semicircular canal /-sur′kyələr/ [L, semi-, half, circulare, to go around, canalis, channel] , any of three bony fluid-filled loops in the osseous labyrinth of the internal ear, associated with the sense of balance. The posterior, superior, and lateral canals, all about 0.8 mm in diameter and perpendicular to each other, open into the cochlea. The posterior canal is the longest.
