Clitoral hood making a tent for the erect clitoris: sexual stimulation causes arousal tumescence
and the clitoris rises up and stretches its foreskin, left anterolateral view
Stimulated erect penis and neglected erect clitoris during penis in vagina penetrative sex (sexual intercourse or coitus)
In the Global Survey of Sexual Attitudes and Behaviors (Laumann et al., 2005), that used computer-assisted telephone interviewing and postal questionnaires to assess sexual problems in 9000 women aged 40–80 years, the prevalence of “inability to reach orgasm” ranged from 17.7% (in Northern Europe) to 41.2% (in Southeast Asia). Kinsey et al. (1953) found that 9% of women reported having been unable to ever experience orgasm. Lloyd (2005), in her book on female orgasm, included a table on orgasm rates during coitus obtained across a number of studies; the percentage for women who reported “always” or “almost always” experiencing orgasm during coitus ranged from 12% to 59%. J Bancroft a, CA Graham The varied nature of women's sexuality: Unresolved issues and a theoretical approach , Hormonal Behaviour. 2011 May; 59(5):717-29
Although approximately 90% of women report orgasm from some form of sexual stimulation, most women do not routinely (and some never) experience orgasm solely from sexual intercourse (Lloyd, 2005). By contrast, nearly 100% of men routinely experience orgasm solely from sexual intercourse. This gender disparity in the reliability of reaching orgasm during sexual intercourse has been thought to reflect evolutionary (Lloyd, 2005) or social (Hite, 1976) processes. An anatomical explanation for this disparity has also been proposed such that variation in the distance between a woman's clitoral glans and her vagina predicts the likelihood that she will experience orgasm in Q3 intercourse (Narjani, 1924). Specifically it was proposed that if this distance is less than 2.5 cm a woman is very likely to have orgasms solely from sexual intercourse. This relationship has not been statistically evaluated, but two historical studies provide data supporting such a relationship (Narjani, 1924; Landis et al., 1940).
Data from two independent samples, collected over 70 years ago and more than 15 years apart, support the notion that the distance between a woman's clitoris and her vagina influences the likelihood that she will regularly experience orgasm solely from intercourse. Women who reported more regularly experiencing orgasm had shorter the clitoral-urinary meatus distance (CUMD) measurements than did women who reported not experiencing or less regularly experiencing, orgasm in intercourse. When orgasms from masturbation were considered there was no meaningful relationship between CUMD and whether or not a woman experienced autosexual orgasms. Thus the influence of CUMD on women's orgasms is likely limited to orgasms solely from sexual intercourse. These results suggest that some of the variability in women experiencing orgasm from intercourse without concurrent clitoral stimulation reflects, as Bonaparte suggested in 1933, the consequences of embryological processes that determine the position of the clitoris relative to the vagina. Thus, some women may be anatomically predisposed to experience orgasm from intercourse, while the genital anatomy of other women makes such orgasms unlikely. While other factors, such as the sexual characteristics of a woman's partner, undoubtedly influence the likelihood of experiencing orgasm solely from intercourse, these data suggest that for some women their genital anatomy strongly influences the occurrence of orgasm in intercourse. K Wallen, EA. Lloyd, Female sexual arousal: Genital anatomy and orgasm in intercourse, Hormones and Behaviour. 2011 May; 59(5):780-92.
Circuit orgasmique (orgasmic circuit) by Gerard Zwang, Pathologie Sexuelle, Paris, 1991
Prior to first coitus, the clitoris is usually the only source of female orgasm. It has the obligatory role of activation-establishment of the epigenetic connection of the orgasmic circuit. If this neural reflex circuit is not active during childhood it will never be functional. In the months or years following first coition, intra-vaginal penetration cannot trigger an orgasm unless this circuit is functional. Ablation of the clitoris during the infancy prevents the establishment of the reflex circuit, and the woman will never be able to experience clitoral or vaginal pleasure. Gerard Zwang: Functional and erotic consequences of sexual mutilations, Presented at the Fourth International Symposium on Sexual Mutilations, University of Lausanne, Lausanne, Switzerland, August 9-11, 1996.***
Orgasm is a complex reflex. It encopasses numerous pathways and nervous connections of such magnitude that one can speak of a vast orgasmic circuit.
At birth this circuit only exists in a rudimentary state. Similarly, other nervous circuits, such as that which controls bipedal locomotion and that which regulates spoken language, exist in a rudimentary stage at birth. The establishment of these circuits is epigenetic, that is, secondary to birth, and dependson the full development of these connections and the synapses connecting the neurons under the influence of endogenous stimulation.