: The normal prostate is a walnut size gland (about 20-30 grams in weight) located deep within the male pelvis. However, men age 50 and older often have some enlargement of the gland causing it to become about the size of a plum or even an orange! I often tell my patients that the prostate is similar to a person's nose - in the sense that it is unique in size and shape for each man! The prostate lies roughly behind the pubic bone and is in close proximity to the rectum. This is what makes a digital rectal examination (DRE) such an important part of a man's annual physical. At the junction of the prostate to the urethra, is the urinary sphincter, the anatomy of which is quite complex. It is NOT a flat muscle like is often incorrectly depicted in pictures, but rather a funnel type muscle of multiple components. Finally, within 1-3 mm of the edge of the prostate are very delicate nerves responsible for sexual function and potency.
There are different "zones" of the prostate which many patients don't understand. There is a peripheral zone which is the part of the prostate closest to the rectum and really, that's the only part that can be examined by a DRE. The transition zone is generally where enlargement of the gland occurs. There is also an anterior zone which can harbor cancer in the minority of patients.
FUNCTIONS: The prostate serves two main functions: 1) as a male sexual gland producing components of the ejaculate and 2) as a conduit for urine from the bladder to the rest of the urethra. So the obvious question is does one really need the prostate to survive? The answer is no. In fact, in those patients in whom the prostate is removed in a sphincter and nerve-sparing manner, the patient may not even need the prostate to have normal urinary control and sexual function. However, prostate removal does result in sterility.