External carotid artery and its branches

Author: Alexandra Sieroslawska MD • Reviewer: Dimitrios Mytilinaios MD, PhD
Last reviewed: December 21, 2020
Reading time: 7 minutes

The external carotid artery is one of the two main divisions of the common carotid artery. It stems from the aortic arch on the left side and from the brachiocephalic trunk on the right side. it climbs the lateral sides of the neck within the carotid sheath, which is found just behind the sternocleidomastoid muscle.

The carotid bifurcation occurs at the level of the thyroid cartilage in the larynx. The external carotid artery is the only division of the common carotid that gives branches to the neck region and supplies the external structures of the head and face.

Key facts
Source	Common carotid artery (at the level of the thyroid cartillage in the larynx)
Branches	Superior thyroid artery Ascending pharyngeal artery Lingual artery Facial artery Occipital artery Posterior auricular artery Maxillary artery Superficial temporal artery Mnemonic: Some Anatomists Like Freaking Out Poor Medical Students
Supplies	(S): Thyroid gland, infrahyoid muscles, sternocleidomastoid muscle (A): Pharynx, prevertebral muscles, middle ear, cranial meninges (L): Intrinsic muscles of the tongue, floor of the mouth (F): Tonsils, palate, submandibular glands (O): Posterior region of the scalp (P): Parotid gland, facial nerve, ear, scalp (M): External acoustic meatus, tympanic membrane, dura mater, calvaria, mandible, gingivae, teeth; temporal, pterygoid, masseter, buccinator muscles (S): Temporal region of the scalp
Clinical relations	Carotid artery disease, atherosclerosis

This article will discuss the course and the anatomy of the external carotid artery.

Contents

Borders and relations
Branches
Mnemonics
Carotid artery disease

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Borders and relations

Medially the hyoid bone, the wall of the pharynx, the superior laryngeal nerve and the parotid gland surround the artery. Laterally, the internal carotid artery passes by in the initial phase of the external carotid artery, along with the superior laryngeal nerve posteroinferiorly.

Posterosuperiorly however, the internal and external branches of the carotid are separated by the: styloglossus muscle, the stylopharyngeus muscle, the glossopharyngeal nerve (CN IX), the pharyngeal branch of the vagus nerve (CN X), part of the parotid gland.

Anteriorly, the artery is covered by the skin, the superficial fascia, the platysma, the deep cervical fascia and the sternocleidomastoid muscle.

The nerves, vasculature and musculature that cross over the external carotid artery during its journey include the: hypoglossal nerve (CN XII), lingual nerve, ranine vein, the common facial nerve, superior thyroid veins, digastric muscle, the stylohyoid muscle, the parotid gland, the deep facial nerve, the temporal vein, internal maxillary veins.

Borders and relations
Medially	Hyoid bone Wall of the pharynx Superior laryngeal nerve Parotid gland
Laterally	Internal carotid artery, superior laryngeal nerve
Posterosuperiorly	Muscles: styloglossus, stylopharyngeus Nerves: glossopharyngeal nerve, pharyngeal branch of the vagus nerve Parotid gland
Anteriorly	Skin, superificial fascia, platysma, deep cervical fascia, sternocleidomastoid muscle
Structures that cross over the artery	Nerves: hypoglossal nerve, lingual ranine, common facial Veins: ranine, superior thyroid veins Muscles: digastric muscle, stylohyoid muscle

Branches

The external carotid artery has eight branches: the Superior thyroid, Ascending pharyngeal, Lingual, Facial, Occipital, Posterior auricular, Maxillary and Superficial temporal arteries. You can easily remember them with the mnemonic Some Anatomists Like Freaking Out Poor Medical Students'.

Superior thyroid artery

The superior thyroid artery (S) is the origin of the superior laryngeal artery that supplies the larynx. The main artery also supplies the thyroid gland, infrahyoid muscles and the sternocleidomastoid muscle. You can remember this by using the mnemonic "I Shall Squeeze Charlie's Glutes", which stands for the branches of the superior thyroid artery; Infrahyoid, Superior laryngeal, Sternocleidomastoid, Cricothyroid and Glandular.

Ascending pharyngeal artery

The ascending pharyngeal artery (A) ascends superiorly along the pharynx, while branching off to the pharynx, prevertebral muscles, the middle ear and the cranial meninges.

Lingual artery

The lingual artery (L) is covered by the hypoglossal nerve (CN XII), the stylohyoid muscle and the posterior belly of the digastric muscle. It runs beneath the hyoglossus muscles and branches into the deep lingual and sublingual arteries which supply the intrinsic muscles of the tongue and the floor of the mouth.

Learn everything about the tongue blood supply.

Facial artery

The facial artery (F) runs around the middle of the mandible before it enters the face, where it gives branches to the tonsils, palate and the submandibular glands.

Occipital artery

The occipital artery (O) supplies the posterior region of the scalp and grooves the base of the skull as it travels. Initially it passes deep to the posterior belly of the digastric muscle.

Posterior auricular artery

The posterior auricular artery (P) runs behind the external acoustic meatus and the mastoid process, separating the two structures. It supplies the adjacent musculature, the parotid gland, the facial nerve (CN VII), the ear and the scalp.

Maxillary artery

The maxillary artery (M) is the larger of the two terminal branches which can precede one another depending on which anatomist you ask. Its branches supply:

the external acoustic meatus
the tympanic membrane
the dura mater
the calvaria
the mandible
the gingivae
the teeth
the temporal muscle
the pterygoid muscle
the masseter muscle
the buccinator muscle

Why not test yourself on the muscles innervated by the branches of the maxillary artery with flashcards?

Superficial temporal artery

The superficial temporal artery (S) supplies only the temporal region of the scalp, as it is the smaller terminal branch and does not have additional named branches or divisions.

Superficial temporal artery (lateral-right view)

Mnemonics

If one looks back to the section of this article termed ‘Branches’, each major artery has been assigned a letter, which corresponds to the first letter of a word in each mnemonic. The order of arteries listed corresponds to the order they branch off from the external carotid artery as it ascends and follows the order of the words in each mnemonic. There are three different mnemonics, of which only one is needed in order to remember the branches.

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Carotid artery disease

Carotid artery disease is a disorder of the common carotid artery or either of its main divisions. It occurs when plaque like growths start to form in these major arteries and limit the amount of blood that flows to the head and neck region. This ailment can become extremely serious, because it can cause ischemia to vital organs such as the brain and it also increases the risk of clot formation.

The best way to treat and also avoid the buildup of arterial plaque is to minimize the risk of it forming in the first place by eating a healthy and well balanced diet, engaging in regular physical activity and avoiding situations where chronic stress is a major factor.