Vestibular system Flashcards
What is the vestibular system responsible for?
helping monitor the orientation of the head in 3 dimensional space. the data collected by the receptor apparatus is integrated in the CNS with visual and proprioceptive data
What does the integration of vestibular data and visual and proprioceptive data do?
1) Maintains general body equilibrium such as posture and balance
2) coordinates movements with the movements of the head (allows the maintenance of visual fixation on an object when the head moves through space
what are the parts that make up the vestibular system?
Parts of the the inner ear
vestibular division of the VIII nerve and CNS pathways
what makes up the vestibular portion of the inner ear?
osseous labyrinth
Membrancous labyrinth
saccule and utricle
What makes up the osseous labyrinth of the vestibular portion of the inner ear?
vestibule
semicircular canal
what makes up the membranous labyrinth of the vestibular portion of the inner ear?
Utricle and saccule (within the vestibule)
semicircular ducts
What are the saccule and utricle?
dilation of the membranous labyrinth and filled with endolymph
what is found in the wall of each saccule and utricle?
a patch of sensory epithelium which are the receptors of the saccule and utricle known as the macula (utricle and sacule)
what are the maculae?
The maculae are specialized mechanoreceptors that monitor the position of the head (static and kinetic)
what is found in the macula?
hair cells
otolithic membrane
dendrites of primary vestibular neurons
What are the hair cells of the macula?
sensory cells made of sterocilia that project from the apical edge
what is the single longer stereocilia projection of the macula known as ?
kinocilium
Where are the hair cells of the macula found?
embedded into the otolithic membrane
What is the otolithic membrane?
gelatinous membrane containing otoliths (crystals of protein of calcium carbonate
what do the dendrites of the primary vestibular neurons found in the macula and do and where are the neuron cell bodies found?
the dendrites engage the base of each hair cell and the neuron cell bodies are in Scarpa’s ganglion
What happens to the maculae receptors as one moves their head from a static position (linear or tilting movements)?
the maculae receptors change their excitability (from static discharge)which results in an increase or decrease of discharge in the macula
What is the effect of head movement on the otolithic membrane and the hairs on the macula?
The otolithic membrane shifts its position relative to the hair cells and the hairs are bent. this causes the hair cells to excite and the vestibular data generated is relayed to the CNS via primary vestibular neurons
What best monitors tilting movements of the head and linear acceleration and deceleration?
The macula utricle and macula saccule
what happens to the maculae during constant velocity?
Maculae reach a static discharge