Ear Anatomy Flashcards
(256 cards)
1
Q
At what age is the mastoid process completely pneumatized
A
2
2
Q
At what month gestation does the ear canal open
A
7
3
Q
What structure lies between the prominence of semi-circular canal and the promontory/oval window?
A
Prominence of the facial canal.
4
Q
Below is a diagram of a right middle ear showing its relationship with the inner ear. Name the structures.Diag001
A
A: Facial nerve. B: Ponticulus.Subiculum
D: Geniculate ganglion.
5
Q
The following diagram is of a right middle ear viewed from below. Name the structures. Diag002
A
- *A**-Facial recess.
- *B**-Facial nerve.
- *C**-Sinus tympani.
6
Q
What range of frequencies can the human ear detect?
A
20-20,000Hz (greatest sensitivity is from 500 to 3000 Hz).
7
Q
What structure is situated just medial to the tip of the cochleariform process?
A
Geniculate ganglion of the facial nerve.
8
Q
What do the utricle and saccule detect?
A
Linear acceleration.
9
Q
Between which ossicles does the chorda tympani run?
A
Manubrium of the malleus and long process of the incus.
10
Q
What is the name of the central bony core of the cochlea through which nerves and vessels travel?
A
Modiolus.
11
Q
What is meant by a “diploic mastoid”?
A
Occupied by bone marrow instead of air cells.
12
Q
What proportion of the population has a pneumatized petrous pyramid?
A
One-third.
13
Q
What structure lies superior to the ponticulus?
A
Oval window.
14
Q
What is the function of the chorda tympani nerve?
A
Parasympathetic innervation to the submandibular and sublingual glands, and taste to the anterior 2/3 of the tongue.
15
Q
What structure is located inferior to the subiculum and posteroinferior to the promontory?
A
Round window.
16
Q
What structure ends blindly at the round window?
A
Scala tympani (lower compartment of the cochlea).
17
Q
Which part of the vestibular labyrinth detects angular acceleration?
A
SCCs
18
Q
What structure lies between the subiculum and ponticulus?
A
Sinus tympani.
19
Q
What structure forms the arcuate eminence?
A
Superior SCC.
20
Q
Which part of the cochlea represents high-frequency sounds?
A
The basal end.
21
Q
What is Trautmann’s triangle?
A
Triangle between the external prominence of the lateral and posterior SCCs and the posterosuperior corner of the mastoid.
22
Q
True/False: The membranous labyrinth is a self-contained system.
A
True.
23
Q
True/False: The position of the cochlear duct is always inferior to the lowest border of the stapes footplate.
A
True.
24
Q
Which of these main structures receives the crura from the three SCCs?
A
Utricle.
25
What does each hillock become?
1. _Tragus_. 2. _Helical crus_. 3. _Helix_. 4. _Antihelix_. 5. _Antitragus_. 6. _Lobule and lower helix_.
26
Which ossicular component develops from membranous bone?
Anterior process of the malleus.
27
When do the ossicles reach adult size and shape?
At the 16th week gestation, they are adult-sized, and by birth, they are adult-shaped.
28
When does the otic capsule finish developing?
By 21-24 weeks, it reaches adult size.
29
What is the last structure of What is the last structure of the inner ear to develop?
Endolymphatic sac
30
**True/False** The tympanic membrane is derived from ectoderm
False; it is derived from ectoderm, mesoderm, and endoderm
31
Which branchial arch does the tensor tympani muscle arise from?
First branchial arch
32
How does a preauricular sinus tract form?
From improper fusion of the 1st and 2nd branchial arches.
33
What does the eustachian tube (ET) develop from?
From the 1st pouch, between the 2nd arch and the pharynx.
34
Which ossicles develop from the first branchial arch (Meckel's cartilage)?
Head and neck of the malleus, body, and short process of the incus.
35
Which ossicles develop from the second branchial arch (Reichert's cartilage)?
Manubrium of the malleus, long process of the incus, and stapes (except footplate)
36
At what age does the EAC reach adult size?
Nine years.
37
Which ossicular components never completely ossify?
Part of the manubrium and the vestibular portion of the stapes footplate.
