What covers the ends of bones in synovial joints?

The ends of bones in synovial joints are covered by articular cartilage, which serves several important functions. This specialized type of hyaline cartilage provides a smooth surface for the articulation of bones, facilitating easy movement within the joint. It acts as a cushion, absorbing shock and reducing friction during joint movement, which helps to protect the underlying bones from wear and tear.

Articular cartilage also plays a role in providing stability to the joint by helping to maintain its shape. The smooth, gliding surface of this cartilage allows for the free movement typical of synovial joints, such as the knee or shoulder. The health of articular cartilage is essential for maintaining joint function, as damage to this cartilage can lead to conditions such as osteoarthritis.

In the context of the other options, while the meniscus (a type of fibrocartilage) provides additional cushioning and stability in certain joints, it does not cover the bone ends directly. The synovial membrane lines the joint capsule and produces synovial fluid, which lubricates the joint but does not itself cover the bones. The joint capsule encloses the entire joint and provides additional protection but is distinct from the articular cartilage functionally and structurally.