Inferior ophthalmic vein

The inferior ophthalmic vein begins in a venous network at the forepart of the floor and medial wall of the orbit; it receives some vorticose veins and other veins from the inferior rectus muscle, inferior oblique muscle, lacrimal sac and eyelids, runs backward in the lower part of the orbit lying above the inferior rectus and divides into two branches.
One of these passes through the inferior orbital fissure and joins the pterygoid venous plexus, while the other enters the cranium through the superior orbital fissure and ends in the cavernous sinus, either by a separate opening, or more frequently in common with the superior ophthalmic vein.