The man also has pelvic floor muscles in the bottom of his belly. They are not sexual organs but are important to a man's sexual wellbeing and sexual pleasure. For most men the ridge below the head of the penis (the frenulum) is the most sensitive part of their penis. The scrotum is the pouch of skin that hangs below the penis and holds both testicles (testes). The testicles are part of the male reproductive system. The testicles produce the male sex hormone, testosterone.