The popliteal fossa is located behind the knee and contains the tibial nerve, common peroneal nerve, popliteal artery and vein, popliteal lymph nodes, and other structures. The knee joint is composed of the tibiofemoral and patellofemoral joints, with articular surfaces on the femur, tibia, and patella. It is supported by extracapsular and intracapsular ligaments including the ACL and PCL. Common injuries include patellar tendinitis from overuse, ACL tears from sudden movements, and collateral ligament tears from blows to the side of the knee.