Terminologia Anatomica in 1998 subdivided the artery into four parts: "cervical", "petrous", "cavernous", and "cerebral". However, in clinical settings, the classification system of the<unk>  usually follows the 1996 recommendations by Bouthillier, describing seven anatomical segments of the<unk> , each with a corresponding alphanumeric 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<unk>  variants. An older clinical classification, based on pioneering work by Fischer, is mainly of historical significance.<unk>  The segments of the<unk>  are as follows: * Cervical segment, or C1, identical to the commonly used cervical portion * Petrous segment, or C2 * Lacerum segment, or C3 *C2 and C3 compose the commonly termed petrous portion * Cavernous segment, or C4, almost identical to the commonly used cavernous portion * Clinoid segment, or C5. This segment is not identified in some earlier classifications and lies between the commonly used cavernous portion and cerebral or supraclinoid portion. * Ophthalmic, or supraclinoid segment, or C6 * Communicating, or terminal segment, or C7 * C6 and C7 together constitute the commonly used cerebral or supraclinoid portion.
Internal carotid artery
Pontine arteries
Trigeminal artery
Ophthalmic artery
Lottery
Central retinal artery
Caliber persistent artery
Abbott's artery