Temporomandibular disorders are a common subgroup of orofacial pain disorders, often referred to as "TMJ". TMD symptoms include pain or discomfort in or around the ear, jaw joint, and/or muscles of the jaw, face, temples, and neck on one or both sides. The pain may arise suddenly and progress with fluctuating frequency and intensity over months to years. Clicking, popping, grating (crepitus), locking, limited opening or deviating jaw movement, chewing difficulties, and headache are also associated with TMD.