Vestibular System Flashcards
Why is balance important?
Fundamental for daily activities: walking, driving, sense of stability and well being
Losing balance is debilitating
____ are leading cause of fatal and non fatal injuries in older adults
Falls
Dizziness vs vertigo:
What is dizziness?
What is vertigo?
Dizziness: unsteadiness, feeling faint, feeling weak
Vertigo: false sensation that the individual or the environment is moving
What are the two main components of the balance system?
Sensory component: what the body tells us about our surroundings
Motor component: what we do to keep our body balanced
In order to be balanced, what two systems need to work properly?
Sensory and motor
What does the vestibular system do?
- Provides info to the CNS for control of skeletal muscle for postural adjustments
- Stabilizes visual environment during movement
- Provides CNS with spatial info about linear and angular acceleration
What are the primary structures of the vestibular system?
Semicircular canals (3 per side)
Utricle
Saccule
Of the primary structures, which are responsible for angular acceleration and which are responsible for linear acceleration?
- Semicircular canals: angular acceleration
- Utricle: linear acceleration (horizontal)
- Saccule: linear acceleration (vertical)
Utricle and saccule anatomy:
What is the macula?
Vestibule with sensory cells
Utricle and saccule anatomy:
What is otolithic membrane?
Gelatinous membrane covered in calcium carbonate crystals (otoconia)
Utricle and saccule anatomy:
Where are the hair cells?
Embedded in the otolithic membrane
Utricle and Saccule anatomy:
What are otoconia?
Calcium carbonate crystals with higher specific gravity than surrounding endolymph
Utricle and saccule:
Stereocilia face which direction
Opposite directions
Hair cells in the utricle and saccule are oriented so each utricle/saccule serve as …
Its own functional pair (have a pair within themselves)
The utricle/saccule also get information from …
So they have ___ and ___ pairing
- contralateral side
- have an equal (within the structure) and opposite (on the other side) pairing
Semicircular canals are responsible for ….
Angular motions, think of a plane
Semicircular canals are paired to the other ear in the following manner
Right anterior to left posterior (RALP)
Left anterior to right posterior (LARP)
Right horizontal to left horizontal
What is the function of the semicircular canals?
- Have excitatory/inhibitory relationship with partner canal
- Brain integrates information from all three pairs to form a representation of head movement relative to space
Semicircular canal anatomy:
What is the ampulla?
Houses the sensory epithelium of each SSC
Semicircular canal anatomy overview
Hair cells sit in the crista ampullaris and are imbedded in the cupula
Semicircular canals:
In what direction do the stereocilia face?
Stereocilia face the same direction
The eyes form the ___ system that is connected to _____ muscles via _____
Peripheral vestibular system, extraocular, brainstem
There are _ extraocular muscles, each controlling eye motion in a ____ direction
Each muscle pairs with specific ____ ______
6, different
Semicircular canals
Stimulation of the semicircular canals results in the movement of the paired extraocular eye muscles.
This is also called …
Also called VOR, vestibulo-ocular reflex
Why do we care about the vesibulo ocular reflex?
Helps keep our eyes on target, disruption indicates nystagmus
What is nystagmus?
Eye twitching that is a sign of vertigo
What are the different vestibular tests?
o Videonystagmography (VNG) testing
o Whole-Body Rotational Chair Test
o Video Head-Impulse Test (vHIT)
o Vestibular evoked myogenic potentials (VEMPs)
o Computerized dynamic posturography (CDP)
o Sensory organization test (SOT)
