External carotid artery and its branches
The external carotid artery is one of the two main divisions of the common carotid artery, which stems from the aortic arch on the left side and from the brachiocephalic trunk on the right side. The external carotid artery 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.
This article will discuss the course and the anatomy of the external carotid artery.
|Source||Common carotid artery (at the level of the thyroid cartillage in the larynx)|
Superior thyroid artery
Ascending pharyngeal artery
Posterior auricular artery
Superficial temporal artery
Mnemonic: Some Anatomists Like Freaking Out Poor Medical Students
Medially: Hyoid bone, wall of pharynx, superior laryngeal nerve, parotid gland
Laterally: Internal carotid artery, superior laryngeal nerve
Posterosuperiorly: Styloglossus muscle, stylopharyngeus muscle, glossopharyngeal nerve, pharyngeal branch of vagus nerve, parotid gland
Anteriorly: Skin, superficial fascia, platysma, deep cervical fascia, sternocleidomastoid muscle
Structures which cross over artery:
Nerves: Hypoglossal nerve, lingual nerve
Veins: Vena comitans of hypoglossal nerve, common facial vein, superior thyroid vein, temporal veins, maxillary veins
Muscles: Digastric muscle, stylohyoid muscle
(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|
- Borders and relations
- Carotid artery disease
Borders and relations
The lateral aspect of the external carotid artery is related to the internal carotid artery as it ascends towards the cranium.
Posteroinferiorly the external carotid artery is related to the superior laryngeal nerve. Posterosuperiorly the internal and external branches of the carotid artery are separated by the: styloglossus muscle, the stylopharyngeus muscle, the glossopharyngeal nerve (CN IX), the pharyngeal branch of the vagus nerve (CN X) and part of the parotid gland.
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 vein, superior thyroid veins, digastric muscle, the stylohyoid muscle, the parotid gland, the deep facial nerve, the temporal vein and the internal maxillary veins.
Superior thyroid artery
The superior thyroid artery is the first branch of the external carotid artery. It arises from the external carotid artery at the level of the hyoid bone.
The superior thyroid artery has several branches which include the superior laryngeal artery, arteries which supply the sternocleidomastoid, cricothyroid and infrahyoid muscles, as well as the anterior, posterior and lateral glandular branches.
You can remember the branches of the superior thyroid artery 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 arises from the medial surface of the external carotid artery between the internal carotid artery and pharynx to reach the base of the cranium. It is the smallest branch of the external carotid artery.
The ascending pharyngeal artery gives rise to the posterior meningeal artery, the inferior tympanic artery and several pharyngeal branches. Additionally, it gives off several unnamed branches which supply surrounding musculature.
Structures supplied by the ascending pharyngeal artery include the pharynx, soft palate, the ear, meninges, muscles of the neck (longus capitis, longus coli), the sympathetic trunk, the hypoglossal, glossopharyngeal and vagus nerves as well as some cervical lymph nodes.
The lingual artery arises from the anteromedial aspect of the external carotid artery at the level of the great cornu of the hyoid bone. It emerges from the external carotid artery between the superior thyroid and facial arteries and is divided into three parts according to the hyoglossus muscle.
The first part of the lingual artery courses medially within the carotid triangle of the neck. It ascends and descends to form a loop which is crossed by the hypoglossal nerve. The second part of the lingual artery courses along the superior border of the hyoid bone and passes between the hyoglossus muscle and middle constrictor muscle of the pharynx. The third part of the lingual artery is also known as the deep lingual artery. At the anterior border of the hyoglossus muscle, the deep lingual artery ascends between the genioglossus muscle medially and the inferior longitudinal muscle of the tongue laterally.
Throughout its course the lingual artery gives off several branches which include the dorsal lingual, sublingual and deep lingual branches. The lingual artery also gives off branches which form a rich anastomosis that supplies the musculature of the tongue. The lingual artery provides arterial supply to the tongue and floor of the mouth.
Learn everything about the tongue blood supply.
