Superior thyroid artery
The superior thyroid artery (Latin: arteria thyreoidea superior) is a branch of the external carotid artery arising from its anterior surface. The superior thyroid artery supplies the thyroid gland, the infrahyoid neck muscles, tissues of the upper part of the larynx, as well as the sternocleidomastoid and cricothyroid muscles.
The superior thyroid artery is the first branch of the external carotid artery, arising just below the level of the greater horn of the hyoid bone. Then it descends along the lateral border of the thyroid gland, where it divides into many branches to supply the gland.
The superior thyroid artery in its course gives off the following branches:
- infrahyoid artery,
- superior laryngeal artery
- sternocleidomastoid artery,
- cricothyroid artery.
The infrahyoid artery passes along the lower border of the hyoid bone below the thyrohyoid muscle and anastomoses with the same artery of the contralateral side to supply the infrahyoid muscles of the neck.
The superior laryngeal artery goes along with the internal laryngeal nerve piercing the thyrohyoid membrane to supply blood to the tissues of the upper part of the larynx. It anastomoses with its fellow artery of the opposite side and with the inferior laryngeal branch of the inferior thyroid artery.
The sternocleidomastoid artery runs downward and laterally across the carotid sheath to supply the middle region of the sternocleidomastoid.
The cricothyroid artery crosses the anterior cricothyroid ligament to supply the cricothyroid muscle.
The thyroid has a rich blood supply; therefore, during thyroidectomy, the superior thyroid artery requires ligation; otherwise, it will bleed profusely.