Rheumatoid Arthritis-An Ailment Which Cripples the Whole World

Joints:
Normal structure:

Joints are of 2 types-diarthrodial or synovial joints with a joint cavity and synarthrodial or nonsynovial joint without cavity. Most of the diseases of joints affect diarthrodial or synovial joints. In diarthrodial joints, the ends of two bones are held together by joint capsule with ligaments and tendons inserted at outer surface of the capsule. The articular surfaces of bones are covered by hyaline cartilage, which is thicker in weight bearing areas than in nonweight bearing areas. The joint space is lined by synovial membrane or synovium, which forms synovial fluid that lubricates the joint during movements. The synovium may be smooth or thrown into numerous folds and villi. The synovial membrane is composed of inner layer of 1 to 4 cell thick synoviocytes and outer layer of loose vascular connective tissue. On electron microscopy, two types of synoviocytes are distinguished: type A and B. Type A synoviocytes are more numerous and are related to macrophages and produce degradative enzymes, while type B synthesize hyaluronic acid.