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{{Short description|Sac of skin that protects the testicles}}
{{Infobox Anatomy |
{{For|the obsolete dinosaur fossil name|Megalosaurus#"Scrotum humanum"}}
Name = {{PAGENAME}} |
{{pp-move}}
Latin = |
{{pp-pc|small=yes}}
GraySubject = 258 |
{{Infobox anatomy
GrayPage = 1237 |
Image = Gray1143.png |
| Name = Scrotum
| Latin = scrotum
Caption = The scrotum. On the left side the cavity of the [[tunica vaginalis]] has been opened; on the right side only the layers superficial to the [[Cremaster]] have been removed. |
| Image = File:Scrotum - Hodensack.JPG
Precursor = [[labioscrotal folds]] |
| Caption = Human scrotum in a relaxed state (left) and a tense state (right)
MeshName = Scrotum |
| Width =
MeshNumber = A05.360.444.661 |
| Image2 =
DorlandsPre = s_06 |
| Caption2 =
DorlandsSuf = 12726162 |
| Precursor = [[Labioscrotal swelling]]s
| System =[[Reproductive system]]
| Artery = [[Anterior scrotal artery]], [[posterior scrotal artery]], [[deep external pudendal artery]], [[superficial external pudendal artery]], [[internal pudendal artery]]
| Vein = [[Posterior scrotal veins]], [[internal pudendal veins]]
| Nerve = [[Posterior scrotal nerves]], [[anterior scrotal nerves]], [[genital branch of genitofemoral nerve]], [[perineal branches of posterior femoral cutaneous nerve]], [[pudendal nerve]], [[perineal nerve]]
| Lymph = [[Superficial inguinal lymph nodes]]
}}
}}
In most terrestrial [[mammal]]s, the '''scrotum''' ({{plural form}}: '''scrotums''' or '''scrota'''; possibly from [[Latin]] ''scortum'', meaning "hide" or "skin")<ref>{{cite book|last=van Driel|first=Mels|title=Manhood: The Rise and Fall of the Penis|publisher=Reaktion Books|year = 2010|page=11|access-date=October 14, 2023|isbn= 978-1-86189-708-4 |url= https://books.google.com/books?id=jt6u0CeVmAoC&dq=%E2%80%9Cscrotum%E2%80%9D+%E2%80%9Cskin%E2%80%9D+%E2%80%9Chide%E2%80%9D+%E2%80%9CLatin%E2%80%9D&pg=PA11}}</ref><ref>{{cite book|last=Spiegl|first=Fritz|title=Fritz Spiegl's Sick Notes: An Alphabetical Browsing-Book of Derivatives, Abbreviations, Mnemonics and Slang for Amusement and Edification of Medics, Nurses, Patients and Hypochondriacs|publisher=Taylor & Francis|year = 1996|page=142|access-date=October 14, 2023|isbn= 978-1-85070-627-4 |url= https://books.google.com/books?id=_CbA5a0u5E0C&dq=%E2%80%9Cscrotum%E2%80%9D+%E2%80%9Cskin%E2%80%9D+%E2%80%9Chide%E2%80%9D+%E2%80%9CLatin%E2%80%9D+%E2%80%9Cscortum%E2%80%9D&pg=PA142}}</ref> or '''scrotal sac''' is a part of the external male [[Sex organ|genitalia]] located at the base of the [[penis]]. It consists of a sac of [[skin]] containing the [[external spermatic fascia]], [[testicle]]s, [[epididymis|epididymides]], and [[vas deferens|vasa deferentia]]. The scrotum will usually tighten during [[Erection|penile erection]] and when exposed to cold temperatures.
In some [[male]] [[mammal]]s, the '''scrotum''' is an external bag of [[skin]] and [[muscle]] containing the [[testicle]]s. It is an extension of the [[abdomen]], and is located between the [[penis]] and [[anus]]. The [[female]] [[Homology (biology)|homologue]] during fetal development is the [[labia majora]].


The scrotum is [[homology (biology)|homologous]] to the [[labia majora]] in females.
In humans and some other mammals the base of the scrotum becomes covered with [[pubic hair]] at [[puberty]].


