The vestibular apparatus serves to hold the balance and to orientate in the room. It consists of three differently oriented semicircular ducts with each one receptor organ (crista ampullaris) as well as utricle and saccule, which contain the macula statica as their receptor organ. The receptor organs consist of supporting cells, between which secondary sensory cells are embedded. These carry each one kinocilium (sensory hair) and several stereocilia (microvilli that can`t move spontaneously) that extend into a gelatinous layer. A deflection of the overlay caused by movement causes the hairs to bend. When the stereocilia bend in direction of the sensory hair, they activate, when they bend into the other direction, they inhibit the nerve fiber. On the tectorial membrane of the macula statica are crystals (statoliths) laying on it. The cristae ampullares primarily register angular, the maculae staticae linear acceleration.
