Question: Can you make a penis bigger in length or girth?
Answer: There is no non-surgical technique to make the penis bigger. Penis pumps may help create a stronger erection, but they will not create a larger penis. Because the penis is composed largely of spongy erectile tissue and not of muscle, it cannot be strengthened or "built up." Surgery may cause scar tissue to grow that can cause a painful or even a shortened erection.
[The Kinsey Institute for Research in Sex, Gender, and Reproduction, Inc.]  

Penis enlargement: FACT OR FICTION?

Penis enlargement procedures (pills, pumps, exercises, surgery) are techniques alleged to make the human penis larger. Often, in the course of advertising fraudulent products, the distinction between temporary enlargement, i.e., erection, and permanent enlargement, is deliberately muddied. [Mayoclinic.com: Penis-enlargement scams: You're more normal than you think]

Alleged permanent procedures range from manual exercises to devices and medical interventions, with reports of successes and failures around the world, and while some are known to be hoaxes, there is no popularly known scientific proof about their effectiveness in general. [Medscape.com: Dangers of Sexual Enhancement Supplements]

Surgical methods
Surgical techniques used for penis lengthening (enhancement phalloplasty) and penis widening (girth enhancement) have been in the urologic literature for many years. In a study conducted at St. Peter's Andrology Centre and Institute of Urology in London, it was determined that most patients who underwent penis-lengthening surgery were unsatisfied with the results. [Fox News. Most Men Unsatisfied With Penis Enlargement Results]

Penis enlargement (length) surgery
Approximately one-third to one-half of the penis is inside the body, and is internally attached to the undersurface of the pubic bone. Penis lengthening involves the release of the fundiform ligament and the suspensory ligament that attaches the two erectile bodies to the pubic bone (ligamentolysis). The suspensory ligament makes the penis arch under the pubic bone. Release of this ligament allows the penis to protrude on a straighter path, further outward to give a longer physical appearance. With the penis on stretch, the ligament is divided close to the pubic bone until all midline attachments have been freed. Once these ligaments have been cut, part of the penile shaft (usually held within the body) drops forward and extends out, enlarging the penis by 2-3cm (0.78-1.18 in.). After surgery, part of the postoperative treatment includes stretching of the penis to prevent the severed suspensory ligament from healing shorter than it was previously. The article "Penile Suspensory Ligament Division for Penile Augmentation: Indications and Results" discussed the subject. According to Nim Christopher, a urologist at St. Peter's Andrology Center in London, among men who have had the surgery, "the dissatisfaction rate was in excess of 70 percent". [Penile Suspensory Ligament Division for Penile Augmentation: Indications and Results]

Real penile lengthening (i.e., lengthening of corporal bodies vs. ligamentolysis) is not a routine and safe procedure because of the high risk of permanently losing the ability to have an erection. It can be done safely only in patients with erectile dysfunction or Mb Peyronies concomitantly with implantation of penile prosthesis. The world's leading urologists specializing in the field of penis enlargement surgery use only ligamentolysis, liposuction of the pubic area, and skin redistribution. They state clearly that surgeons can only expose the penis more outside the body with especially visible results in obese patients and ones with different deformities of penile skin where the penis is layered.

As a result penile surgery is strongly discouraged in all patients with normal, functional penises. Such individuals should not engage in penile enlargement surgery, in addition such a surgery is encouraged only for men born with a congenital abnormality, who have suffered an injury, or who have severe erectile dysfunction. [International Journal of Impotence Research: Efficacy on Daily Penis Stretching Technique to Elongate the "Small Penis"]

Inflatable implants
A further method is to replace the two corpora cavernosa with inflatable penile implants. This is performed primarily as a therapeutic surgery for men suffering from complete impotence; an implanted pump in the groin or scrotum can be manipulated by hand to fill these cylinders from an implanted reservoir in order to achieve an erection. The replacement cylinders are normally sized to be direct replacements for the corpus cavernosa, but larger ones can be implanted.

One advantage to this surgery is that an erection can be created whenever desired, for as long as is desired and as firm as desired. However, this surgical procedure can never be reversed.

Areas of the penis which make up its size, length and width

The penis is made up of three separate cylinders. The two paired cylinders called the Corpora Cavernosa are the force behind a man's erection and are made up of chambers that expand and fill with blood to the point of turgidity, creating the hardness of the erection.

