The endolymph in the semi-circular canals moves at the opposite direction to the rotation of the body. The three axes the semi-circular canals can detect angular rotation are the anterior vertical, the posterior vertical and the horizontal planes. When angular rotation occurs in any of these planes, the endolymph in the semi-circular canals moves the opposite way to the body movement, causing the cupula to be moved and therefore the hair cells in the semi-circular canals will also be pushed in the direction of the endolymph movement. This activates the basolateral membrane the hair cells are located on, and causes the ion channels to depolarise or hyperpolarise, depending on the direction of the hair cell movement**. This will then send a signal through fibers to the vestibular nerve then onto the vestibulocochular nerve, which sends its inputs to the cerebellum. [joc vest] …show more content…
Does nystagmus occur after a person in a rotating chair has achieved constant velocity? Explain. At constant velocity, the hair cells have resumed to their previous more straightened position and so nystagmus does not occur. Inertia is no longer prevalent and the semi-circular canals apparatuses are all at a constant velocity. However, when the chair stops spinning and the endolymph in the semi-circular canals reaches inertia once again, nystagmus will occur as the eyes will still follow the rotation the chair has been spinning in until the endolymph in the semi-circular canals has come to the velocity the body is now