Unit 2: Vestibular System Flashcards
The vestibular system is responsible for helping to monitor the
Orientation of the head in 3-dimensional space
Vestibular data is collected and integrated into the CNS with visual and proprioceptive data used to:
- Maintain general body equilibrium
2. Coordinate eye movements with movements of the head
Structures within the vestibular system include
- Apparatus within the inner ear
- Vestibular division of CNVIII
- CNS pathways
The saccule and utricle are dilations of the membranous labyrinth and filled with
Endolymph
The vestibule and semicircular canals are within the
Osseous labyrinth
The utricle, saccule and semicircular ducts are within the
Membranous labyrinth
Along the wall of each saccule and utricle there is a “patch” of sensory epithelium (the vestibular receptors) called:
Maculae
Specialized mechanoreceptors that monitor the position of the head (static and kinetic)
Maculae
The stereocilia (hair cells, aka sensory cells) project from the apical edge with one long single “hair” called
Kinocilium
If hair cells/stereocilia bend toward the kinocilia, what happens to firing rate?
Increases firing rate
If hair cells/stereocilia bend away from the kinocilia, what happens to firing rate?
Decrease firing rate
The gelatinous membrane that contains otoliths is called
Otolithic membrane
Crystals comprised of protein and calcium carbonate:
Otoliths
What innervates the base of each hair cell?
Dentrites of 1˚ vestibular neurons
Maculae best monitor:
Tilting head movements and acceleration and deceleration phases of linear movement
How many semicircular ducts per inner ear?
3
The posterior semicircular duct is in the ____ plane and monitors information in the _____ plane
Vertical; vertical
The anterior (superior) semicircular duct is in the ____ plane and monitors motion in the ___ plane
Vertical; vertical
The lateral (horizontal) semicircular duct slopes posteriorly and inferiority 30˚ to the ______ plane and monitors motion in the _______ plane
Horizontal; horizontal
Semicircular ducts filled with:
Endolymph
Semicircular ducts surrounded by
Perilymph
Each of the 3 semicircular ducts has a dilation/bulbous end called
Ampulla
Along the wall of each ampulla in the semicircular ducts, there is a patch of specialized sensory epithelium called
Crista ampullaris (plural =cristae)
Cristae ampullaris are what kind of receptors?
Mechanoreceptors
Cristae ampullaris monitor what kind of movement?
Rotational/angular head movement
The gelatinous membrane in which hairs of the crista ampullaris are called embedded in
Cupula
1˚ vestibular neuron cell bodies are located in
Vestibular/Scarpa’s ganglion
Cristae ampullaris change their excitability (static discharge) when head undergoes what kind of motion?
Angular/rotational
Head rotates/moves to the RIGHT, the RIGHT duct rotates to the ____, and the endolymph moves to the ____.
Right; left
Endolymph lags
Ampullopetal
Movements facilitates cristae ampullaris (aka endolymph moves toward cristae)
Ampullofugal
Movement inhibits cristae ampullaris (aka endolymph moves away from cristae)
Decreases discharge movement of cristae / inhibition of the crista ampullaris
Ampullofugal
Increase discharge movement of cristae / facilitation of crista ampullaris
Ampullopetal
Rotation of head to the right (acceleration phase). What is the endolymph doing in the right vs left lateral ducts?
Right lateral duct endolymph is moving through ampulla and into utricle = ampullopetal flow
Endolymph in left lateral duct flows through ampulla into duct = ampullofugal flow
Peripheral processes of the primary vestibular neurons innervate hair cells of the:
Cristae ampullaris and maculae
Central processes of vestibular neurons enter the brainstem as part of the CN
VIII
Some central axons of vestibular pathway enter the ______ through ICP
Cerebellum
Most central axons of the vestibular pathway will synapse in the
Vestibular nuclear complex