Arising from the brachiocephalic trunk of the aortic arch, and the aortic arch itself, the common carotid arteries ultimately branch into the external and internal carotid arteries that provide the oxygenated blood supply to the neck and head. The right and left common carotid arteries, the right and left external carotid arteries, and the right and left internal carotid arteries form what anatomists term the carotid arterial system.

The common carotid arteries normally vary in origin. Although the right common carotid artery arises from the brachiocephalic artery, the left common carotid artery normally splits directly off the aortic arch. Normally the left common carotid branches from the highest point of the aortic arch near the junction of the neck and thorax. The common carotids then branch into the external and internal carotid arteries.

The respective external carotid arteries arising from the common carotid arteries supply blood...