Overview

At the bifurcation the external carotid lies in front of and medial to the internal carotid. It ascends through the carotid triangle, passes deep to the posterior belly of digastric and to stylohyoid, and enters the parotid gland. Behind the neck of the mandible it divides into its two terminal branches.

Surgeons and sonographers tell the two carotid arteries apart in the neck by their branches. The external carotid has branches; the internal carotid has none.

The territories of the two external carotids, and of the external and internal carotid systems, are linked by many anastomoses. One external carotid can therefore be tied off without causing tissue death.

Anatomy

Branches: In order: the superior thyroid artery; the ascending pharyngeal artery; the lingual artery, at the greater horn of the hyoid, which runs deep to hyoglossus; the facial artery, which hooks over the mandible at the front edge of masseter; the occipital artery; the posterior auricular artery; the maxillary artery, the larger terminal branch, which gives the middle meningeal, inferior alveolar and sphenopalatine arteries; and the superficial temporal artery, the smaller terminal branch, whose pulse is felt in front of the tragus.

Function

Supplies the face, scalp, thyroid, larynx, tongue, pharynx, teeth, jaws, nasal cavity and most of the dura mater.

Clinical significance

Giant cell (temporal) arteritis

Giant cell arteritis is inflammation of the external carotid branches and other large arteries in people over 50. Symptoms include a tender superficial temporal artery, headache and jaw claudication, with a raised ESR and CRP. It is treated urgently with high-dose corticosteroids, because inflammation of the ophthalmic artery branches can cause permanent blindness.

Epistaxis

Most nosebleeds come from Kiesselbach's plexus (Little's area) on the anterior nasal septum. Here branches of both the external carotid (sphenopalatine, greater palatine and superior labial arteries) and the internal carotid (anterior ethmoidal artery) join. Posterior nosebleeds come from the sphenopalatine artery.

Facial and temporal pulses

The facial pulse is felt where the artery crosses the mandible at the front edge of masseter. The superficial temporal pulse is felt just in front of the tragus.

Mnemonics

Branches in order

"Some Anatomists Like Freaking Out Poor Medical Students": Superior thyroid, Ascending pharyngeal, Lingual, Facial, Occipital, Posterior auricular, Maxillary, Superficial temporal.

Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.