== Structure ==
The area below the scrotum is the [[perineum]].
[[File:Gray1143.png|thumb|Diagram of the scrotum. On the left side, the cavity of the tunica vaginalis has been opened; on the right side, only the layers superficial to the cremaster muscle have been removed.]]
In regards to humans, the scrotum is a suspended dual-chambered sac of [[Human skin|skin]] and [[muscular tissue]] containing the testicles and the lower part of the [[spermatic cord]]s. It is located behind the [[Human penis|penis]] and above the [[perineum]]. The [[perineal raphe]] is a small, vertical ridge of skin that expands from the [[Human anus|anus]] and runs through the middle of the scrotum front to back. The scrotum is also a distention of the perineum and carries some abdominal tissues into its cavity including the [[testicular artery]], [[testicular vein]], and [[pampiniform plexus]].


==Function==
===Nerve supply===
The function of the scrotum appears to be to keep the testicles at a [[temperature]] slightly lower than that of the rest of the body. For the human, a temperature around 34.4 degrees Celsius (94 degrees Fahrenheit) appears<!--"appears"?--> to be ideal; 36.7 degrees Celsius (98 degree Fahrenheit) may be damaging to [[sperm count]]. The temperature is controlled by making the scrotum tighter or looser, hence moving the testicles closer to the abdomen when it is cold, and away when hot, through the [[cremasteric reflex]], the gradual tightening and loosening of the [[cremaster muscle]] in the abdomen and the [[dartos]] fascia (muscular tissue under the skin) in the scrotum. It makes semen.


{| class="wikitable sortable"
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, necessitating the scrotum. Since this leaves them vulnerable in many species, there is some debate on the evolutionary advantage of such a system. One theory is that making sperm highly sensitive to elevated body temperature prevents impregnation of females who are ill.
|-
! Nerve !! Surface<ref>{{cite book|last=Moore|first=Keith|title=Essential Clinical Anatomy, Third Edition|year=2007|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-6274-8|page=132|author2=Anne Agur }}</ref>
|-
| [[Genital branch of genitofemoral nerve]] || anterolateral
|-
| [[Anterior scrotal nerves]] (from [[ilioinguinal nerve]]) || anterior
|-
| [[Posterior scrotal nerves]] (from [[perineal nerve]]) || posterior
|-
| [[perineal branches of posterior femoral cutaneous nerve]] || inferior
|}


=== Blood supply ===
{| class="wikitable sortable"
|-
! Blood vessels{{sfn|Elson|Kapit|1977|p=}} !!
|-
| [[Anterior scrotal artery]] || originates from the [[deep external pudendal artery]]<ref>{{NormanAnatomy|antthigh}}</ref>
|-
| [[Posterior scrotal artery]] ||
|-
| [[Testicular artery]] ||
|-
|}


===Skin and glands===
== Health issues ==
* [[Sebaceous glands]]
A common problem of the scrotum is the development of masses. Common scrotal masses include
* [[Apocrine glands]]
* sebaceous cyst, also called a [[epidermal cyst]]
* [[hydrocele]]
* [[Smooth muscle]]
* [[hematocele]]
* [[spermatocele]]
* [[varicocele]]


The skin on the scrotum is more highly pigmented in comparison to the rest of the body. The [[Scrotal septum|septum]] is a connective tissue membrane dividing the scrotum into two cavities.<ref>{{cite web
Other conditions include:
| title = Scrotum | publisher = Encyclopædia Britannica
| url = http://www.britannica.com/EBchecked/topic/530078/scrotum
| access-date = 2015-02-24
}}
</ref>


=== Lymphatic system ===
* [[contact dermatitis]]: may cause redness, swelling, and itching of the entire scrotum. Can result from soaps, solvents, detergents, and natural irritants such as poison ivy.
The scrotal lymph initially drains into the superficial inguinal lymph nodes, this then drains into the deep inguinal lymph nodes. The deep inguinal lymph nodes channel into the common iliac, which ultimately releases lymph into the cisterna chyli.
* [[inguinal hernia]]
{| class="wikitable sortable"
* [[yeast infection]]
|-
* swelling resulting from conditions external to the scrotum, including:
! Lymphatic vessels<ref>
** [[heart failure]]
{{cite web
** kidney or liver disease
| title = VIII. The Lymphatic System. 5. The Lymphatics of the Lower Extremity. Gray, Henry. 1918. Anatomy of the Human Body.
| url = http://www.bartleby.com/107/179.html
| access-date = 2015-02-24
}}


