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110-454: In amniotes , the clitoris ( / ˈ k l ɪ t ər ɪ s / KLIT -ər-iss or / k l ɪ ˈ t ɔːr ɪ s / klih- TOR -iss ; pl. : clitorises or clitorides ) is a female sex organ . In humans, it is the vulva 's most erogenous area and generally the primary anatomical source of female sexual pleasure. The clitoris is a complex structure, and its size and sensitivity can vary. The visible portion,

220-463: A crown group definition, Amniota has a slightly different content than the biological amniotes as defined by an apomorphy. Though traditionally considered reptiliomorphs, some recent research has recovered diadectomorphs as the sister group to Synapsida within Amniota, based on inner ear anatomy. The cladogram presented here illustrates the phylogeny (family tree) of amniotes, and follows

330-405: A phallic outgrowth in the embryo called the genital tubercle . In the absence of testosterone , the genital tubercle allows for the formation of the clitoris; the initially rapid growth of the phallus gradually slows and the body and glans of the clitoris are formed along with its other structures. The clitoris has an abundance of nerve endings, and is the human female's most erogenous part of

440-482: A (typically) terrestrial form with limbs and a thick stratified epithelium (rather than first entering a feeding larval tadpole stage followed by metamorphosis , as amphibians do). In amniotes, the transition from a two-layered periderm to a cornified epithelium is triggered by thyroid hormone during embryonic development, rather than by metamorphosis. The unique embryonic features of amniotes may reflect specializations for eggs to survive drier environments; or

550-493: A calcified shell, were not essential and probably evolved later. It has been suggested that shelled terrestrial eggs without extraembryonic membranes could still not have been more than about 1 cm (0.4-inch) in diameter because of diffusion problems, like the inability to get rid of carbon dioxide if the egg was larger. The combination of small eggs and the absence of a larval stage, where posthatching growth occurs in anamniotic tetrapods before turning into juveniles, would limit

660-489: A clitoral, rather than vaginal (or some other), site" and that his nonadaptive belief "has been widely misunderstood as a denial of either the adaptive value of female orgasm in general or even as a claim that female orgasms lack significance in some broader sense". He said that although he accepts that "clitoral orgasm plays a pleasurable and central role in female sexuality and its joys", "[a]ll these favorable attributes, however, emerge just as clearly and just as easily, whether

770-504: A few seconds (usually 5–10) to return to its normal position and 5–10 minutes to return to its original size. If orgasm is not achieved, the clitoris may remain engorged for a few hours, which women often find uncomfortable. Additionally, the clitoris is very sensitive after orgasm, making further stimulation initially painful for some women. General statistics indicate that 70–80 percent of women require direct clitoral stimulation (consistent manual, oral, or other concentrated friction against

880-447: A fibrous matrix and have only a minimal amount of smooth muscle, or that the clitoral glans is "a midline, densely neural, non-erectile structure". The clitoral glans is homologous to the male penile glans . Other descriptions of the glans assert that it is composed of erectile tissue and that erectile tissue is present within the labia minora. The glans may be noted as having glandular vascular spaces that are not as prominent as those in

990-418: A gender transition usually experience dramatic clitoral growth; individual desires and the difficulties of phalloplasty (construction of a penis) often result in the retention of the original genitalia with the enlarged clitoris as a penis analog ( metoidioplasty ). However, the clitoris cannot reach the size of the penis through hormones. A   surgery to add function to the clitoris, such as metoidioplasty,

1100-417: A robust, air-breathing, respiratory system , allow amniotes to live on land as true terrestrial animals . Amniotes have the ability to procreate without water bodies . Because the amnion and the fluid it secretes shields the embryo from environmental fluctuations, amniotes can reproduce on dry land by either laying shelled eggs (reptiles, birds and monotremes ) or nurturing fertilized eggs within

1210-1685: A simplified version of the relationships found by Laurin & Reisz (1995), with the exception of turtles, which more recent morphological and molecular phylogenetic studies placed firmly within diapsids . The cladogram covers the group as defined under Gauthier's definition. † Diadectomorpha [REDACTED] Synapsida (mammals and their extinct relatives) [REDACTED] † Mesosauridae [REDACTED] † Millerettidae [REDACTED] † Pareiasauria [REDACTED] † Procolophonoidea [REDACTED] † Captorhinidae [REDACTED] † Protorothyrididae [REDACTED] Diapsida (lizards, snakes, turtles , crocodiles , dinosaurs , birds, etc.) [REDACTED] Following studies in 2022 and 2023, with Drepanosauromorpha placed sister to Weigeltisauridae ( Coelurosauravus ) in Avicephala based on Senter (2004): † Seymouriamorpha [REDACTED] † Diadectomorpha [REDACTED] † Araeoscelida [REDACTED] † Captorhinidae [REDACTED] † Protorothyris [REDACTED] † Vaughnictis [REDACTED] † Eothyris [REDACTED] † Caseidae [REDACTED] † Oedaleops [REDACTED] † Varanopsidae [REDACTED] † Ophiacodontidae [REDACTED] † Edaphosauridae [REDACTED] † Haptodus [REDACTED] † Sphenacodontidae [REDACTED] Therapsida [REDACTED] [REDACTED] [REDACTED] † Acleistorhinidae [REDACTED] Vestibular bulbs Research indicates that

