The Vestibular System Flashcards
What are otoconia?
calcium carbonate crystals in the saccule and utricle
Each vestibular hair cell has a bundle of _____-filled stereocilia projecting from its apical surface in a staircase-like pattern.
actin
This is a specialized patch of epi in the ampulla of the semicircular canals that contains the sensory hair cells.
crista
Each hair cell has a single _____, which is the tallest cilium located at one side of the hair bundle.
kinocilium
In the saccule, the hair bundles are oriented facing ____ the striola.
away from
Within each crista, all of the hair cells have their stereocilia _____.
oriented the same way
Adjacent cilia are connected by ____ which are attached at their lower end to ion channels.
tip links
The base of the hair cells is bathed in _____.
perilymph
From where does the inferior (descending) vestibular nucleus receive input?
the utricles, saccule, and semicircular canals, with spinal and cerebellar input, too
What is the function of the semicircular canals?
they detect angular acceleration
From where does the lateral (Deiter’s) vestibular nucleus receive input?
the utricles, with spinal and cerebellar input, too
The medial and superior vestibular nuclei give rise to the _____.
medial longitudinal fasciculus
Where is the saccule?
it hangs vertically on the lateral wall of the vestibule
What is the otolithic membrane? What is its purpose?
a gelatinous mass that holds the otoconia in place
Vestibular afferent nerves project to the _____.
ipsilateral vestibular nuclei at the border of the caudal pons and rostral medulla
From where does the superior vestibular nucleus receive input?
the semicircular canals
In the utricle, the axes of polarity of the hair cells is towards the _____.
striola
What tract does the medial vestibular nucleus comprise?
medial longitudinal fasciculus
lateral (Deiter’s) vestibular nucleus –> lateral vestibulospinal tract –> _________ (outcome)
excitation of extensor muscles of the limbs
What are the vestibular sensory organs?
- the utricle
- the saccule
- the 3 ampullae of the semicircular canal organs
What are the 4 major vestibular nuclei?
superior lateral (Deiter’s) medial inferior (descending)
Where is the utricle?
at the floor of the vestibule
What detects linear acceleration of the head and position w/ respect to gravity?
the otolith organs
What do the otolith organs do?
detect linear acceleration of the head and position w/ respect to gravity
What is the striola?
a central region of the epithelium in the utricle and saccule
The semicircular canals project mainly to the _____.
medial and superior vestibular nuclei
In the anterior and posterior canals, the hair cells are oriented with their kinocilia facing _____.
away from the utricle
What is the swelling at the end of each semicircular canal?
the ampulla
What hair bundles would inform the brain if you were riding in an elevator?
the saccular hair bundles
Vestibular afferent nerves have cell bodies in _____.
Scarpa’s ganglion
These are calcium carbonate crystals in the saccule and utricle.
otoconia
Since the saccular hair bundles project horizontally, they are sensitive to ____ displacement of the head.
vertical
The hair bundles are bathed in _____.
endolymph
In the _____ canals, the hair cells are oriented with their kinocilia facing towards the utricle.
horizontal semicircular
The utricles send afferents to the _____ and also to the _____.
lateral vestibular nucleus; medial and inferior nucleus
What is found within each ampulla? What does it contain?
the crista containing the sensory hair cells
In the ______ canals, the hair cells are oriented with their kinocilia facing away from the utricle.
anterior and posterior
What happens when the tip links pull the bundle towards the kinocilium?
the mechano-transduction channels open –> cations from endolymph enter hair cells –> depolarizes –> NT released
inferior (descending) vestibular nucleus –> vermal cerebellum –> ______ (location)
reticular formation and brainstem
What detects angular acceleration?
the semicircular canals
The saccule, utricle, and semicircular canals all project to the ____.
inferior vestibular nucleus
What tract does the lateral (Deiter’s) vestibular nucleus comprise?
the lateral vestibulospinal tract
In the horizontal semicircular canals, the hair cells are oriented with their kinocilia facing ______.
towards the utricle
When do mechano-tranduction channels open?
when the tip links pull the bundle towards the kinocilium
What is the crista?
a specialized patch of epi in the ampulla of the semicircular canals that contains the sensory hair cells
From where does the medial vestibular nucleus receive input?
the utricles and semicircular canals
medial vestibular nucleus –> medial longitudinal fasciculus –> _____ (outcome)
coordination of eye and head movements
In the ____, the axes of polarity of the hair cells is towards the striola.
utricle
Hair cells convert _____ stimuli to _____.
mechanical –> receptor potentials
In the ____, the hair bundles are oriented facing away from the striola.
saccule
What do the semicircular canals do?
detect angular acceleration
