D, Superior view of the cavernous sinus with the anterior clinoid process and roof removed. The roof of the sinus extends back-ward from the area below the anterior clinoid process, which has been removed, into the area be-tween the middle fossa and sella and posteriorly, to the area lateral to the dorsum sellae. The lateral wall of the cavernous sinus, in which the oculomotor, ophthalmic, and trochlear nerves course, has been retracted laterally to show the lower margin of the sinus from inside. E, Enlarged view of the sinus opened from above. Numerous ostia of veins drain the surrounding areas, which open into the cavernous sinus (arrows). The ophthalmic artery enters the optic canal. F, The cavernous sinus shown in C and D is viewed from laterally. The pins have been inserted along the lower edge of the interior of the sinus shown in E. The lower edge of the sinus is located medial to the upper third of Meckel’s cave and trigeminal ganglion and extends for-ward below the ophthalmic nerve, but does not include the area of the maxillary nerve. G, Lateral view of the specimen shown in C. A segment of the oculomotor, trigeminal, trochlear, and abducens nerves has been removed. The arrows have been placed along the lower margin of the dural envelope forming the lower margin of the cavernous sinus. The cavernous sinus does not extend laterally to the mandibular and maxillary nerves, but extends down to just below the carotid sulcus on the body of the sphenoid bone. (Images courtesy of AL Rhoton, Jr.)