Is the Penis a Muscle or a Bone?

If you’re curious about your penis, you’re probably in the largest majority of men ever assembled. From a young age boys explore their bodies, gradually learning everything it can do, and when, and how.

The question of what your penis is, however, might have been answered by some misleading information over the years. Popular nicknames like “boner” and the less-common “love muscle” are actually pretty inaccurate overall.

The erect penis — the part you use for sexual pleasure — contains neither bones nor major muscles. Instead, your penis is a complex assortment of glands, specialized tissues, and, yes, some muscle fibers that help with erectile function.

To take a look inside, so to speak, read on for a brief breakdown of what is (and isn’t) inside your penis.

While you’re likely familiar with many parts of the anatomy of your penis, here’s a brief refresher.

The penis is a collection of blood vessels, vascular structures, connective tissue and nerves. from the root of the penis to the tip of the glans penis (and the opening of the urethra), the majority of the penis’s structure is designed to collect and capture blood, inflate, and become firm enough for penetrative sexual intercourse, for the purpose of delivering semen to the reproductive system of a mate.

That’s right: while there may be plenty of recreational uses for sexual organs, the penis is part of your reproductive system — the genital organs that collectively perform sexual and reproductive functions.

This system includes much more than the penis and testicles — the muscles of your perineal area and pelvic floor, as well as the crura and suspensory ligament, are internal structures that assist in urinary and sexual function.

Your penis is not a muscle, though it does rely on muscles internally and externally to function. The ischiocavernosus muscles, bulbospongiosus muscle and the smooth muscle tissue within your penis itself all work together to make your erection hard and steady its erect direction for sexual penetration.

Sexual arousal occurs when signals travel down your spinal cord through your nervous system to tell the penis to become erect. This can occur through stimulation of erogenous zones like the skin of the penis, the glans penis, and the prepuce or foreskin (in men who have not undergone circumcision), frenulum, scrotum, or perineum. It can also occur due to images, sounds, thoughts, or frankly due to nothing at all as a response of the parasympathetic nervous system.

Sexual activity can eventually result in orgasm and ejaculation, after which the internal structures relax, causing a visible reduction in penis size and firmness as it returns to a flaccid state.

During all of this, it is muscles that are sealing off that blood, maintaining an erect state, forcing semen out of the urethral opening, and finally relaxing to allow the penis to return to a normal state.

While your penis is definitely near your pubic bone and the other bones that make up your pelvis, it is not a bone itself. There are no bones in your penis, nor are there any in your reproductive system generally.

In fact, the most important bones to your penis are actually buried beneath the surface, where they protect and create structure for internal structures of the reproductive system that lead to or connect with the penis.

For any men asking, “Well if there’s no bone, how does it get hard,” the answer is that the penis is firm not because of permanent bone structures that move in or out, but because of permanent “balloon” structures that inflate and deflate.

While there are some species of mammal who do have bones in their penises, the human penis did not evolve in the same way.

While you may assume that your penis can flex, stretch and otherwise move due to the presence of muscles, only a few muscle fibers in the penis actually exist, and their purpose is entirely focused on managing the trapped blood that makes up erections. Instead, it’s the skin and spongy tissue that you can stretch while flaccid.

Things can break besides bones, and while the penis does not contain bones, there is an injury called “penile fracture” that you should be careful to avoid.

Penile fractures occur when an erect penis is, well, bent to the point of “breaking.”

The corpora cavernosa and corpus spongiosum (the spongy tissue segments that holds blood for erectile function) and tunica albuginea (the fibrous tissue that protects them) are tissues that can be damaged, potentially causing internal bleeding and damaging the necessary erectile structures.

When the corpus cavernosum or spongiosum is damaged, it can make erections painful or impossible, and a penile fracture can cause permanent bends in your erections — a condition called Peyronie’s disease.

Injuries can also occur through priapism — erections lasting multiple hours that can lead to permanent damage.

In both cases, damage to the erectile tissue can result in erectile dysfunction.

While your penis being a muscle or a bone (or neither) may not matter to you day to day, the reality is that understanding what makes up your penis can be essential information if you ever experience sexual health problems.

• Because erections are entirely about blood flow regulated by the smooth muscle in the vesselsof your penis, your heart health and vascular health are essential for erections. And restoring them may be necessary to treat certain cases of erectile dysfunction.

• Reduced sensitivity or feeling in your penis may signal damage to the nervous system — damaging the cavernous nerves can stop erections from forming, and pudendal nerve damage can cause pain and ED as well.

• Sexually transmitted infections, UTIs, premature ejaculation and ED are all conditions that a urology or general healthcare professional can help you manage, but you’ll need to have a baseline of knowledge to put their recommendations and treatments to use.

Have more questions? Check out our blog for guides to various sexual health issues, symptoms, and commonly asked questions for answers.