38
At what month(s) gestation does the ear canal open?
Seventh.
39
How many hillocks are there?
Six
40
What is the significance of a congenitally malformed auricle?
The auricle develops early, making malformations of the middle ear, mastoid, and facial nerve more likely.
41
When does development of the external auditory canal (EAC) begin?
The canal begins to develop at 28 weeks gestation.
42
What is the significance of a normal auricle with canal atresia?
The EAC begins formation late (28th week), so the middle ear and ossicles are more likely to be normal.
43
Which branchial arches do hillocks arise from?
The first three arise from the first arch and the last three arise from the second arch.
44
What embryologic structures is the auricle developed from?
The hillocks of His.
45
What are the boundaries of the epitympanum?
**Superiorly: the tegmen
Inferiorly: the fossa incudis
Anteriorly: the zygomatic arch
Posteriorly: the aditus
Medially: the lateral semicircular canal (SCC) and VII
Laterally: the scutum.**
46
Why is the development of the bony otic capsule unique?
1. It is formed from 14 centers of ossification that fuse and leave no suture lines
2. the centers are formed from cartilage, but retain no areas of chondral growth.
3. The bone retains its fetal character, with Haversian canals.
47
When does the otic capsule begin formation?
At 8 weeks, the precursors of the otic capsule are present; at 15 weeks, the ossification centers are present.
48
When does the fallopian When does the fallopian canal begin developing?
Fifth week gestation; its development is not complete until several years after birth.
49
What is the last part of the otic capsule to ossify?
Fissula ante fenestrum.
50
What does the stapes footplate develop from?
Otic mesenchyme
51
What does each Hillock become
* I - tragus
* 2 - helical crus
* 3 - helix
* 4 - antihelix
* 5 - antitragus
* 6 - lobule and lower helix
52
What are the four openings into the temporal bone?
Internal auditory canal (lAC)
vestibular and cochlear aqueducts
subarcuate fossa
53
How much CSF is produced per minute
0.35 - 0.37 cc.
54
What are normal ear canal volumes in children and adults?
0.5-1.0 cm3 in children; 0.6-2.0 cm3 in adults.
55
What is the minimum distance from the center of the stapes footplate to the utricle and saccule
1.2 and 1.4 mm, respectively.
56
What are the average dimensions of the stapes footplate
1.41 x 2.99 mm.
57
How much of the EAC is cartilaginous
1/3.
58
What noise level begins to cause pain?
140 dB.
59
How long is the tube at birth? in adulthood
17 mm, 35 mm.
60
How much of the eustachian tube (ET) is cartilaginous
2/3.
61
What % of preauricular cysts are bilateral
20%.
62
What percent of normal ears emit spontaneous OAEs?
35-60%.
63
What % of people have a dehiscence of the facial nerve in either the tympanic or mastoid segments
50- 55%.
64
What is the average diameter of the lAC
6.8 mm.
65
What is the upper limit of normal diameter of the lAC
8 mm.
66
What are the dimensions of the tympanic membrane (TM)
9 - 10 mm vertically; 8 - 9 mm horizontally.
67
What structures are posterior to the tympanic cavity?
Aditus, posterior sinus, chorda tympani, fossa incudis, pyramidal prominence, and stapedial tendon.
68
What structures are posterior to the tympanic cavity
Aditus, posterior sinus, chorda tympani, fossa incudis, pyramidal prominence, stapedial tendon.
69
At what age is the EAC adult size
Age 9.
70
What structures house the crista?
Ampullae.
71
What is the foramen of Huschke?
An embryologic remnant that normally obliterates in the anteroinferior portion of the medial bony EAC.
72
What is the foramen of Huschke
An embryologic remnant that normally obliterates in the anteroinferior portion of the medial bony external auditory canal (EAC).
73
What ligament supports the stapes
Annular ligament.
74
Which ossicular component develops from membranous bone
Anterior process of the malleus.
75
Where does most movement of the stapes occur
Anterior-superior portion of the footplate.
76
Where in the tympanic and mastoid segments of the facial nerve are the sensory fibers located
Anterolaterally in the tympanic segment, posterolaterally in the mastoid segment.
