In the human body, which part of the inner ear detects head rotation and helps maintain balance?

The semicircular canals detect head rotation and help maintain balance in humans.

These three fluid-filled canals are part of the vestibular system in the inner ear. They are arranged in roughly perpendicular planes, allowing them to sense angular acceleration as the head turns in different directions.

When the head rotates, fluid called endolymph lags behind because of inertia. This movement bends sensory hair cells in an enlarged region called the ampulla. Signals from those cells travel through the vestibular portion of the vestibulocochlear nerve to the brain.

The semicircular canals detect rotational movement rather than sound. The cochlea is the inner-ear organ for hearing, while the otolith organs—the utricle and saccule—detect linear acceleration and head position relative to gravity. Together, these structures help coordinate posture, eye movements, and spatial orientation.