Vestibular System Flashcards
What are the five components of the Vestibular System?
Peripheral receptor apparatus, Central vestibular nuclei, Vestibulocular network, vestibulospinal network, vestibulothalamocortical network.
What is the peripheral receptor apparatus responsible for?
Transducing head motion/position
What is the central vestibular nuclei responsible for?
Integrating and distributing information for motor control and spatial orientation
What is the Vestibuloocular network responsible for?
Control of eye movements
What is the Vestibulospinal network responsible for?
Coordinates head movements, axial musculature and postural reflexes
What is the vestubulothalamocortical network responsible for?
Conscious perception of movement and spatial orientation
What receptors make up the vestibular labyrinth?
Three semicurcular canals and two otolith organs
What are the two components of the vestibular labyrinth?
Bony labyrinth is the protective covering, membranous labyrinth that houses the receptors
What causes Meniere’s Disease and what are the symptoms?
Disrupted endolymph volume distending the membranous labyrinth. Sxs: Fluctuating hearing loss, positional nystagmus, vertigo & Nausea
Describe the differences between Type 1 and Type 2 hair cells.
Type 1- Chalice Shaped, located in the central region of the ampulla
Type 2- Cylindrrical and in the perpheral area
How does the Ampulla transduce angular accelerations into information?
Endolymph is displaced, will displace the cupula to one side or the other and the sterocilia will move.
Describe the Macula system
Hair Cells that have steroecilia that extend into the otolith membrane, which is covered by calcium carbonate crystals called otoconia.
What information does the macula give?
Linear accelerations or gravity.
How does the Macula give information?
Linear accelerations will displace the otoconia, which will inturn bend the stereocilia of the hair cells
What are the large neurons in the lateral vestibular nucleus?
Deiters cells
Where do the primary fibers enter?
Pontomedullary junction
Where do afferents from the semicircular canals majorly and minorly project to?
Majorly- Superior and medial vestibular nuclei
Minor- Lateral and Inferior Vestibular nuclei
Where do the otolith organs (maculae) project to?
Lateral, Medial and inferior vestibular nuclei
Where do saccular afferents project to?
Contralateral oculomotor nucleus
Describe the path of primary vestibulocerebellar fibers.
Go through the juxtaresiform body on the ipsilateral side, have a wide range of targets on the contralateral side, with the end target being the fastigial and dentate nucleus.
Describe what the vestibularoculomotor system does during a leftward head turn.
Horizontal semicircular canal activates neurons in left vestibular nucleus and inhibits right side. Left vestibular neurons excite contralateral abducens, makes contractions in LEFT medial rectus and Right lateral rectus.
How do the eyes compensate for a 360 degree turn, say for a figure skater?
Vestibuloocular reflex directs eyes opposite the direction of rotation, reach a limit, then will SNAP back to the central position, then repeat.
What is the caloric test? How do you interpret results?
Warm or cold water is introduces in the ear. Cold water causes eyes to go to opposite side, warm causes eyes to go to same side. Should give equal results, if not can indicate a unilateral lesion. (COWS)
What is the lateral vestibulospinal tract responsible for?
Coordination of postural control
