Common carotid artery

The common carotid artery is a major artery in the neck that supplies oxygenated blood to the head and neck. It is one of the principal blood vessels responsible for cerebral and facial perfusion. Each side of the body has one common carotid artery, which eventually bifurcates into the internal and external carotid arteries.

Location

The common carotid arteries ascend vertically within the neck on either side of the trachea and esophagus, within the carotid sheath. They lie medial to the internal jugular vein and anterior to the vagus nerve. They are located deep to the sternocleidomastoid muscle and are palpable in the lower anterior neck.

Origin

• Right common carotid artery: Arises from the brachiocephalic trunk posterior to the right sternoclavicular joint.
• Left common carotid artery: Arises directly from the arch of the aorta in the thorax and ascends into the neck.

Course

Both arteries travel superiorly through the neck inside the carotid sheath. They remain unbranched until they reach the level of the C3–C4 vertebra (upper border of the thyroid cartilage), where each bifurcates into:

• Internal carotid artery – supplies the brain, eyes, and forehead
• External carotid artery – supplies the face, scalp, jaw, and neck structures

Carotid Sheath Contents

The common carotid artery lies within the carotid sheath along with:

• Internal jugular vein (lateral)
• Vagus nerve (CN X) (posterior)

Carotid Body and Carotid Sinus

Carotid Sinus

• Located at the bifurcation of the common carotid artery
• Contains baroreceptors that monitor blood pressure
• Innervated by the glossopharyngeal nerve (CN IX)

Carotid Body

• Located near the carotid sinus
• Contains chemoreceptors sensitive to blood oxygen, carbon dioxide, and pH levels
• Innervated by branches of CN IX and CN X

Branches

The common carotid artery does not give off any branches in the neck. It bifurcates into:

• External carotid artery – gives off several branches to the face, scalp, and upper neck
• Internal carotid artery – ascends into the skull to supply intracranial structures

Relations

• Medial: Trachea, esophagus, larynx, thyroid gland
• Lateral: Internal jugular vein
• Posterior: Vagus nerve, sympathetic trunk
• Anterior: Sternocleidomastoid muscle, infrahyoid muscles

Blood Supply and Drainage

• Supplied by: Aortic arch (left) or brachiocephalic trunk (right)
• Drained by: Venous return through internal jugular vein and then into the brachiocephalic vein

Innervation

• Carotid sinus: Glossopharyngeal nerve (CN IX) via the sinus nerve
• Carotid body: Glossopharyngeal and vagus nerves (CN IX and X)

Clinical Relevance

• Carotid pulse: The common carotid artery pulse can be palpated between the trachea and sternocleidomastoid muscle at the level of the thyroid cartilage.
• Carotid stenosis: Narrowing due to atherosclerosis can reduce cerebral perfusion and increase stroke risk.
• Carotid endarterectomy: A surgical procedure to remove plaque and restore blood flow through the internal carotid artery.
• Carotid dissection: A tear in the vessel wall can lead to thrombosis or embolism, potentially causing stroke.
• Carotid sinus hypersensitivity: Exaggerated baroreceptor response may cause syncope from sudden drops in heart rate and blood pressure.