Synovial Fluid
A thick, slippery liquid that fills the space inside joints, lubricating the joint surfaces and providing nutrients to cartilage.
Extended Definition
Synovial fluid, often called joint fluid, is a viscous substance that serves multiple critical functions in joint health. Produced by the synovial membrane lining the joint capsule, this fluid has a consistency similar to egg whites and contains hyaluronic acid, which gives it its characteristic thickness and lubricating properties.
In healthy joints, synovial fluid acts as both a lubricant and a shock absorber. It reduces friction between cartilage surfaces during movement and cushions the joint against impact. Additionally, since cartilage has no blood supply, synovial fluid delivers essential nutrients to cartilage cells and removes waste products.
In joints affected by osteoarthritis, synovial fluid often becomes thinner and less effective at its job. The concentration of hyaluronic acid decreases, reducing the fluid’s ability to protect the joint. This is why viscosupplementation treatments—injections of hyaluronic acid—aim to restore the natural properties of synovial fluid and improve joint function.
Related Terms
More Anatomy Terms
View allAcetabulum
The cup-shaped socket of the pelvis that holds the head of the femur (thigh bone) in the hip joint.
Articular Cartilage
The smooth, white tissue covering the ends of bones in joints. Its breakdown is the primary feature of osteoarthritis.
Bursae
Small, fluid-filled sacs that act as cushions between bones, tendons, and muscles near joints, reducing friction during movement. Singular form is 'bursa.'
Bursa
Small, fluid-filled sacs that cushion bones, tendons, and muscles near joints. Bursitis (inflammation of a bursa) can cause joint pain similar to arthritis.
Cartilage
A smooth, rubbery connective tissue that covers and protects the ends of bones where they meet to form joints, allowing them to glide smoothly during movement.