TMJ - Temporomandibular Joint
TMJ describes the joint where the bottom jaw and base of the skull meet. If you have a problem in this area it is now common to describe this as TMD, tempromandibular dysfunction. The position of the joint is just in front of the ear on both sides of your head.
This is a very complex and controversial subject. Briefly stated, there is a piece of tissue call "the disk" that separates the very top of the lower jaw (mandibular condyle), from the base of the skull (glenoid fossa). When the disk is displaced or changes for whatever reason, you can have a multitude of symptoms ranging from joint noise (popping and clicking), muscle stiffness and pain, tooth pain, grinding of the teeth, and bite changes. The mandibular condyle can change shape and be the source of the problem as well.
Other possibilities causing pain can include many other systemic medical problems like arthritis. There are also studies that now show that if the disk looks healthy and you are in overall good health that you can harbor bacteria in the tissues around the disk and need antibiotic treatment.