Synovial fluid in joints
Joints
Joint is a junction between two bones. It is also called as articulation. Joints are classified into three types-
Fibrous Joints
These are immovable and the bones are firmly united by fibrous tissue. Eg.: Joints found between the skull bones.
Cartilaginous Joints
These joints are slightly movable. Eg.: Intervertebral disks between the bodies of adjacent vertebrae in the spine.
Synovial Joints
These are freely movable joints, e.g., shoulders joint, stifle joint etc. The movement of a joint is normally controlled and united by the action of muscles and ligaments and tendons. All synovial joints have some common characteristics. They have a capsule with an outer fibrous layer consisting of collagen fibres running from the periosteum of one bone to the other.
Ligaments are located in and around the capsule. The inner lining layer of the joint surface is the synovial membrane which produces synovial fluid that lubricates the joint surfaces. Synovial fluid is a transparent viscous liquid and it provides lubrication to the joint provides lubrication to the joint.
Some bones contain special areas of dense fibro cartilage between the articulating cartilage surfaces and are known as menisci. Eg.: Bones that bear great weight. The function of the menisci is to cushion compressive forces acting on the ends of the bones.
Synovial fluid
Synovial fluid is a thick, viscous liquid found in joint cavities, tendon sheath and bursae. It contains small amounts of albumin, globulin, mucin and hyaluronic acid but no fibrinogen.
Synovial fluid functions as a lubricant to reduce friction in the joints and help to nourish the articular cartilages.