A, The orbital part of the orbicularis oculi muscle has been removed and the palpebral part preserved. The supraorbital nerves carry sensation from the skin of the forehead and the infraorbital nerve carries sensation from the cheek, upper lip, and adjacent part of the nose. The supraorbital nerves reach the skin of the forehead by passing through a notch or foramen in the superior orbital rim. The infraorbital nerve arises from the maxillary nerve and passes through the inferior orbital fissure and along the infraorbital groove and canal in the orbital floor to reach the infraorbital foramen. B, Anterior aspect of a coronal section through the right orbit just posterior to the globe and the inferior oblique muscle. The intraorbital part of the optic sheath, an anterior extension of the dura lining the optic canal, surrounds the optic nerve. At this level, the ophthalmic artery has crossed from lateral to medial and the superior ophthalmic has crossed from medial to lateral above the optic nerve. C, Enlarged view of B to show the relationship of the cisternal and canalicular segments of the optic nerve to the intraorbital part. The cisternal segment of the optic nerve courses medial to the supraclinoid segment of the internal carotid artery. The optic sheath surrounds the intracanalicular segment in the optic canal. The optic sheath and the periorbita fuse at the orbital apex to form the annular tendon from which the rectus muscles arise. Fibers from the superior division of the oculomotor nerve enter the lower surface of the levator and superior rectus muscles. The sphenoid sinus and sella are on the medial side of the optic canal. D, The orbital fat has been removed and the lateral rectus muscle has been reflected to expose the ciliary ganglion, which is located inferolateral to the optic nerve. The inferior division of the oculomotor nerve sends individual branches to the inferior and medial rectus and the inferior oblique muscles. The ciliary ganglion has sensory, parasympathetic, and sympathetic roots. The motor (parasympathetic) root of the ciliary ganglion arises from the branch of the inferior oculomotor division to the inferior oblique muscle. Sensory fibers from the globe pass through the short ciliary nerves to reach the ciliary ganglion, where they form the sensory root of the ciliary ganglion, which joins the nasociliary branch of the ophthalmic nerve. Sympathetic fibers reach the ciliary ganglion from the carotid plexus. The ciliary ganglion gives rise to numerous short ciliary nerves that pierce the sclera and terminate in the pupillary sphincter and ciliary muscle. (Images courtesy of AL Rhoton, Jr.)