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.

Dec. 13, 2012