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1320-513: A spandrel based upon the value of single development channels", American philosopher Elisabeth Lloyd suggested that there is little evidence to support an adaptionist account of female orgasm. Canadian sexologist Meredith L. Chivers stated that "Lloyd views female orgasm as an ontogenetic leftover; women have orgasms because the urogenital neurophysiology for orgasm is so strongly selected for in males that this developmental blueprint gets expressed in females without affecting fitness" and this

1430-457: Is a medial band of tissue formed between the undersurface of the glans and the top ends of the labia minora. It is homologous to the penile frenulum in males. The frenulum's main function is to maintain the clitoris in its innate position. The clitoral body (also known as the shaft of the clitoris ) is a portion behind the glans that contains the union of the corpora cavernosa , a pair of sponge-like regions of erectile tissue that hold most of

1540-415: Is a predicament that is likely due to nature easing the process of childbearing by drastically reducing the number of vaginal nerve endings, challenge arguments that vaginal orgasms help encourage sexual intercourse to facilitate reproduction . Supporting a distinct G-spot, however, is a study by Rutgers University , published in 2011, which was the first to map the female genitals onto the sensory portion of

1650-541: Is also related to the Greek word κλείς ( kleís ), "key", "indicating that the ancient anatomists considered it the key" to female sexuality. In addition, the Online Etymology Dictionary suggests other Greek candidates for this word's etymology include a noun meaning "latch" or "hook" or a verb meaning "to touch or titillate lasciviously", "to tickle". The Oxford English Dictionary also states that

1760-407: Is an alternative to phalloplasty that permits the retention of sexual sensation in the clitoris. In clitoridectomy , the clitoris may be removed as part of a radical vulvectomy to treat cancer such as vulvar intraepithelial neoplasia ; however, modern treatments favor more conservative approaches, as invasive surgery can have psychosexual consequences. Clitoridectomy more often involves parts of

1870-568: Is facilitated by their astragalus. Basal amniotes resembled small lizards and evolved from semiaquatic reptiliomorphs during the Carboniferous period. After the Carboniferous rainforest collapse , amniotes spread around Earth's land and became the dominant land vertebrates. They almost immediately diverged into two groups, namely the sauropsids (including all reptiles and birds ) and synapsids (including mammals and extinct ancestors like " pelycosaurs " and therapsids ). Among

1980-522: Is little research into what may cure or remedy the disorder. In some recorded cases, PGAD was caused by or caused, a pelvic arterial-venous malformation with arterial branches to the clitoris; surgical treatment was effective in these cases. In 2022, an article in The New York Times reported several instances of women experiencing reduced clitoral sensitivity or inability to orgasm following various surgical procedures, including biopsies of

2090-448: Is no anatomical evidence of the vaginal orgasm, disagrees with O'Connell and other researchers' terminological and anatomical descriptions of the clitoris (such as referring to the vestibular bulbs as the "clitoral bulbs") and states that "the inner clitoris" does not exist because the penis cannot come in contact with the congregation of multiple nerves/veins situated until the angle of the clitoris, detailed by Georg Ludwig Kobelt , or with

2200-443: Is not especially large, brightly colored, specifically shaped or selectively displayed during courtship". He contrasts this with other female species that have clitorises as long as their male counterparts. He said the human clitoris "could have evolved to be much more conspicuous if males had preferred sexual partners with larger brighter clitorises" and that "its inconspicuous design combined with its exquisite sensitivity suggests that

2310-437: Is occasional or otherwise absent because the vagina has significantly fewer nerve endings than the clitoris. The prominent debate over the quantity of vaginal nerve endings began with Alfred Kinsey . Although Sigmund Freud 's theory that clitoral orgasms are a prepubertal or adolescent phenomenon and that vaginal (or G-spot ) orgasms are something that only physically mature females experience had been criticized before, Kinsey

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2420-450: Is presented in simplified form below. With the advent of cladistics, other researchers have attempted to establish new classes, based on phylogeny , but disregarding the physiological and anatomical unity of the groups. Unlike Benton, for example, Jacques Gauthier and colleagues forwarded a definition of Amniota in 1988 as "the most recent common ancestor of extant mammals and reptiles, and all its descendants". As Gauthier makes use of

2530-403: Is sexually aroused and during vaginal penetration. They assert that since the front wall of the vagina is inextricably linked with the internal parts of the clitoris, stimulating the vagina without activating the clitoris may be next to impossible. In their 2009 published study, it states the "coronal planes during perineal contraction and finger penetration demonstrated a close relationship between

2640-538: Is similar to "males hav[ing] nipples that serve no fitness-related function". At the 2002 conference for Canadian Society of Women in Philosophy , Nancy Tuana argued that the clitoris is unnecessary in reproduction; she stated that it has been ignored because of "a fear of pleasure. It is pleasure separated from reproduction. That's the fear". She reasoned that this fear causes ignorance, which veils female sexuality. O'Connell stated, "It boils down to rivalry between

2750-451: Is sometimes described as an aspect of PGAD. With PGAD, arousal lasts for an unusually extended period (ranging from hours to days); it can also be associated with morphometric and vascular modifications of the clitoris. Drugs may cause or affect clitoral priapism. The drug trazodone is known to cause male priapism as a side effect, but there is only one documented report that it may have caused clitoral priapism, in which case discontinuing

