Articular disc

Articular Disc

The articular disc is a fibrocartilaginous structure found in several synovial joints in the human body. It plays a crucial role in joint function by improving the fit between articulating bone surfaces, distributing loads, and aiding in joint stability and movement.

Structure

The articular disc is composed of dense fibrous connective tissue, which is primarily made up of collagen fibers. This structure is avascular and aneural, meaning it lacks blood vessels and nerves, which contributes to its limited healing capacity. The disc is typically biconcave in shape, allowing it to conform to the contours of the joint surfaces.

Function

The primary functions of the articular disc include:

• **Load Distribution**: The disc helps to evenly distribute the forces exerted on the joint, reducing stress on the articular cartilage and underlying bone.
• **Joint Stability**: By improving the congruency between the joint surfaces, the disc enhances joint stability and reduces the risk of dislocation.
• **Shock Absorption**: The fibrocartilaginous nature of the disc allows it to absorb compressive forces, protecting the joint from impact-related damage.
• **Facilitation of Movement**: The disc allows for smooth movement by reducing friction between the articulating surfaces.

Locations

Articular discs are found in several key joints, including:

• **Temporomandibular joint (TMJ)**: The disc in the TMJ separates the joint into two compartments, allowing for complex movements such as opening, closing, and lateral excursions of the jaw.
• **Sternoclavicular joint**: The disc in this joint helps to stabilize the connection between the clavicle and the sternum, allowing for a wide range of shoulder movements.
• **Distal radioulnar joint**: The triangular fibrocartilage complex (TFCC) includes an articular disc that stabilizes the distal ends of the radius and ulna, facilitating forearm rotation.

Clinical Significance

Damage or degeneration of the articular disc can lead to joint dysfunction and pain. Common conditions associated with articular disc issues include:

• **Temporomandibular joint disorder (TMD)**: Displacement or degeneration of the TMJ disc can cause pain, clicking, and limited jaw movement.
• **Osteoarthritis**: Degeneration of the articular disc can contribute to the development of osteoarthritis in affected joints.
• **Injuries**: Trauma to joints with articular discs can result in tears or displacements, leading to instability and pain.

Related Pages

• Synovial joint
• Fibrocartilage
• Temporomandibular joint disorder
• Triangular fibrocartilage complex