The capacity of the Corpora Cavernosa to fill with blood during arousal limits erection length and thickness, and this function can decrease with age.

The third cylinder of the penis, located in a groove between the two larger cylinders, is called the Corpus Spongiosum, through which semen is ejaculated.

Although some blood enters the corpus spongiosum; the remainder engorges the corpora cavernosa, which expand to hold 90% of the blood involved in an erection, increasing both in length and in diameter. The function of the corpus spongiosum is to prevent compression of the urethra during erection.

*Images and illustrations used above which were originally published in 1918 by the 20th U.S. edition of Gray's Anatomy of the Human Body, are in the public domain as their copyright has expired. This applies worldwide.

Self-applied methods
No scientific research supports the use of any nonsurgical method to enlarge the penis, and no reputable medical society endorses penis-enlargement surgery performed for purely cosmetic reasons.

Cosmetic
Rather than attempt to change the actual size of the penis, one may make it appear bigger, by trimming the pubic hair or by losing weight, or by applying on the penis an adult lotion for men containing Arginine. "In highly vascularized tissues such as lips, gums, genitalia, etc, vasodilation leads to transient, reversible increases in tissue mass and sensitivity. A method for enhancing vasodilation in these tissues would therefore lead to a tissue with enlarged appearance for the duration of vasodilation. "

Pills
"Penis enlargement pills", "penis patches" or ointments are commonly offered over the Internet. This is one of the most common topics for spam email messages. Analyses performed by Flora Research of California and by the University of Maryland have uncovered harmful contaminants in a number of "penis enlargement" pills. Contaminants found included mold, yeast, dangerous E. coli bacteria, pesticides, and lead. Dr. Michael Donnenberg of the University of Maryland has described herbal pills marketed as having "heavy fecal contamination", possibly from animals grazing near the plants harvested for herbal ingredients. [Wall Street Journal: Some Male 'Enlargement' Pills Contain a Variety of Impurities]

In discussing a typical "male enhancement" pill, Dr. Ira Sharlip, a spokesman for the American Urological Association, said "There is no such thing as a penis pill that works. These are all things that are sold for profit. There's no science or substance behind them."

Penis pump
A penis pump is a cylinder that is fitted over the penis, with a manual or motorized pump to create suction. As the apparatus creates a partial vacuum around the penis, blood is drawn into the penis, helping it to become engorged. As vacuum increases, the difference between the inner blood-pressure and the pump pressure increases as well; excessive pressure causes vascular damage rather than a harder penis.

A penis pump with a translucent cylinderPenis pumps, usually described in this context as vacuum pumps, have use in conventional treatment of impotence. The pump itself is essentially as described above, although often made to higher standards of quality with a much higher price, and arrangements for distribution by suppliers of medical equipment.

Flexible compression rings, commonly called cock rings, can be added. Fitted on the open end of the cylinder, then an erection is created by pumping. Then the rings are pushed by hand onto the base of the erect penis before releasing the vacuum. This restricts blood flow out of, but not into the penis, enabling the erection to be held even in the presence of problems of the vascular or nervous system which would otherwise lead to immediate loss of erection. In the best circumstances erections can be maintained for a considerable time, but manufacturers' literature recommends that, for safety, rings should be removed after no more than 30 minutes.

Pumping must be done very carefully to avoid injury. Over-enthusiastic pumping can burst blood vessels and form blisters. In some cases the testicles can be unexpectedly pulled into the cylinder and cause severe pain and injury. It is also believed that the rim of the cylinder can cut into the skin and over time cause damage to the ligaments surrounding the penis. Impatiently pumping without reading explanatory material can produce too much suction (any pressure lower than 10 torr/1,333 Pa) and cause permanent injury. Attempts at using vacuum cleaner units for this purpose have resulted in severe injury as the machine produces far too much suction. However, scientists Graham Rutherford and Anne Henke have also undertaken significant research in this area, being funded by some of the major names in sexual pleasure toys, such as Ann Summers. Mild pumping has led to the strengthening of penis muscles and also, for psychosomatic reasons, has led to decreased masturbatory rates in later life.

The effectiveness of penis pumps was examined by Kazem, Hosseini and Alizadeh. They studied 37 men with penis length less than 10 cm and found no significant change in penile length after using pumps for six months, although the follow-up have found 30% satisfaction with the method.

