Five parts of the moving forward front punch.
My Sensei often told me that there are five moves to the moving forward front punch and only two of them are related to the upper body.
First is the punch, next is the elbow strike, then comes the shin clash, next is driving from the back leg (or guarded back leg) and then finally the knee sweep. The knee sweep is where you have your front foot outside the opponents front foot and you use your knee as a lever to twist their leg and take them down.
1: Guarded back leg
2: Knee sweep
3: Shin clash
5: Elbow strike