The knee is essentially made up of four bones. The femur, which is the large bone in your thigh, attaches by ligaments in a capsule to your tibia. Just below the tibia is the fibula, which runs parallel to the tibia. When the knee moves, it does not just flex and extend, there is also a slight rotation component in this motion. The knee muscles that cross the knee joint are the quadriceps and the hamstrings.
Quadriceps are on the front of the knee, and hamstrings are on the back of the knee.
The ligaments are equally important in the knee joint because they hold the joint together. Problems with ligaments are common. In review, the bones support the knee and provide the rigid structure of the joint, the muscles move the joint, and the ligaments stabilize the joint. The knee also has a structure made of cartilage, which is called the meniscus. The cartilage protects the joint and allows the bones to slide freely on each other.