Canalis semicircularis anterior

The superior or anterior semicircular canal is a part of the vestibular system and detects rotations of the head in around the lateral axis, that is, rotation in the sagittal plane.

This occurs, for example, when nodding one's head.

It is 15 to 20 mm (0.59 to 0.79 in) in length, is vertical in direction, and is placed transversely to the long axis of the petrous part of the temporal bone, on the anterior surface of which its arch forms a round projection.

It describes about two-thirds of a circle.

Its lateral extremity is ampullated, and opens into the upper part of the vestibule; the opposite end joins with the upper part of the posterior canal to form the crus commune, which opens into the upper and medial part of the vestibule.