77
What structures facilitate passage of CSF into the dural venous sinuses
Arachnoid villi.
78
What are the two most important landmarks in the middle fossa approach to the lAC
Arcuate eminence and hiatus for the greater superficial petrosal nerve.
79
When does the otic capsule begin formation
At 8 weeks, the precursors of the otic capsule are present; at 15 weeks, the ossification centers are present.
80
How does the course of the facial nerve differ between adults and children
At birth, the nerve is located superficially within the poorly formed mastoid; with maturation, the nerve is displaced medially and inferiorly.
81
When do ossicles reach adult size and shape
At the 16111 week gestation, they are adult-sized, and by birth, they are adult-shaped.
82
What is the most common site of facial nerve injury during mastoid surgery
At the pyramidal turn posterolateral to the horizontal SCC.
83
What is Arnold's nerve?
Auricular branch of the vagus that innervates skin of the external auditory canal and auricle.
84
Where is Dorello's canal and what nerve does it contain
Between the petrous tip and the sphenoid bone; contains VI and inferior petrosal • smus.
85
Where is the primary auditory cortex
Brodmann 's area 41 in the superficial portion of the temporal lobe.
86
Where is the primary auditory cortex?
Brodmann's area 41 in the superficial portion of the temporal lobe.
87
When does the otic capsule finish developing
By 21 - 24 weeks, it is adult size.
88
Where is the safest place to create an opening in the stape!; footplate
Central area.
89
What is the last branch of the facial nerve before it passes through the stylomastoid foramen
Chorda tympani nerve.
90
What produces CSF
Choroid plexus.
91
What structures are inferior to the falciform crest in the lAC
Cochlear nerve and inferior branch of the vestibular nerve.
92
What is the most anterior structure of the medial wall of the tympanic cavity
Cochleariform process.
93
What is the most anterior structure of the medial wall of the tympanic cavity?
Cochleariform process.
94
What are some clinical clues to an aberrant facial nerve
Congenitally malformed auricle, ossicular abnormalities, craniofacial anomalies, conductive hearing loss.
95
What is Hyrtl's fissure?
Connection between the subarachnoid space near the IX ganglion and the hypotympanum that allows middle ear infections to spread to the brain; normally closes with maturation.
96
What is Hyrtl's fissure
Connection between the subarachnoid space near the IXth ganglion and the hypotympanum that allows middle ear infections to spread to the brain; normally closes with maturation.
97
What is the facial hiatus
Dehiscence of variable size in petrous portion of the temporal bone in the floor of the middle cranial fossa, which marks the entrance of the greater superficial petrosal nerve into the middle cranial fossa.
98
What is the promontory?
Elevation of the medial wall of the tympanic cavity formed by the basal turn of the cochlea.
99
What is the promontory
Elevation of the medial wall of the tympanic cavity formed by the basal turn of the cochlea.
100
What does the vestibular aqueduct carry
Endolymphatic duct and accompanying vein.
101
What does the vestibular aqueduct carry?
Endolymphatic duct and accompanying vein.
102
Where does most of the resorption of endolymph occur?
Endolymphatic sac.
103
What is the last structure of the inner ear to develop
Endolymphatic sac.
104
Where does most of the resorption of endolymph occur
Endolymphatic sac.
105
Describe the path of the facial nerve in the temporal bone
Enters the lAC; travels laterally for a short distance, then, just superior to the promontory, it makes a sharp tum to run posteriorly (at the external/first genu and the geniculate ganglion). Nerve continues posteriorly, with a slight infero-lateral inclination (forming the prominence of the facial canal in the medial wall of tympanic cavity). Behind the base of the pyramidal eminence, the nerve makes a broad tum to descend vertically and somewhat laterally (2"d genu) through the mastoid cavity.
106
What problem results from rupture of the middle meningeal artery
Epidural hematoma.
107
What structures are superior to the falciform crest in the internal auditory canal (lAC)
Facial nerve and superior branch of the vestibular nerve.
108
T/F: The tympanic membrane is derived from ectoderm
False; it is derived from ecto-, meso-, and endoderm.
