Human knee joint with bones and ligaments. The knee joint (Articulatio genus) is a rotation-angle joint between the femoral condyles (parts of the femur in the knee joint with covered in cartilage) and the two flat pans of the tibia head, complemented by the patella (as a sesamoid bone in the tendon of the quadriceps femoris muscle, flapped down in this picture). Two menisci (underneath both femur condyles) compensate for incongruences of the joint surfaces. Additionally, two cross bands (anterior and posterior cruciate ligament) as intraarticular ligaments and two capsule supporting extraarticular ligaments (fibular and tibia collateral ligaments). The knee joint makes it possible to extend and flex the knee, as well as a rotation of the shank when the collateral ligaments are flaccid.