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29 Cards in this Set
- Front
- Back
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What are the functions of the vestibular system?
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1)maintain posture
2) head stabilization and gaze 3) perception of movement |
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Function of semicircular canals?
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detect rotational acceleration
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Function of utricle and saccule?
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linear acceleration/static head position relative to gravitation axis
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What is the difference between vestibular hair cells and auditory hair cells?
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vestibular hair cells have a baseline firing rate and a kinocilium
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What are teh otolith organ?
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CaCO3 cyrstals which shift relative to sensory epithelium and cause shearing between olitic membrane and macula
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What is the microorganization of the otolith organ?
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macula - hair cells sensory epithelium - supporting cells around hair cells otolith membrane striola - axis of mirror symmetry within each maccula |
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What happens during tilt?
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tilt along one axis of striola excite cells on that side and inhibt eclls on the other side
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What is the difference between head tilt and linear acceleration?
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head tilt - sustained
linear acceleration - no head tilt and transient |
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What is the utricle for?
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Horizontal plane
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What is the saccule for?
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verticle plane
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What determines whether you get depolarization or hyperpolarization in response to angular acceleration in the semicircular canals?
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endolymph flow and cupula displacement
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What is the caloric test?
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irrigate ear with cold water and slow movement will occur towards irrigated ear and fast movement away from it
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What happens when the cerebral hemispheres are not intact but brain stem is in tact?
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saccadic movements (fast movemetns) are no longer made but there is slow movement of eye towards irrigated side
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What happens with caloric test if ther is a brain stem lesion?
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vesitibular response is abolished or altered
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What is the vestibulooccular reflex?
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produce eye movements that counter head movements allowing gaze to remian fixed
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What is oscillopsia?
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bouncing vision that occurs with loss of vestibulooccular reflex
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What is the reflex to maintain posture?
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vestibulocervical reflex
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What is reflex to maintian muscle tone?
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vestibulospinal reflex
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What is the difference between depolarization and hyperpolarization in nerve impulses?
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depolarization - increased impulse frequency
hyperpolarization - decreased impulse frequency |
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What happens when you rotate to the left?
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slow eye movement to right
rapid eye movement to left |
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What is nystagmus>?
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rapid repeat eye movement
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What is postrotational nystagmus?
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stop after rotation to left
right side is stimulated nystagmus to right (opposite side) |
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What happens when you rotate your head to the right?
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right semicircular horizontal canal is stimulated and increases firing, left horizontal canal is decreased firign
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What is the rule with slow and fast movements in the caloric test?
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COWS
cold oppsite warm same cold - fast to opposite side, slow to same side warm - fast to same side, slow to opposite side |
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What is the pathway of the vestibuloocular reflex?
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1) scarpas ganglion
2)medial vestibular nucleus 3) inhibit ipsilateral abdunces, stimulate contralateral abducens in pons |
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What is the vestibulospinal reflex?
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uses medial fasicullus, and medial vestibulospinal tract
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What is ocular reflex in patient whose brainstem is intact?
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cold to same side (slow)
warm to oppsoite side (slow) |
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What is the ocular reflex in medial longitudinal fasiculus where fibers cross?
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eye that is irrigated does the right reflex but other eye does not
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What happens in low brainstem lesion?
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no response
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