Anterior coronal view of orbital apex and pterygopalatine fossa. In the midline superiorly, the pituitary gland can be seen situated within the hypophyseal fossa superior to the sphenoid sinus. Laterally, the cavernous segment of the internal carotid arteries can been seen within the cavernous sinus. The maxillary nerve (CN V2) enters the pterygopalatine fossa through the foramen rotundum whereas branches of the maxillary artery enter through the pterygomaxillary fissure. Inferomedial to foramen rotundum is the pterygoid (Vidian) canal that transmits the Vidian nerve also to the pterygopalatine fossa. Preganglionic parasympthetic fibers within this nerve will synapse in the pterygopalatine ganglion and postganglionic fibers with be distributed via branches of the maxillary nerve to target tissues. The Annulus of Zinn (common tendinous ring) is positioned at the apex of the orbit surrounding the optic nerve and serves as the attachment site for the four rectus muscles of the eye (superior, medial, inferior, and lateral). (Image courtesy of AL Rhoton, Jr.)