How Does Penis Enlargement Work? A Definitive Guide Penis enlargement works based on the same principle as muscle building for other parts of your body. When the tissues of the corpus spongiosum and corpus cavernosa in the penis are subjected to stretching, microtears occur. The tissues appear engorged as they heal, making your penis look larger. This facilitates new cell growth to repair those tears. The same thing happens when you build muscle tissue in other places in your body.