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The Physiology of Pleasure

Sexual pleasure involves a lot more than just what's in your -- or your friend's -- pants, but getting to know "the lay of the land" sure doesn't hurt. The truth is, we can experience more pleasure in our sexual encounters if we're better informed about genital sensation. Here are a couple of maps to get you started.


Genitalia -- female, male, transgender and intersexed -- all vary greatly in size, shape, color and response to stimulation. The female external genitalia are referred to as the vulva. This includes the outer lips (or labia), the inner lips, the clitoris and the vaginal opening. Men's external genitalia consist of the penis and scrotum. One to two people out of every thousand are born intersexed, yet surgeons alter most at birth. These individuals are born with genetic or hormonal variations that may affect their genitals, gonads and other characteristics. Intersexed people can have both female and male genitalia in varying combinations, or genitals that are ambiguous. A transgendered person is someone born with a body that doesn't accurately reflect the gender they feel themselves to be, and may possess any of the above sets of genitalia. Transgendered and intersexed folks may name or define their genitalia in any way they feel is accurate. We're all born with bundles of nerve endings in different packages -- how we think of them, what we do with them, and what feels great varies according to the individual.

Some transgendered people choose to pursue hormone therapy and/or sexual reassignment surgery. In male-to-female surgery, the penis is turned inside out so that the walls of the vagina are the former penis shaft, and the sensitive corona of the penis is used to create the clitoris. At present, female-to-male transsexuals can choose between two operations: phalloplasty and metoidioplasty. In phalloplasty a penis is surgically constructed from skin grafts and the clitoris is left at the base of the new penis (above the scrotum) to allow for sexual stimulation. Metoidioplasty involves releasing the testosterone-enlarged clitoris from its hood and creating a scrotum out of the labia majora. The resulting penis can be smaller than one built through phalloplasty but retains sensitivity, whereas a penis created through skin grafts can have limited sensation. Hormones can be taken before or after surgery, and some folks opt to take hormones and have no surgery. The introduction of new hormones into a body causes a variety of physiological changes, including enlargement of the clitoris and shrinkage of the breasts (female to male) and enlargement of the breasts with shrinkage of the penis (male to female). While some transsexual and transgendered people may experience a reduction of sex drive when they begin to take hormones, others will find that their level of arousal increases sharply. Often, these changes in sex drive occur in the first few years of hormone therapy, with the changes leveling out over time.

Pleasure inside the body

The walls of the vagina rest against each other most of the time, yet when aroused can expand to varying degrees to accommodate what feels best, from fingers to large dildos. The outer third is more sensitive than the rest of the vagina and responds well to friction and vibration; the inner two-thirds are smoother, contain fewer nerve endings and are more responsive to pressure and motion. When stimulated the vagina usually self-lubricates; however, lubrication should not necessarily be measured as a sign of arousal, since a woman's natural lubrication can vary for many reasons.

The base of the penis extends inside the body, and pressing your fingers against the area between testicles and anus you can feel the root, or bulb. This area can be pleasurable to touch and is stimulated either through the skin or from within the anus.

G-spot, prostate and ejaculation

The G-spot is the spongy, ridged area on the front wall of the vagina (towards the bellybutton). It is loaded with nerve endings and is an erogenous zone for many women -- yet for some, stimulation of this area may be irritating and unpleasant. The G-spot can best be massaged by inserting a finger, penis or curved sex toy two to three inches into the vagina and stroking towards the front of the body with a "come hither" motion. Some women require quite a bit of pressure; it helps to use a lubricant so the pressure does not feel irritating. Of those who greatly enjoy this type of stimulation, some women experience an ejaculation of fluid upon orgasm or as part of arousal. This fluid is a product of the paraurethral sponge, is clear and odorless, and should not be confused with urine.

