In the horizontal ducts, the kinocilium faces the utricle. Dynamic functions relate to detecting head movements, detected mostly by the semicircular canals and functions importantly with eye movements. The central axons of the vestibular system run with the eight cranial nerve. They are related to an imbalance of synchronized impulses from vestibular sources. Nystagmus is named by the direction of the fast saccade component.
Horizontal nystagmus is the most common, although vertical and rotary nystagmus can occur.
The head is tilted forward 30 degrees, bringing the horizontal canals parallel to the ground. The chair is rotated quickly 10 -12 times and then stopped. Caloric or thermal test. Irrigating the external auditory meatus with warm or cold water sets up convection currents in the endolymph, which displaces the crista ampullaris. Normally nystagmus is towards the side irrigated with the warm water and is away from the side irrigated with cold water.