Scrotum

Scrotum
Human scrotum in a relaxed state (left) and a tense state (right)
Details
Precursor	Labioscrotal folds
Artery	Anterior scrotal artery & Posterior scrotal artery
Vein	Testicular vein
Nerve	Posterior scrotal nerves, Anterior scrotal nerves, genital branch of genitofemoral nerve, perineal branches of posterior femoral cutaneous nerve
Lymph	Superficial inguinal lymph nodes
Identifiers
Latin	Scrotum
MeSH	A05.360.444.661
TA	A09.4.03.001
FMA	18252
Anatomical terminology []

The scrotum is an anatomical male reproductive structure that consists of a suspended dual-chambered sack of skin and smooth muscle that is 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 is found the scrotal septum. It appears as a thin longitudinal line that runs front to back over the entire scrotum. The scrotum contains the external spermatic fascia, testes, epididymis and ductus deferens. It is a distention of the perineum and carries some abdominal tissues into its cavity including the testicular artery, testicular vein and pampiniform plexus. In humans and some other mammals, the scrotum becomes covered with pubic hair at puberty.

The scrotum is biologically homologous to the labia majora in females. Although present in most mammals, the external scrotum is absent in streamlined marine mammals, such as whales and seals, as well as in some lineages of land mammals, such as the afrotherians, xenarthrans, and numerous families of bats, rodents, and insectivores.

The skin on the scrotum is more highly pigmented compared to the rest of the body. The septum is a connective tissue membrane dividing the scrotum into two cavities.

The scrotum lymph drains initially into the superficial inguinal lymph nodes, this then drains into the deep inguinal lymph nodes. The deep inguinal lymph nodes drain into the common iliac which ultimately releases lymph into the cisterna chyli.

Male sex hormones are secreted by the testes later in embryonic life to cause the development of secondary sex organs. The scrotum is developmentally homologous to the labia minora and labia majora. The raphe does not exist in females. Reproductive organs and tissues develop in females and males begin during the fifth week after fertilization. The gonadal ridge grows behind the peritoneal membrane. By the sixth week, string-like tissues called primary sex cords form within the enlarging gonadal ridge. Externally, a swelling called the genital tubercule appears over the cloacal membrane.