For the obsolete dinosaur fossil name, see Megalosaurus#Scrotum humanum . The scrotum is an anatomical male reproductive structure that consists of a suspended sack of skin and smooth muscle that is dual-chambered, present in most terrestrial male mammals and located under the penis. One testis is typically lower than the other, which functions to avoid compression in the event of impact. The perineal raphe is a small, vertical, slightly raised ridge of scrotal skin under which scrotal septum exists. It appears as a thin longitudinal line that runs front to back over the entire scrotum.