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9 Cards in this Set
- Front
- Back
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What are the steps to sensory transdxn by mechanoreceptive hair cells?
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fluid mvmnt bend cilia causing channels on top of cilia to open and allow cation influx. Influx causes depolarization of hair cell membrane which causes Vgated Ca channels to open. Ca causes release of Glu which excites nerve endings causing membrane AP
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What is the macula? Where does the macula lie in relation to the saccule and utricle? Where is otolithic membrane? What is it's funxns?
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Macula lies vertically on anterior wall of saccule and horizonally on floor of utricle. The otolithic membrane lies ontop of the hair cells of the macula allowing for flow. The response of the macula is to sense changes in position of head relative to gravity
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Where are the cristae in relation to semicircular canals? What is their response to movement?
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Cristae form a ridge in ampulla (at base of semicircular canals) and lie transverse t course of canals. They respond to angular acceleration of head
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Where is the lateral vestibulospinal tract located? What funxn does it have? What can be some findings associated w/ it?
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Located in ipsilateral ventral fasiculus. Important in extensor and antigravity muscles- excites extensor motor neurons especially in legs and axial mm. CST inhibits it so if lesion CST, will get unopposed extensor tone in legs
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What is the role of the vestibulospinal tract?
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stabalize head position
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What is the course of the vestibulo-ocular reflex?
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Afferent nerves from CNVIII travel to vestibular nucleus and synapse. An interneuron neuron crosses contralaterally to abducens nucleus. A second interneuron goes from the contralateral abducens nucleus crosses back and ascends in MLF with secondary neurons from vestibular nucleus to CNIII,IV
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If a patient is comatose and has a spinal injury, what can you do to check for the vestibulo-ocular reflex?
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Caloric testing where you irrigate the tympanic membrane with cold water sending convection currents thru endolymph thus stimulating hair cells. Head moves opposite side of irrigated water
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Where do afferent sensory neurons from vestibular nuclei go?
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To postcentral gyrus in area adjacent to face region and next to parietal lobe area containing spatial orientation
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What are clinical manifestations of vestibular dysfunxn?
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Nystagmus, vertigo, Meniere's disease
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