Vestibular Apparatus

VESTIBULAR APPARATUS ANATOMY Sense organ of the inner ear Consist ofThree semicircular canals Otolith organ - saccule and utricle Fluid filled membranous tubes connecting with each other and with cochlear duct. Semicircular canal Contain endolymph Separated from perilymph by bony canal. Three semicircular canals are horizontal, superior, inferior Otolith organ Utricle communicates with saccule by ductus endolymphaticus Utricle and saccule contains projecting ridge called macula Structure z z z z

Crista and macula are specific receptors of the vestibular apparatus Covering projecting ridge – hair cells Large non motile hair – kinocilium located at one end of hair cells Between hair cell lies vestibular division VIII nerve fiber.

FUNCTIONS SACCULE AND UTRICLE provide information about linear acceleration and change in head position. They’re the stretch receptors z Saccule responds to vertical acceleration z Utricle responds to horizontal acceleration Semicircular canals detect angular acceleration during rotation of the head. Role of vestibular apparatus in posture regulation z Vestibulospinal tracts maintain tone in antigravity muscles and coordinate adjustments in response to change in body position. z Conscious awareness of the position and acceleration of the body z Controls eye movements (vestibule ocular reflex.) z Orientation in space.