The vestibule and semi-circular canal are inner-ear components that comprise the vestibular system. Together they detect all directions of head movement. Two types of otolith organs are housed in the vestibule: the saccule, which points vertically and detects vertical acceleration, and the utricle, which points horizontally and detects horizontal acceleration. The otolith organs together sense the head's position with respect to gravity when the body is static; then the head's movement when it tilts; and pitch changes during any linear motion of the head. The saccule and utricle detect different motions, which information the brain receives and integrates to determine where the head is and how and where it is moving.