Vestibular System Flashcards
(42 cards)
Draw the vestibular organ
name important structures [5]
semicircular canals utricle saccule endlymphatic duct cochlea
inputs of vestibular system?
Visual , proprioreceptive and vestibular information
Outputs of vestibular system
mainly reflexes : Stable posture and stable gaze
CNS integrates this and generates responses and controls feelings of nausea, vertigo
Where is vestibular organ found?
Posterior area of inner area
What is the function of hair cells in the inner ear?
The inner ear contains hair cells for hearing and balance
Vestibular hair cells
type
arrangement
Kinocillium - 1 relatively long hair
Stereocilia - 50 shorter ones (stereocilia)
The kinocilium is inserted eccentrically on top of the sense cell; the stereocilia are arranged in parallel rows
Where are stereocilia located?
otolith organs?
semicircular canals?
In macula of otolith organs
in ampulla of semicircular canals
where are the otolith organs located?
what are the otolith organs?
vestibule utricule and saccule joined by a conduit [endolymphatic duct] Utricle is superior and is connected to the semicircular canals saccule connects to cochlea
Movement of endolymph causes what?
Cilia allows the cells to depolarise the cell with movement of the endolymph generated by head movem
How are the hair cells arranged in the utricle?
horizontally
How are the hair cells arranged in the saccule?
vertically
what is the makeup of the semicircular canals?
Hair cells in ampulla - crista , cells surrounded by cupula which helps with hair cell movement
rest of canal is liquid high in K+ - ENDOLYMPH
Where do vestibular nuclei have projections to?
4
Spinal cord
Nuclei of the extraocular muscles
Cerebellum
Centres for cardiovascular + respiratory control
where do vestibular afferent information go to?
4 nuclei
medulla
pons
‘Inferior, medial, lateral (Deiter’s) and superior vestibular nuclei. All four nuclei are found beneath the floor of the fourth ventricle in the medulla and pons, lateral to the sulcus limitans’
Vestibular pathways
Inferior nuclei
vestibulo-ocular reflex
oculomotor
vestibulocerebellar reflexes : balance, vestibular reflexes, and eye movements
Vestibular pathways
what are the lateral , medial, inferior nuclei involved in ?
Vestibulospinal reflex
Which vestibular pathway ?
- spatial orientation and self-motion perception
Information sent to superior vestibular nuclei
> Ventroposterior nucleus
> vestibular cortex
Functions of
Vestibular system
To detect and inform about head movements
To keep images fixed in the retina during head movements
Postural control
What causes depolarization in vestibular systems?
Stereocilia moving towards Kinocilium
depolarization
increase in nerve firing
Stereocilia moving away from kinocilium
what occurs next?
Inhibition
Hyperpolarization
= reduction in nerve discharge
What is involved in angular acceleration?
Semicircular canals
Linear acceleration and tilt
which vestibular organs involved?
Otolith
Utricle : horizontal
Saccule : vertical
VOR
keeps images fixed
vestibular nuclei and oculomotor nuclei
Eye movement in opposite direction to head movement
but same velocity and amplitude
VSR
Lateral tract?
motor neurons to limb muscles
