Thyroarytenoid intramuscular pressures.
The aim of this research has been to investigate the measurement of laryngeal intramuscular fluid pressures as a technique for assessment of laryngeal muscle activity for diagnostic or experimental purposes. Simultaneous measurements of contractile force, intramuscular fluid pressure, and electromyographic signals were made under isometric conditions in the vocal fold muscles of anesthetized dogs during supramaximal stimulation of the recurrent laryngeal nerve. Covariation of force and pressure was studied in twitch and tetanic contractions, over a range of stimulation frequencies. Tetanic pressure rises were usually smaller than in human limb muscles, but were of sufficient magnitude that effects on blood flow and muscle metabolism are probable. Analysis of relations between pressure and force records demonstrated that intramuscular pressure variations correlated closely to isometric force in their time course. This finding suggests the potential significance of this measure as a relatively nonintrusive indicator of the level of force of muscles involved in laryngeal function, and as a physiological measure of importance.