What two bones protect the knee and elbow?

The knee is primarily protected by the femur (thigh bone) and the tibia (shin bone), which are the main bones that form the knee joint. The patella, or kneecap, also plays a protective role in front of the knee. For the elbow, the humerus (upper arm bone) and the ulna (one of the forearm bones) are the key bones that protect the joint. The radius, another forearm bone, also contributes to the elbow's structure and stability.