Most joints are synovial joints formed by a thin lining of synovium which secretes fluid into the joint (Figure 43.1). The joint is covered by a capsule. The synovium not only forms the lining of joints but also covers tendon sheaths and bursae.

The synovial membrane consists of an intimal layer and the subintimal supportive layer of fibrofatty tissue. The intima is 1-2 cell layers thick and composed of synoviocytes. About 90% are fibroblast-like but the other 10% have ultrastructural features of macrophages.

The space between the two articulating bone surfaces is occupied by articular hyaline cartilage (Figure 43.1). It is firm, pliable tissue and resists compressive forces. In young people it is bluish-white and translucent but in later life it becomes opaque and yellow. Cartilage is avascular and devoid of nerves and lymphatics, obtaining nutrients by diffusion from the surrounding synovial fluid.

Cartilage is rather poorly cellular tissue composed of chondrocytes laid down within a matrix or ground substance composed of collagen fibres and proteoglycans. The latter are complex biopolymers consisting of a central protein core with attached chains of carbohydrates. These proteoglycans include chondroitin sulphate and keratin sulphate and can absorb large volumes of water to form gels.


Synovial fluid

Figure 43.1. Synovial joint.

Articular cartilage

Joint capsule

Synovial membrane

Figure 43.1. Synovial joint.

Good Carb Diet

Good Carb Diet

WHAT IT IS A three-phase plan that has been likened to the low-carbohydrate Atkins program because during the first two weeks, South Beach eliminates most carbs, including bread, pasta, potatoes, fruit and most dairy products. In PHASE 2, healthy carbs, including most fruits, whole grains and dairy products are gradually reintroduced, but processed carbs such as bagels, cookies, cornflakes, regular pasta and rice cakes remain on the list of foods to avoid or eat rarely.

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