2860-698: The Carboniferous period . Those of Amniota are defined as the smallest crown clade containing humans , the Greek tortoise , and the Nile crocodile . Amniotes are distinguished from the other living tetrapod clade — the non-amniote lissamphibians ( frogs / toads , salamanders , newts and caecilians ) — by the development of three extraembryonic membranes ( amnion for embryonic protection, chorion for gas exchange , and allantois for metabolic waste disposal or storage), thicker and keratinized skin , costal respiration (breathing by expanding/constricting

2970-456: The G-spot . The only known purpose of the human clitoris is to provide sexual pleasure. Knowledge of the clitoris is significantly affected by its cultural perceptions. Studies suggest that knowledge of its existence and anatomy is scant in comparison with that of other sexual organs (especially male sex organs) and that more education about it could help alleviate stigmas , such as the idea that

3080-456: The amnion , which derives from Greek ἀμνίον ( amnion ), which denoted the membrane that surrounds a fetus. The term originally described a bowl in which the blood of sacrificed animals was caught, and derived from ἀμνός ( amnos ), meaning "lamb". Zoologists characterize amniotes in part by embryonic development that includes the formation of several extensive membranes, the amnion , chorion , and allantois . Amniotes develop directly into

3190-497: The clitoral glans ( glans means "acorn" in Latin ), also known as the "head" or "tip", exists at the top of the clitoral body as a fibro-vascular cap and is usually the size and shape of a pea, although it is sometimes much larger or smaller. The glans is separated from the clitoral body by a ridge of tissue called the corona . The clitoral glans is estimated to have 8,000 and possibly 10,000 or more sensory nerve endings, making it

3300-465: The labia and other genital structures of 50 women from the age of 18 to 50, with a mean age of 35.6., from 2003 to 2004, and the results given for the clitoral glans were 3–10 mm for the range and 5.5 [1.7] mm for the mean. Other research indicates that the clitoral body can measure 5–7 centimetres (2.0–2.8 in) in length, while the clitoral body and crura together can be 10 centimetres (3.9 in) or more in length. The clitoris develops from

3410-473: The placenta . The ancestors of true amniotes, such as Casineria kiddi , which lived about 340 million years ago, evolved from amphibian reptiliomorphs and resembled small lizards. At the late Devonian mass extinction (360 million years ago), all known tetrapods were essentially aquatic and fish-like. Because the reptiliomorphs were already established 20 million years later when all their fishlike relatives were extinct, it appears they separated from

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3520-430: The rib cage ), the presence of adrenocortical and chromaffin tissues as a discrete pair of glands near their kidneys , more complex kidneys , the presence of an astragalus for better extremity range of motion , the diminished role of skin breathing , and the complete loss of metamorphosis , gills , and lateral lines . The presence of an amniotic buffer, of a water-impermeable skin , and of

3630-450: The woman-on-top position or the coital alignment technique , a sex position combining the "riding high" variation of the missionary position with pressure-counterpressure movements performed by each partner in rhythm with sexual penetration, to maximize clitoral stimulation. Same-sex female couples may engage in tribadism (vulva-to-vulva or vulva-to-body rubbing) for ample or mutual clitoral stimulation during whole-body contact. Pressing

3740-462: The G-spot in women who report having orgasms during vaginal intercourse, O'Connell argues that this interconnected relationship is the physiological explanation for the conjectured G-spot and experience of vaginal orgasms, taking into account the stimulation of the internal parts of the clitoris during vaginal penetration. "The vaginal wall is, in fact, the clitoris", she said. "If you lift the skin off

3850-625: The G-spot is not a particular thing" and that it is "a region, it's a convergence of many different structures". Whether the clitoris is vestigial , an adaptation , or serves a reproductive function has been debated. Geoffrey Miller stated that Helen Fisher , Meredith Small and Sarah Blaffer Hrdy "have viewed the clitoral orgasm as a legitimate adaptation in its own right, with major implications for female sexual behavior and sexual evolution". Like Lynn Margulis and Natalie Angier , Miller believes, "The human clitoris shows no apparent signs of having evolved directly through male mate choice . It

3960-449: The amniote ancestors, the next major breakthrough appears to have involved a gradual replacement of the gelatinous coating covering the amphibian egg with a fibrous shell membrane. This allowed the egg to increase both its size and in the rate of gas exchange, permitting a larger, metabolically more active embryo to reach full development before hatching. Further developments, like extraembryonic membranes (amnion, chorion, and allantois) and

4070-420: The arterial blood continues a steady flow and having no way to drain out, fills the venous spaces until they become turgid and engorged with blood. This is what leads to clitoral erection . The prepuce has retracted and the glans becomes more visible. The glans doubles in diameter upon arousal and further stimulation becomes less visible as it is covered by the swelling of the clitoral hood. The swelling protects

4180-486: The base of the penis and has additionally been theorized, with the sentiment from researcher Amichai Kilchevsky that because female fetal development is the "default" state in the absence of substantial exposure to male hormones and therefore the penis is essentially a clitoris enlarged by such hormones, there is no evolutionary reason why females would have an entity in addition to the clitoris that can produce orgasms. The general difficulty of achieving orgasms vaginally, which

4290-402: The blood in the clitoris during erection . It is homologous to the penile shaft in the male. The two corpora forming the clitoral body are surrounded by thick fibro-elastic tunica albuginea, a sheath of connective tissue. These corpora are separated incompletely from each other in the midline by a fibrous pectiniform septum – a comblike band of connective tissue extending between