</ref>!!
==See also==
|-
*[[Raphe]]
| [[Superficial inguinal lymph nodes]] ||
*[[Sex organ]]
*[[Castration]]
|-
*[[Blue balls]]
| [[Popliteal lymph nodes]] ||
*[[Teabagging]]
|-
*''[[Telmatobius culeus]]'', a frog whose name means "Aquatic scrotum"
|}


=== Asymmetry ===
{{reproductive_system}}
One testis is typically lower than the other, which is believed to function to avoid compression in the event of impact; in humans, the left testis is typically lower than the right.<ref>{{cite journal | last1 = Bogaert | first1= Anthony F. | year = 1997 | title = Genital asymmetry in men | url = http://www.hawaii.edu/hivandaids/Genital_Asymmentry_in_Men.pdf | journal = Human Reproduction | volume = 12 | issue = 1 | pages = 68–72 | pmid = 9043905 | doi = 10.1093/humrep/12.1.68 | doi-access = free | access-date = 2015-06-29 | archive-date= 2015-05-28 | archive-url = https://web.archive.org/web/20150528142617/http://www.hawaii.edu/hivandaids/Genital_Asymmentry_in_Men.pdf | url-status = dead }}</ref> An alternative view is that testis descent asymmetry evolved to enable more effective cooling of the testicles.<ref>{{Cite journal | doi=10.1177/147470490900700402|title = On the Origin of Descended Scrotal Testicles: The Activation Hypothesis| journal=Evolutionary Psychology| volume=7| issue=4| pages=147470490900700|year = 2009|last1 = Gallup|first1 = Gordon G.| last2=Finn| first2=Mary M.| last3=Sammis| first3=Becky| doi-access=free}}</ref>
{{human anatomical features}}
[[Category:Male reproductive system]]


=== Internal structure ===
[[zh-min-nan:Im-lông]]
[[File:Figure 28 01 02.JPG|thumb|500px|Image showing musculature and inner workings of the scrotum]]
[[cs:Šourek]]

[[da:Skrotum]]
Additional tissues and organs reside inside the scrotum and are described in more detail in the following articles:
[[de:Skrotum]]
{{div col|colwidth=13em}}
[[es:Escroto]]
* [[Appendix of epididymidis]]
[[eo:Skroto]]
* [[Cremaster muscle]]
[[fr:Scrotum]]
[[gl:Escroto]]
* [[Dartos fascia]]
* [[Efferent ductules]]
[[lt:Kapšelis]]
[[nl:Scrotum]]
* [[Epididymis]]
[[ja:陰嚢]]
* [[Leydig cell]]
* [[Lobules of testis]]
[[no:Pung]]
* [[Paradidymis]]
[[pl:Moszna (anatomia)]]
[[pt:Escroto]]
* [[Rete testes]]
* [[Scrotal septum]]
[[ru:Мошонка]]
* [[Seminiferous tubule]]
[[simple:Scrotum]]
[[su:Kanjut]]
* [[Sertoli cell]]
* [[Spermatic cord]]
[[fi:Kivespussi]]
[[sv:Scrotum]]
* [[Testicle]]
* [[Tunica albuginea of testis]]
[[tl:Bayag]]
[[vi:Bìu dái]]
* [[Tunica vaginalis]]
* [[Tunica vasculosa testis]]
[[zh:阴囊]]
* [[Vas deferens]]

{{div col end}}

== Development ==
{{main|Development of the reproductive system}}
[[File:Human genitalia - development 1.png|thumb|Development of genitals showing [[Homology (biology)|homologues]] from ''indifferent'' to both sexes - male on left]]
During the fifth week after fertilization, the [[genital ridge]] grows behind the peritoneal membrane. By the sixth week, string-like tissues called primary sex cords form within the enlarging genital ridge. Externally, a swelling called the genital tubercule appears over the cloacal membrane.

[[Testosterone]] secretion starts during week eight, reaches peak levels during week 13 and eventually declines to very low levels by the end of the second trimester. The testosterone causes the masculinization of the labioscrotal folds into the scrotum. The [[Penile raphe|scrotal raphe]] is formed when the embryonic, urethral groove closes by week 12.{{sfn|Van De Graaff|Fox|1989|pp=927-931}}

===Scrotal growth and puberty===
Though the testes and scrotum form early in embryonic life, sexual maturation begins upon entering [[puberty]]. The increased secretion of testosterone causes the darkening of the skin and development of [[pubic hair]] on the scrotum.{{sfn|Van De Graaff|Fox|1989|p=935}}

