The integrity of the knee joint depends upon the muscles and tendons about the knee, the articular capsule, the intrinsic ligaments of the joint, and the bone architecture of the tibia and femur.

Lateral motion of the knee joint in extension is controlled by the capsule, collateral ligaments, and cruciate ligaments; in flexion, by the same structures minus the fibular collateral ligament.

Rotary motion of the knee joint in extension is controlled by capsule, collateral ligaments, and cruciate ligaments; in flexion, by the same structures minus the fibular collateral ligament.

Forward gliding of the tibia on the femur is controlled by the anterior cruciate ligament.

Backward gliding of the tibia on the femur is controlled by the posterior cruciate ligament.

Lateral gliding of the tibia on the femur is controlled by the tibial intercondyloid eminence and the femoral condyles with the aid of all the ligaments.

Hyperextension is controlled by both collateral ligaments, both cruciate ligaments, both menisci, the posterior aspect of the articular capsule, the oblique popliteal ligament, and the architecture of the femoral condyles.

Hyperflexion is controlled by both cruciate ligaments, both menisci, the femoral attachment of the posterior aspect of the capsule, the femoral attachment of both heads of the gastrocnemius muscle, and the bone structure of the condyles of the femur and the tibia.

The menisci cushion hyperextension and hyperflexion.

The tibial collateral ligament is closely related to the medial meniscus, but there is no strong fibrous-tissue attachment between them.

The tibial collateral ligament glides forward and backward in extension and flexion.

The drawings from which were made Figures 1 to 12 are the work of Ruth Bialek.