The masticatory muscles are the muscles that the body uses to chew and include the bite, temporal, internal and external pterygoid muscles. The masticatory muscles are usually stronger and more powerful than the expression muscles and are paired left and right. The supraglossal muscles are also part of the masticatory muscles, and the body can only complete a complete chewing motion with the help of the masticatory muscles. If there is a masticatory muscle dysfunctional disease, including myofasciitis, myositis, myospasm, etc., there may be one or more localized masticatory muscle persistent pain, especially when chewing with the mouth open, the pain will be significantly increased, there will also be open mouth distortion. This situation should be treated promptly to avoid affecting the function of chewing.