The menisci and two important pairs of ligaments, the collaterals and the cruciates, are crucial to stability of the knee. Learn the location of these structures from the illustrations below (Fig. 1).

■ The medial and lateral menisci cushion the action of the femur on the tibia. These crescent-shaped fibrocartilaginous discs add a cup-like surface to the otherwise flat tibial plateau.

■ The medial collateral ligament (MCL), not easily palpable, is a broad, flat ligament connecting the medial femoral epicondyle to the medial condyle of the tibia. The medial portion of the MCL also attaches to the medial meniscus.

■ The lateral collateral ligament (LCL) connects the lateral femoral epicondyle and the head of the fibula. The MCL and LCL provide medial and lateral stability to the knee joint.

■ The ACL crosses obliquely from the anterior medial tibia to the lateral femoral condyle, preventing the tibia from sliding forward on the femur.

■ The posterior cruciate ligament (PCL) crosses from the posterior tibia and lateral meniscus to the medial femoral condyle, preventing the tibia from slipping backward on the femur. Although the ACL and PCL lie within the knee joint so are not palpable, they are nonetheless crucial to the anteroposterior stability of the knee.

FIGURE 1. Left knee—medial view.

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