Synovium
The thin membrane lining the inside of joint capsules that produces synovial fluid. Inflammation of the synovium (synovitis) is a key feature of many arthritic conditions.
Extended Definition
The synovium (also called synovial membrane) is a specialized connective tissue that lines the inner surface of joint capsules, tendon sheaths, and bursae. It consists of two layers: an inner layer of synoviocytes (specialized cells) and an outer layer of loose connective tissue.
Key Functions
- Produces synovial fluid - The synoviocytes secrete hyaluronic acid and lubricin, which give synovial fluid its viscous, lubricating properties
- Nourishes cartilage - Since cartilage has no blood supply, it depends on nutrients diffusing from synovial fluid
- Removes debris - Macrophage-like cells in the synovium clear cellular debris and waste from the joint space
- Maintains joint homeostasis - Regulates the chemical environment within the joint
Clinical Significance
In osteoarthritis, the synovium can become inflamed (synovitis), contributing to pain and joint damage. Hyaluronic acid injections work in part by supplementing the synovium’s natural HA production, which decreases with age and arthritis.
Related Terms
More Anatomy Terms
View allAcetabulum
The cup-shaped socket of the pelvis that holds the head of the femur (thigh bone) in the hip joint.
Articular Cartilage
The smooth, white tissue covering the ends of bones in joints. Its breakdown is the primary feature of osteoarthritis.
Bursae
Small, fluid-filled sacs that act as cushions between bones, tendons, and muscles near joints, reducing friction during movement. Singular form is 'bursa.'
Bursa
Small, fluid-filled sacs that cushion bones, tendons, and muscles near joints. Bursitis (inflammation of a bursa) can cause joint pain similar to arthritis.
Cartilage
A smooth, rubbery connective tissue that covers and protects the ends of bones where they meet to form joints, allowing them to glide smoothly during movement.