Common Carotid Arteries
In human anatomy, the left and right common carotid arteries are arteries that supply the head and neck with oxygenated blood; they divide in the neck to form the external and internal carotid arteries. The common carotid artery is a paired structure, meaning that there are two in the body, one for each half. The left and right common carotid arteries follow the same course with the exception of their origin. The right common carotid originates in the neck from the brachiocephalic trunk. The left arises from the aortic arch in the thoracic region. The bifurcation into the external and internal carotid arteries occurs at the upper border of the thyroid cartilage, at around the level of the fourth cervical vertebra (C4.) The left common carotid artery can be thought of as having two parts: a thoracic (chest) part and a cervical (neck) part. The right common carotid originates in or close to the neck, so contains a small thoracic portion.