[Electromyographic study of human extrinsic laryngeal muscles]

Seven cases of human extrinsic laryngeal muscles were studied to determine the electrical activities during phonation, coughing, swallowing, fixation of thorax and respiration. The activities of these muscles all fired during phonation which were synchronous with discharge of the thyroarytenoid muscle (TAM) and increased with increasing volume of voice. They also fired during cough reflex and sphincteric action of larynx, and were basically synchronous with the TAM. They were weak during normal respiration. Although stronger electrical activities were recorded during inspiration in dyspnea, they were weaker than discharge during phonation, cough reflex and sphincteric action of larynx.