Variability of the nerve supply patterns of the human posterior cricoarytenoid muscle.

Abstract

To achieve a successful selective reinnervation of the larynx, an accurate knowledge of the nerve supply of each individual muscle is required. The posterior cricoarytenoid muscle, the only abductor or respiratory muscle of the larynx, plays a vital role in cases of recurrent palsy and orthotopic transplantation. Descriptions of the posterior cricoarytenoid muscle nerve supply pattern vary considerably. The goal of the present study was to establish an accurate morphological description of the posterior cricoarytenoid muscle nerve supply in a large sample of human larynges. Morphologic study of human larynges. The posterior cricoarytenoid muscle nerve supply was studied in a total sample of 75 human larynges obtained from necropsies (47 male and 28 female samples; age range, 41-95 y) and examined by careful dissection using a surgical microscope. The posterior cricoarytenoid muscle nerve supply in all cases (100%) came from the anterior division of the recurrent nerve. However, in six cases (4%) a small branch also arose from the ramus anastomoticus. The number of branches coming from the anterior division varied, ranging from one to six. The two-branch pattern was the most frequent (42.7%), followed by the three-branch pattern (34%) and the one-branch pattern (7.3%). The remaining 16% of cases showed patterns of four, five, or six branches. When two or more branches were present, a connection between them was observed in 64% of cases. Five different types of origin of the various branches were observed along the course of the recurrent nerve in relation to the cricothyroid joint: type a, vertical segment below the cricothyroid joint (7.5%); type b) vertical segment behind the cricothyroid joint (40.5%); type c) vertical segment just above the cricothyroid joint (16%); type ) from the genu, in common with the arytenoid branch, above the cricothyroid joint and just below the cricoarytenoid joint (34%); and type e) oblique segment (2%). Despite the variability of the innervation of the posterior cricoarytenoid muscle and its strong connection with the interarytenoid nerve, this should not preclude successful reinnervation.