Anatomical View Illustrating the Anterior Incisural Space as Seen Through a Pretemporal Transcavernous Approach. a, Dura mater has been opened, and basal cisterns have been widely dissected. b, The optic nerve has been unroofed, and ACP has been removed to expose the clinoidal segment of the ICA. c, Oculomotor nerve has been exposed and dissected toward its entrance into the cavernous sinus. Posterior clinoid process may be well visualized. d, The roof of the cavernous sinus has been opened medial to the third cranial nerve to further expose the posterior clinoid process and upper clivus. The pituitary gland may be seen medial to the ICA. e, Posterior clinoid process and part of the upper clivus have been removed, and dura has been cut. Basilar apex and the interpeduncular and prepontine cistern are adequately exposed. (Images courtesy of E de Oliveira)