 The prostate is a variable-sized gland located in the male pelvis, usually the size of a walnut measuring 3-4 centimeters long by 3-5 centimeters in width. On average the gland weighs about 20 grams. It is found behind the pubic bone, in front of the rectum, and below the bladder, surrounded by the pelvic muscles.
The prostate surrounds the urethra which carries urine from the bladder to the penis and travels in thecenter of the gland. The seminal vesicles attach to the prostate and produce material that mixes with prostatic fluid to form semen. The tubes from the testicles carry sperm to the prostate where the sperm are mixed with the prostate and seminal vesicle fluid. This fluid is then ejaculated during orgasm by a connection to the urethra called the ejaculatory ducts.
For many years the prostate was thought to exist in "lobes", however, we now refer to the prostate ashaving various concentric zones. These zones are termed: anterior fibromuscular stroma, peripheral zone, central zone, and transition zone.
It is the peripheral zone of the prostate that a doctor can feel by a finger in the rectum. Almost all prostate cancers start in the peripheral zone, thus, the importance ofthe rectal examination. The transition zone generally accounts for less than 5% of the total prostate volume. Nonetheless, it is the exclusive site for the development of benign prostatic hyperplasia (BPH) and may therefore become massive.
The central zone is involved with the connection of the seminal vesicles to the prostate and is rarely associated with any disease process. The anterior fibromuscular stroma is the anchoring point of the urethral sphincter that controls urination: it does not have any glands and therefore cancer or enlargement does not develop here. |
