Vestibular system

The sensory system of the inner ear and brain that detects head motion and position. It supports balance, posture, and stable vision during movement.

Semicircular canals: Three fluid-filled inner-ear canals that detect rotational acceleration of the head. Their paired geometry encodes rotation across three spatial planes.
Endolymph: A potassium-rich fluid that fills the membranous labyrinth of the inner ear. Its movement within semicircular canals bends sensory hair bundles.
Dix–Hallpike test: A clinical maneuver that provokes characteristic eye movements in suspected posterior-canal positional vertigo. It helps identify a common mechanical cause of brief positional vertigo.
Cochlea: The spiral-shaped inner-ear structure that converts sound vibrations into neural signals for hearing. It shares the inner ear's architecture but serves hearing rather than balance.
Otolith organs: The utricle and saccule, inner-ear organs that sense linear acceleration and gravity. They distinguish translational motion and head tilt from rotational motion.
Hair cell: A sensory receptor cell that converts mechanical deflection of its hair bundle into electrical signals. Hair cells transduce motion of inner-ear structures into nerve activity.
Epley maneuver: A sequence of head and body positions used to move displaced otoconia out of a semicircular canal. It treats posterior-canal benign paroxysmal positional vertigo by repositioning particles.
Nystagmus: A rhythmic, involuntary eye movement that can arise from vestibular imbalance or other causes. Its direction and pattern can reveal abnormal vestibular drive to eye-movement circuits.
Vestibulo-ocular reflex: A reflex that moves the eyes opposite head movement to stabilize the visual scene. It is the system's fast route from head motion to gaze stabilization.
Vestibular nerve: The branch of the vestibulocochlear nerve that carries balance signals from the inner ear to the brainstem. It carries vestibular receptor output into central processing circuits.

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