Temporomandibular Joint Disc (TMJ Disc)
Feature of the temporomandibular joints. Articular disc composed of tissue like the firm and flexible elastic cartilage of the ear which is positioned between the two bones that form the joint. The disc divides each joint into two.
See also: How Joints Work
About the TMJ
The temporomandibular joint connects the lower jaw, called the mandible, to the bone at the side of the head – the temporal bone. If you place your fingers just in front of your ears and open your mouth, you can feel the joints. Because these joints are flexible, the jaw can move smoothly up and down and side to side, enabling us to talk, chew and yawn. Muscles attached to and surrounding the jaw joint control its position and movement.
When we open our mouths, the rounded ends of the lower jaw, called condyles, glide along the joint socket of the temporal bone. The condyles slide back to their original position when we close our mouths. To keep this motion smooth, a soft disc lies between the condyle and the temporal bone. This disc absorbs shocks to the jaw joint from chewing and other movements.
Also, the tissues that make up the temporomandibular joint differ from other load-bearing joints, like the knee or hip. Because of its complex movement and unique makeup, the jaw joint and its controlling muscles can pose a tremendous challenge to both patients and health care providers when problems arise. NIH – National Institute of Dental and Craniofacial Research