02. Vestibular System (Dennis) Flashcards
What are the two types of hair cells?
Type 1 are chalice shaped and are surrounded by an afferent terminal called a nerve calyx. These are located more centrally on the crista ampullaris.
Type 2 are cylindrical and are innervated by synaptic boutons. These are located more laterally on the crista ampullaris.
What is the origin of the afferent fibers to the vestibular apparatus?
The vestibular ganglion.
Which way would you expect a patient to have nystagmus if you placed cold water in their left ear?
What about warm water in their right ear?
Cold water in the left ear shows right-beat nystagmus.
So does warm water in the right ear.
COWS: Cold water causes nystagmus that beats towards the Opposite side, Warm water beats towards the Same side.
What laminae of the spinal cord recieve vestibular input from the medial and lateral vestibulospinal tracts?
Laminae VII, VIII, and IX
(7 , 8, 9)
Which vestibular nuclei are associated with the lateral vestibulospinal tract?
What about the medial vestibulospinal tract?
Lateral vestibulospinal tract: lateral and inferior vestibular nuclei
Medial vestibulospinal tract: medial, as well as the lateral and inferior vestibular nuclei.
What are the functions of Brodman area 2v and 3a?
They are in the primary somatosensory cortex.
2v: sensation of whole body motion
3a: integration of the motor control of the head and body
Which portion of the vestibular apparatus detects torsional movements for the vestibuloocular reflex?
Vertical canal and utricle.
What is the function of the insular areas of the lateral sulcus and parietoinsular vestibular cortex (PIVC)?
Responds to body motion, somatosensory, proprioceptive, and visual motion stimuli
Lesions cause vertigo and loss of perception
What are the functions of Brodman area 7?
Involved in spatial coding, visual and vestibular motion signals
Integrates cues of body motion in space
Lesions result in confusion in spatial awareness
What is the name of the disease associated with excessive pressure in the membranous labyrinth?
What are the symptoms?
Meniere’s Disease
This causes several symptoms:
Fluctuating hearing loss
Tinnitus
Vomiting
Nystagmus
Other vestibular sx.
Which portion of the vestibular apparatus accounts for horizontal movements for the vestibulocular reflex?
The horizontal semicircular canals and utricle.
What is the function of the medial vestibulospinal tract?
Vestibular stimulation of the neck muscles.
Which portion of the vestibular apparatus detects vertical movements for the vestibulocular reflex?
Vertical semicircular canal and saccule
How do hair cells detect motion?
The vestibular sensory receptors are hair cells with stereocilia that project from the apical surface. They all contain stereocilia and one long kinocilium. That kinocilium causes an activating signal when the stereocilia bend towards it, and an inhibitory signal when they bend away.
Which portions of the vestibular apparatus is involved in the detection of translational movement?
The utricle and saccule.
What two arteries supply the blood supply to the vestibular system?
The labyrinthine artery and the stylomastoid artery.
How does the vestibular system coordinate movements between the right and left?
Vestibulovestibular fibers, which are collateral fibers between the right and left vestibular nuclei (left superior vestibular nucleus to right, and so on).
What are the two different parts of the lateral vestibulospinal tract?
What are their functions?
Anterorostral areas: vestibular stimulation of the cervical spinal cord fibers.
Posterocaudal regions: vestibular stimulation of the lumbosacral cord.
What are the vestibular functions of the prefrontal cortex and superior frontal gyrus?
Receive vestibular signals and are related to the frontal eye field.
Controls “saccades” and smoothes out eye movements.
If the medial longitudinal fasciculus was cut, what muscle would not turn during the vestibulocular reflex?
The ipsilateral (to the turn) medial rectus.
If your head was turning left, your medial rectus would not pull your left eye to the right, because the fibers from the contralateral abducens to the ipsilateral oculomotor nucleus would be severed.
What path do the primary vestibulocerebellar fibers take to reach the cerebellum?
The juxtarestiform body.
What are the two types of vertigo?
Subjective vertigo: patient experiences the sensation of spinning while things
in the environment are not moving.
Objective vertigo: sensation is one of objects spinning while the patient is not
moving.
