synovial fluid

(noun)

A viscous, non-Newtonian fluid found in the cavities of synovial joints. With its yolk-like consistency, its principal role is to reduce friction between the articular cartilage of synovial joints during movement.

Related Terms

(noun)

A viscous fluid found in the cavities of synovial joints that reduces friction between the articular cartilage during movement.

Related Terms

Examples of synovial fluid in the following topics:

  • Structure of Synovial Joints

    • Synovial fluid is the clear, viscid, lubricating fluid secreted by synovial membranes.
    • The main structural differences between synovial and fibrous joints are the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within those capsules (synovial cavities).
    • The water component of synovial fluid is effectively trapped in the joint space by the hyaluronan due to its large, highly negatively charged moieties.
    • The macrophages are responsible for the removal of undesirable substances from the synovial fluid.
    • The synovial bursa is a small, fluid-filled sac lined by synovial membrane containing synovial fluid.

  • Bursitis

    • Bursitis, the inflammation of bursae (small sacs) of synovial fluid, impedes the movement of muscles and tendons over joint bones.
    • Bursitis is the inflammation of one or more bursae (small sacs) of synovial fluid in the body .

  • Bursae and Tendon Sheaths

    • Joints are cushioned by small fluid-filled sacs called bursae and stabilized by tough bands of fibrous connective tissue called tendons.
    • Synovial joints are made up of five classes of tissues: bone, cartilage, synovium, synovial fluid, and tensile tissues composed of tendons and ligaments.
    • The synovial lining in the bursae and tendon sheaths, similar to that within joints, is a slippery, non-adherent surface allowing movement between planes of tissue.
    • Synovial tendon sheaths line tendons only where they pass through narrow passages or retinacula, as in the palm, at the wrist, and around the ankle.
    • A bursa (plural bursae) is a small, fluid-filled sac lined by synovial membrane with an inner capillary layer of fluid (synovial fluid) with the consistency of raw egg white.

  • Synovial Membranes

    • A synovial membrane is the soft tissue found between the articular capsule (joint capsule) and the joint cavity of synovial joints.
    • The synovial membrane (or synovium) is the connective tissue which lines the inner surface of the capsule of a synovial joint and secretes synovial fluid which serves a lubricating function, allowing joint surfaces to smoothly move across each other.
    • The type B synoviocytes manufacture a long-chain sugar polymer called hyaluronan, which makes the synovial fluid together with a molecule called lubricin, which lubricates the joint surfaces.
    • The water component of synovial fluid is effectively trapped in the joint space by the hyaluronan, due to its large, highly negatively charged moeties.
    • The type A synoviocytes are responsible for the removal of undesirable substances from the synovial fluid.

  • Structural Classification of Joints

    • They have a lesser range of movement than synovial joints.
    • These joints (also called diarthroses) have a synovial cavity.
    • Synovial cavities are filled with synovial fluid.
    • The knees and elbows are examples of synovial joints.
    • This diagram of a synovial joint delineates the articular cartilage, articular capsule, bone, synovial membrane, and joint cavity containing synovial fluid.

  • Synovial Joint Movements

    • Synovial joints allow an individual to achieve a wide range of movements.
    • Synovial joints achieve movement at the point of contact of the articulating bones.
    • The main structural differences between synovial and fibrous joints are the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within those capsules (synovial cavities).
    • Several movements may be performed by synovial joints.
    • There are six types of synovial joints.

  • Nerve and Blood Supply

    • Synovial joints are highly innervated but vascularized indirectly by nearby tissues.
    • It supplies the capsule, synovial membrane, and the epiphyses.
    • The synovial cartilage in the capsule acts somewhat like a sponge.
    • A sponge will absorb fluid, but it will release little of that fluid unless it is squeezed.
    • Flexing and extending the joint alternately squeezes the sponge and releases it to reabsorb more fluid.

  • Stability and Range of Motion at Synovial Joints

    • Disuse, causing decrease in synovial fluid, flexibility of ligaments and tendons, and muscle atrophy
    • Aging is another factor that influences motion due to decreased fluid, thinning of cartilage, shortening of ligaments, and loss of flexibility.

  • Rheumatism and Arthritis

    • Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks flexible (synovial) joints .
    • The process involves an inflammatory response of the capsule around the joints (synovium) secondary to swelling (hyperplasia) of synovial cells, excess synovial fluid, and the development of fibrous tissue (pannus) in the synovium.

  • Functional Classification of Joints

    • Diarthrosis – These are the freely-movable synovial joints.
    • Synovial joints are further classified based on the different types of movement they provide, including:
    • Image of a skeleton and skematics of the different classes of synovial joints.