Superior Thyroid Artery Originating from the Ascending Pharyngeal Artery

Abstract

Background: The superior thyroid artery generally originates from the anterior surface of the external carotid artery. The superior thyroid artery originating from the ascending pharyngeal artery is an extremely rare anatomic variation. Nevertheless, some variations in the origin of the superior thyroid artery have been reported in the literature. Such knowledge is important during neck surgeries such as thyroidectomy and radical neck dissection. Here we report the first case of a superior thyroid artery arising from the ascending pharyngeal artery. Case report: During a routine dissection on the neck, a superior thyroid artery originating from the ascending pharyngeal artery was observed on the right side, in a 37-year-old male cadaver. The superior thyroid artery had two segments, a superior (or horizontal) segment and an inferior (or vertical) segment. The superior segment passed posterior to the linguofacial trunk. The inferior segment passed posterior to the superior laryngeal artery and an artery that went to the infrahyoid muscles. These last two arteries came directly from the external carotid artery. The superior thyroid artery terminated in two branches (one lateral and one medial) 6 mm above the superior pole of the right thyroid lobe. Conclusion: The origin of the superior thyroid artery from the ascending pharyngeal artery is an extremely rare anatomical variation. A thorough knowledge of the variations in origin of the superior thyroid artery is decisive for head and neck surgeries.