TeenHealthFX - Answers - You Were Wrong About Penis Muscle!

Penis & Testicle Concerns / Question
Published: November 19, 2002

Dear TeenHealthFX,

In the question Penis Bigger Through Masturbation you said that the penis is a muscle. That's not true at all. There are some muscles in it, but it is not one. If you can't give good advice on this, how can I trust anything else you say?

Signed: You Were Wrong About Penis Muscle!

Dear You Were Wrong About Penis Muscle!,

You are right - of course the penis is not a muscle! Please forgive us - we unfortunately chose our words incorrectly. We think one reason you can trust us is that we willingly correct our mistakes. So thanks for pointing out the error. For more information about male genitalia, see below.

The organs of the male genital system include the prostate, the seminal vesicles, the penis, and, contained in the scrotum, the testicles, epididymides, and vas deferens.

Specialized structures within the penis help it accomplish its two major functions: to transport urine and partake in sex. The urethra, which travels within a cylindrical structure (corpus spongiosum) on the undersurface of the penis, transports urine and seminal fluid (semen).

The penis contains also two cylinders of spongy tissue (corpora cavernosa) that fill with blood (engorge) during sexual excitement, causing the penis to expand. Since the fibrous sheath covering the spongy tissues is limited in its ability to expand, the tissues press against the sheath as they fill with blood, making the penis hard.

Though the penis actually extends far into the body, almost to the rectum, it contains no muscles and cannot be enlarged by exercise. However, the internal section is surrounded by muscles that can be strengthened. For most men, the head is the most sensitive part of the penis, especially around the ridge that connects it to the shaft.

Behind the base of the penis is the scrotum, a pendulous sac containing testicles, which produce both sperm and the male hormone testosterone. Each testicle is suspended from a cordlike structure containing blood vessels and a muscular tube called the vas deferens, which carries the sperm from the testicles to the urethra. Connecting the vas to the testicle is the epididymis, a structure important in the maturation of the sperm leaving the testicles.

The sperm travel through the vas deferens and are stored at its upper end until mixed with the secretions of the seminal vesicles and prostate just prior to ejaculation. The exact purpose of the vesicles is unclear, but it is known that they contribute a portion of the ejaculate. The secretions of the prostate comprise most of the seminal fluid or ejaculate, giving it its whitish color, while the sperm actually account for only a tiny fraction of the seminal fluid.

The tiny Cowper's glands empty into the urethra after it passes through the prostate. It is thought that the glands secrete a small amount of clear, sticky fluid that is often visible prior to ejaculation. Since this fluid may contain sperm and is capable of impregnating a woman, withdrawal of the penis from the vagina prior to final ejaculation is an ineffective means of contraception.

Although the prostate serves no purpose in the urinary system, the prostate normally enlarges (hypertrophies) with age and may eventually interfere with the flow of urine through the urethra (source: Columbia University College of P & S Complete Home Medical Guide).

Signed: TeenHealthFX