== Function ==
The scrotum regulates the temperature of the testicles and maintains it at {{convert|35 |C|F|abbr=off}}, i.e. two or three degrees below the body temperature of {{convert|37|C|F|abbr=off}}. Higher temperatures affect [[spermatogenesis]].{{sfn|Van De Graaff|Fox|1989|p=936}} Temperature control is accomplished by the [[smooth muscle]]s 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 that makes the scrotum appear wrinkly).{{sfn|Van De Graaff|Fox|1989|p=935}}

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.{{sfn|Van De Graaff|Fox|1989|p=936}} Another advantage is it protects the testes from jolts and compressions associated with an active lifestyle. The scrotum may provide some friction during intercourse, helping to enhance the activity.<ref>{{cite book|last1=Jones|first1=Richard|title=Human Reproductive Biology|date=2013|publisher=[[Academic Press]]|page=74|url=https://books.google.com/books?id=M4kEdSnS-pkC&pg=PA74|quote=The rear-entry position of mating may allow the scrotum to stimulate the clitoris and, in this way, may produce an orgasm ...|isbn=9780123821850}}</ref> The scrotum is also considered to be an [[erogenous zone]].<ref>{{cite book|last=Redmon|first=George L.|publisher=Kensington Publishing Corporation|year=2002|title= Sensual for Life|page=176|isbn=978-0-75820-138-6|url=https://books.google.com/books?id=Ny2bBzKgX6YC&pg=PA176}}</ref>

== Other animals ==
A scrotum is present in all [[boreoeutheria]]n land mammals except [[hippopotamus]]es, [[rhinoceros]]es, [[hedgehog]]s, [[Mole (animal)|moles]], [[pangolin]]s, and [[tapir]]s. The testicles remain in the body cavity in all other vertebrates, including [[cloaca]]l animals.<ref>{{cite web |url=https://www.newscientist.com/article/mg15120432.000-science--bumpy-lifestyle-led-to-external-testes.html |title=Science : Bumpy lifestyle led to external testes - 17 August 1996 - New Scientist |access-date=2007-11-06 |work=New Scientist}}</ref>

Unlike [[Placentalia|placental mammals]], some male [[marsupials]] have a scrotum that is anterior to the penis,<ref name="Tyndale-BiscoeRenfree1987">{{cite book|author1=Hugh Tyndale-Biscoe|author2=Marilyn Renfree|title=Reproductive Physiology of Marsupials|url=https://books.google.com/books?id=HpjovN0vXW4C&q=scrotum|date=30 January 1987|publisher=Cambridge University Press|isbn=978-0-521-33792-2}}</ref><ref name="Hyman1992">{{cite book|author=Libbie Henrietta Hyman|title=Hyman's Comparative Vertebrate Anatomy|url=https://books.google.com/books?id=VKlWjdOkiMwC&q=scrotum&pg=PA583|date=15 September 1992|publisher=University of Chicago Press|isbn=978-0-226-87013-7|pages=583–}}</ref><ref name="JonesDickman2003">{{cite book|author1=Menna Jones|author2=Chris R. Dickman|author3=Michael Archer|title=Predators with Pouches: The Biology of Carnivorous Marsupials|url=https://books.google.com/books?id=3YQSDiWHfD0C&q=scrotum|year=2003|publisher=Csiro Publishing|isbn=978-0-643-06634-2}}</ref><ref name="SaundersHinds1997">{{cite book|author1=Norman Saunders|author2=Lyn Hinds|title=Marsupial Biology: Recent Research, New Perspectives|url=https://books.google.com/books?id=FnfVl7MX4YMC&q=scrotum|year=1997|publisher=UNSW Press|isbn=978-0-86840-311-3}}</ref> which is not homologous to the scrotum of placental mammals,<ref name="ArmatiDickman2006">{{cite book|author1=Patricia J. Armati|author2=Chris R. Dickman|author3=Ian D. Hume|title=Marsupials|url=https://books.google.com/books?id=x3S5v971Nk0C&q=scrotum|date=17 August 2006|publisher=Cambridge University Press|isbn=978-1-139-45742-2}}</ref> although there are several marsupial species without an external scrotum.<ref name="Tyndale-Biscoe2005">{{cite book|author=C. Hugh Tyndale-Biscoe|title=Life of Marsupials|url=https://books.google.com/books?id=KqtlPZJ9y8EC&q=scrotum|year=2005|publisher=Csiro Publishing|isbn=978-0-643-06257-3}}</ref>

