Vestibular System Flashcards
What are the parts to the peripheral vestibular system?
- Superior/anterior canals
- Middle/horizontal canals
- Posterior Canals
- Utricle
- Saccule
What structures make up the inner ear?
Cochlea, vestibule, semicircular canals
What are the names of the vestibular nuclei?
superior, inferior, lateral, and medial
What are the functions of the vestibular system?
motion detection
generating compensatory movement
needs to maintain the stability of the body, head, and eyes in space
The horizontal canal is pitched ___ degrees above true horizontal. What is this called?
30
Reed’s line
The semicircular canals are at ___ degrees angles to one another.
90
The cochlear apparatus is at a ___ degree angle to midline.
45
What motion is pitch?
“yes”
Cervical flexion
What motion is yaw?
“no”
cervical rotation L and R
What motion is roll?
cervical extension and rotation
Where is perilymph fluid located?
between boney and membranous labyrinth
Where is endolymph fluid located?
Within membranous labyrinth
____ are hair cells that detect motion via movement of ____.
stereocilia
endolymph
Large hair like projection that detects motion
Kinocilium
What factor (excitation/inhibition) is detected when steriocilium bend toward kinocilium?
excitation
What factor (excitation/inhibition) is detected when stereocilium bend away from kinocilium?
inhibition
Name the pairs of canals that maximize fluid flow?
horizontal
Left anterior, Right posterior
R anterior, L posterior
If you turn your head to the L, you will maximally excite which canal? What is this called?
L horizontal
Yaw
If you turn head to R and pitch, what are you exciting?
L anterior canal
If you turn head to the R and roll, what are you exciting?
R posterior canal
During acceleration, endolymph flows in the same or opposite direction of head movement?
opposite
During deceleration prior to stopping, endolymph flows in the same or opposite direction of head movement?
same
True or False.
Otoliths are sensitive to rotation.
False
What structures are otoliths?
saccule and utricle
You decide to go bungy jumping. What otolith is engaged?
saccule (think dropping a sac)
You are taking a train ride when suddenly the train comes to a screeching halt, what otolith is involved?
utricle
What structures unite with the Vestibular Nuclei complex?
Lateral= LVST
Medial= MVST
Superior= MLF
Inferior= fibers of MVST traverse (no pathway)
This tract extends the length of the spinal cord; responsible for maintaining balance and extensor tone.
Does its fibers runs ipsilateral, contralateral, or both?
LVST
ipsilateral
This tract extends through cervical spine; controls neck and head position.
Does its fibers runs ipsilateral, contralateral, or both?
MVST
Bilateral
Connects the nuclei involved in eye movements to each other and to the vestibular nuclei
MLF
What pathway mediates VOR?
MLF
The vestibulocerebellar pathways have links to what part of the cerebellum?
flocculonodular lobes and cerebellar vermis
If you turn head to the L and pitch, what canal is maximally excited?
R anterior canal
If you turn your head to the L and roll, what canal is maximally excited?
L posterior canal
When you turn your head to the L, this is excitatory or inhibitory to the R horizontal canal?
inhibitory
What are the two components of VOR?
Angular: mediated by SCC
Linear: mediated by otoliths
Stabilizes visual images during head movements.
vestibulo-ocular reflex (VOR)
When you turn your head to the R, which eyes muscles do you engage?
L lateral rectus, R medial rectus
When you turn your head to the R, the MLF on the ___ ascends ipsilateral to CN 3, MLF on the ___ ascends contralateral to CN 6.
Right
Left
In vertical VOR, when extend your neck, the eyes move ___. When you flex your neck, the eyes move ___.
down
up
When eyes and head go in the same direction.
VOR cancellation
The ratio of eye velocity and head velocity
VOR gain
Generates compensatory body movement in order to stabilize the body for postural control.
Vestibulo-spinal reflex (VSR)
____ activity is induced on the side of the head movement, via the ___.
extensor
LVST
____ activity is induced on the opposite side of the head movement.
flexor
This structure adjusts and maintains VOR gain
flocculus
This structure responds to vestibular stimulation
vermis
This structure adjusts duration of VOR responses and processes otolith input
Nodulus
A person’s eyes move slowly to the R and rapidly moves to the L. This is considered a ___ (R or L) beating nystagmus?
Left beating
No matter which direction you look, the nystagmus is always in same direction due to one side being stronger. This is indicative a peripheral or central nystagmus?
Peripheral
This type of nystagmus can be suppressed with fixation.
Peripheral
This nystagmus is seen in darkness but not in light.
Peripheral
Pure vertical nystagmus is always indicative of central or peripheral?
central
