Association of Jaw and Neck Muscle Coordination with Jaw Opening Activity while Chewing in Healthy Individuals

This study was performed to evaluate the association of jaw and neck muscle coordination with jaw movement activity in order to clarify the relationships of electromyogram（EMG）-EMG findings showing coherence between jaw and neck muscle activities and jaw movement activities while chewing in healthy individuals. Sixteen subjects performed gum chewing, with EMG signals in the jaw and neck muscles and jaw movements were simultaneously recorded. Coherence between jaw and neck muscle activities and jaw movements while chewing, as well as first peak frequency of the power spectrum, was analyzed while left and right side chewing using EMG-EMG coherence function analysis. Those results were used to evaluate the relationship of jaw and neck muscle activities with jaw movements while rhythmical chewing. The results suggest a positive correlation between jaw and neck muscle activity coherence and jaw opening activities while chewing, which was especially evident in non-chewing side neck muscle recordings. Considering findings of previous qualitative evaluation suggested coordinated jaw and head movement activities and enlarged jaw opening activity induced by large-food chewing, present study may suggest the association of quantitative synchrony between jaw closing and non-chewing side neck muscle activities with jaw opening activity while chewing performance in healthy individuals.