Most men are fairly familiar with their penis and scrotum. Boys learn to hold their penises while urinating, certainly notice them when they become erect, and generally talk more freely about their genitals among themselves than girls do. Yet the male reproductive system is a complex series of glands and ducts, and few men have a full understanding of how the system operates physiologically.
External Sex Organs
The external sex organs of the male include the penis (which consists of the glans and root) and the scrotum. Here we will discuss these organs and the process of penile erection.
The Penis
The penis is the male sexual organ. It contains the urethra, which carries urine and semen to the outside of the body. The penis has the ability to engorge with blood and stiffen, which evolutionary theorists would tell us allows for easier penetration of the vagina in order to deposit sperm near the cervical os for its journey toward the ovum. Though there is no bone and little muscle in the human penis, the root of the penis is attached to a number of muscles that help eject semen and that allow men to move the penis slightly when erect. Throughout history men have experienced anxiety about penis size. In the accompanying Sex in Real Life, “Penis Size and Male Anxiety,” we’ll discuss this anxiety.
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SEX in Real Life
Penis Size and Male Anxiety
he penis has been defined as the symbol of male sexuality throughout history. Men have often been plagued by concerns about penis function and size—especially size.
Many men assume that there is a correlation between penis size and masculinity, or sexual prowess, and many assume that women prefer a large penis. Others worry about their size and fear that they are not "normal." Although there may be a psychological preference for large penises among some women (just as some men desire women with large breasts), penis size has no correlation with the ability to excite a woman sexually during intercourse or to bring her to orgasm.
The average flaccid penis is between 3 and 4 inches long, and the average erect penis is 6 inches. Men often doubt these statistics, thinking that they are repeated just to reassure them. In fact, the exaggerated opinion most men have of average penis size comes from pornographic films (which tend to use the largest men they can find); from men’s perspective on their own penis (which, from the top, looks smaller than from the sides); and from overesti
mates of actual penis size (researchers consistently find that people’s estimation of the size of penises they have just seen is exaggerated; Shamloul, 2005).
Still, men continue to be anxious about their penis size. Some succumb to the advertisements for devices promising to enlarge their penises. Men who purchase these devices are bound to be disappointed, for there is no nonsurgical way to enlarge the penis, and many of these techniques (most of which use suction) can do significant damage to the delicate penile tissue (D. Bagley, 2002). Other men with size anxiety refrain from sex altogether, fearing they cannot please a woman or will be laughed at when a woman sees them naked. Yet the vast majority of women report that penis size is not a significant factor in the quality of a sex partner.
Gary Griffen, the author of Penis Size and Enlargement, has found that only 15% of men have an erect penis measuring over 7 inches, and fewer than 5,000 erect penises worldwide measure 12 inches (Griffen, 1995). In the end, penis size has been found to be largely dependent on heredity—the father’s penis size correlates well with the sons’ (T. Hamilton, 2002).
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The penis is composed of three cylinders, each containing erectile tissue—spongelike tissue that fills with blood to cause erection. Two lateral corpora cavernosa (CORE-purr — uh cav-er-NO-suh) lie on the upper sides of the penis, and the central corpus spongiosum (CORE-pus spon-gee-OH-sum) lies on the bottom and contains the urethra. The three are bound together with connective tissue to give the outward appearance of a single cylinder and are permeated by blood vessels and spongy tissues that fill with blood when the penis is erect.
The Glans Penis The corpus spongiosum ends in a conelike expansion called the glans penis. The glans penis is made up of the corona, the frenulum (FREN-yu-lum),
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and the meatus (mee-ATE-us; see Figures 5.1 and 5.2). The glans is very sensitive to stimulation, and some males find direct or continuous stimulation of the glans irritating.
The prepuce of the glans penis is a circular fold of skin usually called the foreskin. The foreskin is a continuation of the loose skin that covers the penis as a whole to allow it to grow during erection. The foreskin can cover part or all of the glans and retracts back over the corona when the penis is erect.
In many cultures, the foreskin is removed surgically through a procedure called a circumcision (sir-kum-SI-zhun). Circumcision is practiced by many groups, such as Jews and Muslims, as a religious or cultural ritual; however, there are hygienic reasons why other cultures routinely circumcise their infants. If good hygiene is not practiced, smegma, secretions from small glands in the foreskin, can accumulate, causing a foul odor and sometimes infections. It has also been observed that women married to circumcised men tend to have a lower incidence of cancer of the cervix, and circumcised men have a lower incidence of cancer of the penis, though no one knows exactly why (Alanis & Lucidi, 2004; Burton, 2002). Male circumcision may also reduce STIs in their partners (Zept, 2002), and research has found that in several cities in South Africa and Kenya, circumcised men have a lower risk of HIV infection than noncircumcised men (Auvert et al., 2001; R. C. Bailey et al., 2002).
However, the research doesn’t overwhelmingly support circumcision. In fact, many of the conditions that researchers cite as a benefit for the practice of circumcision are preventable through proper hygiene (Kinkade & Meadows, 2005). Some medical professionals have begun to question the health value of circumcision, which is the single most common surgical procedure performed on male patients in the United States (Boyle et al., 2002). The bottom line is this: although we do know that there may be some medical benefits to circumcision, these benefits are not strong enough for healthcare providers to recommend routine circumcision (Kinkade & Meadows, 2005). Parents are urged to make this decision based on their own experiences, their family, and religious beliefs.
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Frenulum
Corpora spongiosum