Microsurgical anatomy of intralaryngeal distribution of the inferior laryngeal nerve.

The functional results of a partial laryngeal surgery or a laryngeal reinnervation depend on the precise knowledge of the intra laryngeal anatomy of the inferior laryngeal nerve (ILN). Ten human larynges without known laryngeal disorders were obtained from human cadavers for ILN microdissection. Intra laryngeal ILN branching patterns were determined bilaterally. The lengths of the vertical, genu and oblique segments of the anterior division of ILN and the distance between the nerve within the paraglottic space and the cricothyroid articulation (CTA) were measured with a digital microcaliper. The mean lengths of the vertical, genu and oblique segments were 10.82, 5.89 and 9.29 mm, respectively. The mean distance between the nerve in the paraglottic space and the CTA was 11.20 mm. Key anatomical landmarks of the abductor division (vertical and genu segments of ILN) were the lateral border of posterior cricoarytenoid (PCA) muscle and the superior ligament of the CTA. The two-branch pattern for the lateral border of the PCA muscle has been the most frequent (50%). A branch of interarytenoid muscle (IA) originated from the genu segment. One or two branches for the PCA muscle has been identified in 75% of cases from the IA neural plexus on the front side of PCA muscle. The adductor division for the thyroarytenoid muscle and the lateral cricoarytenoid muscle was the oblique segment of the nerve. We conclude that abductor and adductor divisions of intra laryngeal ILN can be readily identified and the knowledge of key landmarks allows preservation of the ILN during partial surgery of the larynx and possibly selective muscle reinnervation.