Posterior cruciate ligament

The posterior cruciate ligament (PCL) is stronger, but shorter and less oblique in its direction, than the anterior cruciate ligament . It is attached to the posterior intercondyloid fossa of the tibia, and to the posterior extremity of the lateral meniscus; and passes upward, forward, and medialward, to be fixed into the lateral and front part of the medial condyle of the femur.

The posterior cruciate ligament is composed of two main bundles: the anterolateral (AL) bundle and the posteromedial (PM) bundle: The AL bundle originates more anteriorly on the lateral wall of the medial femoral condyle and has a more vertical orientation compared to the PM bundle. The PM bundle originates more posteriorly on the same condyle. On the tibial side, the AL bundle inserts medial and anterior to the PM bundle on the PCL facet. The femoral origins of these bundles are approximately 12 mm apart, while their tibial insertions are more closely grouped.

Functionally, the AL bundle is the primary restraint to posterior tibial translation during midrange knee flexion, whereas the PM bundle is more critical in resisting posterior translation in knee extension and deep flexion.

Additionally, the PCL is associated with the meniscofemoral ligaments (MFLs), which further contribute to its function. The anterior MFL (Ligament of Humphrey) and the posterior MFL (Ligament of Wrisberg) attach to the posterior horn of the lateral meniscus and provide additional resistance to posterior tibial translation.

Note: The crucciate ligaments are called cruciate because they cross each other somewhat like the lines of the letter X; and have received the names anterior and posterior, from the position of their attachments to the tibia.