Vestibular system 10/28/16 Flashcards
What are the three systems that help keep a person upright?
- Cerebellum
- Vision
- Vestibular system
What are the first responses (involuntary/reflex) when a person trips?
- Arms go out
- Head goes back
- Back arches
What are the three major divisions of the vestibular system?
- Peripheral apparatus
- Central vestibular nucleus
- Sensory Interactions
What innervates the vestibular apparatus?
-Scarpa Ganglion
How many canals do you find on the vestibular apparatus?
Three
What are the names of the three canals in the vestibular system?
- Anterior (superior)
- Horizontal
- Posterior
What two features help with gravity detection in the vestibular system?
- Utricle
- Saccule
Under normal motion what way is our head tilted?
30 degrees down
What fluid goes into the peripheral apparatus from the CSF and how?
-Perilymph through the perilymphatic duct
What ion is endolymph high in?
K+
What ion is perilymph high in?
Na+
Why is Na+ and K+ important in the peripheral apparatus?
To create gradients
What creates the sensation in the peripheral apparatus?
Sensory Epithelial cells
What do the semicircular canals sense?
-Angular motion
What happens if the hair cells (epithelial sensory cells) pull?
K+ channels are opened
What fluid hits the cupula to push/pull the hair cells?
-Endolymph
What is the cupula?
-Gelatin filled bag around the hair cells
What is linear acceleration?
Up and Down (gravity)
What senses linear acceleration?
- Utricle
- Saccule
What is the otolith membrane?
Structure that surround the hair cells involved with linear acceleration
What is found on top of the otolith membrane that helps overcome inertia?
-Otoconia (bags of calcium)
What does the signaling from the peripheral apparatus?
-Hair cells
What is multimodal convergence?
Immediate integration with other sensory inputs
vestibule with the eye and brain etc..
Where do you find the vestibular nucleus?
Pons and Medulla
What are the four major subdivisions of the vestibular nucleus?
- Superior vestibular
- Lateral vestibular
- Medial vestibular
- Inferior vestibular
What type of motion do the horizontal and superior canal measure?
-Rotational
Which canal places your eyes while moving?
-Horizontal canal
What tracts do the superior vestibular nucleus run upward on?
-Medial longitudinal fasciulus (MLF)
What does the vestibulo-cerebellar network provide coordination of?
- Posture
- Balance
- Eye Movements
If you get drunk what part of the peripheral apparatus is offline?
-The semicircular canals
What part of the peripheral apparatus interacts with the cerebellum?
-Semicircular canals
What network coordinates your eyes and rotational movement?
-Vestibulo-ocular network
Where is the control of the vestibulo-ocular network controlled?
-Pons
What two muscles are involved in the vestibulo ocular network?
- Lateral rectus
- Medial rectus
If you turn your head left quickly what direction does your eyes go?
-Right
What two nuclei does the vestibular nucleus interact with?
- Oculomotor nucleus
- Abducens nucleus
What is a nystagmus?
- Involuntary shaking to and fro movement of the eyes
- Rhythmic and jerky
What are the frequent causes nystagmus?
- Infarction/stroke
- MS
- Spinocerebellar degeneration
- Developmental problems in the pons and cerebellum
- Visual problems such as albinism
How do you test if you horizontal canal is working properly?
Caloric Nystagmus
What is the caloric Nystagmus test?
-Test the horizontal canal with hot or cold water
If you put hot water into the right ear in the caloric nystagmus test what way does your eyes turn?
-Left
If you put cold water into the right ear in the caloric nystagmus test what way does your eyes turn?
-Right
What is the slow phase of the caloric nystagmus test?
-Eyes initial movement
What is the fast phase of the caloric nystagmus test?
-Corrective saccade
If the slow phase it absent in the caloric nystagmus what area of the pathway is damaged?
- Horizontal canal weakness (ipsilateral)
- Damage to the MLF/Pons
If the fast phase is absent from the caloric nystagmus what area is damaged?
-Cerebral damage
If both phases are absent/lost from the caloric nystagmus test what is damaged?
-Bilateral hindbrain
If the person has vertigo problems where the patient says “I’m spinning” what is damaged?
-Vestibular system
If the person says “WOAH, the room is spinning” what is damaged?
-Central vestibular issue
