Common carotid artery
Arteria carotis communis
Also known as: CCA, carotid artery
The common carotid artery is the main artery of the neck on each side. It ascends in the carotid sheath and divides at the upper border of the thyroid cartilage (about C3–C4) into the internal and external carotid arteries.
Overview
Origin. The right common carotid artery arises from the brachiocephalic trunk behind the right sternoclavicular joint. The left arises directly from the aortic arch, so it is longer and has a short thoracic segment.
Course. Each artery runs up the neck inside the carotid sheath. The internal jugular vein lies lateral to the artery, and the vagus nerve lies behind and between the two. The ansa cervicalis lies in the front wall of the sheath, and the sympathetic trunk lies behind it. The artery gives off no branches until it divides.
Bifurcation. At the upper border of the thyroid cartilage the artery divides into the internal and external carotid arteries. At the division, the beginning of the internal carotid widens into the carotid sinus, a baroreceptor. In the fork between the two branches lies the carotid body, a chemoreceptor.
Pulse and landmarks. The carotid pulse is felt at the anterior border of sternocleidomastoid at the level of the thyroid cartilage. Lower down, the artery can be compressed against the carotid tubercle of C6 (Chassaignac tubercle).
- Location
Anterior neck, in the carotid sheath, from behind the sternoclavicular joint to the upper border of the thyroid cartilage.
Anatomy
- Branches
Only its two terminal branches: the internal and external carotid arteries.
- Relations
In front: sternocleidomastoid, the infrahyoid muscles and the superior belly of omohyoid, which crosses the artery at C6. Medially: the trachea and oesophagus, the larynx and pharynx, the thyroid lobe and the recurrent laryngeal nerve. Laterally: the internal jugular vein. Behind: the vagus nerve, the sympathetic trunk and the prevertebral muscles.
Function
- Carries the main arterial supply to the head and neck, including about 70–80% of the blood supply to the brain (via the internal carotid arteries).
- Houses the carotid sinus baroreceptor and the carotid body chemoreceptor at its bifurcation.
Clinical significance
Carotid atherosclerosis and stroke
Turbulent flow at the bifurcation promotes plaque at the origin of the internal carotid. Plaque fragments can embolise, causing transient ischaemic attacks, amaurosis fugax and stroke. A bruit may be heard over the artery. Carotid endarterectomy or stenting helps patients with symptoms and a stenosis of 70% or more, and selected patients with 50–69%.
Carotid pulse assessment
The character of the carotid pulse is useful at the bedside. It is slow-rising in aortic stenosis, collapsing in aortic regurgitation and bisferiens (double-peaked) in mixed aortic valve disease.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.