The Ear and Facial Nerve Flashcards
1
Q
Located within the pertrous portion of the temporal bone
A
The auditory and vestibular apparatus and the majority of the course of the facial nerve (CN VII)
2
Q
The ear is divided into what three portions?
A
External, middle, and inner
3
Q
Serves as the collector and conductor of sound waves
A
External ear
4
Q
The external ear is composed of the
A
Pinna and External ear canal
5
Q
The external ear canal is derived from the
-Lined by ectoderm epithelium
A
First pharyngeal cleft
6
Q
The outer portion of the external ear is cartilaginous and the inner portion is
A
Bony
7
Q
Modified sweat glands in the skin of the external ear
A
Ceruminous glands
8
Q
Secrete cerumen (ear wax) which functions to keep the canal moist and to protect it from bacteria and infection
A
Ceruminous glands
9
Q
Derived from 6 swellings (hillocks) on the first and second pharyngeal arches that border the pharyngeal cleft
A
Auricle
10
Q
The canal leads to the
A
Tympanic membrane
11
Q
The tympanic membrane is derived from fusion of the
A
Ectoderm of first pharyngeal cleft and endoderm of first pharyngeal pouch
12
Q
Separates the external ear from the middle ear
A
Tympanic membrane
13
Q
The external ear receives MOST of its innervation from
A
CN V3
-also receives innervation from branches of CN VII, IX, and X
14
Q
Air filled cavity containing structures that allow it to serve as a conductor and amplifier of sound vibrations
A
Middle Ear (Tympanic cavity)
15
Q
What are the three ossicles within the middle ear?
A
Malleus, inus, and stapes
16
Q
Attached to the inner surface of the tympanic membrane
A
Malleus
17
Q
There are synovial joint connecting
A
Malleus to incus and incus to stapes
18
Q
The footplate of the stapes lies within the
A
Oval window of the inner ear
19
Q
The impingment of sound waveson the tympanic membrane causes the membrane to
A
Vibrte
20
Q
This in turn causes the ossicles to vibrate, which transmits the vibration to the
A
Inner ear
21
Q
The combination of the ratio of size of tympanic membrane to the size of the stapes footplate, and the shape and orientation of the ossicles result in amplification of approximately
A
30 dB
22
Q
this compensates for the loss of energy at the
A
Air/water interface of the inner ear
23
Q
The sensory receptors of the organ of Corti in the cochlea are in an
A
Aqueous environment
24
Q
What are the two muscles in the inner ear?
-reduce the amplitude of vibration that reaches the inner ear
A
Tensor tympani and stapedius
25
The tensor tympani and stapedius reduce the amplitude of vibration that reaches the inner ear, which protects the
Cochlear hair cells
26
A lesion of the facial nerve (VII) may cause
Hyperacusis
27
And increased perception of loudness because of the loss of action of the stapedius
Hyperacusis
28
The middle ear is connected to the nasopharynx by the
Auditory (Eustachian) tube
29
Allows for equalization of air pressure between the middle ear and the environment
-provides the pathway for spread ofinfection from the pharynx to the middle ear
Auditory (Eustachian) tube
30
The middle ear cavity is also continuous with the
Mastoid air cells
31
A middle ear infection can spread to the
Pharnx or mastoid air cells
32
The middle ear, auditory tube, and mastoid air cells are all derived from the
First pharyngeal pouch (lined by endodermal epithelium)
33
The malleus, incus (neural crest) and tensor tympani (mesoderm) are derived from the
First pharyngeal arch
34
The stapes (neural crest) and stapedius (mesoderm) are derived from the
Second pharyngeal arch
35
The tensor tympani is innervated by
CN V3 (nerve of the first arch)
36
The stapedius is innervated by
CN VII (nerve of the second arch)
37
The mucosa of the middle ear cavity is innervated by
-also innervates mucosa of pharynx
CN IX (tympanic branch)
38
Contains the organ for audition, the cochlea, and the organs for vestibular sensation
Inner ear
39
What are the organs for vestibular sensation?
3 semicircle canls, utricle, and saccule
40
Detect rotational movements of the head
-in the three planes of space and each is perpendicular to the other two
The 3 semicircle canals
41
Detect translational movements of the head
Utricle and saccule
42
Detects linear motion in a horizontal plane
Utricle
43
Detects linear motion in a verticle plane
Saccule
44
Within the cochlea is the cochlear duct, which contains the
Organ of Corti
45
On the organ of corti is where we find the
Cochlear hair cells
46
With agin, there is often a loss of hair cells beginning at the high frequency end of the cochlea, resulting in
Hearing loss (presbycusis)
47
The cochlear duct is filled with
Endolymph
48
The cochlear duct is surrounded by
Perilymph
49
In contact with the footplate of the stapes at the oval window
Perilymph
50
Vibration at the footplate of the stapes causes a vibratory wave through the perilymph, which in turn causes vibration of the
Organ of Corti
51
This vibration is transduced by the hair cells to a neural impulse which is carried by the
Cochlear division of CN VIII
52
Innervates the hair cells
Cochlear division of CN VIII
53
Within the semicircular canals, the utricle and saccule are the maculae, which contains the
Vestibular hair cells
54
The maculae also contians
Endolymph
55
Movement of the head causes displacement of these hair cells, and this displacement is transduced into nerve impulses which are carried in the
Vestibular division of CN VIII (innervates the hair cells)
56
The inner ear is derived from a thickening of the skin ectoderm called the
Otic placode
57
Hearing losses may be categorized as
Conductive hearing loss or sensorineural hearing loss
58
If there is a defect in the external or middle ear that prevents or diminishes the conduction of vibration to the inner ear, it is a
Conductive hearing loss
59
A ruptured tympanic membrane, otosclerosis, dislocation of ossicular joints, or excessive cerumen in external ear canal are all examples of
Conductive hearing loss
60
If there is a defect in the inner ear or neural pathway or neural pathway from the inner ear to the auditory cortex of the brain, we have a
Sensorineural hearing loss
61
Damage to cochlear hear cells from overstimulation, aging or infection, or a lesion of CN VIII or the auditory pathways of the brain are examples of
Sensorineural hearing loss
62
What is one way we test for sensorineural and conductive hearing loss?
