vestibular system Flashcards
what are the 3 main inputs in the vestibular system
visual
proprioceptive
and vestibular information
what is the vestibular system
system that allows us to keep balance/ corporate balance e.g posture
what are the outputs of vestibular system
mainly reflexes to maintain stable posture and stable gaze
e.g ocular reflex and postural control
what is role of cns
integrates information and generates responses
where is vestibular organ found
posterior area in inner ear
contain hair cells
where are utricle and saccule located
in vestibule
are joined by conduit
saccule is also joined to cochlea
what are the 3 semicircular canals on each ear
anterior
posterior
lateral
semicircular canals have ampulla on one side and connected to utricle
why are the planes for the anterior and posterior canals important
determine which structure will be stimulated with specific head movement
what are vestibular hair cells called
kinocilium - biggest cilium
stereocilia - hairs on hair cells
what is role of cilia
allows cells to depolarise cell with movement of endolymph generated by head movements
what are the organs in vestibular system
3 semicircular canals and otoliths: utricle and saccule
why are utricle and saccule called otolith organs
contain otoliths(crystals)
cells are located on maculae
- placed horizontally in utricle
- placed vertically in saccule
what do the maculae contain
hair cells, gelatinous matrix and otoliths
what are otoliths
carbonate crystals that help deflection of hairs
what can be found in canals
hair cells located in ampulla
rest of canal has liquid high in potassium called endolymph
what do ampulla has
crista, where hair cells are located
cells are surrounded by cupula which help hair cell movement
what is orientation of canals in head
anterior and posterior canals form 90” angle
lateral canals are horizontal to other canals
where are primary afferents end
in vestibular nuclei and in cerebellum
where do vestibular nuclei have projections to
spinal cord - for postural movement
nuclei of extraocular muscle - for eye movement
cerebellum
centres for cardiovasc and resp control
what is the main processing centre for vestibular system
in parietal lobe - parieto- insular vestibular cortex
what are the vestibular system functions
- detect and inform about head movements
- keep images fixed in retina during head movements
- postural control
explain hair cell potentials
have resting potential - have basal discharge to nerve
hairs moving towards kinocilium generates depolarisation and increase in nerve discharge
hairs moving away - generates hyperpolarisation and reduction in nerve discharge
what movements is utricle sensitive to
horizontal
what movements is saccule sensitive to
vertical
