12 - The Vestibular System Flashcards
Function of vestibular system
Balance
Posture
Spatial orientation
Receptors of vestibular system
Eyes
General proprioceptors - muscles, joints and tendons
Vestibular receptors in inner ear - vestibular apparatus
Perilymph
High Na
Low K+
Similar to CSF - on the outside
Endolymph
High K+
Low Na
Endocochlear potential
Difference between endolymph and perilymph
80-100mV
Structures of the semicircular ducts
Apulllae
Sacculus
Urtriculus
Semicircular ducts
What are hair cells
AKA receptor cells, found in sacculus, ampullae and urtriculus and semicircular ducts
Structure of hair cell
Supporting cell with one kinocillium and many stereocillia adjacent to it
How does hair cell cause depolarisation
When endolymph moves in a way that the kinocillium is separated from stereocillium ion channels open to allow depolarisation –> glutamate is released and vestibule nerve fibres are activated
What is cillia made out of
Gelatine
What are hair cells sensitive to
Kinetic sensitivity
Sensitive to head rotation
Angular acceleration
Oolith membrane
Contains otoconia which are small crystals that compress cilia to activate signalling
Utricles
Left-right motions
Saccules -
Up-down motion
Optikokinetic and rotational nystagmus
Normal
Spontaneous nystagmus
Abnormal
vestibular apparatus damage
BS or cerebellum damage
What are the 4 major nuceli
Superior
Medial
Inferior
Lateral
Superior Vestibular nucleus
Medial longitudinal fasicculus to occulomotor nucleu
Lateral VN
To cerebellum via lateral VS tract regulates anti gravity muscles
Inferior VN
With periphery to thalamus and cortex
Medial VN
Reticular formation to neck muscles to cervical sc
Kinetosis
Motion Sickness
How do you test for Benign Paroxysmal Positional Vertigo
Hallpike Manouvre
Vestibulocerebellar syndrome
Nystagmus
Ataxia
Tinnitus
