Popliteus muscle assists in flexing the leg upon the thigh; when the leg is flexed, it will rotate the tibia inward. It is especially called into action at the beginning of the act of bending the knee, inasmuch as it produces the slight inward rotation of the tibia, which is essential in the early stage of this movement. When the knee is in full extension, the femur slightly medially rotates on the tibia to lock the knee joint in place. Popliteus is often referred to as the "Key" to unlocking the knee since it begins knee flexion by laterally rotating the femur
Medial knee injuries adductor tubercle. The sMCL connects the femur to the tibia. It originates just proximal and posterior to the medial epicondyle (not directly on the epicondyle) and splits into two distinct sections. One tibial section attaches to soft tissue, 1 cm distal to the joint line. The other tibial section attaches directly to the tibia, anterior to the posteromedial tibial crest, 6 cm distal to the joint line. This distal attachment is the stronger of the two and makes up the floor of the pes anserine bursa. The proximal tibial attachment of the sMCL is the primary stabilizer to valgus force