Inferior thyroid artery
The inferior thyroid artery (Latin: arteria thyreoidea inferior) is the largest branch of the thyrocervical trunk. It supplies several structures in the neck including the thyroid gland, the lateral muscles of the upper neck, as well as the larynx, pharynx, trachea, and esophagus.
The inferior thyroid artery passes upwards anterior to the scalenus anterior muscle and turns medially behind the carotid sheath. Reaching the base of the thyroid gland, it divides into superior and inferior branches that supply the posterior inferior parts of the thyroid gland. The superior branch of the inferior thyroid artery provides blood to the parathyroid glands as well. It also forms anastomoses with its contralateral fellow artery and with the superior thyroid artery.
The inferior thyroid artery on its course gives off the following branches:
- muscular branches,
- ascending cervical artery,
- inferior laryngeal artery:
- pharyngeal branches,
- tracheal branches,
- esophageal branches.
The muscular branches of the inferior thyroid artery supply the infrahyoid muscles, longus colli, scalenus anterior, and the inferior pharyngeal constrictor muscles.
The ascending cervical artery supplies the lateral muscles of the upper neck, and gives off one or two spinal branches that supply the spinal cord, meninges, and vertebral bodies.
The inferior laryngeal artery ascends on the surface of the trachea, entering the larynx at the lower border and supplying the laryngeal muscles, and mucosa.
The pharyngeal branches of the inferior thyroid artery supply the lower part of the pharynx.
The tracheal branches supply the trachea, while the esophageal branches of the inferior thyroid artery supply the esophagus.
Some thyroid diseases may require a surgery to remove the thyroid (thyroidectomy). As the recurrent laryngeal nerve runs close the inferior thyroid artery, during thyroidectomy the inferior thyroid arteries must be carefully tied off to avoid damage to the nerves.