The shifting and bending of sensory hairs by otoliths (calcium carbonate crystals within a gelatinous matrix) within the utricle and saccule of the inner ear register changes in the position of the head relative to the gravitational field of the earth. Shifts in the otolith position also provides information about acceleration and deceleration. Angular acceleration is detected by changes in the flow of endolymph in the semicircular canals.