carotid canal

On the interior surface of the temporal bone, behind the rough surface of the apex, is the large circular aperture of the carotid canal, which ascends at first vertically, and then, making a bend, runs horizontally forward and medialward. It transmits into the cranium, the internal carotid artery, and the carotid plexus of nerves. Sympathetics to the head also pass through the carotid canal. They have several motor functions: raise the eyelid (superior tarsal muscle), dilate pupil, innervate sweat glands of face and scalp and constricts blood vessels in head[WP].