Your SlideShare is downloading. ×
~BN18 vestibular system.ppt
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

~BN18 vestibular system.ppt

1,239

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,239
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
38
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. The Vestibular System Lecture 18
  • 2. Orientation: The Vestibular System
    • Position & motion of body in space
      • critical for adaptive interaction
      • largely unnoticed
      • except unusual conditions
        • motion sickness: nausea, dizziness
    • Maintenance of balance & posture
      • coordinating body position with other sensory information ~
  • 3. Receptors for Orientation
    • Inner ear
    • Gravity detectors
      • plane of reference
    • Mechanoreceptors
    • Vestibular Organs
      • otocysts
        • saccule
        • utricle
      • semicircular canals ~
  • 4. Otocysts
    • Liquid-filled “ear sacs”
      • lined with hair cells
      • contain otoliths
        • “ ear stones : direction of acceleration
    • saccule: vertical movement
    • utricle: horizontal movement ~
  • 5. At rest Direction of gravity tilted Acceleration to right
  • 6. Semicircular Canals
    • Rotary acceleration
      • direction & extent of circular movement
        • any direction
    • 3 fluid-filled canals
      • right angles to each other
      • 1 for each major plane
    • Movement causes fluid to circulate
      • displaces cupula ~
  • 7. Semicircular canals Utricle Ampulla Crista hair cells Cupula
  • 8. Vestibular Pathway
    • Vestibulocochlear nerve (VIII)
      • Some axons directly to cerebellum
    • Most axons to medulla
        • vestibular nuclei
      • cerebellum, spinal cord, medulla & pons
      • motor nuclei for eyes (III, IV, & VI)
        • compensates for movement of head
      • temporal cortex (dizziness) ~
  • 9. Vestibular Stimulation
    • Perceive movement in an airplane?
      • No, persisting passive movement
      • Otoliths, fluid move at same speed
    • Vestibular system detects active movements
      • changes in rate of motion
        • acceleration
    • heating/cooling fluid  perception of body motion ~
  • 10. Visual Illusions of Movement
    • Self vection
      • perceive you are moving, but not
      • 2 adjacent trains, cars
      • restricted visual field
        • no background information ~
  • 11. Visual Illusions of Movement
    • Postural sway
      • visual cues help maintain posture
      • illuminated booth, that can sway
      • individual sways with surroundings
      • no vestibular stimulation ~
  • 12. Motion Sickness
    • During passive transportation
        • e.g. riding in car, but not when driving
      • unusual circumstances
        • e.g amusement park rides
      • usually not steady motion
    • Symptoms: nausea, dizziness, vertigo, cold sweats, hyperventilation ~
  • 13. Cause of Motion Sickness
    • Sensory conflict theory
      • Mismatch b/n visual & vestibular info
    • Treisman (1977): cause of vomiting
      • ingestion of natural toxins disrupt visual input & motor coordination
      • vomiting adaptive response to inappropriate stimulus: toxins/motion
    • Dogs: remove vestibular system
      • toxins  no vomiting ~

×