4400-539: The body. When sexually stimulated , it may incite sexual arousal , which may result from mental stimulation ( sexual fantasy ), activity with a sexual partner , or masturbation , and can lead to orgasm . The most effective sexual stimulation of this organ is usually manually or orally , which is often referred to as direct clitoral stimulation; in cases involving sexual penetration , these activities may also be referred to as additional or assisted clitoral stimulation. Direct stimulation involves physical stimulation to

4510-411: The brain; the scans indicated that the brain registered distinct feelings between stimulating the clitoris, the cervix and the vaginal wall – where the G-spot is reported to be – when several women stimulated themselves in a functional magnetic resonance machine. Barry Komisaruk , head of the research findings, stated that he feels that "the bulk of the evidence shows that

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4620-455: The bulbs) by the pars intermedia; their deep surfaces are in contact with the inferior fascia of the urogenital diaphragm ; superficially, they are covered by the bulbospongiosus . The residual spongy part is a strand of erectile tissue that runs ventrally across the external clitoral body and ends as the glans clitoridis . During the response to sexual arousal , the bulbs fill with blood, which then becomes trapped, causing erection . As

4730-555: The class Reptilia is paraphyletic —it has given rise to two other classes not included in Reptilia. Most species described as microsaurs , formerly grouped in the extinct and prehistoric amphibian group lepospondyls , has been placed in the newer clade Recumbirostra , and shares many anatomical features with amniotes which indicates they were amniotes themselves. A different approach is adopted by writers who reject paraphyletic groupings. One such classification, by Michael Benton ,

4840-457: The clitoral body, with the spaces being separated more by smooth muscle than in the body and crura. Adipose tissue is absent in the labia minora, but the organ may be described as being made up of dense connective tissue , erectile tissue and elastic fibers . The clitoral frenulum or frenum ( frenulum clitoridis and crus glandis clitoridis in Latin; the former meaning "little bridle")

4950-468: The clitoral bulbs fill with blood, they tightly cuff the vaginal opening, causing the vulva to expand outward. This puts pressure on nearby structures that include the corpora cavernosa and crura , inducing pleasure. The blood inside the bulb's erectile tissue is released to the circulatory system by the spasms of orgasm , but if orgasm does not occur, the blood will exit the bulbs over several hours. [REDACTED] This article incorporates text in

5060-445: The clitoral glans and the urethra, exiting at the top of the clitoral hood; this piercing is highly risky concerning the damage that may occur because of intersecting nerves. (See Clitoral index .) Persistent genital arousal disorder (PGAD) results in spontaneous, persistent, and uncontrollable genital arousal in women, unrelated to any feelings of sexual desire. Clitoral priapism is a rare, potentially painful medical condition and

5170-508: The clitoral site of orgasm arose as a spandrel or an adaptation". He added that the "male biologists who fretted over [the adaptionist questions] simply assumed that a deeply vaginal site, nearer the region of fertilization, would offer greater selective benefit" due to their Darwinian , summum bonum beliefs about enhanced reproductive success. Similar to Gould's beliefs about adaptionist views and that "females grow nipples as adaptations for suckling, and males grow smaller unused nipples as

5280-429: The clitoris along with other masculinizing effects on their bodies. Abnormal enlargement of the clitoris may be referred to as clitoromegaly or macroclitoris , but clitoromegaly is more commonly seen as a congenital anomaly of the genitalia . Clitoroplasty, a sex reassignment surgery for trans women , involves the construction of a clitoris from penile tissue. People taking hormones or other medications as part of

5390-413: The clitoris and the rest of the vulva engorge and change color as the erectile tissues fill with blood ( vasocongestion ), and the individual experiences vaginal contractions . The ischiocavernosus and bulbocavernosus muscles , which insert into the corpora cavernosa, contract and compress the dorsal vein of the clitoris (the only vein that drains the blood from the spaces in the corpora cavernosa), and

5500-577: The clitoris and vulva in general are visually unappealing or that female masturbation is taboo and disgraceful. The clitoris is homologous to the penis in males. The Oxford English Dictionary states that the Neo-Latin word clītoris likely has its origin in the Ancient Greek κλειτορίς ( kleitorís ), which means "little hill", and perhaps derived from the verb κλείειν ( kleíein ), meaning "to shut" or "to sheathe". Clitoris

5610-470: The clitoris as the main center of sexual response". He considered the vagina to be "relatively unimportant" for sexual satisfaction, relaying that "few women inserted fingers or objects into their vaginas when they masturbated". Believing that vaginal orgasms are "a physiological impossibility" because the vagina has insufficient nerve endings for sexual pleasure or climax, he "concluded that satisfaction from penile penetration [is] mainly psychological or perhaps

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5720-494: The clitoris being partially or completely removed during FGM, which may be additionally known as female circumcision or female genital cutting (FGC). Removing the glans does not mean that the whole structure is lost, since the clitoris reaches deep into the genitals. In reduction clitoroplasty, a common intersex surgery, the glans is preserved and parts of the erectile bodies are excised. Problems with this technique include loss of sensation, loss of sexual function, and sloughing of

5830-402: The clitoris by the shared sensory nerves (especially the pudendal nerve , which gives off the inferior anal nerves and divides into two terminal branches: the perineal nerve and the dorsal nerve of the clitoris ). Due to the glans' high sensitivity, direct stimulation to it is not always pleasurable; instead, direct stimulation to the hood or near the glans is often more pleasurable, with

