Microsurgical anatomy of the superior orbital fissure.

The microsurgical anatomy of the superior orbital fissure was examined in cadaver specimens. The cavernous sinus fills the posterior margin and the orbital contents fill the anterior margin of the fissure. All of the nerves coursing in the walls of the cavernous sinus pass through the superior orbital fissure to reach the orbit. The fissure has a narrow lateral part and a larger medial part. The annular tendon from which the rectus muscles arise is situated in front of the upper half of the medial part of the fissure and is attached to the lateral margin near the junction of the lateral and medial parts. The fissure is divided into three sectors: lateral, central, and inferior. The lateral sector, which corresponds to the narrow lateral part, transmits the trochlear, frontal, and lacrimal nerves and the superior ophthalmic vein, all of which course outside the annular tendon. The central sector, which is situated behind and is aligned with the lateral part of the annular tendon, transmits the superior and inferior divisions of the oculomotor nerve, the abducens and nasociliary nerves, and the sensory and sympathetic roots of the ciliary ganglion, all of which pass through the annular tendon. The inferior sector, which is located below the annular tendon and origin of the inferior rectus muscle, is filled with a posterior extension of the orbital fat and transmits the inferior ophthalmic vein. The relationship and course of the nerves in each sector and the incisions that may be used to open and expose the contents of the fissure are reviewed.