Lecture 13 & 16- Vestibular and Visual Flashcards
what do projections from the vestibular nuclei contribute to
-sensory info about head movement and position
-gaze stabilization
-postural adjustments
-autonomic function and consciousness
semicircular canals contain what receptors and what do they do
cristae- play a role in detecting rotational movements and maintaining balance
utricle and saccule contain what receptors and what do they do
maculae- crucial role in balance and spatial orientation
macula
hair cells enclosed by gelatinous mass topped by calcium carbonate crystals located within the utricle and saccule
otoconia
calcium carbonite crystals that are denser than the surrounding fluid and gelatinous support
vestibular branch of CN 8
transmits info related to head position and head movement
cochlear branch of CN 8
transmits info related to hearing
medial longitudinal fasciculus
Bilateral connections with the extraocular nuclei (CN 3,4,6) and superior colliculus, influencing eye and head movements
vestibulospinal tracts
Both medial and lateral, to lower motor neurons that influence posture
Vestibulocolic pathways
to nucleus of the spinal accessory n, influencing head position
vestibulothalamocortical pathways
providing conscious awareness of head position and movement and input to the corticospinal tracts
vestibulocerebellar pathways
to the vestibulocerebellum, which controls the magnitude of muscle responses to vestibular info
vestibuloreticular pathways
to reticular formation influencing the reticulospinal tracts and autonomic centers for nausea and vomiting
Oscillopsia
subjective sensation of visual objects bouncing when head is moving
abnormalities with eye movement occur with lesions involving
-cranial nerves that control extraocular ms
-strength of extraocular ms
-medial longitudinal fasciculus
-vestibular system
-cerebellum
-eye fields in the cerebral cortex
tropia
deviation of one eye from a forward gaze when both eyes are open
phoria
deviation from a forward gaze, apparent only when the person is looking forward with one eye (the other eye is covered)
motion sickness
may be caused by a conflict between different types of sensory info of by postural instability
seasickness
may be caused by conflict between visual and vestibular info
disorders of the vestibular and visual systems may affect…
receptors, cranial nerves, brainstem nuclei, tracts within the central nervous system, or associated cortical areas
vertigo
illusion of motion