Jelqing
Jelqing is a method intended to enlarge the penis by exercising the smooth muscle and other tissues in the penis, with the goal of permanently increasing the maximum erect size of the penis. This technique, also called "milking", involves wrapping the thumb and index finger around the penis while semi-erect and repeatedly drawing them away from one's body to force blood into the glans, thus encouraging more vascularity in the corpus cavernosa and associated tissues. There is no scientific evidence that this technique actually works.

Risks that exist from this exercise are: burst blood vessels, sometimes causing bleeding from the urethra (which can lead to infection and other complications if not taken care of), and temporary or even permanent erectile dysfunction.

There are many products (tools, instructions, etc.) that one can buy; however, much of what they offer (instructions) is available on forums and free websites.

Jelqing is typically preceded by a warm-up with a hot compress on the genitals, and concluded the same way. The reasoning behind the 'warm-up' mimics the normal operation of the biological processes of the penis during the four stages of arousal. The third stage is heat. At this stage the smooth muscles of the 'glans' can easily expand to their present (not future) greatest potential size.

Clamping
Clamping is a technique that uses a constricting device, such as a shoe string, cable clamp, or a tight cock ring. The clamp is firmly tied, clamped, or put, respectively, on the base of the erect penis while "edgeing" (extended masturbation) with a firmly erect penis. Extreme caution should be used to prevent permanent damage to the tissue. Use of a metal cock ring is not advised because trapped blood engorging the penis can make it impossible to remove.

Stretching and hanging
Stretching consists of attaching a penis stretcher or "extender" device to the penis for set periods of time. The device exerts a constant traction on the penis, which, in theory, lengthens and widens the penis. The traction supposedly causes the cells in the penis to "split" and then reform and expand. In 2002 a study published in the International Journal of Impotence Research concluded that penis extender devices are effective at elongating the penis and furthermore the increases in length correlate with the amount of time the device is worn. A similar study conducted by Paolo Gontero of the University of Turin was published in 2009 in the British Journal of Urology. [A pilot phase-II prospective study to test the ‘efficacy’ and tolerability of a penile-extender device in the treatment of ‘short penis’]

Hanging is perhaps the oldest self-applied method of penis enlargement, with evidence suggesting it was practiced by certain African tribes as much as 2,000 years ago. Weight hanging consists of attaching a device (usually a rope or a strap) that grips the glans or just behind the glans and allows a weight to be suspended for a specific amount of time. Then a conscious effort is made to exercise the penis by raising the weight in repetitions (lasting no more than 5 to 10 minutes at a time) starting with the smallest and lightest weight 1/16 pound to the heaviest usually 1/4 pound or more, to increase the strength and stamina as well as elongation of the penis.

One must be completely healed after circumcision before attempting hanging. Weight hanging, however, can also carry serious risks, which include nerve damage, chronic pain, scarring and impotence. The potential for these risks is dramatically increased if the patient is not directly trained by a qualified certified therapist. The idea behind weight hanging is to stretch the tunica albuginea and other various tissues of the penis. The general effect is to elongate the penis, although widening can also occur.

Hanging carries additional health risks due to the restriction of blood flow to the glans, including possible erectile dysfunction. Many tribal practitioners of weight hanging are impotent, although urination is unaffected.

Measuring the penis

To get the most accurate measurements for an individual's penis size, it has been recommended that several measurements be taken at different times, preferably with different erections on different days. The measurements are then to be averaged together. This is to account for what may be natural variability in size due to factors such as arousal level, time of day, room temperature, frequency of sexual activity, and unreliability of the measurement methods.

Length
The length can be measured with the subject standing and the penis held parallel to the floor. The penis is measured along the top, from the base to the tip. Results are inaccurate if the measurement is taken along the underside of the penis, or if the subject is seated or prone.

Circumference
Penis girth is the measurement of the circumference of the completely erect penis. It is variously quoted as an average of three measurements: just below the glans penis, in the middle of the shaft, and at the base.

Problems
A penis must be completely erect in order to obtain an accurate measurement. This may be difficult to achieve in a clinical setting. At least one Brazilian doctor resorted to injecting penises with drugs to induce erection, which gave more consistent results. Some clinicians measure the penis by stretching the flaccid penis as far as comfortably possible. Self-reported measurements tend to be unreliable because men often want to report a larger penis size.