5940-422: The clitoris is composed of internal parts. Regarding humans, it consists of the glans , the body (which is composed of two erectile structures known as the corpora cavernosa ), the prepuce , and the root . The frenulum is beneath the glans. Research indicates that clitoral tissue extends into the vaginal anterior wall. Şenaylı et al. said that the histological evaluation of the clitoris, "especially of

6050-467: The clitoris is important not as an object of male mate choice, but as a mechanism of female choice". While Miller stated that male scientists such as Stephen Jay Gould and Donald Symons "have viewed the female clitoral orgasm as an evolutionary side-effect of the male capacity for penile orgasm" and that they "suggested that clitoral orgasm cannot be an adaptation because it is too hard to achieve", Gould acknowledged that "most female orgasms emanate from

6160-598: The clitoris is more than just its glans. They concluded that some females have more extensive clitoral tissues and nerves than others, especially having observed this in young cadavers compared to elderly ones, and therefore whereas the majority of females can only achieve orgasm by direct stimulation of the external parts of the clitoris, the stimulation of the more generalized tissues of the clitoris via vaginal intercourse may be sufficient for others. French researchers Odile Buisson ( fr ) and Pierre Foldès reported similar findings to that of O'Connell's. In 2008, they published

6270-465: The clitoris; Australian urologist Helen O'Connell , described as having initiated discourse among mainstream medical professionals to refocus on and redefine the clitoris, noted a direct relationship between the legs or roots of the clitoris and the erectile tissue of the bulbs and corpora, and the distal urethra and vagina while using magnetic resonance imaging (MRI) technology. While some studies, using ultrasound , have found physiological evidence of

6380-478: The coital capacity of the vagina, and absence of pain during sexual activity are the parameters to be judged by the surgeon". ( Cosmesis usually refers to the surgical correction of a disfiguring defect.) He stated that although "expectations can be standardized within these few parameters, operative techniques have not yet become homogeneous. Investigators have preferred different operations for different ages of patients". Gender assessment and surgical treatment are

6490-494: The colloquially shortened form clit , the first occurrence of which was noted in the United States, has been used in print since 1958: until then, the common abbreviation was clitty . Other slang terms for clitoris are bean , nub , and love button . The term clitoris is commonly used to refer to the glans alone. In recent anatomical works, the clitoris has also been referred to as the bulbo-clitoral organ . Most of

6600-451: The complications are from the same as those in the older procedures for this method". Concerning females who have the condition congenital adrenal hyperplasia , the largest group requiring surgical genital correction, researcher Atilla Şenaylı stated, "The main expectations for the operations are to create a normal female anatomy, with minimal complications and improvement of life quality". Şenaylı added that "[c]osmesis, structural integrity,

6710-425: The corpora beneath the descending pubic rami. Concealed behind the labia minora, the crura end with attachment at or just below the middle of the pubic arch . Associated are the urethral sponge , perineal sponge , a network of nerves and blood vessels, the suspensory ligament of the clitoris, muscles and the pelvic floor . The vestibular bulbs are more closely related to the clitoris than the vestibule because of

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6820-547: The corpora cavernosa, is incomplete because for many years the clitoris was considered a rudimentary and nonfunctional organ". They added that Baskin and colleagues examined the clitoris' masculinization after dissection and using imaging software after Masson's trichrome staining , put the serial dissected specimens together; this revealed that nerves surround the whole clitoral body. The clitoris, its bulbs , labia minora, and urethra involve two histologically distinct types of vascular tissue (tissue related to blood vessels ),

6930-416: The corpora cavernosa. The clitoral body is also connected to the pubic symphysis by the suspensory ligament . The body of the clitoris is a bent shape, which makes the clitoral angle or elbow. The angle divides the body into the ascending part (internal) near the pubic symphysis and the descending part (external), which can be seen and felt through the clitoral hood. Lying in the perineum (space between

7040-402: The diapsid line of descent. Post-cranial remains of amniotes can be identified from their Labyrinthodont ancestors by their having at least two pairs of sacral ribs , a sternum in the pectoral girdle (some amniotes have lost it) and an astragalus bone in the ankle. Amniota was first formally described by the embryologist Ernst Haeckel in 1866 on the presence of the amnion , hence

7150-410: The distinction made between clitoral and vaginal orgasms. Feminist Anne Koedt argued that because men "have orgasms essentially by friction with the vagina" and not the clitoral area, this is why women's biology had not been properly analyzed. "Today, with extensive knowledge of anatomy, with [C. Lombard Kelly], Kinsey, and Masters and Johnson, to mention just a few sources, there is no ignorance on

7260-609: The earliest known crown group amniotes, the oldest known sauropsid is Hylonomus and the oldest known synapsid is Asaphestera , both of which are from Nova Scotia during the Bashkirian age of the Late Carboniferous around 318  million years ago . This basal divergence within Amniota has also been dated by molecular studies at 310–329 Ma, or 312–330 Ma, and by a fossilized birth–death process study at 322–340 Ma. The term amniote comes from

7370-400: The early amniotes resembled their amphibian ancestors in many respects, a key difference was the lack of an otic notch at the back margin of the skull roof . In their ancestors, this notch held a spiracle , an unnecessary structure in an animal without an aquatic larval stage. There are three main lines of amniotes, which may be distinguished by the structure of the skull and in particular

