Ah, damn I can see I tried something that didn't went so clear at this scale
the lowest curved line is actually his chin, his mouth is the straight line directly below his nose, because he was supposed to look quite old, with a flabby neck and no visible jawline, just the tip of the chin appearing as protuberance, and his mouth is receded like that of a toothless elder not wearing his denture. Hmm, I will rethink his face as a whole, thanks.