The perineum (: perineums or perinea) in placental

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s is the space between the anus and the genitals. The human perineum is between the anus and

scrotum In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") 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 ...

in the male or between the anus and

vulva In mammals, the vulva (: vulvas or vulvae) comprises mostly external, visible structures of the female sex organ, genitalia leading into the interior of the female reproductive tract. For humans, it includes the mons pubis, labia majora, lab ...

in the female. The perineum is the region of the body between the pubic symphysis (pubic arch) and the

coccyx The coccyx (: coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horse anatomy, horses. In tailless primates (e.g. hum ...

(tail bone), including the perineal body and surrounding structures. The perineal raphe is visible and pronounced to varying degrees.

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. 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

. 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 In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular sex organ, reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The #Vag ...

. 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 line drawn across the surface connecting the ischial tuberosities divides the space into two triangles: * The anterior

urogenital triangle The urogenital triangle is the anterior part of the perineum. In female mammals, it contains the vulva, while in male mammals, it contains the penis and scrotum. Structure The urogenital triangle is the area bound by a triangle with one vertex a ...

contains the

penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate. The term ''pen ...

and

(males) or

(females) * The posterior

anal triangle The anal triangle is the posterior part of the perineum. It contains the anus in mammals. Structure The anal triangle can be defined either by its vertices or its sides. * ''Vertices'' ** one vertex at the coccyx bone ** the two ischial tuber ...

contains the anus The formal anatomical boundaries of the perineum may be said to be: * in front: the pubic arch and the arcuate ligament of the pubis * behind: the tip of the

* on either side: the inferior rami of the pubis and ischial tuberosity, and the sacrotuberous ligament * superiorly: pelvic floor * 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

and the

. In males, it is found between the bulb of the penis and the anus; in females, it is found between the

and anus, and about 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 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. It is attached to the inner surface of each side of the ...

muscle of both sides, thus predisposing the child-bearer to prolapse of the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

rectum The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces temporarily. The adult ...

, or even the

urinary bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the Kidney (vertebrates), kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the ...

. Perineal tears and episiotomy often occur in

childbirth Childbirth, also known as labour, parturition and delivery, is the completion of pregnancy, where one or more Fetus, fetuses exits the Womb, internal environment of the mother via vaginal delivery or caesarean section and becomes a newborn to ...

with first-time deliveries, but the risk of these injuries can be reduced by preparing the perineum, often through massage. At this point, the following muscles converge and are attached: # External anal sphincter # Bulbospongiosus muscle #

Superficial transverse perineal muscle The transverse perineal muscles (transversus perinei) are the superficial and the deep transverse perineal muscles. Superficial transverse perineal ...

# Anterior fibers of the

# Fibers from

male Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...

or female external urinary sphincter # Deep transverse perineal muscle

Fascia

Perineal

fascia A fascia (; : fasciae or fascias; adjective fascial; ) is a generic term for macroscopic membranous bodily structures. Fasciae are classified as superficial, visceral or deep, and further designated according to their anatomical location. ...

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:

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 ('' peri-'' and '' 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 – a fat-filled space at the lateral sides of

anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional s ...

, bounded laterally by the obturator internus muscle, and medially by the pelvic diaphragm and anal canal; its base is the skin **

** pudendal canal – contains internal pudendal artery and the pudendal nerve

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. 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. 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. 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. 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. The perineum is an

erogenous zone An erogenous zone (from Greek , ''érōs'' "love"; and English ''-genous'' "producing", from Greek , ''-genḗs'' "born") is an area of the human body that has heightened Sensory processing, sensitivity, the sexual stimulation, stimulation of wh ...

. This area is also known as the taint or gooch in American slang, as well as the notcha in Australian slang.

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. There is no scientific evidence that this behavior promotes any of the alleged benefits. The practice of exposing a sensitive area of skin to sunlight also increases the risk of skin cancers such as

melanoma Melanoma is the most dangerous type of skin cancer; it develops from the melanin-producing cells known as melanocytes. It typically occurs in the skin, but may rarely occur in the mouth, intestines, or eye (uveal melanoma). In very rare case ...

, squamous cell carcinoma, and basal-cell carcinoma. Doctors recommend safer alternative options such as relaxation, meditation, and mindfulness, which can also achieve the same desired benefits.

Gallery

File:Gray1119.png, Stages in the development of the external sexual organs in the male and female

References

External links

{{Authority control Pelvis Human surface anatomy