Transmaxillary Exposure of the Orbit. A, Insert shows the direction of exposure through the maxillary sinus. This approach is usually performed through a degloving incision in the buccogingival junction rather than through an incision along the lateral margin of the nose. In this specimen, the upper lip and cheek flap have been reflected laterally, and the anterior wall and roof of the maxillary sinus has been opened to expose the lower surface of the orbital contents. B, The orbital fat has been removed to expose the medial and inferior rectus and inferior oblique muscles. The inferior oblique muscle arises from the medial orbital wall and passes laterally below the inferior rectus muscle to the globe. The branch of the inferior division of the oculomotor nerve to the inferior oblique muscle courses along the lateral side of the inferior rectus muscle. C, The inferior rectus muscle has been divided and reflected backward. The ophthalmic artery, in this case, courses below the optic nerve, as occurs in approximately 15% of orbits. The tortuous CRA enters the lower margin of the nerve. D, The ophthalmic artery has been retracted medially to expose a greater length of the CRA. The parasympathetic motor root to the ciliary ganglion arises from the branch of the inferior oculomotor division to the inferior oblique. E, The ophthalmic artery has been retracted further posteriorly to expose the course of the CRA along the lower margin of the optic sheath. F, Another CRA has been exposed from below by removing the orbital floor and retracting the inferior rectus muscle. The CRA has a tortuous course before its entry into the optic sheath. G, Anterior view of the right optic nerve and sheath after removal of the globe. The CRA courses in the center of the optic sheath. The subarachnoid space extends forward between the nerve and sheath. (Images courtesy of AL Rhoton, Jr.)