External carotid artery

At a glance

English

External carotid artery

Latin (TA2)

Carotis externa

System

Artery

Region

Head

Side

Paired, left and right

About the external carotid artery

The external carotid artery is the main artery of the face and of the outside of the head. It begins where the common carotid artery divides, usually at the level of the upper border of the thyroid cartilage (about the fourth cervical vertebra), and runs up to the region posterior to the mandibular neck. There, inside the parotid gland, it ends by dividing into the maxillary and superficial temporal arteries. It is slightly narrower than the internal carotid in childhood, whereas in adults the two are of similar size; the external carotid narrows quickly as it climbs because it gives off so many large branches.

At first it lies in the carotid triangle, more superficial and slightly anterior and medial to the internal carotid, covered by skin, platysma, deep fascia and the front edge of sternocleidomastoid. The hypoglossal nerve, the posterior belly of digastric, stylohyoid and several veins on their way to the internal jugular all cross it. Higher up it buries itself in the parotid gland, deep to both the facial nerve and the retromandibular vein. Between it and the internal carotid lie styloglossus, stylopharyngeus, the glossopharyngeal nerve and the vagal pharyngeal branch. Unlike the internal carotid, it has branches in the neck, which is the simplest way to tell them apart at surgery.

Its branches fall into groups. From the front come the superior thyroid, lingual and facial arteries; from the deep side, the ascending pharyngeal artery; and from the back, the occipital and posterior auricular arteries. The two terminal branches then serve the deep face and the side of the scalp. Between them they supply the thyroid, larynx, tongue, pharynx, face, teeth, nose, scalp and much of the dura.

Its many anastomoses across the midline and with the internal carotid and subclavian systems mean that it can be tied off to control severe bleeding from the face or nose without loss of tissue. These same links can act as a bypass to the brain when the internal carotid is blocked. Its branches are also the route for embolising tumours and vascular malformations of the head and neck.

Course and supply

Arises from

Common carotid artery at its bifurcation, near the upper border of the thyroid cartilage.

Ends in

Ends in the parotid gland posterior to the mandibular neck by dividing into the maxillary and superficial temporal arteries.

Supplies

Supplies the thyroid gland, larynx, pharynx, tongue, face, teeth, nasal cavity, scalp and much of the cranial dura through its eight branches.