The International RLN Anatomic Classification System

With this chapter we offer an anatomy-based classification system of recurrent laryngeal nerve (RLN); a classification that embraces normal anatomy as well as embryological and acquired sources of variation in the trajectory of the right and left RLN in human neck. We endeavor to put forth a classification system that encompasses all of the above sources of variations and is simple and surgically relevant so that it is maximally valuable to the surgeon during thyroidectomy. This classification system relates to the path/trajectory of the main trunk of the RLN. We appreciate that specific interactions between the nerve and the thyroid gland occur at the tubercle of Zuckerkandl (described in Chap. 9), ligament of Berry (described in Chap. 10) and with the inferior thyroid artery (described in Chap. 7). The surgical approach to the nerve can be conceptualized in a number of different ways and this is detailed in Chap. 13. In this chapter both the basic classification of RLN surgical anatomic path in the neck base as it relates to the thyroid surgery as well as vagal carotid sheath anatomy are described.