The Vestibular Pathway Flashcards
What are the inputs to the central pathways of balance?
Visual - eyes
Proprioceptive - sense of joint position in space
Vestibular - eara
Cardiovascular - for perfusion of central pathways
What are the outputs of the central pathways?
Vestibulospinal Tract - provides tone to the back and legs; stabilises the body
Vestibulo-ocular reflex - allows gaze stabilisation
What are the five key vestibular organs of balance?
Lateral semicircular canal Anterior semicircular canal Posterior semicircular canal Utricle Saccule
Which nerve supplies the utricle and lateral and anterior semicircular canal?
Superior vestibular nerve
Which nerve supplies the posterior semicircular canal and saccule?
Inferior vestibular nerve
What is the name of the largest and longest hair cells in the vestibule?
Kinocilium
What is the name of the smaller hair cells in the vestibule?
Stereocilium
What is the arrangement of the kinocilium and stereocilium?
The kinocilium are in the centre surrounded by many stereocilium
How does movement cause firing of impulses?
The fluid within the vestibules moves over the stereocilia causing them to bend towards or away from the kinocilia. The difference is perceived by the inner ear.
What does deflection of the stereocilia towards the kinocilia translate to?
Increased firing of the afferent nerves
What does deflection of the stereocilia away from the kinocilia translate to?
Decreased firing rate of the afferent nerves
What are the otolith organs?
Utricle and saccule
What type of fluid is contained within the vestibular canals?
Endolymph
What is the function of the otolith organs?
To detect forward and backward movement and gravitational forces e.g. if the head is the right way up
What plane does the utricle detect movement in?
Horizontal e.g. driving a car
