What is the primary function of synovial fluid?

The primary function of synovial fluid is to lubricate joints, which is essential for reducing friction between the articular cartilage of synovial joints during movement. This fluid is found in the synovial cavities of joints and serves to cushion the joints, allowing for smoother and more efficient movement. It also helps to supply nutrients and remove waste from the cartilage, which does not have its own blood supply.

In contrast, the other options do not accurately describe the function of synovial fluid. Providing energy relates to metabolic processes that synovial fluid does not participate in. Transporting oxygen is a function primarily associated with blood and respiratory processes, rather than synovial fluid. Lastly, facilitating digestion is a function of digestive fluids, such as saliva and bile, which are unrelated to the role of synovial fluid in joint health.