The temporal manibular joint (or TMJ for short) is the joint between the manidbular bone (or jaw bone) and the temporal bone, one of the three bones that make up the skull. It lies just at the base of the outside of your ear.
Everytime you chew or speak, you use this joint. It is one of the most used, and also most powerful, joints in the human body. It is also a source of a great deal of trouble for some people.
The joint itself is a ball like joint, where the anchor of the jaw fits into a small groove on the temporal bone. There is a thin disk of cartilage that allows the jaw to slide back and forth in the groove.
If for some reason, due to either acute trauma, or a chronic condition, this cartilage wears thin, or the bones are snapped a little out of place, every movement of the jaw causes extreme pain. Eating, speaking and even breathing can be painful activities. And since this joint also lies to such structures as the trigeminal nerve, the carotid artery, the eustachian tube and the superficial temporal artery, the inflamation coming from a disorder here can cause all sorts of problems. The pain associated with TMJ is said to rival that of a migraine.