The common carotid arteries (CCA) are paired branchless arteries of the neck that supply blood to the head, face and neck. Each common carotid bifurcates into internal and external carotid arteries.

origin:
- left: branch of the aortic arch
- right: branch of the brachiocephalic trunk
course: posterior to sternoclavicular joint, lateral to thyroid and trachea
supply: head and neck
main branches: none (usually)
termination: at the carotid bifurcation approximately at the C4 level to form the external and internal carotid arteries
key relationships: internal jugular vein and vagus nerve

Gross anatomy

Origin and course

Although the left and right common carotid arteries follow the same course through the neck, their origin differs.

On the left, the common carotid arises directly from the aortic arch whereas, on the right, the origin is from the brachiocephalic trunk ¹⁰. The left common carotid artery can be thought of as having two distinct parts: thoracic and cervical. Since the right common carotid arises cranially, it only really has a cervical portion.

In the thoracic section, the left common carotid travels upwards through the superior mediastinum to the level of the left sternoclavicular joint where it is continuous with the cervical portion.

The cervical section of both common carotids follows a similar course. Each vessel passes obliquely upwards from behind the sternoclavicular joint to the level of the upper border of the thyroid cartilage, at approximately the C4 level ¹¹. In the lower neck, the two common carotid arteries are separated from each other by the trachea. However, as the carotids ascend in the neck, they diverge becoming separated by the thyroid gland, the larynx and pharynx.

Each common carotid is contained within the carotid sheath which is derived from all three layers of the deep cervical fascia. In addition to containing the common carotid artery, the sheath also comprises the internal jugular vein and vagus nerve: the vein lies lateral to the artery, with the nerve in between the two.

Variant anatomy

vertebral artery arising from the CCA ⁷
variable level of bifurcation
left common carotid arising from brachiocephalic artery, as in a bovine arch
hypoplastic internal or external carotid artery
single terminal branch
- other branch arising directly from aorta
- other branch absent
right common carotid gives rise to thyroidea ima artery

History and etymology

The word carotid in the sense of a major neck artery was first recorded in English in 1667, and ultimately derives from the Greek word κάρος (karos) meaning stupor, as compression of the vessel induced "sleep" ^8,9.