The Innervation of the Human Larynx

To investigate the gross anatomy of the recurrent and superior laryngeal nerves (RLNs and SLNs) in 10 human larynges. Whole larynges were processed to clear all soft tissue while leaving nerves stained. Then the main laryngeal nerves and the muscles they innervate were dissected and analyzed. It was found that in all larynges the RLNs and SLNs are connected by nerve branches other than Galen's anastomosis. The most consistent connection is in the interarytenoid muscle, where RLNs and internal SLNs combine in a neural plexus. A less consistent connection occurs in the piriform fossa, where a continuation of the external SLN passes from the cricothyroid muscle to the thyroarytenoid muscle. Based on these findings it is proposed that there are significant neural connections between the RLN and SLN systems. In addition, limited cross-innervation is seen from side to side in the area of the interarytenoid muscle. Other findings concern the innervation patterns within the laryngeal muscles. The posterior cricoarytenoid, cricothyroid, and thyroarytenoid muscles all appear to be composed of separate bellies based on the configuration of their nerve supply. Most notable is the region of the thyroarytenoid muscle at the vocal cord margin that is innervated by a nerve plexus of extreme complexity. The details of the innervation patterns suggest functional differences within and between laryngeal muscles.