Studies on penis size
While results vary across studies, the consensus is that the mean human penis is approximately 12.9–15 cm (5.1–5.9 inches) in length with a 95% confidence interval of (10.7 cm, 19.1 cm) (or, equivalently, 4.23 inches, 7.53 inches). The typical girth or circumference is approximately 12.3 cm (4.85 inches) when fully erect. The mean penis size is slightly greater than the median size.

Size at birth
The average stretched penile length at birth is about 4 cm (1.6 inches), and 90% of newborn boys will be between 2.4 and 5.5 cm (0.9 and 2.2 inches). Limited growth of the penis occurs between birth and 5 years of age, but very little occurs between 5 years and the onset of puberty. The average size at the beginning of puberty is 6 cm (2.4 inches) with adult size reached about 5 years later.

Size with aging
Authors of a paper reviewing research on area of penis sizes conclude that "flaccid penile length is just under 4 cm at birth and changes very little until puberty, when there is marked growth."

Age is not believed to negatively correlate with penis size. “Individual research studies have ... suggested that penis size is smaller in studies focusing on older men, but Wylie and Eardley found no overall differences when they collated the results of various studies [over a 60 year period].” [Science News: Men Worry More About Penile Size Than Women, Says 60-Year-Old Research Review]

Erect length
Several scientific studies have been performed on the erect length of the adult penis. Studies which have relied on self-measurement, including those from Internet surveys, consistently reported a higher average length than those which used medical or scientific methods to obtain measurements.

The following staff-measured studies are each composed of different subgroups of the human population (i.e. specific age range and/or race; selection of those with sexual medical concerns or self-selection) which could cause a sample bias.

A study published in the September 1996 Journal of Urology concluded that average erect length was 12.9 cm (5.08 inches) (measured by staff). The purpose of the study was to “provide guidelines of penile length and circumference to assist in counseling patients considering penile augmentation.” Erection was pharmacologically induced in 80 physically normal American men (varying ethnicity, average age 54). It was concluded: “Neither patient age nor size of the flaccid penis accurately predicted erectile length.”

A study published in the December 2000 International Journal of Impotence Research found that average erect penis length in 50 Jewish Caucasian males was 13.6 cm (5.35 inches) (measured by staff). Quote: "The aim of this prospective study was to identify clinical and engineering parameters of the flaccid penis for prediction of penile size during erection." Erection was pharmacologically induced in 50 Jewish Caucasian patients who had been evaluated for Erectile dysfunction (average age 47±14y). Patients with penis abnormalities or whose ED could be attributed to more than one psychological origin were omitted from the study.

A study conducted by LifeStyles Condoms found an average of 14.9 cm (5.9 inches) with a standard deviation of 2.1 cm (0.8 inches) (measured by staff). The purpose of this study was to ensure properly sized condoms were available. 401 college students volunteered to be measured during 2001 Spring Break in Cancún, Mexico, of which 300 gained an erection to be clinically measured (without pharmacological aid). The 300 effective measurements makes this study double the size of any prior study that uses medical staff to measure penis size.

A review published in 2007 issue of BJU Internetional, have shown that average erect penis length is 14–16 cm and its girth is 12–13 cm. This paper compares results of twelve studies conducted on different populations in several countries.

An Italian study of about 3,300 Italian men concluded that stretched length was measured on average to about 5 inches. In addition, a correlation between weight and height and penis length was also found. However this was done only on 500 men with a small correlation value.

The Cancún LifeStyle study, in which the circumference of the shaft was measured at three points (base, mid-shaft, and just below the head) and then averaged, found an average of 12.63 cm (4.972 inches) with a standard deviation of 1.3 cm (0.5 inches).

Similar results exist regarding studies of the circumference of the adult fully erect penis, with the measurement taken mid-shaft. As with length, studies that relied on self-measurement consistently reported a significantly higher average than those with staff measuring.

Flaccid length
One study found the mean flaccid penis length to be 3.5 inches (8.9 cm) (measured by staff). A review of several studies have shown average flaccid length to be 9–10 cm. Length of the flaccid penis does not necessarily correspond to length of the erect penis; some smaller flaccid penises can grow much larger, and some larger flaccid penises cannot grow much larger.

