The electromyographic behavior of the thyroarytenoid muscle during swallowing.

The electromyographic (EMG) behavior of the laryngeal adductors (e.g., the thyroarytenoid [TA] muscle) during swallowing has been scarcely studied. However, the detailed analysis of TA muscle is important to understand the physiology of swallowing. We investigated 14 healthy adult subjects. Activation of the TA laryngeal adductor muscle was compared with the mechanically measured laryngeal up-down movement and with the onset of excitation of laryngeal elevators, such as submental (SM) muscles, during swallowing. The laryngeal adductor of TA and laryngeal elevators of SM muscles were electromyographically (integrated/rectified) recorded. The vertical laryngeal movements during swallowing were recorded using a piezoelectric sensor. The EMG behavior of the TA muscle revealed three different activities during swallowing. The basic activity was stable; it almost started with the upward movement of larynx and after the SM-EMG onset. A fore-burst was recorded just before the upward movement of the larynx and a late-burst appeared just after the downward movement. The fore-burst was proposed to be related with oral-laryngeal reflexes, and the late-burst could be a rebound activity after a short expiration of swallowing, while the basic activity is accepted to be a part of activity of central-pattern generator of swallowing program.