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23 Cards in this Set
- Front
- Back
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oval window
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oval window receives vibration from the malleus
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Modiolus
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central axis of the cochlea
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Scalae
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fluid that fills the cochlea
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Otosclerosis
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Arthritis of the ossicles checked via bone conduction--> test through Rhine Test
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Rhine Test
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compares air conduction to bone conduction in the affected ear, bone conduction = louder, in normal people air is louder
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Weber Test
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tuning fork at midline
sensory neural loss--> sound louder in the normal ear conductive loss--> affected ear sounds louder |
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What role do hair cells play in auditory stimulation?
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When there is movement of hair cell projections toward the stereocilia, K+ enters the cell, Ca depolarizes, Ca and K leaves. When the movement is in the opposite direction, the K+ channels are closed. This works because there is a high endolymph K+ concentration
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What is mechanical and electrical tuning?
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mechanical: based on position on the basilar membrane
electrical: spontaneous electrical oscillations |
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What is the pathway of sound conduction? What roles does each play?
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spiral ganglia --> cochlear nuclei --> superior olivary nuclei (measure time differnece) on both sides--> cross midline at acoustic stria (trapezoid body) -->lateral leminiscus--> inferior colliculus (conscious) -->medial geniculate body (thalamus) --> Heschl's gyrus (temporal)
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What occurs in lesions of the central auditory pathway?
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no monaural disability
effect localization of sound peripheral lesions = one ear affected |
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What nerves are involved in regulation of vibration of the ossicles?
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CN 7- stapedius
CN 5- tensor tympani |
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Describe an acoustic scwannoma
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mean age of onset: 50 yo
symptoms: unilateral, tinnitus, vertigo, drug induced, hypovolemia/ glycemia Testing: BP, HR, positional vertigo test -> permanent |
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Benign positional vertigo
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debris in semicircular canals
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Meniere's disease
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pressure from lymphatics
Symptoms: vertigo, tinnitus, hearign loss, discreet episodes, can turn permanent treatment: diuretics |
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What are common causes of vertigo?
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hemorrhage, alcohol, drugs, tumors, demyeylination, ischemia of brain stem
Gold standard test for auditory pathway: BAER test |
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What do the efferent fibers from the auditory cortex do?
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They project downward and reach the cochlear nuclei, project to the 8th nerve to the hair cells and are inhibitory --> lesions = amplified sounds
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What is the auditory go-no-go test?
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Patient should move a finger to one tap, not move in response to two taps --> frontal release signs
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What are the common causes of auditory hallucinations?
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CNS tumors, lesions in and around auditory cortex, associative auditory cortex, AV malformations, contralateral side
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What is characteristic of an auditory hallucination caused by a pons lesion?
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rain on roof, buzzing, musical tunes, orchestra
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What are the differences between peripheral and central disorders causing vertigo?
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peripheral = inner ear, adaptation, delayed nystagmus
central = cerebellum, brainstem, immediate nystagmus |
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What is orthostatic vertigo, how is it tested, and what abnormalities can cause it?
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vertigo induced by standing upt
should drop by 10 mm Hg, incr HR 10 beats causes: hypovolemia, anti HTN meds, autonomic problem, cardiovascular |
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What are the symptoms of vestibular nerve rejection?
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extreme vertigo for weeks to months
treatment: neurectomy of CN 8 getamycin otic drops- perm hearing loss destruction of labyrinth on effected side |
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What are common causes of vertigo?
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vertebrobasilar ischemia/ infarct
encephalitis tumors demyelination of posterior fossa anemia thyroid disorder epileptic seizure |
