Vestibular system Flashcards
What are the main inputs in the vestibular system?
- visual
- rotation and gravity
- pressure
What are the main outputs in the vestibular system?
- vestibulo-ocular reflex: allows you to keep an image fixed in retina when you are moving
- vestibulospinal reflex: postural control
- cerebellar reflex: for cognition monitoring?
Where is the vestibular organ?
posterior part of inner ear
What structure are all 3 semicircular canals joined to?
the utricle
What are the big cilia called in the vestibular organ?
kinocilia
What are the small cilia called in the vestibular organ?
stereocilia
What are the otolith organs?
- utricle and saccule (NO otoliths in semicircular canals)
- crystals on top of hair cells help w/ deflection of cilia
Which semicircular canals form a 90degree angle to each other?
anterior and posterior canals
What happens when the hair cells move towards the kinocilium?
generates depolarisation and an increase in nerve discharge
What happens when the hair cells move away from the kinocilium?
generates hyperpolarisation and a reduction in nerve discharge
Which otolith organ is sensitive to movement in the horizontal plane?
utricle (saccule sensitive to vertical movement)
N.B. this is linear acceleration
What pairs do the semicircular canals work in?
- both laterals work together
- anterior from 1 side works w/ posterior of opposite side (as they share same plane)
What is the vestibule-ocular reflex?
- keeps images fixed in retina
- connection between vestibular nuclei and oculomotor nuclei
- eye movement in opposite direction to head movement, but same velocity and amplitude
What is the vestibulospinal reflex?
- motor neurons to limb muscles (lateral tract)
- motor neurons to neck and back muscles (medial tract)
- postural control, avoidance of falls and compensatory body movement according to head position
What are the main symptoms of a balance disorder?
- vertigo: perception of rotation, things spinning
- dizziness
