The articular disc is a plate of fibrocartilage that is present in movable joints in the body. It is thin and oval in shape. The articular disc separates synovial cavities and this allows separate movements in each cavity.
The fibrocartilagenous nature of the articular disc arises from the fact that it is a combination of fibrous and cartilaginous tissue. This offers flexibility and toughness due to the fibrous part and elasticity imparted by the cartilage part.
The articular disc aids in providing a more uniform and even distribution of forces between the articulating surface of bones. It also helps to stabilize a joint. It directs the flow of synovial fluid to those areas that experience maximum friction.
There are three major regions where the articular disc is present and is important. The first one being the articular disc of the distal radioulnar articulation. It is located in the forearm and involves the ulna and the radial bones. This is a triangular shaped fibrocartilage complex. At its apical end it joins the head of the ulna firmly with the radius at their distal end. The center is perforated. The margins are articulated to the wrists. Both surfaces are lined with synovial membrane.
The second articulation is the temporomandibular articular disc present in the jaw. The articular disc is present between the condyle of the mandible and the mandibular fossa which is a depression present in the temporal bone that articulates with the condyle. The upper surface that connects the fossa is partly concave and convex while the under surface is concave.
The third articulation is present in the shoulder as the sternoclavicular articulation. It is flat and nearly circular. It is present in between the clavicle and the sternum. At its upper end it is attached to the upper and posterior border of the clavicle. At its lower end it is attached to the first rib at its junction with the sternum.