Perineum

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Perineum
The male and female perineum.jpg
The human male perineum (left) and human female perineum (right)
1116 Muscle of the Perineum.jpg
The muscles of the male (left) and female (right) perineum
Details
Pronunciation /ˌpɛrɪˈniːəm/ ; [1]
System Musculoskeletal system
Artery Perineal artery, dorsal artery of the penis and deep artery of the penis
Nerve Perineal nerve, posterior scrotal nerves, dorsal nerve of the penis or dorsal nerve of the clitoris
Lymph Primarily superficial inguinal lymph nodes
Identifiers
Latin perineum, perinaeum
MeSH D010502
TA98 A09.5.00.001
TA2 131
FMA 9579
Anatomical terminology

The perineum (pl.: perineums or perinea) in mammals is the space between the anus and the genitals. The human perineum is between the anus and scrotum in the male or between the anus and vulva in the female. [2] The perineum is the region of the body between the pubic symphysis (pubic arch) and the coccyx (tail bone), including the perineal body and surrounding structures. The perineal raphe is visible and pronounced to varying degrees. The perineum is an erogenous zone. [3] This area is also known as the taint or gooch in American slang.

Contents

Etymology

The word entered English from late Latin via Greek περίναιος ~ περίνεος perinaios, perineos, itself from περίνεος, περίνεοι 'male genitals' and earlier περίς perís 'penis' through influence from πηρίς pērís 'scrotum'. The term was originally understood as a purely male body-part with the perineal raphe seen as a continuation of the scrotal septum since masculinization causes the development of a large anogenital distance in men, in comparison to the corresponding lack of distance in women. [4] As a result of folk etymologies (such as ἰνάω ináō, "to carry off by evacuations"), it is contemporaneously extended to both sexes.

Structure

The perineum is generally defined as the 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 anus and, in females, the vagina. [5] Its definition varies: it can refer to only the superficial structures in this region, or it can be used to include both superficial and deep structures. The perineum corresponds to the outlet of the pelvis.

A line drawn across the surface connecting the ischial tuberosities divides the space into two triangles:

The formal anatomical boundaries of the perineum may be said to be: [6]

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 the penis and the anus; in females, it is found between the vagina and anus, and about 1.25 cm (0.49 in) 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 woman to prolapse of the uterus, rectum, or even the urinary bladder. Perineal tears 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. [8]

At this point, the following muscles converge and are attached:

  1. External anal sphincter
  2. Bulbospongiosus muscle
  3. Superficial transverse perineal muscle
  4. Anterior fibers of the levator ani
  5. Fibers from male or female external urinary sphincter
  6. Deep transverse perineal muscle

Fascia

The terminology of the perineal fascia 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:

  1. skin
  2. superficial perineal fascia: Subcutaneous tissue divided into two layers: (a) A superficial fatty layer, and (b) Colles' fascia, a deeper, membranous layer
  3. deep perineal fascia and muscles:
    Superficial perineal pouch Contains superficial perineal muscles: transversus perinei superficialis, bulbospongiosus, 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, 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
  4. fascia and muscles of pelvic floor (levator ani, coccygeus)

Areas

The region of the perineum can be considered a distinct area from pelvic cavity, with the two regions separated by the pelvic diaphragm. The perianal area ( peri- and anal ) is a subset of the perineum. The following areas are thus classified as parts of the perineal region:

Clinical significance

The anogenital distance is a measure of the distance between the midpoint of the anus and the underside of the scrotum or the vagina. Studies show that the human perineum is twice as long in males as in females. [9] Measuring the anogenital distance in neonatal humans has been suggested as a noninvasive method to determine male feminisation and thereby predict neonatal and adult reproductive disorders. [10]

Extensive deformation of the pelvic floor occurs during a vaginal delivery. Approximately 85% of women have some perineal tear during a vaginal delivery and in about 69% suturing is required. [11] [12] [13] Obstetric perineal trauma contributes to postpartum morbidity and frustration of women after delivery. In many women the childbirth trauma is manifested in advanced age when the compensatory mechanisms of the pelvic floor become weakened making the problem more serious among the aged population. [14] [15]

There are claims that sometimes the perineum is excessively repaired after childbirth, using a so-called "husband stitch" and that this can increase vaginal tightness or result in pain during intercourse. [16]

Society and culture

Perineum sunning is a wellness practice that involves exposing the perineum (area between the genitals and anus) to sunlight. Adherents claim various unproven health benefits such as improved libido, circulation, sleep, and longevity. [17] There is no scientific evidence that this behavior promotes any of the alleged benefits. [17] The practice of exposing a sensitive area of skin to sunlight also increases the risk of skin cancers [18] such as melanoma, squamous cell carcinoma, and basal-cell carcinoma. [19] Doctors recommend safer alternative options such as relaxation, meditation, and mindfulness, which can also achieve the same desired benefits. [20]

See also

Related Research Articles

<span class="mw-page-title-main">Pudendal nerve</span> Main nerve of the perineum

The pudendal nerve is the main nerve of the perineum. It is a mixed nerve and also conveys sympathetic autonomic fibers. It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well as the motor supply to various pelvic muscles, including the male or female external urethral sphincter and the external anal sphincter.

