A leg is composed of your femur, your kneecap, your lower leg (tibia and fibula) and foot. The joints in your leg are your hip joint, knee joint, ankle joint and all joints in your foot and toes.
Your glutes have their main function over the hip joint and move your hip.
The upper leg muscles (hamstrings, quadriceps and adductors) have a function both over your hip and over your knee.
An optimal balance between the muscles and joints in your leg provide a strong foundation for your body, better endurance and more strength. If this balance is disturbed, complaints can occur.