The scrotum is also absent in [[marine mammal]]s, such as [[whale]]s, [[dolphin]]s, and [[Pinniped|seal]]s,<ref name="PerrinWürsig2009">{{cite book|author1=William F. Perrin|author2=Bernd Würsig|author3=J.G.M. Thewissen|title=Encyclopedia of Marine Mammals|url=https://books.google.com/books?id=2rkHQpToi9sC&q=scrotum|date=26 February 2009|publisher=Academic Press|isbn=978-0-08-091993-5}}</ref> as well as in lineages of other land mammals, such as the [[afrotheria]]ns ([[elephant]]s, [[aardvark]]s, etc.), [[xenarthra]]ns ([[armadillo]]s, [[anteater]]s, and [[sloth]]s), and numerous families of [[bat]]s and [[rodent]]s.<ref>{{cite web|title=Scrotum|url=https://www.nlm.nih.gov/medlineplus/ency/article/002296.htm|work=National Institutes of Health|access-date=6 January 2011}}</ref><ref>{{Cite journal | doi=10.1111/jeb.12373| pmid=24735476|title = Cool sperm: Why some placental mammals have a scrotum| journal=Journal of Evolutionary Biology| volume=27| issue=5| pages=801–814|year = 2014|last1 = Lovegrove|first1 = B. G.| s2cid=24332311| doi-access=free}}</ref>
<gallery mode="packed">
Testicular of a bulldog cow Hoden eines Ochsen Venezuela P1140356.JPG|Scrotum of a [[bull]]
File:Male-kangaroo.jpg|Scrotum of a [[kangaroo]]
Red deer testicles.jpg|Scrotum of a [[red deer]]
Jaguar 7374 (5000551901).jpg|Scrotum of a [[jaguar]]
Camel's Testicles (3953363864).jpg|Scrotum of a [[camel]]
Chlorocebus-pygerythrus-private-parts.JPG|Scrotum of a [[vervet monkey]]
</gallery>

== Clinical significance ==

A study has indicated that use of a laptop computer positioned on the lap can negatively affect sperm production.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/4078895.stm |title=Laptops may damage male fertility |work=BBC News |date=2004-12-09 |access-date=2012-01-30}}</ref><ref>{{cite journal|last=Sheynkin|first=Yefim|title=Increase in scrotal temperature in laptop computer users|journal=Hum. Reprod.|date=February 2005|volume=20|issue=2|pages=452–455|doi=10.1093/humrep/deh616|pmid=15591087|display-authors=etal|doi-access=free}}</ref>

=== Diseases and conditions ===

The scrotum and its contents can develop many diseases and can incur injuries. These include:
{{div col|colwidth=13em}}
*[[Candidiasis]] (yeast infection)
*[[Sebaceous cyst]]
*[[Epidermal cyst]]
*[[Hydrocele testis]]
*[[Hematocele]]
*[[Molluscum contagiosum]]
*[[Spermatocele]]
*Paget's disease of the scrotum<ref>
{{cite web
| title = Paget's disease of the scrotum Symptoms, Diagnosis, Treatments and Causes|publisher= RightDiagnosis.com
| url = http://www.rightdiagnosis.com/p/pagets_disease_of_the_scrotum/intro.htm
| access-date = 2015-02-24
}}
</ref>
*[[Varicocele]] - enlargement of the pampiniform venous complex
*[[Inguinal hernia]]
*[[Epididymo-orchitis]]
*[[Testicular torsion]]
*[[Pruritus scroti]] - irritation of the scrotum (itchiness)
*[[Genital warts]] - [[sexually transmitted infection]]
*[[Testicular cancer]]
*[[Dermatitis]]
*[[Undescended testes]]
*[[Chyloderma]] - swollen scrotum caused by a lymphatic obstruction
*[[Mumps]]
*[[Scabies]]
*[[Herpes]] - sexually transmitted infection
*[[Pubic lice]]
* [[Chancroid]] (''[[Haemophilus ducreyi]]'') - sexually transmitted infection
* [[Chlamydia infection|Chlamydia]] (''[[Chlamydia trachomatis]]'') - sexually transmitted infection
* [[Gonorrhea]] (''[[Neisseria gonorrhoeae]]'') - sexually transmitted infection
* [[Granuloma inguinale]] or (''[[Klebsiella granulomatis]]'')
* [[Syphilis]] (''[[Treponema pallidum]]'') - sexually transmitted infection
* Scrotal eczema
* Scrotal psoriasis disease
* Riboflavin deficiency
* [[Chimney sweeps' carcinoma]] (scrotal cancer)

