Vestibular system Flashcards
What makes up the vestibular system
- Peripheral receptor apparatus
- Vestibular thalamocortical
- Central vestibular nuclei
- Vestibular occular reflex
- Vestibular collic reflex
5 Makes up the 5 peripheral vestibular receptors
3 Semicircular canals
2 Otolith receptor
What are the 3 semicircular canals made up of and what is their function.
Transduce rotation head movements and angular acceleration
1. Anterior/superior
- filled with endolymph
- AA = pitch/yes movement
2. Posterior
- AA = roll/ ear to shoulder
3. Lateral/horizontal
- why we do VR at 30 degree angle
- AA= no
What does each semicircular canal contribute to
Each canal connects to utricle and ends in a ampullae enlargement. Sensory receptors are based at the end of the ampullae. The hair cells are in the sensory cells and the cupula surrounds it.
Wat are the 2 otolith organs called and what is their function
Translational head movements
Linear acceleration in relation to gravity
1. Utricle
LA = horizontal
2. Saccule
LA= vertical
What does the otolith organs contribute to
Hair cells extend into the cupula and crystals move across the otolith organs
They respond to tilting of head - pitch & roll
What is pitch & roll
Pitch = head moving forward and backward
Roll = head moving side to side
What happens when your head moves linearly/rotates in relation to gravity?
- Crystal rocks on otolithic membrane move with gravity.
- Otoliths stereocilia picks up movement
- transfers movement to nerve cells
- the 8th cranial nerve sends info to brain & cerebellum; and vestibular nuclei & cerebellum
- the central vestibular nuclei takes input from vestibular, SS, visual and combines it with motor information from cerebellum & cerebral cortex through central processing & rapit output
- The CNS coordinates relevant movement reflexes, inputs and outcomes
Explain the push and pull system
- head and body movement is coded by opposite receptor signals
- the systems work together to coordinate which way our head moves
- the anterior canal and posterior canal of contralateral side form a pair
What happens when your head moves to the left
Your left side depolarizes and right side hyperpolarizes.
This causes angular acceleration to displace the endolymph within the vestibular system.
On the left: The cupula moves & displaces the stereocilia of the hair cells in the same direction
On the right: The otoconia/crystals become displaced due to gravity pulling (not a movement) the stereocilia and bending it, which causes depolarization
What are your 3 vestibular reflexes called
- Vestibular occular reflex
- Vestibulospinal reflex
- Vestibulocollic reflex
What is the role of the vestibulooccular reflex
Stabilizes gaze during movement
Eye counter rotates with eye movements due to the activation of the vestibular system
It stabilizes the image on retina’s during head movements
What is nystagmus
Alternating (slow - compensatory) (fast - saccadic) phases of movement
The direction is specified in the last fast phase
Can be horizontal or vertical
What is the vestibulospinal reflex
Stabilizes the body consisting of several reflexes named according to their timing (dynamic/static) or sensory input (canal/otolith)
Changes in activity of body muscles = induce movements of head that stimulate labyrinthine receptors to stabilize posture
What is the vestibulocollic reflex
Acts on neck musculature to stabilze the head
When there is a reflex head movement it counters the movement sensed by the otolithic semicircular canal organs
