The Penis: Everything You Need to Know

Most men would agree that the penis, though clearly attached, often seems to have a mind of its own. Call it what you like: a unit, trouser worm, or schlong, it's still a strange, disorderly, and frequently disobedient creature. It can be friend or foe, but its inner workings remain a mystery to most of us.

To help us understand the "why" behind some of the most maddening and mystifying tricks the penis can play on its would-be master, we sat down with an expert on the family jewels, Vito Imbasciani, Ph.D., M.D. Imbasciani is a urologist with the Kaiser Permanente Medical Group in Southern California, and he agreed to try to explain some of the penis' most baffling behavior.

Zachary Levin: First of all, what causes "post-pee dribble?"

VI: With a lot of older guys I see, it's because they're peeing through their zipper, and they're obstructing the urethra. If they'd just open their pants and free Willy a little bit, it wouldn't happen. But for most people who consistently dribble after they pee, they're probably over 40, and probably have an enlarged prostate. In a young guy, it's most likely that he's wearing tight jeans, and he's trying to get it out and over his zipper-think of an inverted V. It's just mechanical.

Zachary Levin: Why do men sometimes get hard for no apparent reason?

VI: You can get an erection for any of three main reasons. Sometimes your brain causes it when you see, smell, taste or hear something that turns you on. This centrally originated signal is sent down the spinal cord to the pelvic ganglion, or central relay system, which then sends signals down to the penis.

Then there are the erections you bring on by yourself, by touch. The other unwanted ones are triggered not by the brain, but by the nerves in the penis itself. It could be you're driving along and the motion of the car stimulates the pelvic nerves; you could wake up with a full bladder, and that stimulates the pelvic nerves. A sensory input to the spinal cord sends a signal back to the penis and says to the arteries, "open up!" And you wind up with an unintended erection.

Zachary Levin: When you get one of these untimely erections, is it dangerous to try to hide it by forcing it into a position it doesn't want to be in?

VI: Yes. When a penis is erect, it's as rigid as wood. Now, it might be green wood, but if you bend it, you could break it. This usually happens during sex. I saw a patient recently whose very large girlfriend was on top of him. Her weight pressed down on his very rigid erection the wrong way. His penis was fractured. He had to go to the operating room and get it sewn up.

Zachary Levin: Talk to me about priapism.

VI: Priapus was a little Roman god-he was only about six inches tall, but is always shown in statues with a huge penis. Priapism is the condition of having an erection that will not go down. It's not common, except in people who are predisposed to it. Some people with head trauma, like concussions, will come to the emergency room in a priapistic state. Young black men who have sickle cell anemia are also at risk, because their blood clots, usually in the penis. Some drugs can cause priapism as a side effect, too.

Zachary Levin: What's the stuff, often called pre-come, that leaks out of the penis during foreplay?

VI: The urethra of the penis has little glands along it that provide pre-lubrication. It's something that's evolved over time. Evolution has rewarded animals who reproduce. So anything that helps deliver semen to the uterus is going to survive. This pre-lubrication of the urethra helps it open up, so that semen comes down unfettered. Pre-come is comprised of one of two things (and sometimes both): some of it is the secretions of the little glands of the urethra, and some of it could actually be prostatic secretions, which is true semen.

Zachary Levin: Is there enough sperm in pre-come to get someone pregnant?

VI: You have to assume that it's strong enough. Also, it's not like a washing machine where it suddenly switches to spin-modeor, in this case, urethral versus prostatic secretionsand you can't tell the difference. Better to be safe than sorry and keep it away from the vagina.

Zachary Levin: What about the dreaded blue ballswhat exactly are they?

VI: I call it pelvic congestion. If you're used to a certain level of sexual activity and you haven't emptied your prostate and the seminal vesicles (the storage area for semen), those areas start to feel full. I presume just the way somebody's nose might feel full when they've got a sinus problem and they just want to blow their nose. So it's semen buildup, or prostate congestion. Some guys don't masturbate before dates because they like that feeling. The only way to get rid of the situation is to drain the main vein by ejaculating.

Zachary Levin: I read two interesting statistics in The Penis Book by Joseph Cohen (Kvnemann, 1999). One was that the average speed at which ejaculate shoots out of a man is 25 m.p.h. The other is that the farthest medically recorded distance of ejaculation is 25.5 inches. But I once saw a porno with Ron Jeremy where the only thing stopping his output was the ceiling.

VI: Average speed? I have no idea. As to the second, I'd love to see the, ah, competition. I think we all did it when we were Cub Scouts.

Zachary Levin: I'd like to ask you a few questions regarding semen. I've heard of it referred to as, among other things, a "protein shake." Does it have any nutritional value?

Vito Imbasciani: The chief ingredient of semen is fructose, which derives mainly from the seminal vesicles. I wouldn't say it's good for you per se, but it's certainly not harmful.

Zachary Levin: How much does the average man come? Is it variable?

VI: The average man comes about three milliliters. The rare person may put out five to six milliliters [a teaspoon is 5 milliliters]. If a person hasn't come in while or is really turned on, it's going to be more.

Zachary Levin: Is it true that sperm makes up a very small percentage of the ejaculate?

VI: That's right. The sperm contribution is minimal, accounting for only one percent. Sperm is produced in equal parts between the prostate and the seminal vesicles.

Zachary Levin: Does wearing "tighty whities," or any type of restrictive underwear, negatively affect sperm count?

VI: Yes. It also affects motility, how well the sperm swim. A serious fever will do it, too. If you've had a fever of 103 to 104 degrees, three months down the line (when those sperm have matured and are ready to be ejaculated), your sperm count's gonna drop way down.

Zachary Levin: Along a different vein, surgery to enhance the size of the penis is a growing field. Does this really work? Are there risks involved?

VI: Currently, the surgery offered to lengthen the penis involves cutting the suspensory ligament. When this is cut, it no longer suspends the penis, so you have three-quarters to an inch more showing. The problem is that when you get an erection, it points straight to the floor. It doesn't suspend it at a right angle. An 18-year-old's erection points straight up to his belly button; a guy middle aged points straight out; and I guess as you get very oldif you can still get an erectionit points straight down. That's because the suspensory ligament has lost some of its elasticity.

Zachary Levin: Do you discourage patients interested in this procedure?

VI: Yes. You know, it's also very disfiguring. I've seen photographs of people that have had to have plastic surgery to make them look normal again. It's an ugly looking scar, and the scrotum can come up around the base of the penis: they call it "scrotalization" You know how the balls normally hang down below the penis? They can grow upward because of the scar, along either side of the penis. It starts to look weird.

Zachary Levin: Not to mention that the fat injected in the penis for girthanother aspect of the procedurecan become lumpy and sink to one part of the penis?

VI: That's the most disfiguring part. Sometimes the fat collects at mid-shaft, and doubles the diameter in that one section.

Zachary Levin: You must see things in your practice that most people don't even know exist. Are there any sex toys or penis tricks that can be particularly hazardous to the male organ?

VI: Sure, such as cock ring's metal or leather that are strapped around the base of the penis. They're used to amplify the erection: the blood stays in the penis a lot longer under tighter constriction, almost like a tourniquet. The penis can get very cool and blue. If allowed to go too far, you can get a thrombosis (a blood clot). I had one guy who got tied up by a dominatrix. He had rope tied all around him, including around his testicles. And then I think he did some coke and passed out, so he was like that all night long. He almost lost his penis: the skin was all chafed and he had to stay in the hospital ten days with his penis in traction.