In: Anatomy and Physiology
Describe how fluid movement in the semicircular canals alerts the brain to movement. APs travel down which cranial nerve during this process?
Semicircular canals are a part of vestibular system. They respond to angular acceleration and deceleration. 3 canals lie at right angle to each other and the one which lies atright angle to axis of rotation is stimulated the most.
Each canal is filled with a fluid called endolymph which contain motion sensors within it. At the base of each canal there is a dilated sac called ampulla which contains hair cells and supporting cells(crista ampullaris). These hair cells have cytoplasmic projections called stereocilia which are embedded in cupula. Movement of head moves the canal but endolymph lags behind die to inertia.It causes defletion in cupula and steriocilia bends. This bending causes altered electric signals that is transmitted to brain. It alerts the brain to balance the head.
Vestibular nerve, which is part of 8th cranial nerve(vestibulocochlear nerve) is transmitting these sensory informations from the hair cells to the brain via vestibular ganglion of Scarpa.