Lateral Perspective of the Orbit, Supra- and Infratentorial Parenchyma. Dura has been removed over the entire supratentorial brain and most of the cerebellum and posterior fossa. The transverse sinus is visible covered by dura, coursing to the sigmoid sinus. The sigmoid sinus is visible coursing from the transverse-sigmoid junction to the jugular bulb. The relationship between the mastoid tip and the sigmoid sinus is noted. The vertebral artery courses through the transverse foramen of the atlas (C1), and is visible here turning medially and running along its groove on the superior aspect of C1 (sulcus arteriae vertebralis). The posterior atlantooccipital membrane is a broad ligament connecting the atlas and the posterior foramen magnum. The petrous temporal bone has been drilled to reveal the superior, posterior and lateral semicircular canals. Anteriorly, visible are the ocular muscles, including the lateral and superior rectus muscles and the inferior oblique muscle. The lacrimal gland lies within the superolateral aspect of the orbit and obtains sensory innervation via the lacrimal nerve, a branch of the ophthalmic nerve. (Image courtesy of AL Rhoton, Jr.)