What is the function of synovial fluid in joints?

Synovial fluid plays a crucial role in joint health and function, primarily by providing cushioning and reducing friction between the articular cartilage surfaces of bones within a synovial joint. This viscous fluid fills the synovial cavity and serves multiple important purposes. It acts as a lubricant, allowing for smooth movement of the joint during activities such as walking, running, or any other form of motion. The fluid's viscosity creates a protective layer that helps to prevent wear and tear on the cartilage, thereby contributing to the overall longevity and stability of the joint.

Additionally, synovial fluid contains nutrients and waste products that support the metabolic activity of the cartilage, as cartilage itself does not have a direct blood supply. This characteristic allows for efficient distribution of essential substances, helping to maintain cartilage health.

The other options focus on functions that are not aligned with the primary role of synovial fluid. While ligaments are indeed important for joint stability, they are strengthened by other means, and not directly by synovial fluid. Nerve sensitivity and bone growth also do not correlate with the primary functions of synovial fluid, which focuses more on joint lubrication and protection.