The external carotid arteries supply oxygenated blood to the head region. There is one external carotid artery on the right side of the neck and one on the left side of the neck.

Each begins at the common carotid artery and moves up the neck until it divides into the superficial temporal artery and the maxillary artery. The occipital artery, posterior auricular artery, facial artery, superior thyroid artery, and maxillary artery all branch off from the external carotid artery. These arteries supply blood to the thyroid, larynx (voice box), salivary glands, tongue, nose, oral area, neck, face, ears, and lower portions of the skull.

The external carotid artery is sometimes affected by carotid artery disease, which is caused by a buildup of plaque. The plaque buildup causes decreased blood flow to the brain that can lead to a stroke. Often, no symptoms of carotid artery disease occur before the stroke. Carotid artery disease is the underlying cause of approximately half of all stroke cases in the United States.