The external carotid artery is the major artery of the head and upper neck. It arises from the common carotid artery. It terminates by splitting into the superficial temporal and maxillary artery within the parotid gland.

Structure

Origin

The external carotid artery arises from the common carotid artery just inferior to the upper border of the thyroid cartilage.

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 and the junction of the temporal and internal maxillary veins.

Medial to it are the hyoid bone, the wall of the pharynx, 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 pharyngeal branch of the vagus, and part of the parotid gland.

Branches

thumb|Branches of external carotid artery.

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
  • Superficial temporal artery

Anastomoses

The superior thyroid artery anastomoses with inferior thyroid artery, where the latter arises from thyrocervical trunk of the subclavian artery.

PSV values greater than 200 cm/s are considered to be predictive of more than 50% of external carotid artery stenosis.

Additional images

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

File:mra1.jpg|Magnetic resonance angiography

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References

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  • Diagram at umich.edu