TMJ is the abbreviation of Temporo-mandibular Joint, which is the joint that connects the jawbone to the skull. Every human has one of these joints on each side of the head, somewhere around the ear. Anything that you do to move your jaw requires these joints to function properly. That means you can’t eat, talk, or even smile and frown without functioning TMJ. Place your fingers in front of or inside the ear canals, try opening and closing your mouth to detect the movement of TMJ.
TMJ is a “loose-fitting”, rotating and sliding joint with a fibrocartilage covered, football shaped ball (condyle), fibrous pad (disc), fibrocartilage lined socket (fossa), ligaments, tendons, blood vessels and nerves. The disc functions as a moving shock absorber and stabilizer between the condyle and fossa. As the jaw opens, normally the condyle first rotates and then slides forward within the fossa with the disc between the condyle and the fossa. In normal, healthy joint, the condyle is positioned in the front lower portion of the fossa and the dis moves forward and backward together with the condyle. The area behind the condyle and in front of the ear is full of blood vessels and nerve terminals, which causes TMJ pains when compressed by a condyle that moves too far back during mouth closing.
The muscles of mastication (jaw muscles) attach to the mandible (lower jaw), maxilla (upper jaw), skull and neck. The muscles of mastication open, close, protrude and laterally move the jaw, enabling you to talk, chew, and swallow. The supporting muscles of mastication (neck and shoulder girdle muscles) stabilize the skull on the neck during jaw function. Dysfunction or spasm of these muscles is an important cause for TMD.