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Dartos

4,490 bytes added, 18:00, 29 September 2019
Create Dartos
{Infobox muscle
| Name = Dartos
| Latin = Tunica dartos
| Image = Gray1143.png
| Caption = The [[scrotum]]. (Label for Dartos is at bottom left.)
| Image2 = Gray1144.png
| Caption2 = The [[scrotum]]. (Label for Dartos is at bottom left.)
| Origin = Subcutaneous tissue of [[scrotum]], superficial to superficial fascia (Colles)
| Insertion = Skin and midline raphé of [[scrotum]]
| Blood = [[Artery of Duffy]]{{Citation needed|date=April 2011}}
| Nerve = [[Genital branch of genitofemoral nerve]]
| Action = Corrugates the scrotum
| Antagonist =
}}
The '''dartos fascia''' or simply '''dartos''' is a layer of connective tissue found in the [[penile shaft]], [[foreskin]], and [[scrotum]].<ref name=Campbell10>{{vcite book |
author=Campbell | chapter= | editor=Alan J. Wein, editor | title=Campbell-Walsh Urology | publisher=Philadelphia: Elsevier Saunders | date= | isbn=978-1-4160-6911-9 | pages= }}</ref> The penile portion is referred to as the '''superficial fascia of penis''' or the '''subcutaneous tissue of penis''',<ref>[http://www.unifr.ch/ifaa/Public/EntryPage/TA98%20Tree/Entity%20TA98%20EN/09.4.01.027%20Entity%20TA98%20EN.htm Terminologica Anatomica 98]</ref> while the scrotal part is the dartos proper. In addition to being continuous with itself between the scrotum and the penis, it is also continuous with [[Colles fascia]] of the perineum and [[Scarpa's fascia]] of the abdomen.<ref name=Campbell10 />

It lies just below the skin, which places it just superficial to the external spermatic fascia in the scrotum and to [[Buck's fascia]] in the penile shaft.

In the scrotum, it consists mostly of smooth muscle.<ref>Gray's 16th Edition</ref> The tone of this smooth muscle is responsible for the wrinkled (rugose) appearance of the scrotum.<ref name=Campbell10 />

In females, the same muscle fibers are less well developed and termed ''dartos muliebris,'' lying beneath the skin of the [[vulva|labia majora]].

It receives innervation from postganglionic sympathetic nerve fibers arriving via the [[ilioinguinal nerve]] and the [[posterior scrotal nerves|posterior scrotal nerve]].

==Function==

In the penis, the loose attachment of the dartos fascia to Buck's fascia is responsible for the high degree of mobility of the penile skin over the underlying tissue.<ref name=Campbell10 /> It is also responsible for carrying the blood supply of the penile skin, a longitudinally-coursing anastomotic network of vessels that arise from the external pudendal vessels.<ref name=Campbell10 />

In the scrotum, the tunica dartos acts to regulate the [[temperature]] of the [[testicle]]s, which promotes [[spermatogenesis]]. It does this by expanding or contracting to wrinkle the scrotal skin.

* Contraction reduces the [[area|surface area]] available for heat loss, thus reducing [[heat]] loss and warming the testicles.
* Conversely, expansion increases the surface area, promoting heat loss and thus cooling the testicles.

The dartos muscle works in conjunction with the [[cremaster muscle]] to elevate the [[testis]] but should not be confused with the [[cremasteric reflex]].

The dartos fascia keeps the foreskin close to the glans penis throughout life. In infancy, the dartos fascia operates as a one-way check valve at the tip of the foreskin, allowing urine to pass out, but prohibiting the entry of foreign matter and pathogens.

There is an increase in elastic fibers with increasing maturity that allows the foreskin to become retractable by adulthood and glide freely back and forth.

==Related terms==

Etymology:

: Derived from the Greek δέρνω/derno (beat, flog) and/or δέρμα/derma (skin), meaning "that which is skinned or flayed", possibly due to its appearance.<ref>http://www.dartmouth.edu/~humananatomy/resources/etymology/Abdominal_wall.htm</ref>

Some dartos-related terms:

: '''dartoic''' ''(dar·to·ic)'' (dahr-to'ik) of the nature of a dartos; having a slow, involuntary contractility like that of the dartos.

: '''dartoid''' ''(dar·toid)'' (dahr'toid) resembling the dartos.

==Additional images==
<gallery>
File:Gray1145.png|Transverse section through the left side of the scrotum and the left testis.
File:Slide9eee.JPG|Dartos
File:Penis_cross_section.svg
</gallery>

== References ==
{{Reflist}}

{{Male reproductive system}}
{{Muscles of perineum}}
{{Authority control}}

[[Category:Mammal reproductive system]]
[[Category:Human reproduction]]
[[Category:Fascia]]
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