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
Superior tibiofibular joint Superior tibiofibular joint The proximal tibiofibular articulation (also called superior tibiofibular joint) is an arthrodial joint between the lateral condyle of the tibia and the head of the fibula. The contiguous surfaces of the bones present flat, oval facets covered with cartilage and connected together by an articular capsule and by anterior and posterior ligaments. When the term "tibiofibular articulation" is used without a modifier, it refers to the proximal, not the distal (i.e., inferior) tibiofibular articulation. Injuries to the proximal tibiofibular joint are uncommon and usually associated with other injuries to the lower leg. Dislocations can be classified into