Superior semicircular canal

The superior semicircular canal (anterior semicircular canal), 15 to 20 mm. in length, is vertical in direction, and is placed transversely to the long axis of the petrous portion 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.