109
What is the last part of the otic capsule to ossify
Fissula ante fenestrum.
110
How does a preauricular sinus tract form
From improper fusion of the I st and 2"d branchial arches.
111
What does the eustachian tube develop from
From the 1st pouch, between the 2 nd arch and the pharynx.
112
What are the limits of the fallopian canal
Fundus of the lAC to the stylomastoid foramen.
113
What is the name for the entrance to the fallopian canal
Fundus.
114
What is the foramen of Morgagni
Gap between superior constrictor muscle and skull base.
115
What structure is found in Meckel's cave
Gasserian ganglion of V.
116
What structure is situated just medial to the tip of the cochleariform process
Geniculate ganglion of the facial nerve.
117
Where are the cell bodies for these fibers?
Geniculate ganglion.
118
Where along the course of the facial nerve does this nerve branch off
Geniculate ganglion.
119
What is the sensory innervation of the auricle
Greater auricular nerve (C3), auriculotemporal nerve (V3), lesser occipital nerve (C2,3), auricular branch of the vagus, and sensory branches of VII and IX.
120
What is the blood supply to the geniculate ganglion
Greater superficial petrosal artery (branch of the middle meningeal artery).
121
What three branches of the facial nerve are given off in its course through the temporal bone
Greater superficial petrosal nerve, nerve to the stapedius muscle, chorda tympani.
122
What is the first branch of the facial nerve
Greater superficial petrosal nerve.
123
What nerve carries taste fibers supplying taste buds on the palate
Greater superficial petrosal nerve.
124
Which ossicles develop from the first branchial arch (Meckel's cartilage)
Head and neck of the malleus, body and short process of the incus.
125
Which ossicles can be found in the epitympanic recess
Head of the malleus, body and short process of the incus.
126
Which ossicles can be found in the epitympanic recess?
Head of the malleus, body, and short process of the incus.
127
Which part of the malleus articulates with the incus?
Head.
128
Which part of the malleus articulates with the incus
Head.
129
What is the name of the area of communication between the scala vestibuli and the scala tympani?
Helicotrema.
130
What is the name of the area of communication between the scala vestibuli and the scala tympani
Helicotrema.
131
What structure bisects the internal auditory canal in the vertical direction
Horizontal direction Bill's bar; transverse/falciform crest.
132
What is Hitzelberger's sign
Hypoesthesia of the postauricular area associated with Vllth nerve compression secondary to an acoustic neuroma.
133
Which branchial arch does the tensor tympani muscle arise from
I.
134
What is Donaldson's line
Imaginary line in the plane of the horizontal SCC back to the sigmoid sinus marking the top of the endolymphatic sac.
135
What are the six segments of the facial nerve
Intracranial, internal auditory canal, labyrinthine, tympanic, mastoid/vertical, extratemporal.
136
Why is the development of the bony otic capsule unique
It is formed from 14 centers of ossification that fuse and leave no suture lines; the centers are formed from cartilage, but retain no areas of chondral growth. The bone retains its fetal character, with Haversian canals.
137
Which three cranial nerves are found beneath the floor of the middle ear cavity?
IX, X, and XI.
138
Which 3 cranial nerves are found beneath the floor of the middle ear cavity
IX, X, XI.
139
What is the inferior boundary of the tympanic cavity?
Jugular bulb.
140
What is the inferior boundary of the tympanic cavity
Jugular bulb.
141
Where is the second genu of the facial nerve
Just distal to the geniculate ganglion, at the sinus tympani between the tympanic and mastoid segments.
142
What proportion of the population has a pneumatized petrous pyramid
l/3.
143
What is the blood supply to the inner ear?
Labyrinthine artery (branch of anterior inferior cerebellar artery).
144
What is the blood supply to the inner ear
Labyrinthine artery (branch of anterior inferior cerebellar artery).
145
Which segment is shortest
Labyrinthine.
146
Which segment has the most narrow passageway
Labyrinthine.
147
What portion of the facial nerve is closest to the cochlea
Labyrinthine.
148
What are the four openings into the temporal bone
lAC, vestibular and cochlear aqueducts, and subarcuate fossa.
