Intralaryngeal anatomy of the recurrent laryngeal nerve

Detailed anatomical knowledge of the intralaryngeal course of the recurrent laryngeal nerve (RLN) is critical for performing complex thyroid surgery, partial laryngeal surgery, and selective reinnervation of the larynx specifically for rehabilitation of bilateral vocal fold paralysis and laryngeal transplant. The RLN enters the larynx at the level of the cricopharyngeus where it can divide into an anterior (motor) branch and posterior (sensory) branch; the anterior branch, typically termed the inferior laryngeal nerve, divides into several branches to the laryngeal muscle. First, the nerve innervates the posterior cricoarytenoid muscle, then the interarytenoid muscle, followed by innervation of the lateral cricoarytenoid and thyroarytenoid muscles distally. The posterior cricoarytenoid, interarytenoid, and lateral cricoarytenoid nerves display the most variability from human to human. This variability makes it difficult to reinnervate the posterior cricoarytenoid muscle completely without inadvertently innervating the interarytenoid. The sensory nerves to the larynx are very variable and it is likely that there is significant overlap in the distribution from the recurrent and superior laryngeal nerves. There is also some compelling evidence that there is a motor connection from the superior laryngeal nerve to the laryngeal adductors known as the human communicating nerve, however, the significance of this is unknown.