Weber test
-tuning fork placed against the bone of the skull at the mid line. If sound is heard equally on both sides than things are normal
63
If there is a sensorineural hearing loss on one side, then with the Weber test, the patient will perceive the sound as coming from the
Contralateral side (the normal side)
64
The Weber test allows the clinician to bypass the conductive portion of the ear (external and middle ear) by having the vibration reach the inner ear bone by
Conduction
65
With a Weber test. if there is a CONDUCTIVE hearing loss, what will we see?
Patient will perceive sound as coming from the side with the hearing loss
66
Ambiguous with regard to which type of hearing loss exists on which side
Weber test
67
A vibrating tuning fork is initially placed on the patient’s mastoid process. The vibration is conducted to the patient’s inner ear by bone conduction
RInne test
68
In the Rinne test, as the amplitude of the vibration decreases, the sound perceived by the patient decreases in volume. The patient is asked to tell the examiner when the sound can no longer be heard. At that point, the examiner moves the vibrating tuning fork to the outside of the
External ear canal
69
If the patient reports that they can hear the sound again then they are normal, but if they can not hear the sound outside of the external ear, then they have a
Conductive hearing loss
70
The Rinne test will detect
CONDUCTIVE hearing loss
71
The facial nerve enters the temporal bone through the
Internal auditory meatus
72
The facial nerve then passes across the top of the inner ear to reach the
Geniculate ganglion
73
In the geniculate ganglion are found the cell bodies of the
General sensory and special sensory neurons of the facial nerve
74
Because the geniculate ganglion is a sensory ganglion, it contains only sensory cell bodies and there are
No synapses in this ganglion
75
Pass through the geniculate ganglion
Motor fibers (somatic and preganglionic parasympathetic) of facial nerve
76
At the geniculate ganglion, the facial canal, which contains the facial nerve turns posteriorly (the genu) and then continues along the
Wall of the middle ear
77
At the genu, the facial nerve gives rise to the
Greater petrosal nerve
78
The greater petrosal nerve contains preganglionic parasympathetic fibers destined for the
Pterygopalatine ganglion
79
Also contains special sensory taste fibers destined for the palate
Greater petrosal nerve
80
As the facial nerve continues through the facial canal, it gives rise to the branches to the
Stapediues (somatic motor) and also the chorda tympani
81
Contains special sensory taste fibers coming from the anterior 2/3 of the tongue
Chorda tympani
82
The chorda tympani also contains preganglionic parasympathetic fibers destined for the
Submandibular ganglion (via the lingual nerve)
83
The chorda tympani leaves the facial canal and passes through the middle ear cavity, passing BETWEEN the
Malleus and incus (to reach the petrotympanic fissure)
84
Does NOT innervate anything in the middle ear
Chorda tympani
85
After exiting through the petrotympanic fissure, the chorda tympani enters the infratemporal fossa and joins the
Lingual nerve (branch of CN V3)
86
Serves as the pathway to carry the sensory taste fibers to the anterior 2/3 of the tongue and to carry preganglionic parasympathetic fibers to the floos of the mouth where the submandibular ganglion is located
Lingual nerve
87
The preganglionic parasympathetic fibers from the lingual nerve are headed to the
Submandibular ganglion
88
The facial nerve leaves the temporal bone by exiting through the
Stylomastoid foramen (in the mandibular fossa)
89
After leaving through the stylomastoid foramen, the facial nerve gives off the
Posterior auricular branch
90
Provides sensory innervation behind the ear and somatic motor innervation to some skeletal muscle of the posterior portion of the scalp
Posterior auricular branch of facial nerve
91
The facial nerve then passes through the parotid bed to reach and innervate the
Muscles of facial expression, the posterior belly of the digastric and the stylohyoid muscles
92
Weakness or paralysis of facial muscles, loss of taste or sensation of the anterior 2/3 of the tongue, and decreased salivation are all symptoms of a
Facial nerve lesion
93
A major sign of a facial nerve lesion proximal to the geniculate ganglion is
Reduced lacrimation
94
A major sign of a facial nerve lesion between the geniculate ganglion and stapedius is
Hyperacusis
95
We would not expect lacrimation or hyperacusis, but we would expect all other symptoms with a lesion of the facial nerve between
Stapedius and chorda tympani
96
A lesion of the facial nerve between the chorda tympani and stylomastoid foramen would present with
Los of facial muscle function and sensory abnormality behind the ear
97
A lesion of the facial nerve within the parotid gland would only present with
Loss of facial muscle function
