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Flashcards in Vestibular System Deck (14)
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3 Kinds of Mechanics

Macromechanics - turning head and making fluid move
Micromechanics - hair cells move
Nanomechanics - molecular gates open


3 Semicircular Canals

Lateral for horizontal, and anterior and posterior for vertical


Movement Transduction to Hair Cells (3 special terms)

Ampulla is widened section w/ crista coming up (ridge on floor with hair cells). Hairs project into gelatinous cupula. Endolymph movement causes cupula to move, deflecting hair cells


Lymph Different Concs

Endo: Low Na/High K
Peri: High Na, Low K like CSF.
Gradient allows hairs to function and depol


Alcohol Vestib Effects

Makes cupula less dense than endolymph, leading to stimulation in one direction. Hair cells don't adapt so effects continue until alcohol wears off


2 Structural Types of Hair Cells

Type I (Calyx Type) - aff comes in and forms calyx around cell, eff synapses onto calyx
Type II - aff and eff each synapse on hair cell


3 Reflexes of Vestibular Signals

Vestibulo-ocular - eyes in head
Vestibulo-collic - head on trunk
Vestibulo-spinal - trunk on ground


Vestibulo-ocular Reflex

Turning head right excites R horizontal canal and inhibits L, so R sends excitatory signals to R vestibular nucleus which decussates and excites abducens nucleus, exciting L IV and R III to turn eyes left. L horizontal does opposite everything inhibitorily


2 Components of Nystagmus

Slow: Labyrinthine component
Fast: Corrective component, CNS


2 Sources of Peripheral Vestibular Hypofunction

Loss of unilateral function (like trauma) loses resting activity of ipsilateral nerve and nuclei and difference is interpreted as motion -> nystagus
Benign paroxysmal positional vertigo (BPPV) means loose ooconia bouncing around, any motion relating to gravity causes nystagmus


Caloric Test

Water 7 deg above or below body temp injected into ear, eyes should deviate towards the cold side


VCR Test

Vestibulo-collic reflex, play loud noise to stimulate utricle/saccular shit to test otolinth function


Meniere's Disease

Endolymph fluid imbalance leads to bulging of membranous labyrinth, causing tinnitus/veritgo/hearing loss. Treat by trying to get water out, maybe gentamicin injections


Superior Canal Dehiscence

Hole in osseous labyrinth over semicircular canal exposes membranous canal to sound and pressure stimuli