Posterior cricoarytenoid muscle dynamics in canines and humans

Objectives/Hypothesis: The posterior cricoarytenoid (PCA) muscle is the sole abductor of the glottis and serves important functions during respiration, phonation, cough, and sniff. The present study examines vocal fold abduction dynamics during PCA muscle activation. Study Design: Basic science study using an in vivo canine model and human subjects. Methods: In four canines and five healthy humans vocal fold abduction time was measured using high-speed video recording. In the canines, PCA muscle activation was achieved using graded stimulation of the PCA nerve branch. The human subjects performed coughing and sniffing tasks. High-speed video and audio signals were concurrently recorded. Results: In the canines, the vocal fold moved posteriorly, laterally, and superiorly during abduction. Average time to reach 10%, 50%, and 90% abduction was 23, 50, and 100 ms with low stimulation; 24, 58, and 129 ms with medium stimulation; and 21, 49, and 117 ms with high-level stimulation, respectively. In the humans, 100% abduction times for coughing and sniffing tasks were 79 and 193 ms, respectively. Conclusions: The PCA abduction times in canines are within the range in humans. The results also further support the notion that PCA muscles are fully active during cough.