Non-recurrent nerve from the vagus anterio-medially located in the carotid sheath.

Non-recurrent inferior laryngeal nerve (ILN) arising from the vagus nerve is a rare anatomic variation. The vagus descends vertically in the cervical neurovascular bundle, between and posterior to common carotid artery (CCA) and internal jugular vein (IJV). The vagus has also some anatomic variations. We present a case of two coincident anatomic variations both ILN and the vagus nerve. A patient with multinodular goiter was surgically treated with total thyroidectomy. Both two ILNs were identified, fully exposed and preserved along their cervical courses. We found that the right non-recurrent ILN directly arises from cervical vagal trunk, and enters the larynx at usual point after a short transverse course parallel to the inferior thyroid artery. The vagus nerve, easily exposed after dissection of the right lobe of the thyroid gland, is located medially to the CCA. We discovered the association of non-recurrent ILN and medially located vagus nerve in the same patient. Non-recurrent nerve and medially located vagus nerve in the cervical neurovascular bundle are two different variations. The coincidence of right non-recurrent ILN arising from cervical part of the vagus medial to the CCA in the same patient is a very interesting feature. The safety of thyroid operations is dependent on proper identification, dissection and full exposition of ILN. The safe procedure requires complete knowledge on the anatomy of neural structures including all their anatomic variations.