TMJ is an acronym referring to the jaw joint. The muscles and jaw joint can become damaged for various reasons. For me, it was most likely from teeth clenching, especially at night when people tend to grind their teeth (the old "knashing of teeth" mentioned in the Bible). I now wear a mouth guard at night, but the symptoms are:
1. popping when you open/close the mouth.
2. pain in the joint and muscles.
3. tension in the joint and muscles.
4. pain in the ear (since the joint is next to the ear, it gets referred pain in the ear although the ear is fine).
5. pain in the teeth on that side of the mouth.
My case is "lite" because the muscles are mostly impacted. If the joint is damaged, there isn't a lot that can be done. Some folks kill themselves because the pain can be unimaginable. Isn't the human body wonderful?
I read a book that said doctors are beginning to think there is an irritable BODY symdrome, and that IBS and TMJ are just 2 manifestations of it.
Note: Burt Reynolds suffered from TMJ. His cause was being hit in the face by a stunt man during a movie. It damaged his joint so bad that for years his career suffered and he was on heavy drugs. He lost about 70 pounds and people were gossiping that he was dieing of AIDS. Eventually, I believe he had some sort of major surgery to put in a fake jaw joint, and I guess that helped. Whenever I see an old Western movie, and the guys are having a fist fight, I think "Every time a guy gets hit in the jaw like that (for real), they will suffer from TMJ for the rest of their lives". Of course, in movies every macho guy gets hit 30 times in the jaw and still can have a thick tough steak for dinner!