This is a small nerve arising from the anterior part of the medulla oblongata, just behind the pons varolii. It proceeds in a forward direction in company with the superior maxillary nerve in order to reach the foramen lacerum orbitale, by which it enters the orbit with the ophthalmic division of the fifth.

It gives off a small branch to the retractor muscle of the eye, and is then distributed solely to the outer straight muscle of the eye (external rectus).