Fig. 1

Overview of the quadriceps muscle group including the newly discovered fifth component, the tensor vastus intermedius. Anterior view to the left thigh is shown. The red stickers mark the medial and lateral femoral condyles and center of the neck of the femur respectively. For better visualization the sartorius and rectus femoris muscle are transected and reflected. The components of the extensor apparatus are arranged like the layers of a husk of a corn (on the left top). Superficial lateral and medial fibers in the proximal aspect of the thigh are piled in deeper inner layers at the level of the quadriceps tendon. The vastus medialis is released from its insertion into the vastus intermedius, rectus femoris and patella