Physiology of Balance Flashcards
What are the 2 outputs of the balance system?
Vestibulospinal tract
Vestibulocular reflex
What is different about how older patients keep their balance?
They use their hips to stay balanced
(due to decreased proprioception)
Younger people use ankle flexion
What are the 5 key vestibular “end-organs”
Utricle
Saccule
3 ampullae on semi-circular canals
What is the name given to the longest hair cell which is in a relatively “fixed” position
Kinocillium
What are the remainder of hair cells known as?
Sternocilia
What is the resting potential of the kinocillium and how is this changed?
90 spikes/ second
Deflection of the sternocilia towards the kinocillium increases the resting potential
Deflection of the sternocilia away from the kiniocillium decreases the resting potential
The saccule detects vertical movement. TRUE/FALSE?
TRUE
The utricle detects horizontal movement
Where are the cupula found and what is their function?
In ampullae of semi-circular canals
Can be deflected by movement of perilymph
cilia inside cupula deflect and alter firing rate
This tells brain we are moving in specific direction
What eye sign can indicate an ear lesion?
Nystagmus
How can nystagmus be used to work out which side a lesion is present on?
Eyes move towards lesion side first then flick to opposite side (this is known as the fast phase)
What happens if the patient looks into the direction in which the fast phase of nystagmus occurs?
The fast phase gets faster (occurs in a shorter time)
What pathology could be responsible for a bidirectional nystagmus?
pathology must be present where the vestibular pathways join
=> plaque of MS
What allows us to focus on the horizon?
Vestibulocular reflex
In what condition do patients struggle to focus on the horizon?
oscillopsia (often due to gentamicin toxicity)