The penis and scrotum can contract involuntarily in reaction to cold temperatures or nervousness, referred to by the slang term "shrinkage", due to action by the cremaster muscle. The same issue affects cyclist and exercise bike users, with prolonged pressure on the perineum from the saddle, and the straining of the exercise causing the penis and scrotum to contract involuntarily which is sometimes referred to as "gym balls" or "saddle balls". An incorrect saddle may ultimately cause erectile dysfunction.

Penises that are short when flaccid but more average when erect are colloquially known as growers, where those with greater flaccid lengths that increase little when erect are known as showers.

Flaccid penis length is a poor estimate of erect length, a better estimate is stretched length, that is 12–13 cm, as shown in review by Wylie and Erdley.

Penis enlargement surgery

Most men concerned about their penis size and seeking surgical treatment to enlarge their penis overestimate "normal" penis length. All of the patients studied by Mondaini et al seeking surgical treatment had penis size within the normal range.

Surgical techniques used for penis enlargement (enhancement phalloplasty) -- penis lengthening and penile widening (girth enhancement) -- have been in the urologic literature for many years.

There are two basic ways of enlarging the penis:

Penis lengthening surgery involves the release of the fundiform ligament and the suspensory ligament that attaches the 2 erectile bodies to the pubic bone. Once these ligaments have been cut, part of the penile shaft (usually held within the body) drops forward and extends out, enlarging the penis by 2–3 cm.

Penis widening with PMMA injection. This method involves injection of silicone, PMMA and other materials into the penis and scrotum to achieve girth enlargement.

Fresco of Priapus from Pompeii. Depicted weighing his large erect penis against a bag of gold. Ancient Romans admired the large penis of Priapus. In ancient Greek art, it is common to see smaller male genitalia than one would expect for the size of the man. Renaissance art also followed this aesthetic; note Michelangelo's David. According to Kenneth Dover's landmark study "Greek Homosexuality", Greek art had extreme interest in the genitals, but was not obsessed with size.

The weekly Q&A column "The Straight Dope" deduces, based on pornographic Greek art work and Dover's aforementioned study, that in ancient Greece an uncircumcised and small penis was culturally seen as desirable in a man, whereas a bigger or circumcised penis was viewed as comical or grotesque (at least in the high-brow view), usually being found on "fertility gods, half-animal critters such as satyrs, ugly old men, and barbarians." [The Straight Dope: Why does so much ancient Greek art feature males with small genitalia?]

CBC radio has suggested, based on several sources, that ancient Romans had a viewpoint contrary to that of the Greeks. This was also the case in medieval Arabic literature, where a longer penis was preferred, as described in an Arabian Nights tale called "Ali with the Large Member". As a witty satire of this fantasy, the 9th century Afro-Arab author Al-Jahiz wrote: "If the length of the penis were a sign of honor, then the mule would belong to the (honorable tribe of) Quraysh".

Modern perceptions and sexual preference
Males may quite easily underestimate the size of their own penis relative to that of others, because of the foreshortening obtained from looking down, or because of the accumulation of fat at the base of the penis. A survey by sexologists showed that many men who believed that their penis was of inadequate size had average-sized penises. Another study found sex education of standard penile measurements to be helpful and relieving for patients concerned about small penis size, most of whom had incorrect beliefs of what is considered medically normal. One source of continued debate is the extent to which women actually prefer certain penis sizes.

A 2005 Internet survey of 52,031 heterosexual men and women found only 55% of participating men were satisfied with their penis size, whereas 85% of participating women said they were "very satisfied" with the size of their partner's penis, and only 6% of women rated their partner as smaller than average. In the same data set, 70% of women expressed dissatisfaction with their breasts, whereas the majority of men (56%) were satisfied with their partner's breasts and only 20% of men wished their partner had larger breasts. [American Psychological Association: Does Size Matter? Men’s and Women’s Views on Penis Size Across the Lifespan]

A study published in BMC Women's Health, surveyed women's preferences concerning penis size and concluded that width rather than length is a more important factor of sexual stimulation. [BBC Womens Health: Penis size: Survey of female perceptions of sexual satisfaction]

Similar results were found in a cover story published in Psychology Today, which surveyed 1,500 readers (about 2/3 women) about male body image. Many of the women were not particularly concerned with penis size and over 71% thought men overemphasized the importance of penis size and shape. Details were examined among the women with a size preference. Generally women cared more about width than men thought, and less about length. "...the number one reason women preferred a thicker penis was that it was more satisfying during intercourse." It's suggested this is because a wider penis provides more friction to the clitoral area while a longer penis reaches an area less stimulable. The same article comments that there is a strong correlation whereby “Women who rated themselves as more attractive were particularly concerned with larger size. Of women describing themselves as 'much more attractive than average,' 64% cared strongly or moderately about penis width and 54% cared about penis length. Women who rated their own looks as average were about 20 percentage points lower." [Psychology Today: Men's bodies--the survey; How women feel about penis length and width.]