149
What is the function of the greater superficial petrosal nerve
Lacrimation.
150
Which part of the malleus creates the malleolar prominence of the TM
Lateral process.
151
What is the scutum?
Lateral wall of the epitympanum.
152
What is the scutum
Lateral wall of the epitympanum.
153
Does the foramen rotundum lie lateral or medial to the pterygoid canal
Lateral.
154
Which part of the incus articulates with the stapes?
Lenticular process (medial side of long process).
155
Which part of the incus articulates with the stapes
Lenticular process (medial side of long process).
156
Which part of the ossicular chain has the most tenuous blood supply and is most prone to necrosis?
Long process of the incus.
157
Which ossicle has the most tenuous blood supply and is most prone to necrosis
Long process of the incus.
158
How does the composition of gas in the middle ear differ from that of room air?
Lower oxygen level and higher carbon dioxide and nitrogen levels.
159
Between which ossicles does the chorda tympani run
Manubrium of the malleus and long process of the incus.
160
Which ossicles develop from the second branchial arch (Reichert's cartilage)
Manubrium of the malleus, long process of the incus, stapes (except footplate).
161
Where in the ossicular chain does the tensor tympani muscle insert?
Manubrium of the malleus.
162
What is the name of the central bony core of the cochlea through which nerves and vessels travel
Modiolus.
163
What three nuclei supply fibers to the facial nerve
Motor nucleus in caudal aspect of the pons, superior salivatory nucleus (dorsal to the motor nucleus), and nucleus of the solitary tract in medulla.
164
What is the function of the glossopharyngeal nerve
Motor to the stylopharyngeus; taste to posterior 1/3 tongue; parotid gland stimulation; sensation of postauricular skin, pharynx, soft palate, tympanic cavity, and eustachian tube.
165
What are the nuclei of the vagus nerve
Nucleus ambiguus, dorsal motor nucleus, and the nucleus of the solitary tract.
166
Which of these controls voluntary motor information
Nucleus ambiguus.
167
Which of these nuclei receives taste, proprioceptive, and cutaneous sensory information
Nucleus of the solitary tract.
168
Which of these receives sensory information
Nucleus of the solitary tract.
169
What is meant by a "diploic mastoid"
Occupied by bone marrow instead of air cells.
170
How much of the EAC is cartilaginous?
One-third.
171
What is Korner's septum
Otherwise known as the "false bottom," it represents the suture line between the petrous and squamous portions of the temporal bone.
172
What is Korner's septum?
Otherwise known as the "false bottom," it represents the suture line between the petrous and squamous portions of the temporal bone.
173
What does the stapes footplate develop from
Otic mesenchyme.
174
Which cells emit otoacoustic emissions (OAEs)?
Outer hair cells.
175
Which planes are the oval and round windows oriented in
Oval window is in the sagittal plane; round window is in the transverse plane.
176
Which planes are the oval and round windows oriented in?
Oval window is in the sagittal plane; round window is in the transverse plane.
177
What structure lies superior to the ponticulus
Oval window.
178
How can one discern fibrous dysplasia from Paget's disease of the temporal bone on CT scan
Paget's disease involves the otic capsule while fibrous dysplasia does not.
179
What is the function of the chorda tympani nerve
Parasympathetic innervation to the submandibular and sublingual glands, and taste to the anterior 2/3 of the tongue.
180
Which has greater sensory innervation-pars tensa or pars tlaccida?
Pars flaccida.
181
Which has greater sensory innervation-pars tensa or pars flaccida
Pars flaccida.
182
What does the facial nerve provide general sensation for?
Part of the auricular concha, external auditory canal, and tympanic membrane.
183
Which ossicular components never completely ossify
Part of the manubrium and the vestibular portion of the stapes footpJate.
184
How does perilymph differ from endolymph?
Perilymph has a pH of 7.2, is high in sodium, low in potassium, and does not contain chloride; endolymph has a pH of 7.5, is low in sodium, and relatively high in potassium and chloride.
185
How does perilymph differ from endolymph
Perilymph has a pH of 7.2, is high in sodium, low in potassium, and does not contain chloride; endolymph has a pH of 7.5, is low in sodium, and relatively high in potassium and chloride.
