vestibulocohclear nerve 1 part 2 Flashcards Preview

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Flashcards in vestibulocohclear nerve 1 part 2 Deck (35):
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in ampulla , located within cristae

hair cells

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hair cells supporting cells

crista

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cupula

gelatinous mass hair cells are embedded in

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tf cupula only half ways across wall of ampulla

f entire way through ampulla wall

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Bending of the stereocilia toward the utricle (-----l canals) activates CN----axons

Bending of the stereocilia toward the utricle (horizontal canals) activates CN-VIII axons

angular acceleration

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angular accelration

relative difference in movement between head and the endolymph; endolymp pushes against cupula

bending its hair cells

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moving head to right

will make stereocilia move to Kinocilium on the right b/c endolymph moves to left 

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constant ang velocity when head is moving right

endolymph will stay in that direction and activate stereocilia in the other side of the head

when initial angular accel occurs; channels open on the side of hed turn because endolymp in opposit direction of head turn

when on the deceleration the direction changes and points toward Kinocilium on other side of head because it is now traveling indirection of head turn

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Kinocilium of hair cells are oriented ------ utricle in the horizontal canals the (opposite in anterior and posterior canals)

Kinocilium of hair cells are oriented toward utricle in the horizontal canals the (opposite in anterior and posterior canals)

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if head moves to right then

endolymph move to left in Semicircular Canals

inc firing in right semicirculat canals

Angular acc.

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left rotation

left left horizontal semicircular canal excited

Increase contraction of the L medial rectus and R lateral rectus

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Allow fixation on an object even though the head is moving

Vestibulo-ocular Reflex

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eyes move the direction opposite of the rotation)

Vestibulo ocular reflex

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connections between the vestibular nucleus

and CN III, IV and VI in Vestibulo-ocular Reflex

 

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decrease contraction of the L lateral rectus and R medial rectus

With L rotation of head

 

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Oriented horizontally when upright

utricle

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Oriented vertically when upright

sacule

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forward - back motions [eg. car] and side-to-side

linear (horizontal) acceleration

by urticle

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elevator)

Detects linear (vertical) acceleration

by saccule

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 Provides information about static head position

saccule and utricle

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maculae(Hair cells (vestibular receptor cells)) on 

utricle and saccule

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within the membranous labyrinth

hair cells and supporting cells

maculae of utricle and saccule

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embather in otolithic membrane and bathed in endolymph

hair cells of the macula

(utricle and saccule)

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carbonate crystals called otoconia or otoliths

make the otoconial membrane denser than the endolymph

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moves with even subtle head movements

otolithic membrane

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Linear movements

induces movement of the otolithic membrane

Input to CNS via cranial nerve VIII

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Bending of the stereocilia toward the kinocilium

causes depolarization and an increase in firing 

in utricle and saccule

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Hair cells are aligned within the macula

along the striola

(utricle and saccule)

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within internal auditory meatus

Vestibular Ganglion

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Superior, Inferior, Medial and Lateral Vestibular Nuclei

bilaterally to Medial (neck) and Lateral Vestibulospinal Tract(SC)

 

Vestibular Nuclei and their Efferents

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bilat to To other cranial nerve nuclei

Superior, Inferior, Medial and Lateral Vestibular Nuclei

 

Vestibular Nuclei and their Efferents

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Superior, Inferior, Medial and Lateral Vestibular Nuclei

ips to cerebellum

Vestibular Nuclei and their Efferents

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Vestibulo ThalamoCortical Pathway

lateral and superior vestibular nuclei project to the VPL

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from the thalamus,

the vestibular neurons project to parietal cortex

 

Vestibulo ThalamoCortical Pathway