G, The posterior clinoid process has been removed to increase access to the upper portion of the basilar artery. H, The anterior part of the tentorial edge has been removed to expose the upper margin of the posterior trigeminal root in Meckel’s cave and to provide increased access to the upper anterior part of the posterior fossa. The trochlear nerve was preserved in opening the anterior part of the tentorial edge. I, Another dissection in which the anterior clinoid process and roof of the cavernous sinus were removed to expose the posterior clinoid process in the interval between the carotid anteriorly and the oculomotor posteriorly. J, The posterior clinoid was removed to provide increased access to the upper part of the basilar artery. (Images courtesy of AL Rhoton, Jr.)