synovialmembranet

Synovialmembranet is not a standard anatomical term; this article summarizes the synovial membrane, or synovium, the soft tissue that lines the inner surface of diarthrodial joint capsules and covers intra-articular structures such as bursae and tendon sheaths. It is a highly vascularized, lubricating tissue essential for smooth joint movement.

Anatomically, the synovial membrane consists of two layers: the intima, or lining, and the subintima, a connective tissue layer. The intima contains two principal cell types: Type A synoviocytes, which resemble macrophages and help remove debris, and Type B synoviocytes, which are fibroblast-like and produce components of synovial fluid. The subintima houses blood vessels, nerves, and loose connective tissue with adipocytes and immune cells. The membrane is not a true epithelium and lacks a basement membrane in most regions.

Functionally, the synovial membrane secretes synovial fluid, a viscous lubricant rich in hyaluronic acid and proteoglycans, reducing friction between articular surfaces. The fluid nourishes avascular cartilage and lubricates the joint. The membrane also participates in immune surveillance and inflammatory responses, and can respond to injury or wear with changes in vascularity and cell activity.

Clinical relevance includes synovitis, which can occur in inflammatory and degenerative joint diseases such as rheumatoid arthritis and osteoarthritis. Chronic inflammation may lead to pannus formation and joint damage. Diagnostic assessment may involve imaging or biopsy to evaluate synovial thickening, effusion, or inflammatory activity.