<span class="mw-page-title-main">Levator ani</span> Broad, thin muscle group, situated on either side of the pelvis

The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis.

<span class="mw-page-title-main">Bulbospongiosus muscle</span> Superficial muscle of the perineum

The bulbospongiosus muscles are a subgroup of the superficial muscles of the perineum. They have a slightly different origin, insertion and function in males and females. In males, these muscles cover the bulb of the penis, while in females, they cover the vestibular bulbs.

<span class="mw-page-title-main">Pelvic floor</span> Anatomical structure

The pelvic floor or pelvic diaphragm is an anatomical location in the human body, which has an important role in urinary and anal continence, sexual function and support of the pelvic organs. The pelvic floor includes muscles, both skeletal and smooth, ligaments and fascia. and separates between the pelvic cavity from above, and the perineum from below. It is formed by the levator ani muscle and coccygeus muscle, and associated connective tissue.

<span class="mw-page-title-main">External anal sphincter</span> Flat plane of skeletal muscle fibers

The external anal sphincter is an oval tube of skeletal muscle fibers. Distally, it is adherent to the skin surrounding the margin of the anus. It exhibits a resting state of tonical contraction.

<span class="mw-page-title-main">Perineal nerve</span> Nerve of the perineum

The perineal nerve is a nerve of the pelvis. It arises from the pudendal nerve in the pudendal canal. It gives superficial branches to the skin, and a deep branch to muscles. It supplies the skin and muscles of the perineum. Its latency is tested with electrodes.

<span class="mw-page-title-main">Pelvic cavity</span> Body cavity bounded by the pelvic bones

The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet. Its lower boundary is the pelvic floor.

<span class="mw-page-title-main">Transverse perineal muscles</span>

The transverse perineal muscles are the superficial and the deep transverse perineal muscles.

<span class="mw-page-title-main">Perineal membrane</span> Anatomical term

The perineal membrane is an anatomical term for a fibrous membrane in the perineum. The term "inferior fascia of urogenital diaphragm", used in older texts, is considered equivalent to the perineal membrane.

<span class="mw-page-title-main">Deep perineal pouch</span> Anatomic space enclosed partly by the perineum

The deep perineal pouch is the anatomic space enclosed in part by the perineum and located superior to the perineal membrane.

<span class="mw-page-title-main">Urogenital triangle</span> Anterior part of the perineum

The urogenital triangle is the anterior part of the perineum. In female mammals, it contains the vagina and associated parts of the internal genitalia.

<span class="mw-page-title-main">Anal triangle</span> Posterior part of the perineum

The anal triangle is the posterior part of the perineum. It contains the anal canal.

<span class="mw-page-title-main">Outline of human anatomy</span> Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

<span class="mw-page-title-main">Muscular branches of perineal nerve</span> Nerve of the perineum

The deep branch of the perineal nerve is a nerve of the perineum. It is a branch of the perineal nerve, from the pudendal nerve. It supplies the superficial transverse perineal muscle, bulbospongiosus muscle, ischiocavernosus muscle, the bulb of penis, levator ani, and the external anal sphincter.

<span class="mw-page-title-main">Defecography</span> Visualisation of the mechanics of a patients defecation

Defecography is a type of medical radiological imaging in which the mechanics of a patient's defecation are visualized in real time using a fluoroscope. The anatomy and function of the anorectum and pelvic floor can be dynamically studied at various stages during defecation.

<span class="mw-page-title-main">Human anus</span> External opening of the rectum

In humans, the anus is the external opening of the rectum located inside the intergluteal cleft. Two sphincters control the exit of feces from the body during an act of defecation, which is the primary function of the anus. These are the internal anal sphincter and the external anal sphincter, which are circular muscles that normally maintain constriction of the orifice and which relax as required by normal physiological functioning. The inner sphincter is involuntary and the outer is voluntary. Above the anus is the perineum, which is also located beneath the vulva or scrotum.

<span class="mw-page-title-main">Perineal tear</span> Medical condition

A perineal tear is a laceration of the skin and other soft tissue structures which, in women, separate the vagina from the anus. Perineal tears mainly occur in women as a result of vaginal childbirth, which strains the perineum. It is the most common form of obstetric injury. Tears vary widely in severity. The majority are superficial and may require no treatment, but severe tears can cause significant bleeding, long-term pain or dysfunction. A perineal tear is distinct from an episiotomy, in which the perineum is intentionally incised to facilitate delivery. Episiotomy, a very rapid birth, or large fetal size can lead to more severe tears which may require surgical intervention.

