Anatomy and function of the knee
What makes up your knee?The knee joint is the point at which the femur bone of the thigh meets the tibia bone of the lower leg. All the components of the knee - bones, cartilage, synovial membrane, ligaments, tendons and muscles - must work together properly for the knee to move smoothly.
Cartilage is a protective cushioning that keeps the bones from rubbing against one another.
In a healthy knee, a thin, smooth tissue liner called the synovial membrane releases a fluid that lubricates the knee, reducing friction as the bones move.