Vestibular B6 Flashcards
3 semicircular canals, what are they?
anterior, posterior, horizontal
3 semicircular canals connect to the _______
utricle
Sensory receptors of the semicircular canals reside in the ________ at the base of each ampulla.
cupula
The _______ organs are located in the utricle and saccule.
otolith
Each canal ends with a single prominent enlargement, the _________.
Ampulla
The semicircular canals transduce rotational head movements called _____________.
Angular acceleration
Sensory receptor cells in the vestibular system, like those in the auditory system, are called __________ because of the _________ that project from the apical surface of the cell
Hair cells
stereocilia
When fluid comes around canal what happens?
Cupula moves and is pushed to one side or another, this displaces the stereocilia
Rotational head movements produce ________________ that cause the endolymph in the membranous ducts to be displaced in opposite direction relative to head movement.
Angular accelerations
Stereocilia are arranged from shortest to tallest, tallest one is called the ____________.
kinocilium
Movement of stereocilia toward the kinocilium causes the hair cells to ________.
Depolarize which results in an increased rate of firing in vestibular afferent fibers. (how we sense movement of our head)
If stereocilia are deflected away from the kinocilium, it causes the hair cells to ___________
Hypepolarize, and afferent firing rate decreases. (how we sense movment of our head)
Head turn to left, what happens?
Left horizontal canal is activated
Head turn to right what happens?
Right horizontal canal is activated
If you turn your head to the left, which way does lymph flow and which sides are excited, and inhibited? know it for right head turn too. (just opposite)
(slide 17) Lymph flows to right, Excitation of left
Inhibition on right
Head turn to right, excites the ____________ and inhibits the ___________.
Right horizontal canal
Left horizontal canal
Receptor cells in each vestibular organ are innervated by ______________ that join with cochlea to comprise the Vestibulocochlear CN8)
primary afferent fibers
The cell bodies of these bipolar vestibular afferent neurons are in the _________ ganglion, which lies in the internal acoustic meatus.
vestibular
The central processes of these bipolar cells enter the brainstem and terminate in the ____________ .
IPSILATERAL vestibular nuclei
The vestibular system influences _______ and reflexive _________ adjustments of the head and body through 2 main descending tracts.
muscle tone
postural
Medial vestibulocochlear (Medial longitudinal Fasciculus, MLF), a long tract that runs through the entire brainstem. Descends in ___________ and __________.
Medial medulla
Medial spinal cord
(BILATERAL)
MLF ends in ____________ and does what?
Cervical cord.
Head and neck movment
Medial vetstibulospinal tract (MVST)
The Lateral vestibulospinal tract courses ___________ through the lateral medulla in a deep position. Synapses where? Function?
IPSILATERAL
Synapses LMN in ventral horn
Stabilize the center of gravity and preserve upright posture.
Non-specific term that generally means a spatial disorientation that may or may not involve feelings of movement.
Dizziness and Vertigo
Patient experiences sensation of spinning while things in environment are not moving.
Subjective vertigo
Sensation is one of the environment is spinning and the patient is not moving.
Objective vertigo
Disease involved with an increase of endolymph volume. Severe vertigo, positional nystagmus, nausea
Meniere’s disease
One of the most common vestibular disorders observed clinically is what? Brief episodes of vertigo, that coincide with particular changes in body position.
Benign Paroxysmal Positional Vertigo
With a tumor on the vestibulocochlear nerve on the right side, the patient will sense their head turning to which side when stationary?
Left
Patients often present with severe vertigo, nausea, and vomiting yet have no accompanying hearing loss or CNS abnormalities.
Vestibular Neuritis
Can impair or abolish firing rates. Normal function on contralateral side will lead to sensation of head/ body movement toward the intact side.
Unilateral CNS damage in vestibular nuclei
