The patella or kneecap is a thick, triangular bone which articulates with the femur and covers and protects the front of the knee joint. It develops from the tendon of the Quadriceps femoris muscle, which contracts to straighten the leg. The patella increases the leverage that the tendon can exert on the femur by increasing the angle at which it acts.
This article is a stub. You can help Wikipedia by fixing it.