How does the vestibular system maintain balance?

The answer

The vestibular system, located in the inner ear, consists of three semicircular canals oriented at right angles to each other (detecting rotational movement in three planes) and two otolith organs, the utricle and saccule (detecting linear acceleration and head tilt relative to gravity). When the head moves, fluid (endolymph) in the semicircular canals shifts and deflects hair cells, generating nerve signals proportional to the speed and direction of rotation. The otolith organs contain calcium carbonate crystals (otoconia) resting on a gel layer above hair cells; when the head tilts or accelerates, gravity and inertia shift the crystals, bending the hair cells. The brain integrates vestibular information with visual input and proprioceptive feedback to maintain balance, stabilize gaze during movement (via the vestibulo-ocular reflex), and create spatial orientation. When these inputs conflict, the result is often motion sickness.