Procedures 3

  1. Semicircular Canals
    • 3 each and oriented at 90degrees to each other, pair of canals for each plane
    • provide info about rotational movement of the head; roatation, side to side, up and down
  2. Canal's fluid
    filled with endolymph
  3. Cupula
    • hair cells which bend in response to endolymph movement
    • when bent, hair cells lead to action potentials which are carried over vestibular divisions of cranial nerve VIII into the brain stem
  4. Otolith Organs: Saccule and Utricle
    • each have specialized receptor area called macule
    • weight of otoconia bends the hair cells to signal linear motion and info regarding head position to nucleus
  5. Macule
    has specialized hair cells upon which is a gelatinous matrix with otoconia (ear rocks) embedded in it
  6. 3 Main Functions of the Central Vestibular System
    • Gaze Stabilization
    • postural stability
    • spacial orentations
  7. Gaze Stablilization
    as we move our heads, reflexes occur automatically which keep visual images in the fovea. Called VOR
  8. Postural Stability
  9. Medial Vestibularspinal tract
    influences head control
  10. Lateral Vestibularospinal Tract
    goes to proxminal extensor muscles
  11. Spatial Orientation
    info goes to cortex for conscious awareness of orientation of body and head in space
  12. Other outputs from the vestibular system to infulence level of arousal
    • info from vestibular nucleus also goes to the reticular activating system
    • ex. rocking chair relaxing
    • shaking head to wake up
  13. info from the vestibular nucleus also influences ANS and can lead to
    • nausea and vomiting
    • these symptoms often are present in a vestibular pathology
  14. Dizziness
    • not exact term
    • means feeling a tendency to fall
  15. Vertigo
    • illusion of movement, usually of spinning
    • occurs most often with Acute Unliateral Peripheral Vestibular pathology
    • results bc brain cant make snese of the disrupted input
  16. Lightheadedness
    feeling about ready to faint
  17. Dysequilibrium
    feeling unsteady or off balance
  18. Benign Paroxysmal Positional Vertigo BPPV
    caused by the otoconia being displaced into the SSC
  19. Unilateral Vestibular Hypofunction UVH
    caused by pathology in peripheral vestibular system on one side
  20. Bilateral Vestibular Hypofunction BVH
    caused by pathology in peripheral vestibular system on both sides
  21. Bening Paroxysmal Positional Vertigo
    • most common peripheral vestibular pathology
    • hallmark is vertigo onset with certain positions
    • sudden vertigo occurs because the otoconia dislogde from the utricle and saccule, migrate into the SCC and in certain postions cause bending of the hair cells
    • short lasting
    • tx is manuvers to reposition the otoconia back into the otoliths
  22. UVH causes
    viral infections, vascular events, trauma
  23. UVH Presentation
    there is usually rapid onset of vertigo, spontaneous nystagmus, postural instability, dysequilibrium
Card Set
Procedures 3