The Relationship Between the Non-recurrent Laryngeal Nerve and the Inferior Thyroid Artery.

The non-recurrent inferior laryngeal nerve (NRLN) represents a risk factor for nerve injury during thyroid surgery. The aim of this study is to investigate the traveling patterns of NRLNs and its relationships to inferior thyroid arteries (ITAs). We had 11 patients showing NRLNs on the right side who underwent thyroidectomies. The NRLNs were classified into four different types, according to the traveling patterns. We evaluated the anatomical position of the ITA as follows: (1) three types according to the joint location with the thyroid gland; and (2) three types according to the level of the retro-esophageal subclavian artery (RSA). The traveling patterns of NRLN could be classified into four types, descending, vertical, ascending, and V-shaped. ITA was joined variably with the thyroid gland on the superior, middle, and inferior positions. The levels of the RSA were also located at different positions, the first thoracic vertebra, the second vertebra, and the third vertebra. During thyroid surgery, the surgeon must be aware of the existence of anatomical variations of NRLNs and ITAs. The anatomy of the NRLN and the ITA are frequently irregular, and there is no correlation between the traveling pattern of NRLN and the level of the RSA.