Editing Perineum (section)

==Structure==
The perineum is generally defined as the [[surface anatomy|surface region]] between the [[pubic symphysis]] and the [[coccyx]]. The perineum is below the [[pelvic diaphragm]] and between the legs. It is a diamond-shaped area that includes the [[human anus|anus]] and, in females, the [[vagina]].<ref>[[Henry Gray|Gray, Henry]]. ''Anatomy of the Human Body''. Philadelphia: Lea & Febiger, 1918; Bartleby.com, 2000.</ref> Its definition varies: it can refer to only the superficial structures in this region or include both superficial and deep structures. The perineum corresponds to the [[outlet of the pelvis]].

A [[Anatomical line|line]] drawn across the surface connecting the [[tuberosity of the ischium|ischial tuberosities]] divides the space into two triangles:
* The anterior [[urogenital triangle]] contains the [[Human penis|penis]] and [[scrotum]] (males) or [[vulva]] (females)
* The posterior [[anal triangle]] contains the [[Human anus|anus]]

The formal anatomical boundaries of the perineum may be said to be:<ref>{{NormanAnatomyFig|perineumboundaries}}</ref>
* in front: the [[pubic arch]] and the [[Inferior pubic ligament|arcuate ligament]] of the [[pubis (bone)|pubis]]
* behind: the tip of the [[coccyx]]
* on either side: the [[inferior pubic ramus|inferior rami of the pubis]] and [[ischial tuberosity]], and the [[sacrotuberous ligament]]
* superiorly: [[pelvic floor]]<ref>Daftary, Shirish; Chakravarti, Sudip (2011). Manual of Obstetrics, 3rd Edition. Elsevier. pp. 1-16. {{ISBN|9788131225561}}.</ref>
* inferiorly: skin and fascia

===Body===
The '''perineal body''' (or '''central tendon of perineum''') is a pyramidal fibromuscular mass in the middle line of the perineum at the junction between the [[urogenital triangle]] and the [[anal triangle]]. In males, it is found between the [[bulb of penis|bulb of the penis]] and the [[Human anus|anus]]; in females, it is found between the [[vagina]] and anus, and about {{Cvt|1.25|cm}} in front of the latter.

The perineal body is essential for the integrity of the [[pelvic floor]], particularly in females. Its rupture during vaginal birth leads to widening of the gap between the anterior free borders of [[levator ani]] muscle of both sides, thus predisposing the child-bearer to prolapse of the [[uterine prolapse|uterus]], [[rectocele|rectum]], or even the [[cystocele|urinary bladder]]. [[Perineal tear]]s and [[episiotomy]] often occur in [[childbirth]] with first-time deliveries, but the risk of these injuries can be reduced by preparing the perineum, often through massage.<ref>{{cite journal |last1=Shipman |first1=M. K. |last2=Boniface |first2=D. R. |last3=Tefft |first3=M. E. |last4=McCloghry |first4=F. |title=Antenatal perineal massage and subsequent perineal outcomes: a randomised controlled trial |journal=British Journal of Obstetrics and Gynaecology |volume=104 |issue=7 |pages=787–91 |date=July 1997 |pmid=9236642 |doi=10.1111/j.1471-0528.1997.tb12021.x|s2cid=33507861 |doi-access= }}</ref>

At this point, the following muscles converge and are attached:
# [[External anal sphincter]]
# [[Bulbospongiosus muscle]]
# [[Superficial transverse perineal muscle]]
# Anterior fibers of the [[levator ani]]
# Fibers from [[external sphincter muscle of male urethra|male]] or [[external sphincter muscle of female urethra|female external urinary sphincter]]
# [[Deep transverse perineal muscle]]

===Fascia===
Perineal [[fascia]] terminology can be confusing, and there is some controversy over the nomenclature. This stems from the fact that there are two parts to the fascia, the superficial and deep parts, and each of these can be subdivided into superficial and deep parts.

The layers and contents are as follows, from superficial to deep:
{{ordered list
| [[Human skin|skin]]
| superficial perineal fascia: [[Subcutaneous tissue]] divided into two layers: (a) A superficial fatty layer, and (b) [[Colles' fascia]], a deeper, membranous layer
| deep perineal fascia and muscles:
{{wikitable| class="wikitable"
| [[Superficial perineal pouch]] || Contains superficial perineal muscles: [[Transversus perinei superficialis muscle|transversus perinei superficialis]], [[Bulbospongiosus muscle|bulbospongiosus]], [[Ischiocavernosus muscle|ischiocavernosus]]
 |-
 | Inferior fascia of [[urogenital diaphragm]], or [[perineal membrane]] || A membranous layer of the [[deep fascia]]
 |-
 | [[Deep perineal pouch]] || Contains the deep perineal muscles: [[transversus perinei profundus muscle|transversus perinei profundus]], [[Sphincter urethrae membranaceae muscle|sphincter urethrae membranaceae]]
 |-
 | [[Superior fascia of the urogenital diaphragm]] || Considered hypothetical by some modern anatomists, but still commonly used to logically divide the contents of the region
}}
| fascia and muscles of [[pelvic floor]] ([[levator ani]], [[coccygeus]])}}

===Areas===
The perineum region can be considered a distinct area from the pelvic cavity, with the two regions separated by the [[pelvic diaphragm]]. The perianal area (''[[wikt:peri-#Prefix|peri-]]'' and ''[[anus|anal]]'') is a subset of the perineum. The following areas are thus classified as parts of the perineal region:
* perineal pouches: superficial and deep (see above for details)
* [[ischioanal fossa]]&nbsp;– a fat-filled space at the lateral sides of [[anal canal]], bounded laterally by the obturator internus muscle, and medially by the pelvic diaphragm and anal canal; its base is the skin
** [[anal canal]]
** [[pudendal canal]]&nbsp;– contains [[internal pudendal artery]] and the [[pudendal nerve]]