Posterior Cricoarytenoid Bellies: Relationship Between Their Function and Histology

Objectives/Hypothesis. Complete physiological information about human posterior cricoarytenoid muscle (PCA) is essential and is not only of basic science interest but also could lead directly to understanding phonation and many clinical issues in neurolaryngology. The purpose of the study was to investigate and compare the histochemical and morphological properties to know contractile muscle fiber characteristics of two bellies of the PCA. Study Design. Cross-sectional experimental study. Methods. The PCAs were harvested from the total laryngectomy simples. Serial transverse sections of the two PCA bellies were performed and studied by immunohistochemical analysis. Results. Two separate muscle bellies were always identified within 15 PCA. The following muscle fiber types were observed: I, I-IIA, and IIA. Comparisons of the vertical and horizontal bellies of the PCA reveled differences in the fiber-type composition. Conclusion. In our experience, the PCA should be considered as a combination of two functional subunits, which significantly differ in their muscle fiber-type composition.