Comparison of video-recorded laryngeal movements during swallowing by normal young men with piezoelectric sensor and electromyographic signals.

The movement of the larynx in five young men during the swallowing of a liquid was examined by simultaneously recording a video-movie, the trajectory of a piezoelectric sensor, and the surface electromyogram of the suprahyoid muscles (SH). The movies revealed swallowing was associated with four characteristic spatial points of laryngeal movement: (1) a slight movement in the superior posterior direction (1.9 +/- 1.2 s; mean +/- SD of the time elapsed after the command to swallow was issued); (2) the initiation of anterosuperior elevation (2.3 +/- 1.3 s); (3) the turn at the highest position (3.2 +/- 1.2 s); and (4) the return to the initial position (4.1 +/- 1.4 s). The piezoelectric sensor and the SH electromyogram also detected characteristic temporal points that closely corresponded to the characteristic temporal points captured by the video. The advantages of using movies in swallowing research are discussed.