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
Tuberosity of the tibia necessary to allow for normal function. Tenderness in the tibial tuberosity can arise from Osgood-Schlatter’s syndrome or deep infrapatellar bursitis. A bony prominence on the tibial tuberosity can be the result of ongoing Osgood-Schlatter’s irritation in an adolescent with open growth plates, or what remains of Osgood-Schlatter’s in adults. Tuberosity of the tibia The tuberosity of the tibia or tibial tuberosity or tibial tubercle is a large oblong elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end. It gives attachment to the patellar ligament, which attaches