TMJ is a short form for Temporomandibular joint (TMJ) syndrome, which is a condition where the joint is injured, displaced or damaged leading to a localized pain.
In TMJ Syndrome, the muscles of the jaw may be pulling forcefully against the bones and teeth. There are a host of causes including: injury to the teeth or jaw, misalignment of the teeth, teeth grinding, poor posture, stress, arthritis, and gum chewing. Each case is different and physical examination of the head, face, neck and jaw, can help in diagnosis.