Why are the three semicircular canals arranged at right angles to one another?

The three semicircular canals—the anterior, posterior, and lateral (horizontal) canals—are arranged at approximately right angles to one another to enable the detection of rotational and angular movements in three-dimensional space.123

Because each canal is oriented in a different plane, this configuration allows the vestibular system to perceive the orientation and motion of the head regardless of the direction of rotation. When the head rotates, the inertia of the endolymph fluid within the canals causes it to lag behind, exerting pressure that deflects the cupula and stimulates the sensory hair cells at the base of the canal. By working in tandem with the corresponding canals in the opposite ear, this orthogonal arrangement provides the brain with precise information about head movement, which is essential for maintaining balance and stabilizing vision during motion.231