Osseous anatomy of the orbital apex.

(Fig 4D). The osseous anatomy of the orbital apex may be difficult to conceptualize because of the different shapes and orientations of the optic canal, superior and inferior orbital fissures, and foramen rotundum. However, knowing this anatomy is crucial to evaluate complex fractures, tumors, and inflammatory processes involving the orbital apex. Evaluating osseous anatomy of the orbital apex with computed tomography (CT) requires knowledge of its three-dimensional appearance (1–8). The optic canal forms an angle of about 458 with the sagittal plane of the head, slightly tapers anteriorly, and is bounded medially by the body of the sphenoid bone, superiorly by the superior root of the lesser wing of the sphenoid bone, inferolaterally by the optic strut (that is, the inferior root of the lesser wing of the sphenoid bone), and laterally by the anterior clinoid process (Fig 1). Inferolateral to the optic canal and separated from it by the optic strut is the superior orbital fissure, a gap between the greater and lesser wings of the sphenoid bone that is somewhat comma-shaped, appearing bulbous inferiorly and thin superolaterally (Fig 1). The fissure’s bulbous part is located anterior to the cavernous sinus. Just inferior and posterior to the superior orbital fissure is the foramen rotundum, a parasagittally oriented thin channel at the upper part of the base of the sphenoid bone, which has a trough-shaped posterior configuration (Fig 1). The foramen rotundum communicates posteriorly with the middle cranial fossa and anteriorly with the upper part of the pterygopalatine fossa. The pterygopalatine fossa and the inferior orbital fissure have a unique relationship. The inferior orbital fissure, its long axis forming an angle of about 458 with the head’s sagittal plane, is located between the lateral wall and