The cerebral part of carotid artery is the intradural segment. it extends from the exit of the ophtalmic artery to its division into the anterior and middle cerebral arteries. It includes these 3 last segment:
The clinoid segment, or C5, is another short segment of the internal carotid that begins after the artery exits the cavernous sinus at the proximal dural ring and extends distally to the distal dural ring, after which the carotid artery is considered 'intra-dural' and has entered the subarachnoid space. The clinoid segment normally has no named branches, though the ophthalmic artery may arise from the clinoid segment.
The ophthalmic segment, or C6, extends from the distal dural ring, which is continuous with the falx cerebri, to the origin of the posterior communicating artery. The ophthalmic segment courses roughly horizontally, parallel to the optic nerve which runs superomedially to the carotid at this point.The named branches of the ophthalmic segment are the ophthalmic artery and the superior hypophyseal artery.
The communicating segment, or terminal segment, or C7, of the internal carotid artery passes between the optic and oculomotor nerves to the anterior perforated substance at the medial extremity of the lateral cerebral fissure. Angiographically, this segment extends from the origin of the posterior communicating artery to the bifurcation of the internal carotid artery. The named branches of the communicating segment are the posterior communicating artery and the anterior choroidal artery.
This definition incorporates text from the wikipedia website - Wikipedia: The free encyclopedia. (2004, July 22). FL: Wikimedia Foundation, Inc. Retrieved August 10, 2004, from http://www.wikipedia.org