The facial artery emerges from the external carotid artery just above the lingual artery within the carotid triangle. Occasionally the facial artery will arise from a common trunk with the lingual artery. It travels in an anterosuperior direction, deep to the digastric and stylohyoid muscles, curving around the inferior border of the mandible to enter the face. It ascends along the angle of the mouth and passes deep to the zygomaticus major and risorius muscles, ascending along the lateral side of the nose before terminating at the medial angle of the orbit.
The facial artery gives rise to the following branches including the ascending palatine, submental, inferior and superior labial and angular arteries as well as tonsillar and glandular branches.
The facial artery supplies all structures in the face from the inferior border of the mandible anterior to the masseter muscle to the medial corner of the eye. It also supplies the soft palate, palatine tonsil, pharyngotympanic tube and submandibular gland.
The occipital artery arises from the posterior aspect of the external carotid artery. It courses posterior and superiorly, deep to the posterior belly of the digastric muscle. It passes between the transverse process of the atlas (C1) and the mastoid process of the temporal bone. It extends through the occipital groove of the temporal bone where it is joined by the greater occipital nerve. It pierces the investing layer of deep cervical fascia to ascend within the dense superficial fascia of the scalp.
Main branches of the occipital artery include the upper and lower sternoclediomastoid branches. Additionally the occipital artery gives off the auricular, mastoid, occipital, meningeal and descending branches.
The occipital artery supplies the sternocleidomastoid, trapezius and deep muscles of the neck as well as the meninges, pinna of the ear and mastoid air cells.
Posterior auricular artery
The posterior auricular artery arises from the posterior aspect of the external carotid artery, above the posterior belly of digastric. It ascends in the neck between the parotid gland and styloid process. It then travels in a groove which lies between the auricular cartilage and mastoid process of the temporal bone.
The posterior auricular artery gives off the stylomastoid and posterior tympanic arteries as well as auricular, occipital and parotid branches.
Within the neck the posterior auricular artery provides arterial supply to the digastric, stylohyoid and sternocleidomastoid muscles as well as the parotid gland. Within the head the posterior auricular artery supplies the extrinsic auricular muscles, the external acoustic meatus, the auricle, middle ear, facial nerve and mastoid air cells.
The maxillary artery is the larger of the two terminal branches and arises from the external carotid artery within the parotid gland. From the parotid gland, the maxillary artery passes anteriorly between the neck of the mandible and the sphenomandibular ligament to enter the infratemporal fossa. It then extends between the pterygoid muscles to enter the pterygopalatine fossa via the pterygomaxillary fissure.
The maxillary artery is divided into three parts according to its location. The first part is located between the neck of the mandible and sphenomandibular ligament. The second part is associated with the lateral pterygoid muscle while, the third part lies within the pterygopalatine fossa.
Branches of the first part include: the middle meningeal and inferior alveolar arteries as well as the smaller deep auricular, anterior tympanic and accessory meningeal arteries.
Branches of the second part include: the deep temporal, masseteric, buccal and pterygoid arteries.
Finally, branches of the third part include the posterior superior alveolar, infraorbital, pharyngeal, descending palatine and sphenopalatine arteries as well as the artery of the pterygoid canal.
Test your knowledge on the arteries of the head from a lateral view with this quiz.
Why not test yourself on the muscles innervated by the branches of the maxillary artery with flashcards?
Superficial temporal artery
The superficial temporal artery arises as the smaller terminal branch of the external carotid artery. It similarly arises within the substance of the parotid gland behind the neck of the mandible. It ascends from the parotid gland superficially alongside the auriculotemporal nerve to the scalp. It terminates by dividing into its terminal frontal and parietal branches.
Branches of the superficial temporal artery include the transverse facial, zygoaticoorbital and middle temporal arteries. Additionally it provides parotid, anterior auricular, occipital frontal and parietal branches.
The superficial temporal artery provides arterial supply to the skin and muscles of the side of the face and scalp. It also provides arterial supply to the parotid gland and temporomandibular joint.
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.
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