• The vast majority of the so-called joint seen by clinicians involve muscle pain or tenderness, clicking, and limitation of mandibular movement, due to muscle fatigue or spasm; these painful conditions of the masticatory or cranium stabilizing muscles with alteration in mandibular function have been referred to as a myofascial pain dysfunction syndrome (MPDS) I. J', and may be described as an extracapsular disorder. It must be differentiated from intracapsular problems and therefore should not be classified as a temporomandibular joint disorder per se. The characteristic symptoms arise from the muscles of mastication, primarily the lateral pterygoids and masseters, along with the temporalis and medial pterygoids in various combinations. Although patients' complaints center around the jaw and sometimes include the ear, examination frequently discloses more extensive involvement of the musculature. Patients may exhibit tenderness to palpation of muscles in the neck, shoulders and arms, as far peripherally as the forearms.