Scrotum

The scrotum is found in most male mammals, including humans. It is the sack that contains the testes. In humans the scrotum hangs just below the penis. It is described as follows:

the pouch that contains the testes and their accessory organs. It is composed of skin, the tunica dartos, fascia, and the tunica vaginalis testis. Each testis is connected to a cremaster muscle descending from the abdominal wall. During cold weather these muscles draw the testes closer to the body to maintain their temperature, and in hot weather the reverse occurs; the scrotum usually follows this movement.