[The role of the cricopharyngeal muscle in phonation]

Intraluminal esophageal manometry has been employed to study cricopharyngeal muscular function at different pitch levels. The activity of the cricopharyngeal muscle (CP) increases continually with rising pitch but is not influenced by the vocal sound pressure level. In the lower part of the chest register, the muscular pressure is lower than the pharyngo-esophageal pressure at rest. At high pitch levels, the pressure is higher than during swallowing. The CP has a dual function: With increasing pitch, the CP cooperates synergistically with the cricothyroid muscle (CT), indicated by increasing muscular pressure in the upper esophageal sphincter. On the other hand, the CP shortens the vocal cords by rotating the cricoid cartilage in anterior direction, thus acting antagonistically to the CT.