The scrotum is a pouch made from skin and muscle located underneath the penis. The main purpose of this sac is to hold the testicles. The scrotum plays a big part in protecting the testicles from fluctuating temperatures, which can decrease the amount of viable sperm that a man produces. When the temperature around the scrotum drops, the muscles in it contract, drawing the testicles up toward the body to keep them warm. On the other hand, when the temperature gets too warm, the muscles in the scrotum relax, allowing the testicles to hang lower and cool off.
The scrotum is also known as the scrotal sac.