[Masticatory muscles. Part IX. Pain in the jaw muscles]

Masticatory muscle pain is considered as a local expression of myofascial pain. The relationship with Myofascial Pain Syndrome and Fibromyalgia is not well understood. Muscle pain is generated through nociceptors served by small-diameter fibres, where processes of sensitization and neurogenic inflammation are important. In contrast to the 'vicious circle' concept, limitation of movement and loss of muscular power seem to be the result of the pain (pain-adaptation model). The diagnosis of muscle pain is made by algometry, while treatment should be simple, reversible and non-invasive.