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36 Cards in this Set
- Front
- Back
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what 6 structures make up the membranous labyrinth?
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3 semicircular canals, saccule, utricle, cochlea
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the hair cells in the cristae of the semicircular canals are stimulated by what?
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angular acceleration (head turns)
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the hair cells of the maculae of the utricle and saccule are stimulated by what?
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linear acceleration
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cell bodies of the vestibular portion of CN VIII are located in what ganglia?
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scarpa's
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what are the three pairs of semicircular canals?
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left horizontal--right horizontal
left anterior--right posterior left posterior--right anterior |
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what is the gelatinous mass that is deflected within the crista ampullaris?
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cupula
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the vestibular system is ______ and therefore doesn't detect steady state differences in head position
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dynamic
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the direction of hair cell depolarization in both ears is directed (toward/away from) the face
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toward! increasing firing in one side results in decreased firing in the other side
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hair cells contain ____ kinocilium and ____ stereocilia in their cuticle region
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1, 40-70
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what are the mechanical linkages between stereocilia?
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tiplinks
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what opens when tiplinks are stretched?
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K+ channels
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hair cells normally have a small influx of K+ so closing K+ channels results in what?
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hyperpolarization
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the influx of K+ into the stereocilia activates what?
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voltage-dependent Ca2+ channels
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what is the ion concentration like in endolymph?
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high K+, low Na+
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what is the ion concentration like in perilymph?
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low K+, high Na+
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the amplitude of depolarization/hyperpolarization depends on the amount of what?
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deflection of hair cells
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what are otoconia?
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calcium carbonate crystals that cover the otolithic membrane
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where are the hair cells of the utricle and saccule located?
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macula
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the macula of the utricle is (vertical/horizontal) and the macula of the saccule is (vertical/horizontal)
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horizontal, vertical
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the utricle macula senses what?
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head tilt due to gravity and linear acceleration in the horizontal plane
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the saccule macula senses what?
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head position when lying down and vertical acceleration
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hair cells in utricle point (toward/away from) striola and hair cells in saccule point (toward/away from) striola
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toward, away from
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where is scarpa's ganglion located?
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internal auditory meatus
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the superior scarpa's ganglia innervates what 4 things?
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utricle macula, anterior saccule macula, horizontal canal ampulla, anterior canal ampulla
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the inferior scarpa's ganglia innervates what 2 things?
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posterior saccule macula & posterior canal ampulla
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most primary afferents project to what nucleus?
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vestibular nuclei (floor of 4th ventricle)
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the lateral vestibular nucleus descends as what tract?
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lateral vestibulospinal tract (LVST). ipsilateral down length of cord. adjusts body to tilts/movements.
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the medial vestibular nucleus descends as what tract?
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medial vestibulospinal tract (MLF). ipsi AND contralateral down cord to mid thorax. mediate posture of upper extremities.
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the medial vestibular nucleus ascends as what 2 things?
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1. vestibulo-ocular reflex to CN III, IV, and VI nuclei
2. to flocculonodular lobe of cerebellum |
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the superior vestibular nucleus ascends as what 2 things?
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1. vestibulo-ocular reflex to CN III, IV, and VI nuclei
2. ipsi AND contralateral to VPI nucleus of thalamus |
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the inferior vestibular nucleus ascends as what?
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to flocculonodular lobe of cerebellum
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you rotate your head left. which ampulla do you deflect? which way do your eyes turn? which muscles do you contract?
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left horizontal ampulla
both eyes turn right L medial rectus & R lateral rectus muscles |
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nystagmus is pathologic if ....?
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it occurs spontaneously or is sustained
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cool water in right ear causes nystagmus in which direction?
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left (cold opposite- warm same)
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what causes Meniere's syndrome?
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excess endolymph pressure caused by inadequate endolymph reuptake
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what are the symptoms of Meniere's syndrome?
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dizziness, vomiting, nausea, nystagmus, hearing loss, trouble walking
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