The Synovial Membrane
Definition
Is the soft tissue found between the articular capsule (joint capsule) and the joint cavity of synovial joints.
Synovial fluid is the clear, viscid, lubricating fluid secreted by synovial membranes.
Morphology
Consists of two layers :-
The outer layer, or subintima,
The inner layer, or intima
The layers seal the synovial fluid from the surrounding tissue
Effectively stop the joints from being squeezed dry when subjected to impact, as while running.
The intimal cells are synoviocytes and are of two types, fibroblastic (type B synoviocytes) and macrophagic (type A synoviocytes)
Type B synoviocytes manufacture a long-chain sugar polymer called hyaluronan & lubricin, which lubricates the joint surfaces.
The macrophages are responsible for the removal of undesirable substances from the synovial fluid.
The surface of synovium may be flat or may be covered with finger-like projections (villi),
Just beneath the intima, most synovium has a dense net of small blood vessels that provide nutrients for synovium and the avascular cartilage.
Applied Anatomy
Synovitis - inflammation
Synovioma - cancer of the synovium
Joint effusion - excessive secretion of synovial fluid
