The perineum in humans is the space between the

anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, ...

and

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum co ...

in the male, or between the anus and the

vulva The vulva (plural: vulvas or vulvae; derived from Latin for wrapper or covering) consists of the external female sex organs. The vulva includes the mons pubis (or mons veneris), labia majora, labia minora, clitoris, vestibular bulbs, vulv ...

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 horses. In tailless primates (e.g. humans and othe ...

(tail bone), including the perineal body and surrounding structures. There is some variability in how the boundaries are defined. The

perineal raphe The perineal raphe is a visible line or ridge of tissue on the body that extends from the anus through the perineum to scrotum (male) or labia majora (female). It is found in both males and females, arises from the fusion of the urogenital folds, a ...

is visible and pronounced to varying degrees. 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 sensitivity, the stimulation of which may generate a sexual response, suc ...

. The word perineum 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

seen as a continuation of the

scrotal septum The septum of the scrotum is a vertical layer of fibrous tissue that divides the two compartments of the scrotum. It consists of flexible connective tissue. Its structure extends to the skin surface of the scrotum as the scrotal raphe. It is an ...

since

masculinization Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens. Virilization is most commonly used in three medical and biology ...

causes the development of a large

anogenital distance Anogenital distance (AGD) is the distance from the midpoint of the anus to the genitalia, the underside of the vagina, the clitoris or the scrotum. It is considered medically significant for a number of reasons, in both humans and other animals ...

in men, in comparison to the corresponding lack of distance in women. As a result of

folk etymologies Folk etymology (also known as popular etymology, analogical reformation, reanalysis, morphological reanalysis or etymological reinterpretation) is a change in a word or phrase resulting from the replacement of an unfamiliar form by a more famili ...

(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

and, in females, the

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...

. 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 Line most often refers to: * Line (geometry), object with zero thickness and curvature that stretches to infinity * Telephone line, a single-user circuit on a telephone communication system Line, lines, The Line, or LINE may also refer to: Art ...

drawn across the surface connecting the ischial tuberosities divides the space into two triangles: * The anterior urogenital triangle, contains the

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males d ...

(males) or

(females) * The posterior

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

containing the

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 The sacrotuberous ligament (great or posterior sacrosciatic ligament) is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends. Structure It runs from the sacrum (the lowe ...

* superiorly: pelvic floor * inferiorly: skin and fascia

Perineal 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

. In males, it is found between the bulb of the penis and the

; in females, it is found between the

and anus, and about 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 woman to prolapse of the

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...

rectum The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the l ...

, or even the

urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine ente ...

Perineal tear 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 c ...

s and

episiotomy Episiotomy, also known as perineotomy, is a surgical incision of the perineum and the posterior vaginal wall generally done by a midwife or obstetrician. Episiotomy is usually performed during second stage of labor to quickly enlarge the open ...

often occur in

childbirth Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births glob ...

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 The external anal sphincter (or sphincter ani externus ) is a flat plane of skeletal muscle fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus. Anatomy The external anal sphincter measures about 8 ...

# Bulbospongiosus muscle # Superficial transverse perineal muscle # Anterior fibers of the levator ani # Fibers from

male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot reproduce sexually without access to ...

or female external urinary sphincter #

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

Fascia

The terminology of the perineal

fascia A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal organs ...

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: #

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

# superficial perineal fascia:

Subcutaneous tissue The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and m ...

divided into two layers: (a) A superficial fatty layer, and (b) Colles' fascia, a deeper, membranous layer # deep perineal fascia and muscles: :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: * 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 segme ...

, 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

Extensive deformation of the pelvic floor occur during a vaginal delivery. Approximately 85% of women have some

perineal tear 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 c ...

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. The

is a measure of the distance between the midpoint of the

and the underside of the

or the

. 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. There are claims that sometimes the perineum is excessively repaired after childbirth, using a so-called "

husband stitch The husband stitch or husband's stitch, also known as the daddy stitch, husband's knot and vaginal tuck, is a surgical procedure in which one or more additional sutures than necessary are used to repair a woman's perineum after it has been torn ...

" and that this can increase vaginal tightness or result in pain during intercourse.

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, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...

squamous cell carcinoma Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the ...

, 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:Male_perineum.jpg, Annotated male perineum: 1. Perineum. 2. Raphe perinealis. 3. Anus. 4. Testicles, Scrotum. 5. Raphe scrotalis. Image:Gray1119.png, Stages in the development of the external sexual organs in the male and female

References

External links

Perineum at The Anatomy Lesson
by Wesley Norman (Georgetown University) {{Authority control Pelvis Human surface anatomy