The carotid arteries are major blood vessels in the neck that supply blood to the brain, neck, and face. There are two carotid arteries, one on the right and one on the left. In the neck, each carotid artery branches into two divisions:
The internal carotid artery supplies blood to the brain.
The external carotid artery supplies blood to the face and neck.
The common carotid artery is a paired structure.
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 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. There are studies in the bioengineering literature that have looked into characterizing the geometric structure of the common carotid artery from both qualitative and mathematical (quantitative) standpoints.
The average diameter of the common carotid for adult males and females is 6.5 mm and 6.1 mm respectively.
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.)