Combined Action of Laryngeal Muscles

Abstract

In the lightly halothane anesthetized dog the cricothyroid and posterior crico-arytenoid muscles are active simultaneously. With electrical stimulation of the cricothyroids, laryngeal resistance is increased and cross sectional area of the larynx decreased. With electrical stimulation of the posterior crico-arytenoids, laryngeal resistance is decreased and cross sectional area of the larynx increased. Stimulation of the cricothyroid and posterior crico-arytenoid muscles simultaneously results in an even lower airway resistance and an even larger cross sectional area than the posterior crico-arytenoid muscles can accomplish alone. This synergism is described and illustrated.