What type of structure cushions the knee joint?

The correct answer is the crescent-shaped menisci. The menisci are fibrocartilaginous structures in the knee joint that serve a crucial role in cushioning and stabilizing the joint. They are located between the femur (thigh bone) and the tibia (shin bone), acting as shock absorbers during weight-bearing activities and movement. The shape of the menisci allows them to effectively distribute the load across the knee, reduce friction between the articulating bones, and help maintain joint stability.

While cartilage pads are another form of cushioning in joints, the specific structures referred to in the context of the knee joint are the menisci. Bursae sacs are fluid-filled structures that reduce friction between tissues such as bone, muscles, and tendons, providing cushioning in certain areas but not serving the primary role of cushioning the knee joint itself. Synovial membranes produce synovial fluid, which lubricates the joint and nourishes the cartilage but does not directly cushion the joint. Thus, the crescent-shaped menisci are the primary structures that provide cushioning to the knee joint.