<P> The medial collateral ligament ( MCL ) , or tibial collateral ligament ( TCL ) , is one of the four major ligaments of the knee . It is on the medial ( inner ) side of the knee joint in humans and other primates . Its primary function is to resist valgus forces on the knee . </P>
what is the function of the medial collateral ligament
to resist valgus forces on the knee