Ch. 16: Vestibular and Visual System Flashcards
How many semicircular canals are there in the inner ear? What angles do they face?
- 3 per side of the body
- Anterior: 45º forward
- Posterior: 45º deg backward
- Horizontal: tilted 30º off horizontal
What is the function of the semicircular canals?
Keeps eyes focused on the world around you
(All 3 together can detect any direction your head moves)
What is the purpose of the hair cells in the inner ear and where are they located?
- Provide Baseline activity and when moving
- Located at one end of each semi circle in fluid
- bend of hair cells → creates AP’s
What is “paired activity” of the semicirular canals?
AP’s inc on side toward rotation and dec proportionally on side away from rotation.
(Anterior semicircle or right is in line with posterior semicircle on left)
Why are the semicircular canals important?
stabilize VISION when HEAD is moving
What is inside the Otolithic Organs?
Have hair cells that are anchored in jelly with rocks on top.
How do the Otolithic Organs generate AP’s?
- Respond to pull of gravity (helps w/postural stabilty - connected to vestibulospinal tract (keep you upright).
- Gravity pulls hair cells → they bend → generate AP’s
How many Otolithic Organs do you have?
2 per side
Otolithic Organs respond to what type of movement?
- Linear acceleration/deceleration
- Chang in pull of gravity
What are the inputs to the vestibular nuclei (CN VIII)?
- Vestibular Information - head movement & pull of gravity
- Visual Information - light information - can see relative position
- Unconscious proprioceptive info - position of body and joints in space
- Tactile Info - pressure sensors in skin
- Auditory info - change of sound detects movement
What are the outputs from the vestibular nuclei (CN VIII)?
- Cerebral Cortex - “I’m dizzy”
- Med Longitudinal Fasciculus/Extraocular (CN II, IV, VI) nuclei - eyes controlled relative to head movement
- Superior Colliculus/Accessory N - contract muscles to keep you up right
- Med vestibulospinal tract - posture of head & upper body - maintain equillibrium
- Lat vestibulospinal tract - posture of trunk & lower body - maintain equillibrium
- Reticular Formation - affect consciousness = nausea & vomitting
- Cerebellum - Can influence posture & eye movements
What are the Nasal Retina?
- Half of retina closest to nose
- “temporal” visual field
What are the Temporal Retina?
- Closest to temple
- “Nasal” visual field
What light info does the Optic Nerve Receive?
info from ALL visual space
What light info does the Optic Tract Receive?
Only one field of vision
(ex: pulls right visual field from both eyes to left side of brain through chiasm)