Balance Flashcards
vertigo
spinning sensation caused by inner ear disease - symptom not a disease
inputs of balance
vision
proprioception/somatosensation
vestibular
hair cells join to form what in the vestibular system?
neuroepithelium
where are the neuroepithelia?
membraneous labyrinth bathes in endolymph
longest cilium
kinocollium
which direction are cilia pulled in excited hair cell>
towards kinocillium
which direction are hair cells pulled in inhibited hair cells
away from kinocillium
role of Maculae
detects linear movements on a horizontal or vertical plane
maculae in utricle
when moving horizontally, the maculae lag behind which changes AP firing rate down the vestibular nerves (detected in the brain as motion)
maculae in sacculle
maculae are on the wall and vertical movement causes displacement.
Dislodging of crystals so they end up elsewhere in the vestibular system is called…
BPPV - Benign Paroxysmal Positional Vertigo.
what is BPPV caused by?
- Benign Paroxysmal Positional Vertigo.
Dislodging of crystals so they end up elsewhere in the vestibular system
ampulla and hair cells
§ Ampulla swelling at each end of the canal filled with endolymph.
□ Modified version of the macula within - crista (made up of endothelium hair cells with a clump of gel which is cup shaped (cupula) but no otoconia)
what happens When you move your head in an angular motion that aligns with the orientation of one of the canals?
the fluid in the canal displaces the crista which changes the firing rate of AP
□ Detected by the brain as angular acceleration or movement
vestibulo-ocular reflex (VOR)
Each semi-circular canal is wired to the extraocular muscles of the eyes to keep vision focused when the head moves
Oscillopsia
vision move when you move, unable to fix vision
loss of function of vestibular apparatus causes…
spinning sensation called vertigo
swaying
imbalance/poor equilibrium
diseases causing damage to vestibular apparatus include
vestibular neuritis
labyrinthitis
menieres disease
BPPV
loss of visual inputs causes…
poor equilibrium/imbalance
diseases causing damage to visual inputs include
macular degeneration
cateracts
sudden blindness
diabetic retinopathy
sense dominance on stable surface
50% somatosensory
25% vestibular
25% vision
sense dominance on unstable/uneven surface
73% vestibular
13% vision
12% somatosensory
reflex to prevent small movements
ankle
reflex to prevent medium movements
hip
reflex to prevent large displacement
step strategy/use a wall
causes of falls in elderly
centre of gravity drops beyond base of support
base of support falls relative to centre of gravity (most common)
blockage in labyrinth artery may cause…
deafness
loss of balance
nerve supply to labyrinth
Superior and inferior vestibular nerve
- Superior supplies supplies utricle, lateral semi-circular canal and superior semicircle canal
- Inferior supplies saccule and inferior semi-circular canal
where are crista
in ampulla
central cause of nystagmus
leaky integrator
nystagmus
disorder of ocular position
jerky slow/fast movement
directed away from underactive labyrinth and vestibular nucleus
obeys alexanders law
alexanders law
nystagmus is greater when looking in direction of the fast phase (due to faulty integrator and asymmetric vestibular tone).
