TMJ stands for Temporomandibular Joint Disorder. This can be manifested in pain when you open your mouth wide or chew, as well as an audible pop when you open your mouth, locked jaw, and more. TMJ is caused by myofascial problems, dislocation, displaced discs, or a degenerative joint disease such as rheumatoid arthritis or osteoporosis. TMJ is often treated with chiropractic care, massage, hot/cold therapy, and exercise