Donald S. Cooper PhD, Maisie Shindo MD, Malcolm H. Hast PhD
Uttam Sinha MD, Dale H. Rice MD

The aim of this research was to investigate the contractile properties of the posterior cricoarytenoid (PCA) muscle. Simultaneous measurements were made of the isometric force, temperature, and electromyographic activity of the dorsal cricoarytenoid muscle of anesthetized dogs during supramaximal stimulation of the recurrent laryngeal nerve for twitch and tetanic contraction. The conduction delay between stimulation of the recurrent nerve at the level of the larynx and the onset of the muscle action potential averaged 2.0 plus or minus 0.2 milliseconds (ms), and the latent period between the onset of electrical activity of the muscle and the onset of contraction had a mean duration of 3.3 plus or minus 0.8 ms. The mean of isometric contraction times found was 33.3 plus or minus 2.0 ms, shorter than most previous studies of canine PCA muscle. Tetanic frequency defined as smooth contraction was higher than previous estimates. Considerations of scaling of physiological time based on animal mass were applied to analysis of the experimental findings to make possible systematic comparison of previous findings across species and animal size.