A, Anterior view of the right orbit. The walls of the orbit are formed by seven bones. They are the frontal, zygomatic, sphenoid, lacrimal, ethmoid, and palatine bones, and the maxilla. The lateral border of the orbital opening is formed by the frontal process of the zygoma, except the upper part, which is formed by the zygomatic process of the frontal bone. The lower margin of the orbital opening is formed laterally by the zygoma and medially by the maxilla. The upper part of the medial border is formed by the frontal bone and the lower part is formed by the frontal process of the maxilla. The medial part of the upper border contains the frontal sinus. The superior orbital fissure is bounded above by the lesser wing of the sphenoid bone, below by the greater wing, and medially by the sphenoid body. The frontal bone forms the narrow lateral apex of the superior orbital fissure. The inferior orbital fissure is bounded posteriorly by the greater sphenoid wing and anteriorly by the maxilla. The supraorbital margin is notched or is the site of one or several small foramina that transmit the supraorbital nerves and vessels. The infraorbital groove, which transmits the infraorbital branch of the maxillary nerve, leads forward out of the inferior orbital fissure to cross the floor to reach the infraorbital canal, which ends in the infraorbital foramen. B, Anterior aspect of the right optic canal. The optic canal, which transmits the optic nerve and ophthalmic artery, opens into the superomedial corner of the orbital apex. The optic canal is situated at the junction of the lesser wing with the sphenoid body. It is separated from the superior orbital fissure by the optic strut, a bridge of bone, which extends from the lower margin of the anterior clinoid to the sphenoid body. The optic strut is also referred to as the posterior root of the lesser wing. The tendinous ring, referred to as the annular tendon, from which the four rectus muscles arise, is attached to the upper, lower, and medial margin of the optic canal. The lateral edge of the annular tendon is attached to the midportion of the lateral edge of the superior orbital fissure, where a bony prominence on the greater wing marks the junction of medial and lateral parts of the fissure. C, Roof of the right orbit viewed from below. The roof of the orbit is formed by the orbital plate of the frontal bone anteriorly and the lesser sphenoid wing posteriorly. The lacrimal fossa is the depression in the anterolateral part of the roof in which the lacrimal gland rests. There is another small depression on the antero-medial part of the roof that serves as the attachment for the trochlea of the superior oblique muscle. The optic foramen is situated posteriorly at the junction of the roof and medial wall. The ethmoid air cells and sphenoid sinus are located along the medial edge of the orbital roof. D, Superior aspect of the floor of the anterior cranial fossae that forms the roof of both orbits. The cribriform plate of the ethmoid bone is situated in the midline between the orbital roofs. The crista galli serves as the site of attachment of the cerebral falx. Anteriorly, the frontal sinus splits into two laminae that enclose the frontal sinuses. The internal carotid artery exits the carotid canal above the foramen lacerum and passes forward in the carotid sulcus on the lateral part of the sphenoid body. (Images courtesy of AL Rhoton, Jr.)