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For the obsolete dinosaur fossil name, see Megalosaurus#"Scrotum humanum".

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	D012611
TA98	A09.4.03.001 A09.4.03.004
TA2	3693
FMA	18252
Anatomical terminology[edit on Wikidata]

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 is located under the penis. The scrotum contains the external spermatic fascia, testes, epididymis, ductus deferens. Stream-lined, aquatic mammals such as whales and seals typically lack an external scrotum. It is an distention of the perineum and carries abdominal tissues some into its cavity including the testicular artery, testicular vein and pampinform 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.

Structure

Innervation

Blood supply

Function

The function of the scrotum is to keep the temperature of the testes at about 35-36 degrees Celsius (95-96.8 degrees Fahrenheit), i.e. one to two degrees below the body temperature of 37 degrees Celsius (98.6 degrees Fahrenheit). High scrotum temperature is damaging to sperm production. Temperature control is accomplished by the smooth muscles of the scrotum moving the testicles either closer to or further away from the abdomen dependent upon the ambient temperature. This is accomplished by the cremaster muscle in the abdomen and the dartos fascia (muscular tissue under the skin).

Having the scrotum and testicles situated outside the abdominal cavity may provide additional advantages. The external scrotum is not affected by abdominal pressure. This may prevent the emptying of the testes before the sperm were matured sufficiently for fertilization. Some mammals — elephants and marine mammals, for example – do keep their testes within the abdomen and there may be mechanisms to prevent this inadvertent emptying.

Abdominal muscles, and changes in intra-abdominal pressure, can often lift and lower the testicles within the scrotum. Contraction of the muscle fibers of the dartos tunic (or fascia) is completely involuntary and results in the appearance of increased wrinkling and thickening of the scrotal skin. The testicles are not directly attached to the skin of the scrotum, so this dartos contraction results in their sliding toward the abdomen. They also, in some men, can be lifted the same way by tightening the anus and pelvic muscles, doing Kegel exercises.

Although the ideal temperature for sperm growth varies between species, it usually appears, in warm-blooded species, to be a bit cooler than internal body temperature, making the scrotum necessary. Since this leaves the testicles vulnerable in many species, there is some debate on the evolutionary advantage of such a system. One theory is that the impregnation of females who are ill is less likely when sperm is highly sensitive to elevated body temperatures. An alternative explanation is to protect the testes from jolts and compressions associated with an active lifestyle. Animals that have stately movements – such as elephants, whales, and marsupial moles – have internal testes and no scrotum.

Clinical significance

A study has indicated that use of a laptop computer positioned on the lap can negatively affect sperm production.

A common problem of the scrotum is the development of masses. Common scrotal masses may have any of a variety of causes, including a sebaceous cyst, also called an epidermal cyst; a hydrocele, a hematocele, a spermatocele or a varicocele.

Another condition is blisters caused by chafing or scratching of the scrotum while it is damp. This condition is often seen in males undergoing puberty, as emerging pubic hairs cause an itch and an urge to scratch. Powdering the scrotum to absorb moisture can help to prevent this discomfort. Contact dermatitis may cause redness, burning, swelling, and itching of the entire scrotum. It can result from soaps, solvents, detergents, and natural irritants such as poison ivy. Inguinal hernia and yeast infection may occur, and there may be swelling resulting from conditions external to the scrotum, including heart failure, kidney or liver disease, cherry angioma and testicular torsion.

Skin conditions which have not been successfully identified may be referred to as non-specific scrotal dermatitis.

See also

• Scrotal infusion, a temporary form of body modification
• Testes
• Epididymis
• Ductus Deferens

Bibliography

Books

• This article incorporates text in the public domain from page 1237 of the 20th edition of Gray's Anatomy (1918)
• Van De Graaff, Kent M.; Fox, Stuart Ira (1989). Concepts of Human Anatomy and Physiology. Dubuque, Iowa: William C. Brown Publishers. ISBN 0697056759.
• Elson, Lawrence; Kapit, Wynn (1977). The Anatomy Coloring. New York, New York: Harper & Row. ISBN 0064539148.{{sfn|Elson|1977|p=}}
• "Gross Anatomy Image". Medical Gross Anatomy Atlas Images. University of Michigan Medical School. 1997. Retrieved 2015-02-23.
• Berkow, MD, editor, Robert (1977). The Merck Manual of Medical Information; Home Edition. Whitehouse Station, New Jersey: Merck Research Laboratories. ISBN 0911910875. {{cite book}}: |last1= has generic name (help)CS1 maint: multiple names: authors list (link)

References

1. "Scrotum". National Institutes of Health. Retrieved 6 January 2011.
2. Moore, Keith; Anne Agur (2007). Essential Clinical Anatomy, Third Edition. Lippincott Williams & Wilkins. p. 132. ISBN 0-7817-6274-X.
3. Elson 1977. sfn error: no target: CITEREFElson1977 (help)
4. "About the Male Reproductive System". KidsHealth. Retrieved 6 January 2011.
5. "Science : Bumpy lifestyle led to external testes - 17 August 1996 - New Scientist". Retrieved 2007-11-06.
6. "Science : Bumpy lifestyle led to external testes - 17 August 1996 - New Scientist". Retrieved 2007-11-06.
7. "Laptops may damage male fertility". BBC News. 2004-12-09. Retrieved 2012-01-30.
8. Sheynkin, Yefim; et al. (February 2005). "Increase in scrotal temperature in laptop computer users". Hum. Reprod. 20 (2): 452–455. doi:10.1093/humrep/deh616. PMID 15591087. {{cite journal}}: Explicit use of et al. in: |author2= (help)

• Misplaced Pages articles incorporating text from the 20th edition of Gray's Anatomy (1918)
• Mammal male reproductive system