Vestibular system, apparatus of the inner ear involved in balance. The vestibular system consists of two structures of the bony labyrinth of the inner ear, the vestibule and the semicircular canals. The vestibular system is the sensory system that provides the leading contribution to the sense of balance and spatial orientation for the purpose of coordinating movement with balance.
The utricle and saccule are the two otolith organs in the vestibular system.They are part of the balancing system (membranous labyrinth) in the vestibule of the bony labyrinth. They detect motion and orientation using otoconia and a viscous fluid. The utricle detects linear accelerations and head-tilts in the horizontal plane and the saccule detects linear accelerations and head tilts in the vertical plane. .
The three semicircular canals of the bony labyrinth are designated according to their position: superior, horizontal, and posterior. The superior and posterior canals are in diagonal vertical planes that intersect at right angles. Each canal has an expanded end, the ampulla, which opens into the vestibule.