The inferior thyroid artery is the largest branch of the thyrocervical trunk. This artery supplies several structures in the neck, including the thyroid gland, lateral muscles of the upper neck, larynx, pharynx, trachea and esophagus.

The inferior thyroid artery arches 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 also provides arterial blood supply to the parathyroid glands. Also, this artery forms anastomoses with its contralateral fellow artery and with the superior thyroid artery.

Branches

On its course, the inferior thyroid artery gives off the following branches:

The muscular branches of the inferior thyroid artery supply the infrahyoid muscles, longus capitis muscle and longus colli muscle, anterior scalene muscle 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. Alternatively, it may arise from the thyrocervical trunk.

The inferior laryngeal artery ascends on the surface of the trachea, entering the larynx at its lower border and supplying the laryngeal muscles and laryngeal mucosa.

The pharyngeal branches of the inferior thyroid artery supply the lower part of the pharynx.

The tracheal branches supply the cervical part of the trachea, and the esophageal branches of the inferior thyroid artery provide blood supply to the cervical part of the esophagus.

Clinical note: Some thyroid gland diseases may require surgery to remove the thyroid (this procedure is called thyroidectomy). The recurrent laryngeal nerve (a branch of the vagus nerve (CN X)) runs close to the inferior thyroid artery, and during thyroidectomy, these arteries must be carefully tied off to avoid damage to the nerves.

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Inferior thyroid artery