Vestibular Function pp Flashcards
Sense of body position in space
Systems used
Vestibular
Proprioceptive
VIsual
Major fx of Vestibular Syster
Subjective awareness of body position & movement
Postural tone & equilibrium
Stabilization of the eyes during head movements
Stereocilia workings
Bending toward kinocilium depolarizes
Bending away hyperpolarizes
Utricular macula changes
Gravity and Acceleration displaces the otolithic membrane
Response of vestibular nerve axon from otolith
Needs info from both sides
Otolith Ocular Reflexes
Head tilted to one side eyes rotate to other
Maintain visual field horizontal
Depend on tonic input utricle & saccule
Vestibulo Ocular Reflex response to head turns
Developed in response to small head turns
Eyes move in opposite direction to facilitate fixation on visual target while head is moving
VOR sensory input
Driven by vestibular input
Even whepatients have their eyes closed
Visual input keeps the reflex accurate
VOR head to righ
Fast phase - moves eye back to midline
Post Rotary Nystagmus
After person stops turning
Endolymph inertia
Feel like moving the opposite direction
Eye movements corresponds to illusionary turning
Cold hot
cold fast away
hot fast towards
Dolls Eye Maneuver
To evaluate brainstem injury
Absent response no movement while test moves head
Probably a lesion in brainstem
Vertigo
Sense world is spinning (dizzy)
Benign Paroxysmal Positional Vertigo
Most common
Free floating particles w/in posterior semicircle
Meniere Syndrome
Imbalance btw the production & reabsorption of endolymph
Endolymphatic hydrops leading to rupture membranous labrynth
Contamination depolarizes afferent & hair cells die
