Vestib - intro Flashcards
what are the 3 main functions of the vestib system
- stabilize visual images on fovea of retina during head mvmts to allow clear vision
-> gaze stability (VOR) - provides info used for spatial orientation
-> sensing and perceiving motion (SCC’s hair cells, otoliths) - maintains postural stability during head mvmts
-> postural control (VSR)
what is an important challenge in assessing postural control
impossible to assess w/o assessing vestib
what are 3 central processing components for postural control and which are vestibular components
sensory organization *
sensory adaptation *
anticipatory post control
what are 2 motor outputs for postural control and which are vestibular components
VSR **
motor strategies
- ankle, hip
- stepping (ROM, ms performance, coordination)
what are the 2 main components of the peripheral vestib system
vestibular labyrinth
vestibular nerve
what are the 2 main components of the central vestib system
vestibular nuclei
vestibulo-cerebellum
what are the 2 main components of perception via the vestib and what is the function of this
thalamus
vestib cortex
ability to perceive where we are in space, complex process requires lot of communication
what are the main peripheral vestibular apparatus components
3 SCC - ant, post, lat
2 otolith organs (in vestibule)
- utricle, saccule
function of 3 SCC vs 2 otolith organs
SCC = angular velocity of head
otolith = linear motion & acceleration
where do all SCCs open at both ends to
the utricle
what are the ampullas
expanded portion of each canal that houses vestibular receptor which can detect mvmts
what are the cupulas: location, composition
w/i ampulla, at end of canal
gelatinous membrane surrounded by endolymph
what are 3 functional components of the hair cells found in cupulas
- stereocilia and kinocilia (taller)
- cell bodies
- afferent and efferent nere endings
what role do the crista ampullaris hair cells embedded in the cupula play
hair cells will either dec or inc firing vestib nerve in order for brain to know what direction your head is rotating
describe the process of head rotation direction being detected and relayed w/i the SCC
forces from head mvmt pushes endolymph fluid opposite direction
-> deflects cupula & contained sensory hair cells also in opposite direction to rotation
that excites or inhibits signalling to vestib nerve in order for us to know where our heads are in space
what are 2 major components of hair cells
stereocilia
kinocilium
direction of cupular deflection and what response is created
deflection of stereocilia TOWARDS kinocilium EXCITES CN VIII
deflection of stereocilia AWAY from kinocilium INHIBITS CN VIII
what is the constant firing rate of hair signals in the cupula at rest and what is the significance
70-100 spikes/sec
allows system to be capable of detecting mvmt
what is the significance of the speed of head rotation
the quicker you move, the more displacement of cupula and brain is able to detect speed and more accurately the deflection
what are the 2 functions of the otolith organs
static head tilt (gravity)
linear acceleration/decel (inertia)
what is the composition of the otolith organs
otolithic membrane made up of otoconia and gelatinous layer
hair cells bend when otoconia displaced relative to head
where does info from the peripheral vestib system go to and what happens next
higher sensors - vestib and nuclear complexes in medulla and vestib cerebellum
- relayed for further integration w other sensory info and related info ab our physical state, environment, etc.
what are the divisions of the vestibular nerve and what do they each innervate
superior vestib nerve
- lateral SCC
- anterior SCC
- utricle
inferior vestib nerve
- posterior SCC
- saccule
what are the 5 main vestib system projections
thalamus
parietoinsular vestib cortex (PIVC)
cerebellum
VSR
VOR