186
What fluid surrounds the membranous labyrinth?
Perilymph.
187
What fluid surrounds the membranous labyrinth
Perilymph.
188
What is Gradenigo's syndrome
Petrositis involving VI in Dorello's canal causing retro-orbital pain, diplopia and otorrhea.
189
What is the name of the opening through which the chorda tympani nerve enters the infratemporal fossa
Petrotympanic fissure (canal of Huguier).
190
What is the pars tensa
Portion of the TM inferior to the mallear fold and prominence.
191
Where in the ossicular chain does the stapedius muscle insert?
Posterior neck of the stapes.
192
Besides the muscles of facial expression, what muscles does the facial nerve innervate?
Posterior belly of the digastric, stylohyoid, and stapedius muscles.
193
Where in the ossicular chain does the stapedius muscle insert
Posterior neck of the stapes.
194
What does the inferior vestibular nerve innervate
Posterior SCC and macula of the saccule.
195
What artery accompanies the chorda tympani
Posterior tympanic artery.
196
Which wall of the EAC is shorter-the anteroinferior or posterosuperior
Posterosuperior (approximately 25 mm whereas anteroinferior wall is 31 mm).
197
Which wall of the EAC is shorter-the anteroinferior or posterosuperior?
Posterosuperior (approximately 25 mm, whereas anteroinferior wall is 31 mm).
198
What structure lies between the prominence of the lateral semicircular canal (SCC) and the promontory/oval window
Prominence of the facial canal.
199
What structure is located inferior to the subiculum and posteroinferior to the promontory
Round window.
200
What structure ends blindly at the round window
Scala tympani (lower compartment of the cochlea).
201
Where are cupula found?
SCCs
202
What information is relayed through the superior ganglion
Sensation from the EAC and posterior auricle via Arnold's nerve.
203
What information is relayed through the inferior ganglion
Sensation from the epiglottis and larynx.
204
What is the clinical significance of the foramen of Huschke?
Serves as a potential route for spread of tumor from the parotid gland to the temporal bone.
205
What is the clinical significance of the foramen of Morgagni
Serves a potential route for spread of nasopharyngeal tumors to the skull base and brain.
206
What is the clinical significance of the foramen of Huschke
Serves as a potential route for spread of tumor from the parotid gland to the temporal bone.
207
What structure lies between the subiculum and ponticulus
Sinus tympani.
208
How many are there and which branchial arches do they arise from
Six... the first three arise from the first arch and the last three arise from the second arch.
209
What opening in the medial wall of the pterygopalatine fossa permits the passage of neurovascular structures into the nasal passages
Sphenopalatine foramen.
210
What is the largest artery in the pterygopalatine fossa
Sphenopalatine.
211
What are the layers of the tympanic membrane?
Squamous epithelium, radiating fibrous layer, circumferential fibrous layer, and mucosa.
212
What are the layers of the TM
Squamous epithelium, radiating fibrous layer, circumferential fibrous layer, mucosa.
213
What are the four parts of the temporal bone?
Squamous, tympanic, petrous, and mastoid.
214
What are the four parts of the temporal bone
Squamous, tympanic, petrous, mastoid.
215
Cochleariform process: tensor tympani...... pyramidal process: \_\_\_\_
Stapedius.
216
What structure produces endolymph
Stria vascularis.
217
What structure produces endolymph?
Stria vascularis.
218
What structures create three small depressions in the posterior portion of the medial wall of the tympanic cavity
Subiculum, ponticulus.
219
Where is the tympanic **notch of Rivinus**?
Superior portion of the tympanic ring (squamous portion of temporal bone).
220
What are the 2 ganglia of the vagus nerve
Superior (jugular) ganglion and inferior (nodose) ganglion.
221
What does the superior vestibular nerve innervate
Superior and lateral SCCs, utricle, saccule.
222
Where is the tympanic notch of Rivinus
Superior portion of the tympanic ring (squamous portion of temporal bone).
223
Which of these nuclei sends parasympathetic fibers to salivary glands
Superior salivatory nucleus.
