The temporomandibular joint (TMJ) is a common cause of facial pain and headache. Located where the lower jaw and skull meet, the TMJ is a ball and socket joint that allows the lower jaw (mandible) to move and function. Symptoms of TMJ disorders may include earaches, headaches and a limited range of jaw movement. Patients may also complain of clicking or grating sounds in the joint, or pain when opening or closing their mouths. Some patients experience a combination of muscle and joint problems. Causes of TMJ disorders include osteoarthritis, cartilage displacement or injury, rheumatoid arthritis, or stress.