Posterior cruciate ligament the tibia. The PCL is located within the knee joint where it stabilizes the articulating bones, particularly the femur and the tibia, during movement. It originates from the lateral edge of the medial femoral condyle and the roof of the intercondyle notch then stretches, at a posterior and lateral angle, toward the posterior of the tibia just below its articular surface. Although each PCL is a unified unit, they are described as separate anterolateral and posteromedial sections based off where each section's attachment site and function. During knee joint movement, the PCL rotates such that the anterolateral section stretches in
Femur the bone. Some species of whales, snakes, and other non-walking vertebrates have vestigial femurs. One of the earliest known vertebrates to have a femur is the "eusthenopteron", a prehistoric lobe-finned fish from the Late Devonian period. Structures analogous to the third trochanter are present in mammals, including some primates. In invertebrate zoology the name "femur" appears in arthropodology. The usage is not homologous with that of vertebrate anatomy; the term "femur" simply has been adopted by analogy and refers, where applicable, to the most proximal of (usually) the two longest jointed segments of the legs of the arthropoda. The two