FSG 5 Flashcards
Vestibular: where are receptors located?
hair cells in inner ear
- SCC
- otolithic organs (utricles, saccules)
- ampulla
Why is vestibular info so important?
- postural control
- control of eye movements
Info gets to the central vestibular system via
hair cells innervated by CN 8 » vestibular apparatus » vestibular nuclei
SCC signaling to flocculonodular lobe: result
coordination
SCC signaling to superior and medial vestibular nuclei
eye movements
VOR = gaze stabilization
function of the lateral vestibulospinal tract
postural adjustments in limbs and trunk
lateral VST origin
macula
lateral VST end
postural muscles in limbs and trunk
medial VST origin
macula
medial VST end
cervical SC
medial VST function
postural adjustments in cervical SC
SCC talks mostly to this nucleus
medial vestibular nucleus
SCC respond to
rotational acceleration/deceleration
posterior SCC detects
lateral flexion
lateral (horizontal) canal detects
“no” motion
anterior (superior) canal detects
“yes” motion
How are postural adjustments achieved?
reciprocal connections between vestibular nuclei and
- SC
- RF
- superior colliculus
- CN 11 nucleus
- vestibular CC
- cerebellum
Where are the vestibular nuclei located?
in the pontomedullary junction
axons from the (nasal/temporal) retina project ipsilaterally to lateral geniculate body
temporal
axons from the (nasal/temporal) retina cross the chiasm to the contralateral lateral geniculate body
nasal
retina » pretectal area =
pupillary reflexes
retina » tectum =
- orientation
- visually guided eye movements
retina » LG » VC =
visual guidance and object identification
two major types of eye movements
- conjugate
- vergence
conjugate eye movements
both moving in the same direction
vergent eye movements
eyes toward midline or away from midline
VOR: which canal pairs does it use?
can occur in canal pairs of any plane
