Vestibular Flashcards
Role of the Vestibular System
- Estimate body position and movement
- postural control
- control of eye movements
Peripheral Vestibular System Functions
- Stabilize visual images on the fovea of the retina during head movement allow for clear vision
- maintain postural stability, especially during movement of head
- provide information for spatial orientation
What is in the Bony Labyrinth
Perilymphatic fluid + supportive connective tissue
What is in the Membranous Labyrinth
Vestibule, 3 semicircular canals & Cochlea
What are the otoliths organs
Utricle and Saccule
What are the 3 semicircular Canals
Anterior, Posterior & Horizontal
What plane does the Utricle and Saccule detect movement in?
Utricle: Horizontal
Saccule: Vertical
What are the stereocilia in the otoliths and what do they do?
Motion receptors - gravity dependent
Move towards kinocilium = excitatory
Move away from Kinocilium = inhibitory
What are otoconia
On top of macula
Control directions of macula
What position is the Anterior Canal most sensitive in?
Forward Rotation
What motion is the Posterior Canal Sensitive to?
Backward rotation
What direction is the horizontal canal most sensitive?
“No” motion
What is the Ampulla and what does it contain?
Bulbous formation at the start or finish of each canal
-contains cupola, which houses stereocilia
What type of movement goes with the semicircular canals?
Angular velocity/Rotation
Describe relationship between anterior and posterior canal
When one is excited, the other is inhibited
What is the relationship with the horizontal canals?
They work together
When one is excited, the other is inhibitory
What plane and degrees correlate with the Anterior, Posterior and Horizontal Plane?
Anterior: 45 degrees off sagittal
Posterior: 45 degrees off sagittal
Horizontal” 30 degrees above horizontal plane
What is VOR
Vestibule-Ocular Reflex
- Stable vision during head motion
- Gaze stabilization
- results in eye movements that equally counter head movements
In regards to VOR
Explain what is excited and inhibited when you rotate your head to the Left
Excitatory:
L semicircular canal, R Abducens, L Oculomotor
Inhibitory: R semicircular canal, L Abducens, R Oculomotor
What is the function of the Vestibular Nu
- Eye movement control for gaze stability during movement (Oculomotor)
- Postural Control and movement (BS)
- Spatial Orientation (Cortex)
- Autonomic Nervous system control
What are the 4 sets of subnuclei
Lateral (Dieter’s)
Medial
Superior
Inferior
What does the Lateral Nu do
Outputs to the cerebellum (feedback) and to lateral vestibulospinal tract to facilitate extensors
-posture; muscles of trunk and legs
What does the Medial Nu do
Provides descending output to muscles of head and neck Mia MLF
-head position
What does the Superior Nu do
Provides ascending output via MLF to Oculomotor Nu
