The highlighted structure in the M20 Deluxe Leg Model could be either the tibia or fibula, based on its location and appearance. The tibia is the larger medial bone and the fibula is the lateral slender bone. Without the image, an exact answer cannot be determined.
In the M20 Deluxe Leg Model, if the structure highlighted and indicated by the leader line is on the medial side of the leg and appears larger and more robust, it is likely the tibia, which is the larger, weight-bearing bone of the leg. However, if the highlighted structure is on the lateral side and more slender, it is the fibula. The femur is the thigh bone and would be higher up in the leg model, connecting to the pelvis at the hip joint and extending down to the knee joint. The patella, or kneecap, is triangular and would be found anterior to the knee joint, embedded in the quadriceps tendon. Without seeing the actual picture referenced by the question, it is not possible to give a specific answer as to whether the structure is the femur, patella, tibia, or fibula. However, based on the description given in your references, these definitions should help you identify the correct bone that the leader line is pointing to.