Temporomandibular Joint (Jaw Joint)

The temporomandibular joint is the name for the twin joints that connect the lower jaw to the skull. It functions like a rotational slip-joint that enables the heads of the joints of the lower jaw – the condyles – to achieve both rotational and translatory movement. The jaw joint is quite unique because it is the only joint in the human body whereby two joints are connected to the rigid lower jaw in such a way that movement in one joint is always accompanied by a corresponding movement in the other one.

The actual bony parts of the jaw joint are the two appendages of the lower jaw (Condyloid Process) and the joint cavities of the temporal bone (os temporale). The surfaces of the joints are covered by a hyaline cartilage.

The jaw joint is surrounded by a connective tissue. It is divided into an upper and lower compartment by a flexible pad – the disc. The disc consists of a fibrous tissue. It is almost round, thin in the middle and thick at the edges. With its biconcave shape it resembles a flattened red blood cell. This means that, no matter how the jaw moves, it remains connected with the joint heads (condyles) that fit exactly into the thin middle part of the discus. Each side of the disc overlaps the joint capsule. At the back, the joint capsule goes into the bilaminar zone that is bordered on the top and bottom by layers of strong connective tissue that enclose a loose connective containing blood vessels, nerves and fatty tissue.

The range of movement of the jaw joint is limited by the joint capsule and the adherent ligaments. The strongest of these ligaments is the short Ligamentum Laterale that stretches from the temporal bone to the joint appendages and acts as kind of lateral brace.

Interestingly, many doctors derive a special sensitivity to disorders and extensive diagnostics and therapy from the complex anatomy of the jaw joint. Actually, the jaw joint shows a great tolerance to changes in form and position. It functions very well and without  any great difficulty despite displaced disci, degenerated joint cartilage and even in case of a degenerative arthrosis. Therefore patients shouldn’t become confused because of drastic statements about their jaw joint given by doctors. The jaw joint shows a great tolerance even in case of severe changes in form which keeps on functioning perfectly.