Abstract
The intrinsic laryngeal muscles (ILMs) play an important role in hightly specialized laryngeal functions. Morphological analysis was made to investigate histochemical properties compared with non-laryngeal skeletal muscles and to see if whether there were any reflections of physiological specialization in the structure of ILMs.
Forty-five ILMs from ten middle-aged male cadavers were removed and examined by using en-zyme histochemical methods. According to enzyme reactivities (mainly myosin ATPase), ILM fibers were classified into two types (type 1 and type 2 fibers in the skeletal muscle classification). Type 2 c fibers were identified, but type 2 fibers' subdivisions were not clear. In muscle fiber type composition, the thyroarytenoid muscle had the highest proportion of type 2 fibers, the posterior cricoarytenoid muscle had the highest proportion of type 1 fibers, and the other muscles had intermediate values. ILM fibers had more variability in size than skeletal muscles. ILM fiber size had difference among subjects, but not in the individual.
.These findings correspond to the development and speciality of physiological activity in human larynges.
