TMJ refers to the Temporo-mandibular Joint, or jaw joint. You have a pair of these joints, one on each side of the head between the lower jaw (mandible) and the side (temporal) bone of the skull, just in front of the ear.The TMJ’s function is to allow the lower jaw to move so that you can chew and swallow, speak, yawn and do all the other normal jaw movements. This joint also allows you to clench and/or grind your teeth. The temporo-mandibular joint is a synovial joint and includes ligaments, tissue between the jawbone and the ear canal and a fibrous disc which sits between the head of the mandible (condyle) and the joint surface (articular surface) of the skull.
TMD stands for Temporo-Mandibular Disorders and includes a whole range of conditions which can affect the joint. Some clinicians will use the term TMJ to refer to these disorders.
The temporo-mandibular joint is different from the body’s other joints. The combination of hinge and sliding motions makes this joint among the most complicated in the body. Also, the tissues that make up the temporo-mandibular joint differ from other synovial joints, like the elbow or hip.
Because of its complex movement and unique makeup, the jaw joint, its associated muscles and other structures give rise to a variety of unique conditions as well as those conditions which can affect all the joints.