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What roles do articular cartilage and synovial fluid play in a synovial joint?

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Front and back views of the human skeleton are shown side by side, with labeled bones including the skull, spine, ribs, pelvis, arms, legs, hands, and feet. Insets detail the bones of the foot and hand, highlighting major bone groups and anatomical terms. — human skeleton Front and back views of the human skeleton.

In a synovial joint, articular cartilage and synovial fluid work together to ensure smooth movement and joint health.

Articular Cartilage

Articular cartilage is a type of hyaline cartilage that covers the articulating surfaces of bones. It is both deformable and elastic, allowing it to recover its shape after stress. Because it lacks a direct blood supply and is separated from the bone by a calcified layer, it relies on synovial fluid for its nourishment. Its smooth, though microscopically irregular, surface facilitates movement, and its ability to deform helps improve the fit between "mating" bone surfaces.12

Synovial Fluid

Synovial fluid is a viscous, thixotropic liquid secreted by synovial tissue. It serves two primary functions:
* Lubrication: It forms elastohydrodynamic films between moving bone surfaces, reducing friction.2
* Nutrition: As a dialyzate of blood plasma, it provides essential nutrients to the articular cartilage.2

The movement of the joint helps distribute this fluid across the cartilage surfaces, ensuring effective lubrication and nutrient delivery.2