The rectus femoris muscle is one of the four part sof the quadriceps (quads) muscle and is a key part of the complex. The patella (kneecap) is embedded in its tendon.
The of muscle, bone and tendon complex reaches from the hip, through the femur and patella to the tibia. The four heads of the quads muscle are intimately involved with a network of fibrous tissue on the sides of the patella (retinaculum) and the whole works pretty much as a unit, and is called 'the extensor mechanism'.