7480-415: The embryonic membrane. Evolution of the amniote egg required increased exchange of gases and wastes between the embryo and the atmosphere. Structures to permit these traits allowed further adaption that increased the feasible size of amniote eggs and enabled breeding in progressively drier habitats. The increased size of eggs permitted increase in size of offspring and consequently of adults. Further growth for

7590-506: The external anatomy of the clitoris – glans, hood, and shaft. Stimulation of the labia minora, due to it being connected with the glans and hood, may have the same effect as direct clitoral stimulation. Though these areas may also receive indirect physical stimulation during sexual activity , such as when in friction with the labia majora, indirect clitoral stimulation is more commonly attributed to penile-vaginal penetration . Penile-anal penetration may also indirectly stimulate

7700-525: The external parts of the clitoris) to reach orgasm. Indirect clitoral stimulation (for example, by means of vaginal penetration) may also be sufficient for female orgasm. The area near the entrance of the vagina (the lower third) contains nearly 90 percent of the vaginal nerve endings, and there are areas in the anterior vaginal wall and between the top junction of the labia minora and the urinary meatus that are especially sensitive, but intense sexual pleasure, including orgasm, solely from vaginal stimulation

7810-408: The first complete   3D sonography of the stimulated clitoris and republished it in 2009 with new research, demonstrating how erectile tissue of the clitoris engorges and surrounds the vagina. Based on their findings, they argued that women may be able to achieve vaginal orgasm through stimulation of the G-spot because the clitoris is pulled closely to the anterior wall of the vagina when the woman

7920-427: The first of which is trabeculated , erectile tissue innervated by the cavernous nerves . The trabeculated tissue has a spongy appearance ; along with blood, it fills the large, dilated vascular spaces of the clitoris and the bulbs. Beneath the epithelium of the vascular areas is smooth muscle . As indicated by Yang et   al.'s research, it may also be that the urethral lumen (the inner open space or cavity of

8030-479: The form of vertical piercings, and, to a lesser extent, horizontal piercings. The triangle piercing is a very deep horizontal hood piercing and is done behind the clitoris as opposed to in front of it. For styles such as the Isabella piercing , which passes through the clitoral shaft but is placed deep at the base, they provide unique stimulation and still require the proper genital build. The Isabella starts between

8140-424: The front of the labia commissure , where the edges of the labia majora meet at the base of the pubic mound . It is partially formed by fusion of the upper labia minora . The hood's function is to cover and protect the glans and external shaft. There is considerable variation in how much of the glans protrudes from the hood and how much is covered by it, ranging from completely covered to fully exposed, and tissue of

8250-399: The glans from direct contact, as direct contact at this stage can be more irritating than pleasurable. Vasocongestion eventually triggers a muscular reflex, which expels the blood that was trapped in surrounding tissues, and leads to an orgasm. A short time after stimulation has stopped, especially if orgasm has been achieved, the glans becomes visible again and returns to its normal state, with

8360-448: The glans, of the clitoris is typically roughly the size and shape of a pea and is estimated to have at least 8,000 nerve endings . Sexological , medical, and psychological debate has focused on the clitoris, and it has been subject to social constructionist analyses and studies. Such discussions range from anatomical accuracy, gender inequality , female genital mutilation , and orgasmic factors and their physiological explanation for

8470-481: The glans. One way to preserve the clitoris with its innervations and function is to imbricate and bury the glans; however, Şenaylı et al. state that "pain during stimulus because of trapped tissue under the scarring is nearly routine. In another method, 50 percent of the ventral clitoris is removed through the level base of the clitoral shaft, and it is reported that good sensation and clitoral function are observed in follow-up"; additionally, it has "been reported that

8580-515: The increase in size and yolk content of eggs may have permitted, and coevolved with, direct development of the embryo to a large size. Features of amniotes evolved for survival on land include a sturdy but porous leathery or hard eggshell and an allantois that facilitates respiration while providing a reservoir for disposal of wastes. Their kidneys (metanephros) and large intestines are also well-suited to water retention. Most mammals do not lay eggs, but corresponding structures develop inside

8690-417: The labia majora. The anterior sections of the bulbs unite to create the bulbar commissure, which forms a long strip of erectile tissue dubbed the infra-corporeal residual spongy part (RSP) that expands from the ventral shaft and terminates as the glans. The RSP is also connected to the shaft via the pars intermedia (venous plexus of Kobelt ). When engorged with blood, the bulbs cuff the vaginal opening and cause

8800-570: The labia minora also encircles the base of the glans. There is no identified correlation between the size of the glans or clitoris as a whole, and a woman's age, height, weight, use of hormonal contraception , or being postmenopausal , although women who have given birth may have significantly larger clitoral measurements. Centimetre and millimetre measurements of the clitoris show variations in size. The clitoral glans has been cited as typically varying from 2 mm to 1 cm (less than an inch) and usually being estimated at 4 to 5 mm in both

8910-410: The latter, however, was limited by their position in the terrestrial food-chain , which was restricted to level three and below, with only invertebrates occupying level two. Amniotes would eventually experience adaptive radiations when some species evolved the ability to digest plants and new ecological niches opened up, permitting larger body-size for herbivores, omnivores and predators. While

