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Flashcards in AUDITORY SYSTEM Deck (10)
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1. A 70 year old woman has the following Weber and Rinne test results :
Test Left Ear Right Ear
Weber
Rinne No lateralization
AC > BC Lateralization
BC > AC
AC = air conduction; BC = bone conduction
The patient’s otologic findings are most consistent with which of the following conditions?
A. Otoselerosis involving the right ear
B. Otosclerosis involving the left ear
C. Presbycusis involving the right ear
D. Presbycusis involving the left ear
E. A normal examination

1-A The woman has otosclerosis involving the right ear. A patient with unilateral conduction deafness hears the vibration more loudly in the affected ear, and bone conduction is greater than air conduction. Otosclerosis is a conduction defect and involves the ossicles of the middle ear. The most common type of hearing loss in adults. It has a strong autosomal dominant inheritance pattern. Presbycusis, the most common cause of sensorineural hearing loss in adults, affects the cochlea or the cochlear nerve (CN VIII)

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2. All of the following statements concerning conductin deafness are correct EXCEPT
A. the sound of a vibrating tuning fork placed on the vertex is heard best in the deaf ear
B. it may be the result of an acoustic neuroma
C. it may be the result of otosclerosis
D. it my be the result of otitis media
E. it may be the result of wax in the external auditory meatus

2-B Conduction deafness is produced by interruption of the passage of sound waves throuht the external or middle ear. An acoustic neuroma is a tumor of the vestibulacochlear nerve located in the internal auditory meatus or in the cerebellopontine angle of the posterior cerebral fossa. This tumor causes unilateral nerve deafness. In conduction deafiness, a vibrating tuning fork placed on the vertex of the skull would he heard best in the deaf ear; this is the weber test.

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3. All of the following statements concerning nerve deafness are correct EXCEPT
A. in patients with partial nerve deafness, air conduction is better than bone conduction
B. it may result from a middle ear infection
C. it may result from a tumor in the internal auditory meatus
D. it may results from toxins and drugs
E. it may result from degenerative disease of the organ of Corti

3-B Sensorineural, or nerve, deafness results from damage to the organ of Corti, the cochlear nerve, or the central neural pathway. Middle ear infection (otitis media) results in conduction deafness. In patients with partial nerve deafness, air conduction is better than bone conduction

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4. The auditory pathway includes all of the following structures EXCEPT the
A. trapezoid body D. lateral lemniscus
B. nucleus of the inferior colliculus E. medial geniculate body
C. inferior olivary nucleus

4-C The inferior olivary nucleus is a cerebellar relay nucleus found in the medulla. The superior olivary nucleus is an important way station in the auditory pathway; it is found in the pons at the level of the facial nucleus

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5. All of the following statements concerning the auditory system are correct EXCEPT
A. the membranous labyrinth is irrigated by a branch of the anterior inferior cerebellar artery
B. it is characeterized by multiple decussations at all levels
C. it is characterized by pitch localization at all levels
D. it detects sound frequencies from 20 Hz to 50 kHz
E. it can discriminate intensity changes between 1 dB and 2 dB

5-D The auditory system detects sound frequencies from 20 Hz to 20.000 Hz. The membranous labyrinth is perfused by the labyrinthine artery. This is usually a branch of the anterior inferior cerebellar artery (in 85% of patients) but, in some eases, it is a direct branch of the basilar artery (in 15%)

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6. All of the following statements concerning the tympanic cavity are correct EXCEPT
A. it contains the chorda tympani
B. it contains parasympathetic input to the submandibular and sublingual glands
C. it contains two striated muscles
D. it communicates with the nasopharynx
E. it receives sensory innervation by the vagal nerve

6-E The tympanic cavity contains the chorda tympani (of CN VII), which supplies taste to the anterior two-thirds of the tongue. The chorda tympani also contains parasympathetic input to the submandibular and sublingual glands. It contains two striated muscles, the tensor tympani (innervated by CN V) and the stapedius (innervated by CN VII). It communicates, via the auditory tube, with the nasopharynx. The tympanic branch of the glossopharyngeal nerve (CN IX) innervates the mucosa of the middle ear.

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7. All of the following statements concerning the organ of Corti are correct EXCEPT
A. it receives input from the brainstem
B. it is innervated by bipolar neurons of the spiral ganglion
C. it contains mechanoreceptors
D. it contains inner and outer hair cells
E. it is a structure of the middle ear

7-E The organ of Corti, an inner ear structure, lies within the cochlear duct. It contains the peripheral receptor cells of the auditory system. The inner and outer hair cells. Hair cells are mechanoreceptors, receive input from the brainstem via the efferent cochlear bundle, and are innervated by bipolar neurons of the spiral ganglion (of CN VIII)

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8. All of the following statements concerning the basilar membrance are correct EXCEPT
A. it separates the cochlear duct form the scala tympani
B. it has a pitch localization along its length
C. it is in contact with endolymph
D. it gives rise to the tectorial membrance
E. its destruction at the apex the cochlea results in a bearing loss in the low frequency range

8-D The basilar membrance supports the organ of Corti, separates the cochlear duct from the scala tympani, and is in contact with both endolymph and perilymph. The basilar membrance has a pitch localization along its length; high frequencies areregistered at the base of the cochlea, low frequencies at the apex. The tectorial membrance is a projection of the spiral limbus that overlies the hair cells of the organ of Corti.

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9. All of the following statements concerning the hair cells of the organ of Corti are correct EXCEPT
A. they are mechanoreceptors
B. they project centrally to the cochlear nuclei
C. they are stimulated by vibrations of the basilar membrance
D. they are derived from the otic placode of the rhombencephalon
E. they contain stereocilia that are embedded in the tectorial membrance

9-B The hair cells of the spiral ganglion of Corti are mcchanoreceptors. Vibrations of the basilar membrance force the streerocillia (microvillia) of the hair cells against the overlyng tectorial membrance; this shearing force is the adequate stimulus. Hair cells stimulate the afferent bipolar neurons of the spiral ganglion, which project centrally to the cochlear nuclei of the brainstem. The inner ear is derived from the otic placode of the rhombencephalon.

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10. All of the following agents can cause nerve deafness EXCEPT
A. cytomegalovirus D. streptomycin
B. marijuana E. syphilis
C. rubella

10-B There is no evidence to date that marijuana is a human teratogen