The temporomandibular joint (TMJ) is one of the most complicated joints in your body. You have one on each side of your face, just in front of your ears, where the temporal bone of the skull connects to the lower jaw (mandible). Your TMJs open and close like a hinge and slide forward, backward, and from side to side. When you bite and chew, they sustain an enormous amount of pressure.
As with other joints, the surfaces of your TMJs are covered with cartilage. Like the knee joint, the two parts of the joint are separated by a small disc, or meniscus, that prevents the bones from rubbing against each other. Muscles that enable you to open and close your mouth also serve to stabilize these joints, which are located about ½ inch (1.25 cm) in front of each ear canal.
A range of problems can affect the TMJs and the muscles surrounding them. These problems usually occur between the ages of 20 and 50. Most often, the cause of TMJ is a combination of muscle tension, anatomical problems, and injury. Sometimes, there may be a psychological component as well.
Like all of your joints, your TMJ may develop osteoarthritis, rheumatoid arthritis, and other inflammatory conditions. In rare instances, tumours may develop in this area. But for most people, pain in the area of the TMJ isn't serious. Discomfort and pain may be temporary or chronic and sometimes goes away with little or no treatment.