vestibular system Flashcards
what does the vestibular system do
maintain balance posture and spatial awareness
which 3 receptor systems are integrated by the vestibular system
eyes
general proprioceptive and cutaneous receptors
vestibular apparatus
where is the vestibular apparatus
inner ear
2 parts of the labyrinth
vestibular part
auditory part
what is the fluid inside the labyrinth
endolymph
what fluid bathes the labyrinth
perilymph
difference in potassium and sodium concentration in the endolymph and perilymph
endo - high K, low Na
peri - low K, high Na
what connects the vestibular part and auditory part of the labyrinth
ductus reuniens
are the utricle, saccule, semicircular canals, ampullae, and cochlear in the auditory or vestibular part of the labyrinth
vestibular -utricle, saccule, ampullae, and semicircular canals
auditory - cochlear
how many semicircular canals are there
3
what are the otolithic organs
utricle and saccule
what is the tallest stereocilium on a vestibular hair cell called
kinocilium
which cranial nerve do vestibular hair cells synapse to
CN VIII
what happens when the stereocilia on a hair cell are bent
hair cell hyperpolarised or depolarised
which NT is released at the synapse between hair cells and CNVIII
Glutamate
which part of the vesibular apparatus has hair cells surrounded by a gelatinous cupula
Ampullae of semicircular ducts
what are hair cells in the semicircular canals sensitive to
Movement
head rotation
acceleration/deceleration
angular acceleration/rotation
Complementary bilateral signalling
what do otoliths in the utricular and saccular macula detect
linear acceleration
head tilt
Gravity
what provides 3d representation of the direction of linear force
hair cells of utricles and saccules
what divides the macula
striola
are hair cells in the utricles and saccules polarised towards or away from the striola
utricles - towards
saccules - away
what are hair cells in the saccule and utricle sensitive to
gravity
head tilt
linear acceleration
nystagmus
initial slow rotation of the eyes followed by compensatory flick back
which reflex dysfunction causes nystagmus
vestibulo-occular reflex
is the direction of nystagmus defined by the slow or fast component
fast
does nystagmus move towards or away from the affected side
fast part away from affected side
vestibular lesion symptoms
nystagmus
vertigo
vomiting
dizziness
balance problems
vestibular lesion symptom treatment
antiemetics
antihistamines
benzodiazepines
why does the caloric reflex test cause eye movement
water heats semicircular canal -> convection of endolymph -> nerve firing -> body thinks head rotatingf -> eyes move to compensate
which parts of the brain produce the fast and slow eye movements in the caloric reflex test
slow - brainstem
fast - cortex
what does the hallpike manoeuvre test for
benign paroxysmal positional vertigo
how is the hallpike manoeuvre done
head lowered to table and turned to one side, repeated on other side if result negative
hallpike manoeuvre positive and negative result
positive - dizziness and nystagmus when affected ear pointed to floor
negative - no effect
which nerves control eye movements
CN III IV VI
central control of vestibular function
premotor areas - plan movement
area 3a - converge w signals from muscle spindles
posterior parietal cortex - converge w visual and somatosensory signals
cingulate gyrus - activity associated with pain, attention, motivation, and emotions
PIVC - converge w proprioceptive signals
What structures does the vestibular complex in the brainstem connect to
Vestibulospinal tract
Reticular formation
Cerebral cortex
Thalamus
Superior colliculus
Ant and Flocculonodular lobes of cerebellum
Fastigial cerebellar nucleus
