vestibular system Flashcards
(15 cards)
vestibulo-ocular reflex (VOR)
alternating pursuit and saccades in response to body/head motion; eyes move in opposite direction to head movement
4 functions of vestibular system
autonomic responses, visual stability, balance/posture, spatial orientation
the pathways for vestibular system functions all begin with
vestibular nerve (semicircular canals, utricle, saccule) and vestibular nuclei (superior, medial, lateral, inferior)
the vestibular nerve consists of
semicircular canals, utricle, saccule
the vestibular nuclei consists of
lateral, medial, superior, inferior vestibular nuclei
pathway for autonomic responses of vestibular system
vestibular nerve > vestibular nuclei > area postrema
pathway for spatial orientation of vestibular system
vestibular nerve > vestibular nuclei > thalamus > cortex
pathway for visual stability of vestibular system
vestibular nerve > vestibular nuclei > oculomotor nuclei > extraocular muscles
which oculomotor nuclei (the cranial nerves for the eyes) goes to which extraocular muscles in the visual stability pathway?
abducens > lateral rectus
trochlear > superior oblique
oculomotor > superior, medial, inferior rectus & inferior oblique
2 pathways for balance/postural stability of vestibular system
vestibular nerve > vestibular nuclei > cerebellum/spinal cord
list the 5 possible routes after vestibular nerve > vestibular nuclei for the functions of vestibular system
area postrema, thalamus>cortex, oculomotor nuclei>extraocular muscles, spinal cord, cerebellum
at lower frequencies (lower rotation frequency), eyes lag ___ (more or less)
more
gain (and what is it for VOR in the dark?)
ratio of eye velocity to head velocity, less than 1 for VOR in the dark (eyes move slower than head)
velocity storage
VOR is more accurate than the sensory signal from vestibular nerve fibres (afferent neurons) below 0.2Hz
constant-velocity rotation
initial accurate perception of angular velocity, then perception of motion slows down and finally stops after 20 seconds
