Which ligament is located on the outside of the knee joint?

The lateral collateral ligament (LCL) is located on the outside of the knee joint, and it connects your femur to your fibula (a lower-leg bone that is smaller than the tibia).3 The LCL prevents excessive adduction of the knee (i.e., movement toward the central axis of the body).

The medial collateral ligament (MCL) is located on the inside of the knee joint, and it connects the femur to your tibia. This ligament prevents excessive valgus angulation of the knee (i.e., a knock-kneed position).

The anterior cruciate ligament (ACL) runs diagonally down the middle of the knee and connects the femur to the tibia. This ligament prevents your shinbone from sliding too far forward during running, hopping, and activities that involve changing direction quickly (cutting).

The posterior cruciate ligament (PCL) is the strongest and largest ligament in the knee. It runs diagonally down the back of your knee, connecting your femur to your tibia. The main function of the PCL is to prevents your tibia from moving too far backward.

Your LCL and MCL, the two collateral ligaments in your knee, work to control the sideways movement of your knee joint. The two cruciate ligaments in your knee (your ACL and PCL) work to control the backward and forward movement of your knee joint.