What is the primary function of the joint cavity?

The primary function of the joint cavity is to contain synovial fluid. This fluid acts as a lubricant, reducing friction between the articular cartilages of the bones when they move, which is crucial for smooth and pain-free joint function.

While the joint cavity does indeed provide a space that allows for movement of the bones, its most significant role revolves around the presence and function of the synovial fluid. The fluid not only lubricates but also serves to nourish the articular cartilage and acts as a shock absorber, facilitating the movements that occur at the joint. This lubrication and cushioning effect are essential for joint health and mobility.

Other functions mentioned, like connecting ligaments to bones or supporting the body's weight, are important but are carried out by different structures associated with the joints rather than the joint cavity itself.