{{div col end}}

== See also ==
{{Anatomy-terms}}
* [[Retroperitoneal lymph node dissection]]
* [[Scrotal infusion]], a temporary form of body modification
* [[Testicular self-examination]]

== Bibliography ==

; Books
* {{Grays}}
* {{cite book |last1=Van De Graaff|first1=Kent M.|last2=Fox|first2=Stuart Ira|title=Concepts of Human Anatomy and Physiology|date=1989|publisher=William C. Brown Publishers|location=Dubuque, Iowa|isbn=978-0697056757|url=https://archive.org/details/conceptsofhumana00vand}}
* {{cite book |last1=Elson|first1=Lawrence|last2=Kapit|first2=Wynn|title=The Anatomy Coloring Book |date=1977|publisher=Harper & Row|location=New York, New York|isbn=978-0064539142|url=https://archive.org/details/anatomycoloringb00kapi}}
*{{cite web| ref=UnivMi | title = Gross Anatomy Image |series= Medical Gross Anatomy Atlas Images|publisher= University of Michigan Medical School|date=1997| url=http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/atlas/abdo_wall63.html# |access-date = 2015-02-23
}}
* {{cite book |ref=merckmanual |last1=Berkow |first1=Robert |title=The Merck Manual of Medical Information; Home Edition |date=1977 |publisher=Merck Research Laboratories |location=Whitehouse Station, New Jersey |isbn=978-0911910872 |url=https://archive.org/details/merckmanualofmed00berk}}
<!-- <nowiki>{{sfn|merckmanual|1977|p=}}</nowiki>
<nowiki>{{sfn|Elson|1977|p=}}</nowiki>
<nowiki>{{sfn|UnivMi|1977|p=}}{{sfn|vandegraaff|1989|p=}}</nowiki> -->

== References ==
{{Commons category|Scrotums}}
{{Reflist|2}}
{{Human regional anatomy}}
{{Male reproductive system|state=collapsed}}
{{Sex}}
{{Portal bar|Anatomy}}
{{Authority control}}

[[Category:Scrotum| ]]
[[Category:Mammal male reproductive system]]
[[Category:Integumentary system]]
[[Category:Human male reproductive system]]
[[Category:Sex organs]]
[[Category:Testicle]]

Latest revision as of 21:55, 8 April 2024

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

Scrotum
Human scrotum in a relaxed state (left) and a tense state (right)
Details
PrecursorLabioscrotal swellings
SystemReproductive system
ArteryAnterior scrotal artery, posterior scrotal artery, deep external pudendal artery, superficial external pudendal artery, internal pudendal artery
VeinPosterior scrotal veins, internal pudendal veins
NervePosterior scrotal nerves, anterior scrotal nerves, genital branch of genitofemoral nerve, perineal branches of posterior femoral cutaneous nerve, pudendal nerve, perineal nerve
LymphSuperficial inguinal lymph nodes
Identifiers
Latinscrotum
MeSHD012611
TA98A09.4.03.001
A09.4.03.004
TA23693
FMA18252
Anatomical terminology

In most terrestrial mammals, the scrotum (pl.: scrotums or scrota; possibly from Latin scortum, meaning "hide" or "skin")[1][2] or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin containing the external spermatic fascia, testicles, epididymides, and vasa deferentia. The scrotum will usually tighten during penile erection and when exposed to cold temperatures.

The scrotum is homologous to the labia majora in females.

Structure[edit]

Diagram of the scrotum. On the left side, the cavity of the tunica vaginalis has been opened; on the right side, only the layers superficial to the cremaster muscle have been removed.

In regards to humans, the scrotum is a suspended dual-chambered sac of skin and muscular tissue containing the testicles and the lower part of the spermatic cords. It is located behind the penis and above the perineum. The perineal raphe is a small, vertical ridge of skin that expands from the anus and runs through the middle of the scrotum front to back. The scrotum is also a distention of the perineum and carries some abdominal tissues into its cavity including the testicular artery, testicular vein, and pampiniform plexus.

