Activity of temporal and lip muscles during swallowing and chewing.

The activity of the anterior and posterior portions of the temporal muscle and in the upper and lower lips were studied electromyographically in 50 girls, aged 9-13 years with normal occlusion. The recordings were made during swallowing of water, saliva, apple and peanuts as well as during chewing of apple and peanuts. The maximal mean voltage amplitudes during swallowing varied notably with the test medium and were larger for solid than for fluid media. The amplitudes were the same for both portions of the temporal muscle, but always greater for the lower lip than for the upper. Many girls swallowed fluid media without demonstrable activity of the anterior portion of the temporal muscle, while absence of demonstrable activity in the lips was rare. No correlation was found between the degree of activity of the lips during swallowing of fluid and solid substances. The amplitudes during chewing were the same for both portions of the temporal muscle, but larger for the lower lip than for the upper. The amplitudes found for the two portions of the temporal muscle and for the upper and lower lips were intercorrelated both during swallowing and chewing. No correlation was found between the amplitudes from the lower lip and from the temporal muscle during swallowing. The amplitude from the upper lip during swallowing was correlated only with that from the posterior portion of the temporal muscle. Palpation of muscular activity of the temporal muscle during swallowing is of little or no value for estimating the degree of activity of the lip during swallowing. [ABSTRACT FROM AUTHOR]