  the internal carotid artery is major paired artery, one on each side of the head and neck, in human anatomy. they arise from the common carotid arteries where these bifurcate into the internal and external carotid arteries; the internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as face, scalp, skull, and meninges. ==classification== terminologia anatomica in 1998 subdivided the artery into four parts: "cervical", "petrous", "cavernous", and "cerebral".  however, in clinical settings, the classification system of the internal carotid artery usually follows the 1996 recommendations by bouthillier, describing seven anatomical segments of the internal carotid artery, each with a corresponding alphanumberic identifier -- c1 cervical, c2 petrous, c3 lacerum, c4 cavernous, c5 clinoid, c6 ophthalmic, and c7 communicating. the bouthillier nomenclature remains in widespread use by neurosurgeons, neuroradiologists and neurologists. the segments are subdivided based on anatomical and microsurgical landmarks and surrounding anatomy, more than angiographic appearance of the artery. an alternative embryologic classification system proposed by pierre lasjaunias and colleagues is invaluable when it comes to explanation of many internal carotid artery variants. an older clinical classification, bas
Arteries_of_the_head_and_neck