vestibular and balance Flashcards
what is the role of the postural system
maintains steady balance in the presence of gravity - uses reflexs and autonomic responses
what two sensory modalities are utilised in posture
vision and vestibular
what is the role of the semi circular canals in the vestibular system of balance
scapula (receptor) detects head rotation and activates amupllary nerve - one in each ear so impulses can be compared
in rotation one side depolarise whilst the other hyper polarises to tell which why the head is rotating
what is the role of the utricle and saccule in the vestibular system
translational motion and linear movement
maculae (receptor) - part of the otolithic membrane which surrounds hair cells
if you told to the left there depolarisation if you tilt to the right there is hyperpolasrisation - mediated by glutamate release via Ca2+ influx which is determined by initial K + influx from initial receptor
utricle - horizontal
saccule - vertical
which nerves are being innervated in the vestibular system
ampullarf nerves, utricular nerves and saccular nerves
once the nerves of the vestibular system are stimulated where do they send the impulses to
cerebellum, limb motor neurones and medial longitudinal fasiculus which then react to changes in posture
what is the role of CN VI / 3 in the VOR
vestibulo-ocular reflex which keeps the eyes facing forward on head movement
how do lower motor limbs react in the vestibule system reflex
anticipatory and feedforward postural control - postural changes due to environmental changes
what is the mechanism of postural instability
feedforward and feedback which aid postural control
what does a vestibular schwanoma cause
presses on other CN’s tints hearing loss and balance issues (CN8), facial weakness (CN7) and facial numbness (CN5)
what does Menieres syndrome cause
poressure, earache, tinitus and dizziness - episode of falling
due to increased endolymph and rupturing of the membranous labyrinth
what is benign paroxysmal positional vertigo
caused by calcium carbonate crystals dislodged from otoliths that float into canals - movement in the canals gives illusion of movement and disorientation
what is ototoxicity
damage by drugs or chemicals which damages CN8
what diseases and disorders lead to disrupted postural control secondary to vestibular system
vestibular neuritis, brainstem carcinoma
infarction and haemorrhage
how does a medulloblastoma affect the vestibular system
childhood tumour growth within cerebellum
unable to utilise relevant lateral vestibular information from utricals and saccules - postural instability
