Lecture 24- Vestibular System 1 Flashcards
Where do the vestibular nuclei project to?
- cerebellum
- nuclei of extra-ocular muscles
- reticular formation
- spinal cord
What are the 2 types of receptors in the vestibular system?
- static- respond to linear accelerations (maculae of utricle and sacule)
- kinetic- respond to angular movements of the head
Which receptors are more involved in the static position of the head (linear)?
maculae of the utricle and saccule
Which receptors are more involved in head rotation (angular)?
cristae of the semicircular canals
What are the 3 functions of the vestibular system?
- sensation of spatial orientation
- postural control to prevent falling
- stabilization of eyes during head movement
What results in the hair cell when the stereocilium is bent TOWARDS the kinocilium?
depolarization
What results in the hair cell when the stereociliium is bent AWAY FROM the kinocillium?
hyperpolarization
What is directional sensitivity?
property of the hair cell in which movement of hairs in one direction increases firing whereas movement in the opposite direction decreases firing rate
Why is the bending of the cilia referred to as a “graded generator potential”?
because the firing is proportional to the bending
Which maculae is appx horizontal when standing?
utricle
Which maculae is appx vertical when standing?
saccule
What is the name of the gelatinous material where the hair cells embed their cilia?
otolith
What is the purpose of the crystals on the otolith?
to make the otoliths denser than the endolymph so that this otolith with move the hair cells in response to head movement
How is direction of head movement coded?
by which hair cells are active
How is magnitude of head movement coded?
rate of firing of afferent fiber
What vestibular organs are involved in angular acceleration?
kinetic receptors- the 3 semicircular canals and their associated ampulla and cristae
What are the hair cells of the ampulla embedded in?
cupula
How is the cupula different than the otolithic membrane?
the cupula is the same density of the endolymph whereas the otolith is more dense due to the crystals
What is the name of the fluid found within the bony labrinyth? What about the membranous labyrinth?
body labyrinth-perilymph
membranous labyrinth- endolymph
What is the name of the widened space where each semicircular canal connects with the utricle?
ampulla
What is found within the ampulla?
the cristae ampullaris
When you turn your head to the right your eyes move to the _______?
left
What connects the vestibular nuclei to the 3,4 and 6th CN nuclei?
MLF- Medial Longitudinal Fasiculus