In the male, the prostate gland is comparable to the G-spot. The prostate is an internal organ that produces ejaculatory fluid and is tucked close to the root of the penis. Ejaculation is often considered the same as orgasm, yet some men can have orgasms without releasing ejaculatory fluid, and vice-versa. The prostate is a source of great pleasure for many men -- some have orgasms from its stimulation alone -- and it can be used to enhance genital stimulation, though for some this may feel unpleasant. The prostate can best be massaged by inserting a finger two to three inches into the anus and stroking towards the front of the body with a "come hither" motion, exactly as you would for a G-spot stroke within the vagina. When aroused, the prostate swells and hardens, becoming more receptive to firm stimulation.

Anal pleasure

The anus, richly endowed with nerve endings, is the closest erogenous neighbor of the genitals and contracts rhythmically during orgasm. Stimulating the anus can indirectly stimulate the penile or clitoral legs (see below), or can directly stimulate the prostate gland. Inside, there are two sphincter muscles. The external muscle can be tensed at will, while the internal muscle can tense automatically, even if you are trying to relax. When stimulating the anus use plenty of lubrication and go very slowly, always listening to the feedback of the person who is being penetrated. With the anus there are particular safety concerns. Rectal tissue is very thin and does not self-lubricate, so it can tear easily (make sure to use lots of lube), and it's important not to insert anything that might break or have sharp edges. Also, the involuntary expanding and contracting of the sphincter muscle can quickly pull in (as well as push out) anything you're inserting, so be sure that the item you use has a flared base to prevent it from "getting lost" in the anal canal. Not everyone enjoys anal stimulation, but those who do find it adds an extra dimension to their sexual repertoire.

External touching and masturbation

The clitoris and head of the penis contain concentrated bundles of nerve endings that respond pleasurably to touch and other types of stimulation. The clitoris is tucked under folds of skin where the top of the labia meet, and pulling back the skin will usually reveal what is referred to as the clitoral glans, or head. (In some women the glans is obscured by the hood.) The visible part of the clitoris is just the tip of the iceberg. Directly beneath the surface of the glans is something that feels like a short rod of cartilage. This is the clitoral shaft. Inside the body, the clitoral shaft separates into two legs that extend in a wishbone fashion for about three inches on either side of the vaginal opening. The entire clitoris consists of erectile tissue just like the erectile tissue of the penis. During sexual arousal the tissue fills with blood, and the glans, shaft and legs swell, becoming firm and sensitive. In many cases the swelling -- or erection -- of the clitoris is visible. Because of the internal position of the legs, when you stimulate the urethra, vagina or anus, you indirectly stimulate the clitoris as well.

The head of the penis (also called the glans) is more sensitive than the shaft, particularly the ridge around the base. The coronal ridge is comparable to the tip of the clitoris. Spongy erectile tissue and blood vessels run the length of the penis, and extend into the body. These separate into two legs, comparable to the legs of the clitoris. During sexual arousal erection may occur when this tissue fills with blood and the penis swells, becoming more firm and sensitive. Erection, however, is not always a measure of arousal. All men are born with a foreskin, a retractable nerve-rich hood covering the head of the penis. Some men are circumcised, meaning that this skin covering has been cut off. Since an uncircumcised glans is protected by a foreskin, it is usually more sensitive when exposed. Stimulation of the foreskin itself can be very pleasurable. Some men find stimulation of the urethral opening -- where urine comes out -- pleasant, while others find it irritating. When a man is aroused, the urethral opening can lubricate itself with a clear substance called pre-ejaculate. The ridge of skin running from the underside of the head, down the shaft and along the middle of the scrotum to the anus is also sensitive to touch, and touching here can be quite pleasurable.

The scrotum is the loose sac of skin and muscle hanging below the penis, containing the testicles. The testicles are very sensitive, and though even light tapping on them may be painful, for some men firm pressure, steady pulling or squeezing the scrotum can feel good.

Many folks learn their capacity for pleasure and orgasm by investigating what feels good when they touch themselves. What feels right at a particular time or age may change, and masturbation techniques can be explored throughout the course of our lifetimes. No matter the physical stage of the individual, all people can have rewarding sex lives whether solo or partnered.