Your jaw pain acts like a sliding hinge, allowing you to open and close your jaw. The bones of the joint have a cartilaginous covering with a shock-absorbing disc between them. This keeps the movement of the jaw smooth and unhindered.   Painful TMJ disorders may occur if: the disc erodes or moves out of its proper alignment arthritis occurs in the joint there is damage in the joint due to a blow or other impact   There are also some risk factors that make some people more likely to develop a TMJ disorder: various types of arthritis jaw injury long-term grinding or clenching of teeth certain connective tissue diseases