Peyronie's disease is where plaques (segments of flat scar tissue) form under the skin of the penis. These plaques can cause the penis to bend or become indented during erections. The plaques can often be felt through the skin, and can also be painful.
How Does the Penis Normally Work?
Male Reproductive System
The main roles of the penis are to carry urine out of the body and sperm into the woman's vagina. There are 3 tubes inside the penis. One is called the urethra. It's hollow and carries urine from the bladder through the penis to the outside. The other 2 tubes are called the corpora cavernosa. These are soft, spongy tubes that fill with blood to make the penis stiff during an erection. The 3 tubes are wrapped together by a very tough fibrous sheath called the tunica albuginea. During sex, the stiffness of the penis makes it hard enough to push into the woman's vagina. Then the urethra acts as a channel to carry semen into the vagina.