Genitalia
Male Genitalia
Men grow up seeing and touching their penises every day. This can lead to a false sense of understanding. There's more than meets the eye with male genitals…
Starting with the obvious, you have pubic hair, a penis and a scrotum. The area between the root of the penis and the abdomen, typically covered in coarse hair, consists of a pad of fat that covers the pubic bone. This bone protects internal sexual organs like the seminal vesicles, prostate gland, and vas deferens. More on those later.
The penis is a shaft of spongy tissue with three purposes: urination, sexual intercourse, and ejaculation. Penises average about 3 and a half inches in length when flaccid (soft) and 5-6 inches in length and 4-5 inches in girth when erect. Variation in size has no affect on sexual functioning.
On the outside of the penis, you may or may not have a prepuce, orforeskin. The foreskin is a double-layer sheath of skin that covers theglans (head) of the penis, ending in the frenar band, a ring of skin that, in most men, slides back over the glans when the penis becomes erect.
The glans of the penis looks a bit like the cap of a mushroom; it is an area of skin very sensitive to the touch. It has a few noteable parts: the meatus, on the tip of the penis, is the entrance into the urethra; the frenulum, at the base of the glans, is a y-shaped, membranous area where the foreskin attaches to the penis, much like the membrane on the underside of your tongue. The bottom ridge of the glans, the corona, is quite sensitive. There is a narrow area called the sulcus that connects the glans to the shaft.
Along the shaft of the penis is a fair bit of loose skin. It is loose to allow for expansion of the penis during sexual arousal. There are quite a large number of nerve endings in this skin, but the bulk of the sensitivity is focused in the glans.
Inside the shaft of the penis are 4 major features: the urethra, the corpus spongiosum, and the corpora cavernosa. The urethra is a soft tube that leads back into the body to the bladder. More on the urethra later.
The corpus spongiosum is a chamber of spongy tissue surrounding the urethra. The tissue here is filled with blood vessels and tiny spaces called sinuses that fill with blood during sexual arousal.
The corpora cavernosa are a twin set of spongy bodies located on the anterior side of the penis (the side closer to your belly). Like the corpus spongiosum, the tissue is full of blood vessels and sinuses that fill with blood and expand during sexual arousal. The corpora cavernosa make up the bulk of erectile functioning in the penis.
All three of these masses of spongy tissue extend back well into the body, so that the penile shaft that you see is only part of what becomes erect during sexual functioning.
The scrotum is a sack of skin that contains the testes and the epididymis. The testes (or testicles) are glands stuffed with seminiferous tubules, which produce sperm. Wrapped around the back of the testicles is the epididymus, a holding area for mature sperm. The epididymus narrows into the vas deferens.
The vas deferens, leading from the testicles to deep inside the body, carries sperm from the testes to the ejaculatory duct. There, the sperm mixes with semen, produced by the nearby seminal vesicle. From there, the semen will travel along the urethra and out of the body.
Other important parts located internally are the cowper's gland (located just above the root of the corpus spongiosum) which produces pre-ejacuatory fluid, and the prostate gland, which blocks off the urethra at the opening to the bladder, to keep urine from entering the semen.
Female Genitalia
For many women, their genitals are a mystery, and there's a pretty good reason for that: when a woman looks down, all she sees is a triangle of hair. Women's parts are hidden from their view and as a result they tend not to know very much about their genitals. However, understanding your anatomy is an integral part of your sexual life.
Let's start at the outside and work our way in. That triangle of hair grows out of a fatty pad that covers the pubic bone. The pubic bone protects internal organs like the uterus and cervix. More on those later.
Below that is the vulva proper. The vulva is made up the labia majora - the hairy, fleshy lips on the outside - and the labia minora - the red, wrinkly flaps that are buried under the outer lips (sometimes they peak out between the outer lips). During sexual arousal these lips engorge with blood, swelling and becoming darker.
Between the inner lips you'll find the vestibule, housing the clitoris, Skene's ducts, the urethra and the vagina.
The clitoris is a membranous shaft on the anterior side of the vulva (at the top, closer to your belly than your back). Only the glans (tip) is visible, and that only when you pull back the hood. There's quite a lot to it beyond what you can see, though.
The clitoris has been called "a vestigial penis," and it is kind of like a penis, but it is in no way vestigial. It is like a penis insofar as it has a head and a shaft and it composed of erectile tissue. But unlike the penis, the only function of the clitoris is sexual pleasure. It has no other purpose, while the penis is also responsible for urination and ejaculation.
Below the clitoris is the urethra, framed by the Skene's ducts. The urethra is a tube that leads from the bladder to the outside of the body to expel urine. The Skene's ducts are somewhat more mysterious. They are the exit place of the Skene's glands, which current literature suggests are the female homologue to the male prostate. The tissue is erectile and performs the same functions as the prostate: namely, it produces a it blocks off the urethral opening. More on this when we talk about the vagina.
Farther back still, we have the vagina. This is a "potential space," a tubular set of muscles that lead from the cervix to the outside of the body. The vagina averages about 3 inches in length and can expand to about 4 inches during sexual stimulation. During sexual arousal, the Skene's glands and the vagina swell so that a couple of inches inside the anterior wall (closer to your belly than your back) of the vagina, you can feel the Skene's glands through the vaginal wall. This is the rather mysterious "G" spot. In some women, caresses here (when the woman is aroused) are very pleasurable, and in other women caresses are painful or else just feel like she has to urinate.
The first 2 or 3 inches of the vagina are made up of a sensitive ring of pubococcygeal muscle that can be voluntarily contracted. You can practice contracting and relaxing these muscles by stopping the flow of urine. Once you've located the muscles, you can squeeze them anytime you like. Strengthening your PC muscles with these exercises (called Kegel exercises, after the man who invented them) can improve sexual functioning and sexual awareness.
The vagina ends at the cervix. The cervix is the entrance to the uterus. The uterus in turn stretches into a pair of fallopian tubes, which attach to the ovaries. These are reproductive organs in the literal sense, but they are not directly involved in sexual response.
