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Ask the expert Penis
Last updated September 15, 2020. 4 minute read

Penis anatomy questions: muscle or bone?

The penis is composed of many different tissue layers, but one of the main components is smooth muscle. Smooth muscle acts much differently than skeletal muscle.

Dr Seth D Cohen Md Mph

Seth D. Cohen, MD, MPH

Dr. Seth Cohen, MD, is Assistant Professor in the Department of Urology and Obstetrics and Gynecology, and the Director of the Sexual Dysfunction Program at NYU Langone Health. His current research is being conducted on erectile dysfunction, male sexual dysfunction, low testosterone and peyronie’s disease. Dr. Cohen is board-certified in urology.

Reviewed by Yael Cooperman, MD

Q: Is the penis a muscle?

A. “Your liver is an organ, the skin is an organ, so the penis is an organ,” says Dr. Cohen. “The penis is composed of many different tissue layers, but one of the main components is smooth muscle. Smooth muscle acts much differently than skeletal muscle.”

Essentially, there are two types of muscles in the body. There are skeletal muscles, like your abs or your biceps, which you use voluntarily to do things like maintain posture and lift things up. Smooth muscles, on the other hand, are constantly working on their own to keep internal functions, like blood flow and food digestion, running smoothly (Starkebaum, 2019). 

“In the corpus cavernosa, two spongy tubes of smooth muscle tissue dilate and allow blood to leak out of the cavernosal arteries to fill the tubes,” Cohen explains. “In the flaccid state, there is little blood flow, but when aroused, the arteries and smooth muscle dilate so blood can maximally fill the penis for penetrative intercourse.”


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Q: My penis is curved — is that normal?

A. “Another misconception is that penises should be arrow-straight, but they are not,” he says. “Men watch porn and see these large, straight rock-hard penises, but most people are born with some type of curve to their penis.” 

And if you’re not happy with your penis size, you’re not alone. Research has found that almost 70% of men reported being dissatisfied with the size of their penis (Tiggermann, 2008). 

“Men tend to be penocentric,” Cohen says, which means they can’t stop thinking about their penis (typically size or curvature) penis, just like women may be focused on their hips or breast size. This dissatisfaction can lead men to seek out ways to alter their penis, either through surgery or other non-surgical methods (Littara, 2019). Penis implants, stretching exercises, and injections are a few examples of ways men try to adjust the size of their penis. But many of these procedures are risky and can even cause permanent damage. And unfortunately, there’s no way to get that back. 

“Do not attempt any penis stretching exercises without medical supervision,” Cohen says. “I personally counsel people on exercises and penile devices used to help straighten a penile curvature and prevent length loss in diseases like prostate cancer, severe diabetes, and Peyronie’s disease (which is when plaque builds up in the penis, causing it to bend).” 

Cohen also warns about turning to the internet, where there are tons of videos on how to perform medically unsanctioned penis stretching exercises, such as “jelqing.”   

“I’m not sure where or when this started, but someone decided if you stretch your penis X amount of times per day, you’ll get inches of length. Most patients I’ve seen have done permanent damage this way,” he says. “It’s like someone grabbing your arm and pulling on it as hard as they can to stretch your muscles and ligaments — something eventually gives way and can break.” 

Q: Can you break a penis?

A. “Not easily, but the answer is yes, you can break a penis,” Cohen says. 

While a penis can break, that doesn’t mean it’s a bone. 

“The penis is not a bone. Some animals have bones in their penises, but humans don’t,” he explains. “If you apply enough pressure to an erect penis, you can cause a tear or rupture in the soft tissue, and that’s called a penile fracture. It’s usually a medical emergency that requires surgery, so you don’t lose the permanent function of your penis.” 

Luckily, penile fractures aren’t that common, with an estimated 1 in 100,000 occurring each year in the United States (Rodriguez, 2019). Trauma like this happens when an erect penis is forcefully bent, which most commonly happens during masturbation or vigorous sex (Mirzazadeh, 2017). 

“For the fractures, I’ve taken care of, a lot of times, men are doing something they’re not supposed to be doing, and then they wind up fracturing it,” Cohen says. “The typical sexual position is reverse cowgirl, but it can happen in almost any position. Essentially the penis misses the entrance of the vagina, hitting the pelvic bone, causing a severe bend and rupture. You eventually see men with crooked penises from that kind of repetitive trauma — the penis will start to curve up or down like a snake.” 

“Crazy sexual maneuvers with the addition of alcohol, as well as rough sex, are always a recipe for disaster,” he adds. “I’m not going to tell people not to try different things with their intimate partner. As long as you do it safely, everything should work out fine. You have to live your life, just be smart. If you treat your body like a temple, it will last a lifetime.”