Structures in the Lateral Wall of the Sinus, from above Downwards (a) Oculomotor nerve: In the anterior part of the sinus. It divides into superior and inferior divisions which leave the sinus by passing through the superior orbital fissure: (b) Trochlear nerve: In the anterior part of the sinus, it crosses superficial to the oculomotor nerve, and enters the orbit throught the superior orbital fissure; (c) Ophthalmic nerve: In the anterior part of the sinus. It divides into the lacrimal, frontal and nasocillary nerves; (d) Maxillary nerve: It leaves the sinus by passing through the foramen rotundum on its way to the pterygopalatine fossa. (e) Trigeminal ganglion: The ganglion and its dural cave project into the posterior part of the lateral wall of the sinus.