Nerve supply[edit]

Nerve Surface[3]
Genital branch of genitofemoral nerve anterolateral
Anterior scrotal nerves (from ilioinguinal nerve) anterior
Posterior scrotal nerves (from perineal nerve) posterior
perineal branches of posterior femoral cutaneous nerve inferior

Blood supply[edit]

Blood vessels[4]
Anterior scrotal artery originates from the deep external pudendal artery[5]
Posterior scrotal artery
Testicular artery

Skin and glands[edit]

The skin on the scrotum is more highly pigmented in comparison to the rest of the body. The septum is a connective tissue membrane dividing the scrotum into two cavities.[6]

Lymphatic system[edit]

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

Lymphatic vessels[7]
Superficial inguinal lymph nodes
Popliteal lymph nodes

Asymmetry[edit]

One testis is typically lower than the other, which is believed to function to avoid compression in the event of impact; in humans, the left testis is typically lower than the right.[8] An alternative view is that testis descent asymmetry evolved to enable more effective cooling of the testicles.[9]

Internal structure[edit]

Image showing musculature and inner workings of the scrotum

Additional tissues and organs reside inside the scrotum and are described in more detail in the following articles:

Development[edit]

Main article: Development of the reproductive system
Development of genitals showing homologues from indifferent to both sexes - male on left

During the fifth week after fertilization, the genital ridge grows behind the peritoneal membrane. By the sixth week, string-like tissues called primary sex cords form within the enlarging genital ridge. Externally, a swelling called the genital tubercule appears over the cloacal membrane.

Testosterone secretion starts during week eight, reaches peak levels during week 13 and eventually declines to very low levels by the end of the second trimester. The testosterone causes the masculinization of the labioscrotal folds into the scrotum. The scrotal raphe is formed when the embryonic, urethral groove closes by week 12.[10]

Scrotal growth and puberty[edit]

Though the testes and scrotum form early in embryonic life, sexual maturation begins upon entering puberty. The increased secretion of testosterone causes the darkening of the skin and development of pubic hair on the scrotum.[11]

Function[edit]

The scrotum regulates the temperature of the testicles and maintains it at 35 degrees Celsius (95 degrees Fahrenheit), i.e. two or three degrees below the body temperature of 37 degrees Celsius (99 degrees Fahrenheit). Higher temperatures affect spermatogenesis.[12] 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 that makes the scrotum appear wrinkly).[11]

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.[12] Another advantage is it protects the testes from jolts and compressions associated with an active lifestyle. The scrotum may provide some friction during intercourse, helping to enhance the activity.[13] The scrotum is also considered to be an erogenous zone.[14]

Other animals[edit]

A scrotum is present in all boreoeutherian land mammals except hippopotamuses, rhinoceroses, hedgehogs, moles, pangolins, and tapirs. The testicles remain in the body cavity in all other vertebrates, including cloacal animals.[15]

Unlike placental mammals, some male marsupials have a scrotum that is anterior to the penis,[16][17][18][19] which is not homologous to the scrotum of placental mammals,[20] although there are several marsupial species without an external scrotum.[21]

The scrotum is also absent in marine mammals, such as whales, dolphins, and seals,[22] as well as in lineages of other land mammals, such as the afrotherians (elephants, aardvarks, etc.), xenarthrans (armadillos, anteaters, and sloths), and numerous families of bats and rodents.[23][24]

Clinical significance[edit]

A study has indicated that use of a laptop computer positioned on the lap can negatively affect sperm production.[25][26]

Diseases and conditions[edit]

The scrotum and its contents can develop many diseases and can incur injuries. These include:

See also[edit]

This article uses anatomical terminology.

Bibliography[edit]

Books
  • Public domain 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 978-0697056757.
  • Elson, Lawrence; Kapit, Wynn (1977). The Anatomy Coloring Book. New York, New York: Harper & Row. ISBN 978-0064539142.
  • "Gross Anatomy Image". Medical Gross Anatomy Atlas Images. University of Michigan Medical School. 1997. Retrieved 2015-02-23.
  • Berkow, Robert (1977). The Merck Manual of Medical Information; Home Edition. Whitehouse Station, New Jersey: Merck Research Laboratories. ISBN 978-0911910872.

