Anatomy of the Prostate Gland

The prostate is part of a man's reproductive system. It is a walnut-sized, donut-shaped gland located between the bladder and the penis and in front of the rectum and under the bladder. (It can be felt by placing a finger in the rectum.) One of the prostate's main duties is to create the seminal fluid that mixes with and carries sperm out of the penis upon ejaculation. The prostate also helps to pump the semen and sperm with sufficient power out of a man's body on its way to fertilizing a woman's egg. The prostate functions as a gland and contains muscle fibers that contract and relax.

The urethra, the tube that carries urine from the bladder and out of the body through the penis, passes through the center of the prostate. The microscopic nerves that control erection are attached to both sides of the prostate as they extend to the penis. The prostate is not a vital organ; however, it is surrounded with lots of small and sensitive nerves and blood vessels that can be damaged as a result of the disease and its treatment.

Urine continually collects in the bladder. Every so often the muscles at the bottom of the bladder relax, while the muscles surrounding the bladder contract, squirting the urine into the urethra that runs through the prostate and continues through the penis, all the way to the tip and out of the body.

The prostate sits right in front of and below the bladder and is wrapped around the urethra, but it has nothing to do with a man's urinary apparatus. The prostate happens to be where it is because it is needed for ejaculation, and the ejaculate passes through the same urethra as the urine does.

That's why prostate problems interfere with a man's ability to urinate and to have sex.

The prostate is divided into five zones:

The peripheral zone, which is located in the rear part of the prostate near the rectum and which contains three-fourths of the glands in the prostate and is where most prostate cancer occurs.

The central zone, which is involved in the connection of the seminal vesicles to the prostate, and which contains most of the rest of the organ's glands

The anterior zone, which is primarily smooth muscle tissue, is located in the front part of the prostate.

The transition zone, the zone that enlarges with "benign prostatic hyperplasia" (BPH), a non-cancerous enlargement of the prostate.

The pre-prostatic tissue, which contains muscles that help prevent semen from flowing backward into the bladder during ejaculation.