Illustration of an anterior view of an opened flexed knee joint showing the femoral condyles and the horseshoe-shaped fibrocartilage menisci associated with the tibial plateau. Between the condyles is the anterior cruciate ligament (ACL) to the front with the posterior cruciate ligament (PCL) behind. Menisci are load-bearing, reduce friction and create a concave surface for femoral movement. The ACL prevents excessive posterior displacement of the femur. The PCL prevents excessive anterior displacement of the femur. From Lizars, J. 1823 A system of anatomical plates of the human body. W.H. Lizars, Edinburgh.