Final answer:
The Posterior Cruciate Ligament (PCL) is a key structure in the knee that prevents anterior displacement of the femur on the tibia when the knee is flexed and bears weight, contributing to overall knee stability.
Step-by-step explanation:
The Posterior Cruciate Ligament (PCL) is an intracapsular ligament of the knee, which extends from the posterior, superior surface of the tibia to the inner aspect of the medial condyle of the femur. Its primary function is to prevent anterior displacement of the femur when the knee is flexed and weight bearing, such as when walking downhill. The PCL is critical for knee stability, especially in preventing the femur from sliding forward over the tibia. In contrast, the anterior cruciate ligament (ACL) extends from the anterior, superior surface of the tibia to the inner aspect of the lateral condyle of the femur and resists hyperextension of the knee.