Another study, conducted at Groningen University Hospital, asked 375 sexually active women (who had recently given birth) the importance of penis size and concluded: "Although clearly in the minority, a nevertheless considerable percentage of the women respondents attached substantial importance to the size of the male sexual organ". [What Importance Do Women Attribute to the Size of the Penis?]

A study undertaken at Utrecht University found that the majority of homosexual men in the study regarded a large penis as ideal, and having one was linked to self esteem. [The length of his penis is key to a homosexual man's self esteem and how he sees his body in general, according to a recent Dutch study undertaken at Utrecht University.]

The term size queen is slang terminology for a person of either sex who prefers a larger-than-average penis on their sexual partner(s).

Popular culture
Widespread private concerns related to penis size have led to a number of folklore sayings and popular culture reflections related to penis size. These include beliefs that it is possible to predict the size of someone's penis by observing other bodily features such as the hands, feet, nose or height, and in some cases so-called "penis panic" - a form of mass hysteria involving the believed removal or shrinking of the penis, known as genital retraction syndrome. Penis size, and sexual anxiety generally, have led to products such as penis pumps, pills, and other dubious means of enlargement becoming some of the most marketed products in spam mail.

The media has equated a man's penis size with both power and masculinity. Furthermore the perception of having a large penis is linked to higher self esteem. [Does size matter? Men's and women's views on penis size across the lifespan. Lever, Janet; Frederick, David A.; Peplau, Letitia Anne]

The suggested link between penis size, foot size and height has been investigated by a relatively small number of groups. Two of these studies have suggested a link between penis size and foot size, while the most recent report dismissed these findings. One of the studies suggesting a link relied on the subjects measuring the size of their own penis, which may well be inaccurate. The second study found statistically significant although "weak" correlation between the size of the stretched penis and foot size and height A potential explanation for these observations is that the development of the penis in an embryo is controlled by some of the same Hox genes (in particular HOXA13 and HOXD13) as those that control the development of the limbs. Mutations of some Hox genes that control the growth of limbs cause malformed genitalia (hand–foot–genital syndrome). However the most recent investigation failed to find any evidence for a link between shoe size and stretched penis size. Given the large number of genes which control the development of the human body shape, and the effects of hormones during childhood and adolescence, it would seem unlikely that an accurate prediction of penis size could be made by measuring a different part of the human body. [SpringerLink.com: The relationships among height, penile length, and foot size]

Other studies correlating the size of the human penis with other factors have given intriguing results. Notably one study analysing the self-reported Kinsey data set found that homosexual men had statistically larger penises than their heterosexual counterparts. One potential explanation given is a difference in the exposure to androgen hormones in the developing embryo. The study author's opinion is that evidence points towards both orientations being equally likely to exaggerate. [Salon.com: Research says erect gay penises are bigger]

Penis size and female genital response
According to some sex researchers and therapists, several misconceptions have developed surrounding penile-vaginal intercourse. Many men exaggerate the importance of deep vaginal penetration in stimulating a woman to orgasm. [WebMD: Sex: Fact and Fiction What’s the average penis size? How fast is premature ejaculation? Exactly where is the G-spot? Grab a ruler and a stopwatch as the experts sort sex myths from the facts.]

