Vestibular Function Flashcards
what are the 3 major functions of the vestibular system
subjective awareness of body position/movement
postural tone and equilibrium
stabilization of eyes in space during head movements
what are the otolith organs
utricle saccule
what are the semicircular canals
anterior, posterior, horizontal
what do otolith organs contain
a macule which contains hair cells
what are teh senosry receptor cells in the vestibular system
hair cells
what happens if stereocilia are bent towards kinocilium
cell depolarizes adn releases additional neurotransmitter
what happens if stereocilia are bent away from kinocilium
hyperpolarizes adn decreass neurotransmitter release
how is the macula of utricle oriented
parallel to ground
how is macula of saccule oriented
vertical to ground when head is upright
how are hair cells in the ampulla/cupula stimulated
by angular acceleration
how do semicircualr canals respond to head turning
horizontal canal receptors on one side increase their firing rate and receptors on the other side decrease firing
vestibulo-ocular reflex
response to head terns
if head is tilted to one side how do the eyes rotate
in opposite direction
what is the function of VOR
help maintain visual field in horizontal plane
what is the slow conjugate movement of the eyes that compensates for head turns driven by
vestibular system
what direction is slow eye movement
away from head turn
what direction is fast eye movement
towards head turn
rotatory nystagmus
slow phase of nystagmus - opposite direction of head turn
fast phase nystagmus
moves eyes back to midline, in direction of head turn
post-rotatory nystagmus
occurs after a person stops turning
caloric test for vestibular function
water test
cold water
fast phase to opposite ear
warm water
fast phase towards same ear
what happens if you do a carloric test in an unconcious pt
they do not have the fast phase
