primate Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...

s, and specifically in humans, the labia majora (: labium majus), also known as the outer lips or outer labia, are two prominent longitudinal

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 ...

folds that extend downward and backward from the

mons pubis In human anatomy, and in mammals in general, the ''mons pubis'' or pubic mound (also known simply as the mons , and known specifically in females as the ''mons Venus'' or ''mons veneris'') is a rounded mass of fatty tissue found over the pubic s ...

to the

perineum The perineum (: perineums or perinea) in placentalia, placental 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. The perineum is ...

. Together with the

labia minora The labia minora (Latin for 'smaller lips', : labium minus), also known as the inner labia, inner lips, or nymphae, are two flaps of skin that are part of the primate vulva, extending outwards from the inner Vagina#Vaginal opening and hymen, vagi ...

, they form the

labia The labia are the major externally visible structures of the vulva. In humans and other primates, there are two pairs of labia: the ''labia majora'' (outer lips) are large and thick folds of skin that cover the vulva's other parts, while the ''la ...

of the

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 ...

. The labia majora are homologous to the male

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 ...

Etymology

''Labia majora'' is the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

plural for big ("major") lips. The Latin term ''labium/labia'' is used in anatomy for a number of usually paired parallel structures, but in English, it is mostly applied to two pairs of parts of the

—labia majora and

. Traditionally, to avoid confusion with other lip-like structures of the body, the vulvar labia were termed by anatomists in Latin as ''labia majora (''or ''minora) pudendi.''

Embryology

Embryologically, they develop from

labioscrotal folds The labioscrotal swellings (genital swellings or labioscrotal folds) are paired structures in the mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-pro ...

. The labia majora after puberty may become of a darker color than the skin outside them and grow

pubic hair Pubic hair (or pubes , ) is terminal hair, terminal body hair that is found in the sex organ, genital area and pubic region of adolescent and adult humans. The hair is located on and around the sex organs, and sometimes at the top of the inside ...

on their external surface.

Function and structure

The main function of the labia majora is to cover and protect the other parts of the vulva. The labia majora contain the

, interlabial sulci,

clitoral hood In female humans and other mammals, the clitoral hood (also called preputium clitoridis, clitoral prepuce, and clitoral foreskin) is a fold of skin that surrounds and protects the glans of the clitoris; it also covers the external clitoral shaft ...

, clitoral glans, frenulum clitoridis, the

Hart's Line The vulval vestibule (also known as the vulvar vestibule or vestibule of vagina) is the part of the vulva between the labia minora. At the innermost part are the vaginal introitus and urinary meatus. The Bartholin's and Skene's glands each have ...

, and the

vulval vestibule The vulval vestibule (also known as the vulvar vestibule or vestibule of vagina) is the part of the vulva between the labia minora. At the innermost part are the vaginal introitus and urinary meatus. The Bartholin's and Skene's glands each ha ...

, where the external openings of the

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

and 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 ...

are located. Each labium majus has two surfaces, an outer, pigmented and covered with strong,

; and an inner, smooth and beset with large

sebaceous A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in t ...

follicles. The labia majora are covered with

squamous epithelium Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

. Between the two, there is a considerable quantity of areolar tissue and

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

, besides vessels, nerves, and

glands A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

. Below the skin of the labia majora, there is a tissue called the ''dartos muliebris'', which gives them a wrinkled appearance.

Pudendal cleft

The labia majora constitute the lateral boundaries of the pudendal cleft. The pudendal cleft, also known as the vulvar cleft or cleft of Venus (''rima vulvae'' or ''rima pudendi'' in Latin), is a vertical fissure between the labia majora starting at the basal point of the

. After puberty, the clitoral hood and the labia minora can protrude into the pudendal cleft to a variable degree.

Commissures

The labia majora are thicker in front, and form the anterior labial commissure where they meet below the

. Posteriorly, they are not really joined, but appear to become lost in the neighboring integument, ending close to, and nearly parallel to, each other. Together with the connecting skin between them, they form another

commissure A commissure () is the location at which two objects wikt:abut#Verb, abut or are joined. The term is used especially in the fields of anatomy and biology. * The most common usage of the term refers to the brain's commissures, of which there are at ...

, the posterior labial commissure, which is also the posterior boundary of the vulva. The interval between the posterior commissure and the

anus In mammals, invertebrates and most fish, the anus (: anuses or ani; from Latin, 'ring' or 'circle') is the external body orifice at the ''exit'' end of the digestive tract (bowel), i.e. the opposite end from the mouth. Its function is to facil ...

, from 2.5 to 3 cm in length, constitutes the

. The anterior region of the perineum is known as the

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 ...

, which separates it from the anal region. Between the labia majora and the inner

thigh In anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of bone tissu ...

s are the labiocrural folds. Between the labia majora and labia minora are the interlabial sulci. Labia majora

atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), malnutrition, poor nourishment, poor circulatory system, circulation, loss of hormone, ...

after

menopause Menopause, also known as the climacteric, is the time when Menstruation, menstrual periods permanently stop, marking the end of the Human reproduction, reproductive stage for the female human. It typically occurs between the ages of 45 and 5 ...

In non-human primates

While the labia majora is present in all female primates, many have them until adulthood or become inconspicuous around that period. Primates besides humans that always have visible labia majora are

bonobo The bonobo (; ''Pan paniscus''), also historically called the pygmy chimpanzee (less often the dwarf chimpanzee or gracile chimpanzee), is an endangered great ape and one of the two species making up the genus ''Pan (genus), Pan'' (the other bei ...

s, strepsirrhines,

tarsier Tarsiers ( ) are haplorhine primates of the family Tarsiidae, which is the lone extant family within the infraorder Tarsiiformes. Although the group was prehistorically more globally widespread, all of the existing species are restricted to M ...

s, cebid monkeys, and

gibbon Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical forests from eastern Bangladesh and Northeast Indi ...

s. In non-primate female

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, the labia majora are absent since the labioscrotal swellings have disappeared as a fetus. Because of this, the pudendal cleft refers to the slit between the labia vulvae in those mammals.

Use in grafting

The fat pad of the labia majora can be used as a

graft Graft or grafting may refer to: *Graft (politics), a form of political corruption *Graft, Netherlands, a village in the municipality of Graft-De Rijp Science and technology *Graft (surgery), a surgical procedure *Grafting, the joining of plant ti ...

, often as a so-called "Martius labial fat pad graft", and can be used, for example, in urethrolysis.

References

External links

Labia Majora Medical Definition
() {{DEFAULTSORT:Labia Majora Mammal female reproductive system Vulva de:Schamlippe#Die großen (äußeren) Schamlippen