9020-401: The majority of their subjects could only achieve clitoral orgasms, while a minority achieved vaginal orgasms. On that basis, they argued that clitoral stimulation is the source of both kinds of orgasms, reasoning that the clitoris is stimulated during penetration by friction against its hood. The research came at the time of the second-wave feminist movement , which inspired feminists to reject

9130-399: The majority of women preferring to use the hood to stimulate the glans, or to have the glans rolled between the labia, for indirect touch. It is also common for women to enjoy the shaft being softly caressed in concert with the occasional circling of the glans. This might be with or without digital penetration of the vagina, while other women enjoy having the entire vulva caressed. As opposed to

9240-452: The medication may be a remedy. Additionally, nefazodone is documented to have caused clitoral engorgement, as distinct from clitoral priapism, in one case, and clitoral priapism can sometimes start as a result of, or only after, the discontinuation of antipsychotics or selective serotonin reuptake inhibitors (SSRIs). Because PGAD is relatively rare and, as its concept apart from clitoral priapism, has only been researched since 2001, there

9350-408: The most sensitive erogenous zone . The glans also has numerous genital corpuscles . Research conflicts on whether the glans is composed of erectile or non-erectile tissue. Some sources describe the clitoral glans and labia minora as composed of non-erectile tissue; this is especially the case for the glans. They state that the clitoral glans and labia minora have blood vessels that are dispersed within

9460-432: The mother ( marsupial and placental mammals ). This distinguishes amniotes from anamniotes ( fish and amphibians) that have to spawn in aquatic environments . Most amniotes still require regular access to drinking water for rehydration, like the semiaquatic amphibians do. They have better homeostasis in drier environments, and more efficient non-aquatic gas exchange to power terrestrial locomotion , which

9570-448: The name. A problem with this definition is that the trait ( apomorphy ) in question does not fossilize , and the status of fossil forms has to be inferred from other traits. Older classifications of the amniotes traditionally recognised three classes based on major traits and physiology : This rather orderly scheme is the one most commonly found in popular and basic scientific works. It has come under critique from cladistics , as

9680-408: The number of holes behind each eye. In anapsids , the ancestral condition, there are none; in synapsids (mammals and their extinct relatives) there is one; and in diapsids (including birds, crocodilians , squamates , and tuataras ), there are two. Turtles have secondarily lost their fenestrae, and were traditionally classified as anapsids because of this. Molecular testing firmly places them in

9790-462: The other tetrapods somewhere during Romer's gap , when the adult tetrapods became fully terrestrial (some forms would later become secondarily aquatic). The modest-sized ancestors of the amniotes laid their eggs in moist places, such as depressions under fallen logs or other suitable places in the Carboniferous swamps and forests; and dry conditions probably do not account for the emergence of

9900-433: The penis in a gliding or circular motion against the clitoris or stimulating it by the movement against another body part may also be practiced. A vibrator (such as a clitoral vibrator ), dildo or other sex toy may be used. Other women stimulate the clitoris by use of a pillow or other inanimate object, by a jet of water from the faucet of a bathtub or shower, or by closing their legs and rocking. During sexual arousal,

10010-408: The result of referred sensation". Masters and Johnson 's research, as well as Shere Hite 's, generally supported Kinsey's findings about the female orgasm. Masters and Johnson were the first researchers to determine that the clitoral structures surround and extend along and within the labia. They observed that both clitoral and vaginal orgasms have the same stages of physical response, and found that

10120-411: The root of the clitoris and the anterior vaginal wall". Buisson and Foldès suggested "that the special sensitivity of the lower anterior vaginal wall could be explained by pressure and movement of clitoris' root during a vaginal penetration and subsequent perineal contraction". Researcher Vincenzo Puppo, who, while agreeing that the clitoris is the center of female sexual pleasure and believing that there

10230-411: The root of the clitoris, which does not have sensory receptors or erogenous sensitivity, during vaginal intercourse. Puppo's belief contrasts the general belief among researchers that vaginal orgasms are the result of clitoral stimulation; they reaffirm that clitoral tissue extends, or is at least stimulated by its bulbs, even in the area most commonly reported to be the G-spot. The G-spot is analogous to

10340-787: The sexes: the idea that one sex is sexual and the other reproductive. The truth is that both are sexual and both are reproductive". She reiterated that the vestibular bulbs appear to be part of the clitoris and that the distal urethra and vagina are intimately related structures, although they are not erectile in character, forming a tissue cluster with the clitoris that appears to be the location of female sexual function and orgasm. Genital modification may be for aesthetic , medical or cultural reasons. This includes female genital mutilation (FGM), sex reassignment surgery (for trans men as part of transitioning ), intersex surgery , and genital piercings . Use of anabolic steroids by bodybuilders and other athletes can result in significant enlargement of

10450-399: The similarity of the trabecular and erectile tissue within the clitoris and its bulbs, and the absence of trabecular tissue in other parts of the vulva, with the erectile tissue's trabecular nature allowing engorgement and expansion during sexual arousal. The vestibular bulbs are typically described as lying close to the crura on either side of the vaginal opening ; internally, they are beneath

10560-729: The size of the adults. This is supported by the fact that extant squamate species that lay eggs less than 1 cm in diameter have adults whose snout-vent length is less than 10 cm. The only way for the eggs to increase in size would be to develop new internal structures specialized for respiration and for waste products. As this happened, it would also affect how much the juveniles could grow before they reached adulthood. A similar pattern can be seen in modern amphibians. Frogs that have evolved terrestrial reproduction and direct development have both smaller adults and fewer and larger eggs compared to their relatives that still reproduce in water. Fish and amphibian eggs have only one inner membrane,