224
What structure forms the arcuate eminence
Superior SCC.
225
In its tympanic segment, between which structures does the facial nerve travel
Superiorly, the lateral SCC; inferiorly, the oval window.
226
What are the boundaries of the epitympanum
Superiorly, the tegmen; inferiorly, the fossa incudis; anteriorly, the zygomatic arch; posteriorly, the aditus; medially, the lateral semicircular canal and VII; laterally, the scutum.
227
What are the boundaries of the tympanic cavity
Superiorly, the tegmen; inferiorly, the jugular wall and styloid prominence; anteriorly, the carotid wall, eustachian tube, and tensor tympani; posteriorly, the mastoid, stapedius, pyramidal prominence; medially, the labyrinthine wall; laterally, the TM and scutum.
228
What structure separates the epitympanic recess from the cranial cavity
Tegmen tympani.
229
What is the significance of a congenitally malformed auricle
The auricle develops early, making malformations of the middle ear, mastoid, and VII more likely.
230
What structures are anterior to the tympanic cavity?
The carotid artery, ET, and the canal for the tensor tympani muscle.
231
What structures are anterior to the tympanic cavity
The carotid artery, ET, and the canal for the tensor tympani muscle.
232
When does development of the external auditory canal begin
The channel begins to develop at 28 weeks.
233
What is the significance of a normal auricle with canal atresia
The EAC begins formation late (28th week), so the middle ear and ossicles are more likely to be normal.
234
How is the facial hiatus clinically significant
The geniculate ganglion usually lies deep to the hiatus, but in 5 - I 0% of patients, it lies under the dura within the hiatus and without a bony covering.
235
What embryologic structures is the auricle developed from
The Hillocks of His.
236
Which part of the malleus does the anterior ligament attach to?
The neck, near the anterior process.
237
Which part of the malleus does the anterior ligament attach to
The neck, near the anterior process.
238
What is the function of the nervus intermedius?
To carry visceral motor fibers to the lacrimal gland, minor salivary glands, and mucosal glands of the palate and nose (via the greater superficial petrosal nerve), and general sensory fibers from the auricular concha and external auditory canal.
239
What is the function of the special visceral afferent fibers of the facial nerve?
To provide taste to the anterior 2/3 of the tongue and palate (via the chorda tympani).
240
What is Trautmann's triangle
Triangle between the external prominence of the lateral and posterior SCCs and the posterosuperior comer of the mastoid.
241
T /F: The membranous labyrinth is a self-contained system.
True.
242
T /F: The position of the cochlear duct is always inferior to the lowest border of the stapes footplate.
True.
243
How much of the ET is cartilaginous?
Two-thirds.
244
Where is the most common site of dehiscence
Tympanic segment superior to the oval window.
245
Where do most facial nerve injuries occur during middle ear surgery
Tympanic segment.
246
How does facial nerve innervation to the upper face differ from that to the lower face
Upper motor neurons sending information to the upper face cross twice in the pons; upper motor neurons sending information to the lower face cross only once in the pons. Therefore, lesions proximal to the nucleus only affect the lower face.
247
Where does the chorda tympani arise in relation to the stylomastoid foramen
Usually 4 - 7 mm superior.
248
What are the main structures of the vestibular portion of the membranous labyrinth
Utricle, saccule, and semicircular canals.
249
What are the main structures of the vestibular portion of the membranous labyrinth?
Utricle, saccule, and semi-circular canals.
250
Which of these receives the crura from the three semicircular canals
Utricle.
251
What are the three nerves of the tympanic plexus?
V3, IX (Jacobson's nerve), and X.
252
What are the three nerves of the tympanic plexus
V3, IX (Jacobson's nerve), X.
253
What nerve innervates the palatopharyngeus and palatoglossus muscles
Vagus.
254
What three systems determine balance?
Vestibular, vestibulo-ocular (visual), and vestibulospinal (proprioceptive) systems.
255
Which cranial nerve has the longest intracranial course
VI.
256
Adenocarcinoma of the endolymphatic sac is more common in patients with what disease
Von Hippel-Lindau disease.
