MEASUREMENT OF ADDUCTORY FORCE OF INDIVIDUAL LARYNGEAL MUSCLES IN AN IN-VIVO CANINE MODEL

In this experiment, the adductory properties of three intrinsic laryng eal muscles (the thyroarytenoid [TA], lateral cricoarytenoid [LCA], an d interarytenoid [IA]) were studied and quantified. Using an in vivo c anine laryngeal model, a recently developed ''tensionometer'' was used to measure the adductory force produced by each of these muscles at t he vocal process of the arytenoid. Isolated muscle activation was obta ined by stimulating selective terminal branches of the anterior divisi on of the recurrent laryngeal nerve. Results indicate that the LCA is the strongest adductory muscle, followed by the TA and the Ik Videolar yngoscopy revealed that LCA contraction causes adduction of the vocal fold and vocal process, with the predominant effect on the process. TA stimulation leads primarily to adduction of vocal fold, and the IA ad ducts mainly the vocal process. Implications of these findings are dis cussed.