Time sequence of the activity of the temporal and masseter muscles in healthy young human adults during habitual chewing of different test foods

Abstract

Surface electromyographic records of the masseter and temporal muscles were obtained from 20 healthy young adults during habitual chewing of carrots and crustless white bread, representing hard and soft foods. Chewing of hard food induced, in contrast to that of the soft, more vigorous jaw movements characterized by increased rate and shorter duration of chewing strokes as well as higher frequency and amplitude of spikes in each stroke. The masseter muscle was always first in contraction followed by the contraction of the anterior and then that of the posterior part of the ipsilateral temporal muscle. This delay was shorter in records taken during chewing of carrots than of white bread. There was marked variation between individuals, but chewing patterns, characteristic for each subject, could be recognized.