Problems with the jaw joints, muscles or nerves can all cause pain. Long-lasting jaw pain may indicate a temporomandibular joint (TMJ) disorder, also called myofascial pain disorder. TMJ disorder pain can affect either or both sides of the face. The temporomandibular joint is made up of bones, muscles, ligaments and discs. It's a complex system that lets us talk, chew and even yawn. If any part of the system isn't working right, you can feel pain.