Influences of swallowing volume and viscosity on regulation of levator veli palatini muscle activity during swallowing

Summary This study examined the aspect of the regulation of velum movement in the transition from the oral to pharyngeal phases of swallowing in relation to changes in the swallowing volume and viscosity by means of measurment of levator veli palatini muscle activity. The subjects were nine normal adults, ranging in age from 24 to 30 years. The swallowing volume was set at 1/4, 1/2 and 1 volume of the optimum volume of green tea for swallowing determined in each subject, and the viscosity was adjusted to 0, 2·0 and 4·6 Pa·s by mixing with thickener. Nine test foods were prepared in total. The electromyographic activity of the levator veli palatini muscle was monitored using bipolar hooked wire electrodes. The levator veli palatini muscle activity was defined as the integrated electromyographic wave. The mean in swallowing each test food was determined in each subject. The levator veli palatini muscle activity increased with the swallowing volume for all subjects (P