The most sensitive area of the female genitals includes the vulva, clitoris, and the section of vagina closest to the outside of a woman's body, which is roughly 10 centimeters (4 in) in length. Research has found that portions of the clitoris extend into the vulva and vagina. Given that the median penis size is above this length, the majority of penises are likely of sufficient length to fully satisfy their partners. [BBC News: Mascall, Sharon, “Time for Rethink on the Clitoris”]

While many women find penile stimulation of the cervix to be uncomfortable or painful, others report it to be key to orgasm. The cervix may be confused with the anterior or posterior fornix, the deepest point of the vagina, above and below the cervix, respectively. The cervix and fornix are close to each other, making it possible for there to be indirect and/or simultaneous stimulation between them. [AskMen.com: what is cul-de sac? Pleasure Spots]

The fornix is said to be another possible orgasm trigger area. Tests have shown that pressure on this area causes the vagina to lubricate very quickly. The area of sexual response in the anterior fornix has also been called the epicentre, T-Spot, AFE-Zone, AFE or A-Spot; while in the posterior fornix it has been called epicenter (as well) or cul-de-sac (since the cul-de-sac, also known as the rectouterine pouch, may be indirectly stimulated by pressure on the posterior fornix). [SexualTips.net: Questions and Answers about Sexual Anatomy]

During arousal, the vagina lengthens rapidly to an average of about 10 centimeters (4 in), but can continue to lengthen in response to pressure. As the woman becomes fully aroused, the vagina tents (last 2⁄3 expands in length and width) while the cervix retracts. The walls of the vagina are composed of soft elastic folds of mucous membrane skin which stretch or contract (with support from pelvic muscles) to the size of the penis. This means (with proper arousal) the vagina stretches or contracts to accommodate virtually any size penis, from small to large. [Netdoctor.co.uk: Facts about penis size Written by Dr David Delvin]

Other variance in penis size: Micropenis
An adult penis with an erect length of less than 7 cm or just over 2 inches but otherwise formed normally is referred to in a medical context as having the micropenis condition. The condition affects 0.6% men. Some of the identifiable causes are deficiency of pituitary growth hormone and/or gonadotropins, mild degrees of androgen insensitivity, a variety of genetic syndromes, and variations in certain Homeobox genes. Some types of micropenis can be addressed with growth hormone or testosterone treatment in early childhood. [New Scientist: Length-boosting surgery for 'micro-penises']

A news post on New Scientist dated December 6, 2004 reads "A new surgical procedure has allowed men with abnormally short penises to enjoy a full sex life and urinate standing up, some for the first time. Tiny "micro-penises" have been enlarged to normal size without losing any erogenous sensation, say UK doctors."

Environmental influence on penis size
It has been suggested that penis size differences between individuals is caused not only by genetics, but also by environmental factors such as culture, diet, chemical/pollution exposure, etc. Endocrine disruptor resulting from chemical exposure has been linked to genital deformation in both sexes (among many other problems). Chemicals from both synthetic (e.g. pesticides, anti-bacterial Triclosan, plasticizers for plastics, etc...) and natural (e.g. chemicals found in tea tree oil and lavender oil) sources have been linked to various degrees of endocrine disruption. Both Polychlorinated biphenylPCBs and the plasticizer DEHP have been associated with smaller penis size. DEHP metabolites measured from the blood of pregnant women have been significantly associated with the decreased penis width, shorter anogenital distance, and the incomplete descent of testicles of their newborn sons, replicating effects identified in animals. Approximately 25% of US women have phthalate levels similar to those in the study. [Environmental Health Perspectives: Decrease in Anogenital Distance among Male Infants with Prenatal Phthalate Exposure]

Penis size and condom use
Various studies have examined condom breakage. Ninety-two monogamous heterosexual couples (aged 18 to 40 for women, 18-50 for men) were enrolled in a prospective study of Durex Ramses condoms. At each sexual encounter, a diary was completed which included information on condom use, and breaks and slips. In France a random telephone survey of 20,000 individuals drew on 4,500 sexually active people, of whom 731 had used a condom in the previous year and 707 provided information on difficulties of use. In Australia 3658 condoms were used by 184 men in a study which looked, among other things, at penis size as a factor for breakage or slippage. [International Journal of Impotence Research: Penile length is normal in most men seeking penile lengthening procedures]

Although the most common type of condom, those made of latex, have great ability to stretch, they are vulnerable to dry friction (ie, the dry rubbing motion of sexual activity when there is tight pressure or a lack of smooth lubricated movement) as well as other mistakes of usage. For example, in a separate study of people practicing anal sex, condom breakage was linked more to excessive friction (in this case due to low usage of a sexual lubricant) than to penis size per se.

The rate of condom breakage for correctly used condoms was 1.34% and of slippage 2.05%, with a total failure rate of 3.39%. Penis size did not influence slippage, but penis circumference and broken condoms were strongly correlated, with larger sizes increasing the rate of breakage.