What is the primary function of the MCL in the knee?

The primary function of the medial collateral ligament (MCL) in the knee is to prevent excessive valgus displacement of the tibia relative to the femur. The MCL is a key ligament on the inner side of the knee joint, and it plays a critical role in maintaining the stability and integrity of the knee during various movements.

When forces are applied to the knee, especially from the lateral side, the MCL helps resist this lateral stress, preventing the knee from bending outward (valgus angle). This protective mechanism is particularly important during activities such as running, jumping, and cutting, where the knee is susceptible to forces that could lead to injury.

While the other choices highlight important aspects related to knee function and stability, they do not accurately capture the primary role of the MCL. For instance, preventing anterior displacement of the femur is primarily the role of the anterior cruciate ligament (ACL), not the MCL. Supporting the lateral meniscus is more associated with the role of other structures such as the popliteus muscle and lateral ligaments. Lastly, enhancing the stability of the patella relates to the role of the patellar tendon and other ligaments around the kneecap rather than the MCL itself. Thus, the