Blood Supply of the Thyroid The blood supply of the thyroid gland comes from two sources. The superior thyroid artery arising from the external carotid artery. The inferior thyroid artery arises from the thyrocervical trunk which is a branch of the subclavian artery. Both vessels divide into anterior and posterior branches. The anterior division of the superior artery anastomoses with the anterior division of the inferior thyroid artery. The posterior divisions create the same anastomosis posteriorly. Courtesy: Ashley Davidoff, MD