Vestibular System S2M1

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Vestibular System S2M1
2011-08-12 08:52:29
Ross S2M1

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  1. What are the functions of the Vestibular System
    • 1. Provides information about the position and movement of the head
    • 2. Stabilizes head movements
    • 3. Coordination of head and eye movements, and body posture
  2. What are the three main inputs for spatial orientaion
    • Visual
    • Proprioceptive
    • Vestibular
  3. What is car sickness a result of physiologically
    This happens when there is sensory conflict such as the eyes are saying that there is no movement, but the vestibular system is sensing movement
  4. What are the receptor organs in the vestibular system
    • Cristae Ampullares
    • Maculae (Utricle and Saccule)
  5. What do the Utricle and Saccule sense
    Linear acceleration
  6. What do the Cristae Ampullae sense
    Angular acceleration
  7. In the vestibular system when are action potentials being sent at a higher rate
    When the hair cells are becoming depolarized by the movement of the stereocilia towards the Kinocilium
  8. What causes the hair cells in the Vestibular system to hyperpolarize
    When the stereocilia are leaning away from the Kinocilium
  9. The movement of what moves the cilia in the cupula
  10. When the head moves, what way does the endolymph move
    The Endoloymph moves in the opposite direction as the head rotation
  11. What is the most important force working on the Macula
  12. Why doesn't the otolith membrane move by the movement of the endolymph
    • Its higher density prevents the movement by the endolymph
    • Gravity will move the otolith as a result of a head tilt
  13. Displaced otoconia
    • a.k.a. Vertigo
    • Can follow head trauma
    • In some it is benign
  14. Benign paroxysmal positional vertigo
    • Brief episodes of vertigo typically related to changes in position
    • Results from the displacement of the otoconia in the semicircular canals that push the cupula
  15. What are the branches of the Vestibular nerve
    • Post. Ampullary
    • Saccular
    • Utriculoampullary (utricle, anterior, and lateral ampullary)
  16. Acoustic neuroma
    Damage to the Vestibular portion of the vestibularcochlear (XIII) nerve causing vertigo, loss of balance, and an unsteady gait
  17. What is the most common place of damage that results in Acoustic Neuroma
    Pontocerebellar angle
  18. What happens when the cochlear nerve is damage
    Loss of hearing and Tinnitis
  19. What can be potentially damaged in a large acoustic neuronima (Neuroma)
    • CN; V, VI, VII, VIII, IX, X, XII
    • Cerebellum
    • Pyramidal tract
  20. Wallenburgs syndrome will display what symptoms (PICA syndrome)
    • Hoarseness of voice & Difficulty swallowing (Nucleus Ambiguus)
    • Miosis & Ptosis (Sympathetic)
    • Reduced feeling in face (Descending tract of V)
    • Vertigo & Nystagmus (Vestibular nucleus)
    • Unsteady gait (Inferior cerebellar peduncle)
    • "The symptons I have when I go to Wally world!"
  21. What are the afferent vestibular connections
    • Vestibular nerve
    • Cerebellum (Flocculonodular lobe)
    • Spinovestibular (proprioception)
    • Visual info
    • Reticular formation
    • Commissural fibers
  22. What are the efferent vestibular connections
    • Occulomotor, Abducens, Trochelar nuclei
    • Cerebellum
    • Spinal cord
    • Reticular formation
    • Thalamus
    • Hair cells (Efferent)
  23. What causes the stabilty of the information taken in from head movements and eye movement from activities like walking or driving on a bumpy road
    Vestibulo-ocular reflex (VOR)
  24. How does the vestibulo-ocular reflex (VOR) react to a turn of the head to the left
    • Left semicircular canal excitation
    • Rt Abducens nuclei (VI) flexes lat. rectus muscle of rt eye
    • Left Occulomotor nucleus (III) flexes the medial rectus of the left eye
    • Other side inhibits
    • Eyes turn to the right for a forward gaze
  25. What fascicle connects the vestibular and eye muscle nuclei in a vestibulo-ocular reflex (VOR)
    Medial longitudinal fascicle
  26. Nystagmus
    Involuntary alternating eye movements
  27. How can one induce nystagmus without sophisticated equipment
    By irrigating the ear with cold or warm water
  28. What effects does warm or cold water injected into the ear do
    • Cold - induces nystagmus away (Opposite) form the irrigated ear
    • Warm - induces nystagmus to the Same side
    • "COWS"
  29. Lateral vestibular tract is important for
    Antigravity muscles mainly ipsilateral extensors
  30. Medial vestibular tract is important for
    Mainly head and neck coordination
  31. Over stimulation of the vestibular nerve can cause what symptoms
    • Nausea
    • Vomiting
    • Sweating
    • Changes in cardiovascular and respiratory functions
  32. A lesion to the left vestibular nerve would cause what
    Stumbling to the left
  33. Menieres disease
    • High endolymphatic pressure effecting both cochlear and vestibular functions
    • Recurring episodes of vertigo accompanied by progressive hearing loss
    • "What Jane Eyre causes in Men"
  34. True Vertigo
    Spinning sensation
  35. Vestibular neuritis
    • Infection/inflammation of Scarpa's ganglion or the nerve
    • Intense vertigo for several days
    • Unsteadiness lasting weeks/months
  36. The sacculus has what feature that makes it effective for testing
    It is sensitive to sound waves as well making the pathway visibly in tact by innitiating movement in the sternocleidomastoid muscle by stimulating it with sound
  37. Scarpas ganglia is used for what nerve
    Vestibular nerve only