Synovium

Synovium

The Synovium, also known as the synovial membrane, is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath. It makes direct contact with the synovial fluid that lubricates the joints.

Structure

The synovium is a thin, two-layered membrane. The outer layer, or subintima, can be of almost any type of connective tissue, while the inner layer, or intima, consists of a sheet of cells thinner than a piece of paper. The cells of the intima are like fibroblasts, but they have surface features of epithelial cells.

Function

The synovium's main task is to make and maintain the synovial fluid, a viscous liquid that lubricates the joints and nourishes the cartilage. This fluid is an ultrafiltrate of blood, mixed with proteins secreted by the synovium. The synovium removes particles and cell debris from the synovial fluid as it circulates.

Clinical significance

Inflammation of the synovium, known as synovitis, can cause pain and swelling in joints. This is a common symptom in rheumatoid arthritis and other joint disorders. In these conditions, the synovium thickens and may invade the surrounding tissues, damaging the joint. Treatments aim to reduce inflammation and pain, and to preserve joint function.

See also

• Synovial joint
• Synovial fluid
• Synovitis
• Rheumatoid arthritis