E, Anterior aspect of a coronal section at the level of the ciliary ganglion. The inferior division of the oculomotor nerve splits into three branches that innervate the inferior and medial rectus and inferior oblique muscles. The nasociliary branch of the ophthalmic nerve passes through the annular tendon, and the frontal and lacrimal branches pass outside the annular tendon through the lateral part of the superior orbital fissure. The nasociliary nerve and ophthalmic artery course above the optic nerve at this level. F, Section located just anterior to the lateral end of superior orbital fissure at the level of the posterior ethmoidal canal. At this level, the ophthalmic artery courses on the lateral side of the optic nerve and the nasociliary nerve courses between the optic nerve and ophthalmic artery. The recurrent meningeal artery passes above the ophthalmic artery. The orbital smooth muscle spans the inferior orbital fissure. G, Enlarged view of the section shown in F after removal of the orbital fat. At this level, the oculomotor nerve has split into a superior division that supplies the superior rectus and levator muscles and an inferior division that innervates the inferior rectus, medial rectus, and inferior oblique muscles. The central retinal artery arises from the ophthalmic artery and courses below the optic nerve. The superior ophthalmic vein exits the intraconal area by passing between the heads of the superior and lateral rectus muscles, and the inferior ophthalmic vein passes between the heads of the lateral and inferior rectus muscles. H, Section through the orbital apex immediately in front of the superior orbital fissure. The annular tendon is divided into medial and lateral parts. The medial part is located in front of the optic canal and the lateral part is situated in front of the superomedial part of the superior orbital fissure. The optic nerve and ophthalmic artery pass through the medial part. The superior and inferior divisions of the oculomotor nerve and the abducens and nasociliary nerves and the sensory root of the ciliary ganglion pass through the lateral part. The superior ophthalmic vein and the recurrent meningeal artery course between the superior and lateral rectus muscles and exit the superior orbital fissure by passing outside the annulus. The inferior ophthalmic vein has exited the intraconal area at this level and is coursing below the lateral rectus muscle on its way to the cavernous sinus. This section crosses the inferior division of the oculomotor nerve proximal to its subdivision into individual branches. (Images courtesy of AL Rhoton, Jr.)