TMJ is the first letters of the three anatomic parts of the head. T = Temporal bone (skull), M = Mandible (lower jaw), J = Joint (connects two bones together) and called temporo-mandibular-joint. 

TMJ has a dense anatomy of nerves, muscles, blood vessels, ligaments, tendons, sympathetic fibers, and synovial fluid within a small joint socket.  All body joints (hip, knee, wrist, ankle, finger etc.) have either hinge movement or circular movement, or a combination of the two.  However, TMJ has not only hinge and circular movement, but also has a sliding movement, which moves in and out of the joint socket.  There are two TM joints in the mandible but they move as one piece. Thus, if one joint is injured or out of its joint socket, the other joint will usually become affected. 

TMJs are associated with many small muscles and are held together by a group of ligaments.  These muscles and ligaments can be damaged and the disc can become displaced.  Like other joints of the body, the TM joints can experience similar diseases and injuries and are vulnerable to injuries.  If this delicate and sensitive joint complex receives constant distress, this can cause trauma and damage to the joint components, and eventually manifest various pain and dysfunctions to the body.

The function of the TMJ is to hold the jaw within a certain boundary and guide the jaw movement in chewing, talking, singing, yawning, and swallowing etc.  It also keeps open the airway for breathing while you are asleep.  TMJ may be the second most moving part in our body next to the heart.  An average person moves the TM joint 2,000-2,500 times a day and, if someone likes to talk excessively or chew gum, it may move 5,000 times or even 10,000 times a day.  Surprisingly, even with this much movement, the TM joint can function a lifetime with proper maintenance and balance. 

However, TMJ is the least respected joint in the human body because of a lack of understanding of its complex anatomical structure, complicated internal mechanical movements, mysterious influence to the body function and health, and difficulty in correcting, treating and managing it when it develops TMJ symptoms.