vestibulocohclear nerve 1 part 2 Flashcards
in ampulla , located within cristae
hair cells
hair cells supporting cells
crista
cupula
gelatinous mass hair cells are embedded in
tf cupula only half ways across wall of ampulla
f entire way through ampulla wall
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
angular accelration
relative difference in movement between head and the endolymph; endolymp pushes against cupula
bending its hair cells
moving head to right
will make stereocilia move to Kinocilium on the right b/c endolymph moves to left
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
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)
if head moves to right then
endolymph move to left in Semicircular Canals
inc firing in right semicirculat canals
Angular acc.
left rotation
left left horizontal semicircular canal excited
Increase contraction of the L medial rectus and R lateral rectus
Allow fixation on an object even though the head is moving
Vestibulo-ocular Reflex
eyes move the direction opposite of the rotation)
Vestibulo ocular reflex
connections between the vestibular nucleus
and CN III, IV and VI in Vestibulo-ocular Reflex
decrease contraction of the L lateral rectus and R medial rectus
With L rotation of head
Oriented horizontally when upright
utricle
Oriented vertically when upright
sacule
forward - back motions [eg. car] and side-to-side
linear (horizontal) acceleration
by urticle
elevator)
Detects linear (vertical) acceleration
by saccule
Provides information about static head position
saccule and utricle
maculae(Hair cells (vestibular receptor cells)) on
utricle and saccule
within the membranous labyrinth
hair cells and supporting cells
maculae of utricle and saccule
embather in otolithic membrane and bathed in endolymph
hair cells of the macula
(utricle and saccule)
carbonate crystals called otoconia or otoliths
make the otoconial membrane denser than the endolymph
moves with even subtle head movements
otolithic membrane
Linear movements
induces movement of the otolithic membrane
Input to CNS via cranial nerve VIII
Bending of the stereocilia toward the kinocilium
causes depolarization and an increase in firing
in utricle and saccule
Hair cells are aligned within the macula
along the striola
(utricle and saccule)
within internal auditory meatus
Vestibular Ganglion
Superior, Inferior, Medial and Lateral Vestibular Nuclei
bilaterally to Medial (neck) and Lateral Vestibulospinal Tract(SC)
Vestibular Nuclei and their Efferents
bilat to To other cranial nerve nuclei
Superior, Inferior, Medial and Lateral Vestibular Nuclei
Vestibular Nuclei and their Efferents
Superior, Inferior, Medial and Lateral Vestibular Nuclei
ips to cerebellum
Vestibular Nuclei and their Efferents
Vestibulo ThalamoCortical Pathway
lateral and superior vestibular nuclei project to the VPL
from the thalamus,
the vestibular neurons project to parietal cortex
Vestibulo ThalamoCortical Pathway
