Читать книгу Musculoskeletal Disorders - Sean Gallagher - Страница 110

Diarthroses are designed for movement and include all synovial joints. These are the most common types of joints and are defined as two or more bones whose ends are covered by hyaline cartilage, united by a fibrous tissue capsule that encloses the joint, and separated by a joint cavity. The cavity is filled with synovial fluid produced by a synovial membrane (a vascular connective tissue) lining the interior of the fibrous capsule. The synovial membrane cells produce and secrete synovial fluid, a lubricant that provides a smooth, nearly frictionless, gliding motion of opposing joint surfaces. The synovial fluid also nourishes the articular (hyaline) cartilage covering the bones. This type of joint allows the most movement, although lower stability. As a consequence, extrinsic and intrinsic ligaments usually reinforce synovial joints. Some synovial joints also have other distinguishing features such as menisci, labrums, or fibrocartilage articular discs that allow for shock absorption and/or additional stability. Nearly all of the joints of the upper and lower limbs are synovial.