<span class="mw-page-title-main">Pelvis</span> Lower torso of the human body

The pelvis is the lower part of the trunk, between the abdomen and the thighs, together with its embedded skeleton.

Descending perineum syndrome refers to a condition where the perineum "balloons" several centimeters below the bony outlet of the pelvis during strain, although this descent may happen without straining. The syndrome was first described in 1966 by Parks et al.

<span class="mw-page-title-main">Vaginal support structures</span> Structures that maintain the position of the vagina within the pelvic cavity

The vaginal support structures are those muscles, bones, ligaments, tendons, membranes and fascia, of the pelvic floor that maintain the position of the vagina within the pelvic cavity and allow the normal functioning of the vagina and other reproductive structures in the female. Defects or injuries to these support structures in the pelvic floor leads to pelvic organ prolapse. Anatomical and congenital variations of vaginal support structures can predispose a woman to further dysfunction and prolapse later in life. The urethra is part of the anterior wall of the vagina and damage to the support structures there can lead to incontinence and urinary retention.

References

  1. ↑ OED 2nd edition, 1989 as /pɛrɪˈniːəm/ and /pɛrɪˈniːəl/.
  2. ↑ "Perineum definition and meaning | Collins English Dictionary". www.collinsdictionary.com.
  3. ↑ Winkelmann RK (1959). "The erogenous zones: their nerve supply and significance". Mayo Clin Proc. 34 (2): 39–47. PMID   13645790.
  4. ↑ Simkin Oliver (2016). "Περίς, πηρίς and περίναιος". Revista de Lingüística y Filología Clásica. LXXXIV (2): 353–362. doi: 10.3989/emerita.2016.18.1532 .
  5. ↑ Gray, Henry. Anatomy of the Human Body. Philadelphia: Lea & Febiger, 1918; Bartleby.com, 2000.
  6. ↑ perineumboundaries
  7. ↑ Daftary, Shirish; Chakravarti, Sudip (2011). Manual of Obstetrics, 3rd Edition. Elsevier. pp. 1-16. ISBN   9788131225561.
  8. ↑ Shipman, M. K.; Boniface, D. R.; Tefft, M. E.; McCloghry, F. (July 1997). "Antenatal perineal massage and subsequent perineal outcomes: a randomised controlled trial". British Journal of Obstetrics and Gynaecology. 104 (7): 787–91. doi:10.1111/j.1471-0528.1997.tb12021.x. PMID   9236642. S2CID   33507861.
  9. ↑ McEwen, Gerald N.; Renner, Gerald (January 2006). "Validity of anogenital distance as a marker of in utero phthalate exposure". Environmental Health Perspectives. 114 (1): A19–20. doi:10.1289/ehp.114-a19b. PMC   1332693 . PMID   16393642.
  10. ↑ Michelle Welsh, et al.: "Identification in rats of a programming window for reproductive tract masculinization, disruption of which leads to hypospadias and cryptorchidism". Journal of Clinical Investigation, 13 March 2008.
  11. ↑ Sleep J, Grant A, Garcia J, Elbourne D, Spencer J, Chalmers I. West Berkshire perineal management trial. Br Med J (Clin Res Ed). 1984; 289(6445): 587-90.
  12. ↑ McCandlish R, Bowler U, van Asten H, Berridge G, Winter C, Sames L, Garcia J, Renfrew M, Elbourne D. A randomised controlled trial of care of the perineum during second stage of normal labour. Br J Obstet Gynaecol. 1998; 105(12): 1262-72.
  13. ↑ Grant A, Sleep J. Repair of perineal trauma. In: Enkin M, Keirse MJNC, Chalmers I, Eds. A Guide to Effective Care in Pregnancy and Childbirth. Oxford: Oxford University Press, 1989: 240-43.
  14. ↑ Barrett G, Pendry E, Peacock J, et al. Women's sexuality after childbirth: a pilot study. Archives of Sexual Behavior 1999; 28(2): 179-91.
  15. ↑ Tinelli A, Malvasi A, Rahimi S, et al. Age-related pelvic floor modifications and prolapse risk factors in postmenopausal women. Menopause 2010; 17(1): 204-12.
  16. ↑ Vinopal, Lauren (17 August 2017). "Are Husbands and Doctors Conspiring to Sew New Moms Up Too Tight?". Fatherly. Retrieved 15 October 2017.
  17. 1 2 Beth Daley (23 December 2020). "There's no magic way to boost your energy. But 'perineum sunning' isn't the answer". The Conversation.
  18. ↑ EJ Dickson (27 November 2019). "Sorry, Anus Tanning Is Not Really a Thing". Rolling Stone.
  19. ↑ Marci Robin (7 December 2019). "Dermatologists Are Warning People Not to Try Perineum Sunning". Allure.
  20. ↑ Leah Groth (21 February 2020). "So, Perineum Sunning is a Thing Now—Here's Why Doctors Definitely Don't Want You to Try It". Health.com.
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