a large vestibular schwannoma fully occupying
the widened internal auditory canal. The
cochlear and vestibular nerves are displaced
inferiorly. There is a fibrinous precipitate in the
endolymphatic and perilymphatic spaces (male,
age 81 yr).
PATHOLOGIC CONDITIONS OF THE TEMPORAL BONE
With few exceptions, this text is limited to the presentation of normal
anatomy and its variants. However, one of the reasons for learning normal
anatomy is to develop the ability to recognize the abnormal. The photographs
(Figs. 29–35) which accompany several different pathologic entities. The
photographs were taken from horizontal sections of celloidin-embedded
temporal bones.
CHAPTER 8: STEREOSCOPIC VIEWS OF THE TEMPORAL BONE ■ 239
Figure 30
Sarcoma of the temporal bone. At age 24 the patient
developed right serous otitis and was treated by a
ventilation tube in the tympanic membrane. At age 26
she experienced multiple cranial nerve palsies and
right hemiparesis. Physical examination showed a
tumor mass in the inferior part of the middle ear
which biopsy proved to be a chondromyxosarcoma.
She died 12 days after attempted surgical removal.
The petrous apex was destroyed by the neoplasm;
the tumor infiltrated the mesotympanum, hypotympanum, and infralabyrinthine regions. Compression
of the eustachian tube caused serous otitis media and
pressure occlusion of the internal carotid artery for
the hemiparesis (female, age 27 yr).
Figure 31
Perforation of the tympanic membrane. There is a
large posteroinferior perforation of the tympanic
membrane with fibrous thickening of the anterior
and inferior margins. The manubrium is medially
displaced, presumably by the unopposed pull of
the tensor tympani muscle. The inferior part of
the external auditory canal (EAC) contains a
plug of dried exudate and epithelial debris (male,
age 69 yr).
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