The temporomandibular joint (TMJ) combines a hinge action with sliding motions. The parts of the bones that interact in the joint are covered with cartilage and are separated by a small shock-absorbing disk, which normally keeps the movement smooth.
Painful TMJ disorders can occur if:
- The disk erodes or moves out of its proper alignment
- The joint's cartilage is damaged by arthritis
- The joint is damaged by a blow or other impact
In many cases, however, the cause of TMJ disorders isn't clear.