any structural anomaly of the bilaterally paired branched arteries that deliver oxygenated nutrient filled blood from the heart to the head, neck, and brain; of the two common carotid arteries, which extend headward on each side of the anterior neck, the left originates in the arch of the aorta over the heart; the right originates in the brachiocephalic trunk, the largest branch from the arch of the aorta; each common carotid artery divides into an external and an internal carotid artery near the top of the thyroid