抄録
The human intrinsic laryngeal muscles (ILMs) are highly specialized for phonation, respiration, and deglutition. Motor endplates (MEPs) and their arrangement in the muscles may be related to the specific function of the larynx. Histochemical techniques were used to determine the distribution of the MEPs in the human ILMs. MEPs of four sets of ILMs obtained from autopsy larynges were clearly visualized using acetylcholinesterase stains (Karnovsky's method & Namba's method). The human ILMs did not show a narrow-band pattern of MEPs which had been observed in the skeletal muscles of the extremities. MEPs were diffusely located throughout the whole length of the thyroarytenoid and lateral cricoarytenoid muscle. A wide-band pattern of MEPs was found in the middle two thirds of the cricothyroid muscle. MEPs in the posterior cricoarytenoid muscle were loosely arranged. In the interarytenoid muscle, MEPs were distributed in an inverted “Y” or fan-shape configuration. Some muscle fibers had more than one MEP, indicating possibilities of multiple innervation. The difference in distribution pattern of MEPs of the laryngeal muscles from that of the skeletal muscles may be attributed to physiological differences between the two muscle groups.
