Among the most complex joints in the body are the two connecting your lower jaw to your skull. They slide and rotate in front of the ear, allowing the lower jaw, or mandible, to move up and down, side to side, and forward and back. Properly aligned, all this occurs without a hitch. When they’re out of alignment, watch out; you may be in for trouble, spelled TMD. The most common form of myofascial TMD is myofascial pain–discomfort in the muscles, and connective tissue covering the muscles, that control the jaw, neck, and shoulder. Another kind of TMD is internal joint derangement, which means a dislocated jaw, displaced disc–the cushion of cartilage between the jaw bone and skull–or injury to the jaw. And the third kind of TMD is degenerative joint disease, including osteoarthritis or rheumatoid arthritis in the jaw joint.