Absence of the left inferior thyroid artery: clinical implications.

Dissection of an adult male cadaver revealed an absence of the left inferior thyroid artery; its usual area of distribution to the thyroid gland was supplied by the right inferior thyroid artery. Absence of the left inferior thyroid artery occurs in 1-6% of cases. The inferior thyroid artery arises commonly from the thyrocervical trunk, passes posterior to the carotid sheath and supplies the inferior pole of the corresponding lobe of the thyroid gland; its branches can course anterior or posterior to or between branches of the recurrent laryngeal nerve. During thyroid surgery it is imperative to identify the relationship of the inferior thyroid artery to the recurrent laryngeal nerve or to establish its absence because injury to the nerve can be a major complication; awareness of significant variations of the surgical anatomy of the thyroid gland is vital for preserving the integrity of important structures.