10670-401: The soft shell. Indeed, many modern-day amniotes require moisture to keep their eggs from desiccating . Although some modern amphibians lay eggs on land, all amphibians lack advanced traits like an amnion. The amniotic egg formed through a series of evolutionary steps. After internal fertilization and the habit of laying eggs in terrestrial environments became a reproduction strategy amongst

10780-470: The subject [of the female orgasm]", she stated in her 1970 article The Myth of the Vaginal Orgasm . She added, "There are, however, social reasons why this knowledge has not been popularized. We are living in a male society which has not sought change in women's role". Supporting an anatomical relationship between the clitoris and vagina is a study published in 2005, which investigated the size of

10890-539: The transverse and longitudinal planes. A 1992 study concluded that the total clitoral length, including glans and body, is 16.0 ± 4.3 mm (0.63 ± 0.17 in), where 16 mm (0.63 in) is the mean and 4.3 mm (0.17 in) is the standard deviation. Concerning other studies, researchers from the Elizabeth Garrett Anderson and Obstetric Hospital in London measured

11000-401: The two main steps in intersex operations. "The first treatments for clitoromegaly were simply resection of the clitoris. Later, it was understood that the clitoris glans and sensory input are important to facilitate orgasm", stated Atilla. The clitoral glans' epithelium "has high cutaneous sensitivity, which is important in sexual responses", and it is because of this that "recession clitoroplasty

11110-434: The urethra), which is surrounded by a spongy tissue, has tissue that "is grossly distinct from the vascular tissue of the clitoris and bulbs, and on macroscopic observation, is paler than the dark tissue" of the clitoris and bulbs. The second type of vascular tissue is non-erectile, which may consist of blood vessels that are dispersed within a fibrous matrix and have only a minimal amount of smooth muscle. Highly innervated ,

11220-419: The use of dry fingers, stimulation from well-lubricated fingers, either by vaginal lubrication or a personal lubricant , is usually more pleasurable for the external clitoris. As the clitoris' external location does not allow for direct stimulation by penetration, any external clitoral stimulation while in the missionary position usually results from the pubic bone area. As such, some couples may engage in

11330-459: The vagina on the side walls, you get the bulbs of the clitoris – triangular, crescental masses of erectile tissue". O'Connell et   al., having performed dissections on the vulvas of cadavers and used photography to map the structure of nerves in the clitoris, made the assertion in 1998 that there is more erectile tissue associated with the clitoris than is generally described in anatomical textbooks and were thus already aware that

11440-487: The vaginal opening, this does not appear to be the case and tunica albuginea does not envelop the erectile tissue of the bulb. The vestibular bulbs are homologous to the bulb of penis of the male and consist of two elongated masses of erectile tissue. Their posterior ends are expanded and are in contact with the greater vestibular glands ; their anterior ends form the infra-corporeal residual spongy part (RSP), which are tapered and joined to one another (the commissure of

11550-428: The vestibular bulbs are more closely related to the clitoris than to the vestibule because of the similarity of the trabecular and erectile tissue within the clitoris and bulbs, and the absence of trabecular tissue in other genital organs, with the erectile tissue's trabecular nature allowing engorgement and expansion during sexual arousal . Ginger et al. state that although a number of texts report that they surround

11660-436: The vulva and anus ) and within the superficial perineal pouch is the root of the clitoris , which consists of the posterior ends of the clitoris, the crura and the bulbs of vestibule . The crura ("legs") are the parts of the corpora cavernosa extending from the clitoral body and form an upside-down "V" shape. Each crus (singular form of crura) is attached to the corresponding ischial ramus  – extensions of

11770-470: The vulva to expand outward. Although several texts state that they surround the vaginal opening, Ginger et   al. state that this does not appear to be the case and tunica albuginea does not envelop the erectile tissue of the bulbs. In Yang et al.'s assessment of the bulbs' anatomy, they conclude that the bulbs "arch over the distal urethra, outlining what might be appropriately called the 'bulbar urethra' in women". The clitoral hood or prepuce projects at

11880-497: The vulva, pelvic mesh surgeries (sling surgeries), and labiaplasties . The Times quoted several researchers who suggest that surgeons' lack of training in clitoral anatomy and nerve distribution may have been a factor. Amniote Amniotes are tetrapod vertebrate animals belonging to the clade Amniota , a large group that comprises the vast majority of living terrestrial and semiaquatic vertebrates. Amniotes evolved from amphibious stem tetrapod ancestors during

11990-504: Was later devised as an alternative, but reduction clitoroplasty is the method currently performed". What is often referred to as a "clitoris piercing" is the more common (and significantly less complicated) clitoral hood piercing . Since piercing the clitoris is difficult and very painful, piercing the clitoral hood is more common than piercing the clitoral shaft or glans, owing to the small percentage of people who are anatomically suited for it. Clitoral hood piercings are usually channeled in

12100-464: Was the first researcher to harshly criticize the theory. Through his observations of female masturbation and interviews with thousands of women, Kinsey found that most of the women he observed and surveyed could not have vaginal orgasms, a finding that was also supported by his knowledge of sex organ anatomy. Scholar Janice   M. Irvine stated that he "criticized Freud and other theorists for projecting male constructs of sexuality onto women" and "viewed

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