The external carotid artery is the major

artery An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

of the head and upper neck. It arises from the

common carotid artery In anatomy, the left and right common carotid arteries (carotids) () are artery, arteries that supply the head and neck with oxygenated blood; they divide in the neck to form the external carotid artery, external and internal carotid artery, inte ...

. It terminates by splitting into the superficial temporal and

maxillary artery The maxillary artery (eg, internal maxillary artery) supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible. Structure The maxillary artery, the larger of the two terminal branches ...

within the parotid gland.

Structure

Origin

The external carotid artery arises from the

just inferior to the upper border of the thyroid cartilage. At its origin, this artery is closer to the skin and more medial than the internal carotid, and is situated within the carotid triangle.

Course and fate

It curves to pass anterosuperiorly before inclining posterior-ward to reach the space posterior the neck of the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

, where it divides into the superficial temporal and

within the parotid gland. It rapidly diminishes in size as it travels up the neck, owing to the number and large size of its branches.

Relations

At the origin, external carotid artery is more medial than

internal carotid artery The internal carotid artery is an artery in the neck which supplies the anterior cerebral artery, anterior and middle cerebral artery, middle cerebral circulation. In human anatomy, the internal and external carotid artery, external carotid ari ...

. When external carotid artery ascends the neck, it lies more lateral than internal carotid artery. The external carotid artery is covered by the skin, superficial fascia, platysma muscle, deep fascia, and anterior margin of the sternocleidomastoid; it is crossed by the hypoglossal nerve, by the lingual, ranine, common facial, and superior thyroid veins; and by the digastricus and stylohyoideus muscles; higher up it passes deeply into the substance of the parotid gland, where it lies deep to the

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of ta ...

and the junction of the temporal and internal maxillary veins. Medial to it are the

hyoid bone The hyoid-bone (lingual-bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid-cartilage. At rest, it lies between the base of the mandible and the third cervical verte ...

, the wall of the

pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

, the superior laryngeal nerve, and a portion of the parotid gland. Posterior to it, near its origin, is the superior laryngeal nerve; and higher up, it is separated from the internal carotid by the styloglossus and stylopharyngeus muscles, the

glossopharyngeal nerve The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper Medulla oblongata, medulla, just anterior (closer to the nose) to t ...

, the pharyngeal branch of the vagus, and part of the parotid gland.

Branches

As the artery travels upwards, it gives the following branches: * In the carotid triangle: ** Superior thyroid artery, arising from its anterior aspect ** Ascending pharyngeal artery - arising from medial, or deep, aspect ** Lingual artery - arising from its anterior aspect ** Facial artery - arise from its anterior aspect ** Occipital artery - arising from its posterior aspect ** Posterior auricular artery - arising from posterior aspect The external carotid artery terminates as two branches: *

Maxillary artery The maxillary artery (eg, internal maxillary artery) supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible. Structure The maxillary artery, the larger of the two terminal branches ...

* Superficial temporal artery

Anastomoses

The superior thyroid artery anastomoses with inferior thyroid artery, where the latter arises from thyrocervical trunk of the subclavian artery. Terminal branch of facial artery anastomose with ophthalmic artery of

. Posterior auricular artery anastomose with occipital artery, another branch of external carotid artery. One of the branches of superficial temporal artery anastomose with lacrimal and palpebral branches of ophthalmic artery.

Development

In children, the external carotid artery is smaller than the internal carotid; but in the adult, the two vessels are of nearly equal size.

Diagnostics

Left external carotid artery with normal spectral doppler

The condition and health of the external carotid arteries is usually evaluated using Doppler ultrasound, CT angiogram or phase contrast magnetic resonance imaging (PC-MRI). Typically, blood flow velocities in the external carotid artery are measured as peak systolic velocity (PSV) and end diastolic velocity (EDV). PSV values greater than 200 cm/s are considered to be predictive of more than 50% of external carotid artery stenosis.

Additional images

File:External carotid artery with branches.jpg, Branches of external carotid artery File:mra1.jpg,

Magnetic resonance angiography Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate ...

References

External links

* * ()
Diagram at umich.edu
{{DEFAULTSORT:External Carotid Artery Arteries of the head and neck Otorhinolaryngology