4.18 Vestibular Flashcards
2 components of vestibular
- peripheral
- central
What is in the peripheral vestibular system?
inner ear receptors that signal position and movement of the head
The central vestibular system consists of neurons that: (4)
- contribute to conscious orientation and acceleration through space
- mediate reflexive adjustments to maintain visual acuity and equilibrium
- have both sensory and motor function
- have extensive cerebellar connections
Which system depends heavily on vestibular? Why?
- visual
- eyes move in a compensatory way with the head
Where do semicircular canals primarily project?
medial and superior vestibular nuclei
not as much to lateral and inferior nuclei
semicircular canals are for detection of
rotation
What is a major function of the lateral vestibular nucleus?
serves as an important UMN for the lateral vestibulospinal tract
What is a major function of the medial vestibular nucleus
important UMN for medial vestibulospinal tract
The macula is for
linear acceleration
What interacts with the hypothalamus that is important for endocrine autonomics?
RF
What does the RF do with respect to vestibular?
controls autonomic responses to vestibular inputs
lack of RF input (I think) my cause these vestibular effects
- nausea
- vomiting
- dizziness
- pallor
- sweating
*carsick
What are the superior and medial vestibular nuclei for?
eye coordination
Which CNs do the superior and medial vestibular nuclei affect? Which reflex is this associated with?
3, 4, 6
VOR
components of the bony labyrinth
- 3 semicircular canals
- 2 otolithic organs
- membranous labyrinth
How do the semicircular canals detect rotation?
via movement of endolymph
position of canals to one another
orthogonal
canals open at each end at the
utricle
The utrical is an
otolithic organ
swelling at the end of the canals
ampulla
What does the ampulla contain?
crista
What does the crista contain?
- support cells
- hair cells embedded in gelatinous cupula
What does the 90˚ orientation of the canals imply?
only 1 set of hair cells affected at a time
Hair cells are how this happens
signaling of head acceleration
Hair cells are embedded in the
cupula
If hair cells bend toward the _____, we get activation
kinocilium
If hair cells bend toward the _____, we get inhibition
stereocilia
Baseline activity of hair cells
always firing tonically
Activation/inhibition causes
speeding up or slowing down of firing rate
How do the canals work?
- work in pairs
- get essentially equal and opposite actions
What happens when the R side is being activated?
get roughly the same amt of inhibition from the L side
What happens to the fluid during spinning?
- fluid speeds up to match rate of turning
- when you stop, the fluid sloshes back
With a single plane of rotation, how many pairs of canals are being affected?
ONE