References[edit]

Wikimedia Commons has media related to Scrotums.
  1. ^ van Driel, Mels (2010). Manhood: The Rise and Fall of the Penis. Reaktion Books. p. 11. ISBN 978-1-86189-708-4. Retrieved October 14, 2023.
  2. ^ Spiegl, Fritz (1996). Fritz Spiegl's Sick Notes: An Alphabetical Browsing-Book of Derivatives, Abbreviations, Mnemonics and Slang for Amusement and Edification of Medics, Nurses, Patients and Hypochondriacs. Taylor & Francis. p. 142. ISBN 978-1-85070-627-4. Retrieved October 14, 2023.
  3. ^ Moore, Keith; Anne Agur (2007). Essential Clinical Anatomy, Third Edition. Lippincott Williams & Wilkins. p. 132. ISBN 978-0-7817-6274-8.
  4. ^ Elson & Kapit 1977.
  5. ^ antthigh at The Anatomy Lesson by Wesley Norman (Georgetown University)
  6. ^ "Scrotum". Encyclopædia Britannica. Retrieved 2015-02-24.
  7. ^ "VIII. The Lymphatic System. 5. The Lymphatics of the Lower Extremity. Gray, Henry. 1918. Anatomy of the Human Body". Retrieved 2015-02-24.
  8. ^ Bogaert, Anthony F. (1997). "Genital asymmetry in men" (PDF). Human Reproduction. 12 (1): 68–72. doi:10.1093/humrep/12.1.68. PMID 9043905. Archived from the original (PDF) on 2015-05-28. Retrieved 2015-06-29.
  9. ^ Gallup, Gordon G.; Finn, Mary M.; Sammis, Becky (2009). "On the Origin of Descended Scrotal Testicles: The Activation Hypothesis". Evolutionary Psychology. 7 (4): 147470490900700. doi:10.1177/147470490900700402.
  10. ^ Van De Graaff & Fox 1989, pp. 927–931.
  11. ^ a b Van De Graaff & Fox 1989, p. 935.
  12. ^ a b Van De Graaff & Fox 1989, p. 936.
  13. ^ Jones, Richard (2013). Human Reproductive Biology. Academic Press. p. 74. ISBN 9780123821850. The rear-entry position of mating may allow the scrotum to stimulate the clitoris and, in this way, may produce an orgasm ...
  14. ^ Redmon, George L. (2002). Sensual for Life. Kensington Publishing Corporation. p. 176. ISBN 978-0-75820-138-6.
  15. ^ "Science : Bumpy lifestyle led to external testes - 17 August 1996 - New Scientist". New Scientist. Retrieved 2007-11-06.
  16. ^ Hugh Tyndale-Biscoe; Marilyn Renfree (30 January 1987). Reproductive Physiology of Marsupials. Cambridge University Press. ISBN 978-0-521-33792-2.
  17. ^ Libbie Henrietta Hyman (15 September 1992). Hyman's Comparative Vertebrate Anatomy. University of Chicago Press. pp. 583–. ISBN 978-0-226-87013-7.
  18. ^ Menna Jones; Chris R. Dickman; Michael Archer (2003). Predators with Pouches: The Biology of Carnivorous Marsupials. Csiro Publishing. ISBN 978-0-643-06634-2.
  19. ^ Norman Saunders; Lyn Hinds (1997). Marsupial Biology: Recent Research, New Perspectives. UNSW Press. ISBN 978-0-86840-311-3.
  20. ^ Patricia J. Armati; Chris R. Dickman; Ian D. Hume (17 August 2006). Marsupials. Cambridge University Press. ISBN 978-1-139-45742-2.
  21. ^ C. Hugh Tyndale-Biscoe (2005). Life of Marsupials. Csiro Publishing. ISBN 978-0-643-06257-3.
  22. ^ William F. Perrin; Bernd Würsig; J.G.M. Thewissen (26 February 2009). Encyclopedia of Marine Mammals. Academic Press. ISBN 978-0-08-091993-5.
  23. ^ "Scrotum". National Institutes of Health. Retrieved 6 January 2011.
  24. ^ Lovegrove, B. G. (2014). "Cool sperm: Why some placental mammals have a scrotum". Journal of Evolutionary Biology. 27 (5): 801–814. doi:10.1111/jeb.12373. PMID 24735476. S2CID 24332311.
  25. ^ "Laptops may damage male fertility". BBC News. 2004-12-09. Retrieved 2012-01-30.
  26. ^ 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.
  27. ^ "Paget's disease of the scrotum Symptoms, Diagnosis, Treatments and Causes". RightDiagnosis.com. Retrieved 2015-02-24.
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