The Human Penis: Everything there is to know about it

12 min read
The Human Penis: Everything there is to know about it

Around 4 billion humans have a penis - that's just about half of the entire population of the planet! The penis is the male sex organ and is used for both urination and reproduction, as I'm sure you're aware. If you've got one, you're probably fairly used to it at this point - but when was the last time you stopped to think about what it's actually made up of, and how it really works?

Though it looks fairly simple from the outside, the human penis is actually quite a complex organ, comprised of multiple parts and pieces. In this article, we'll take a look at the anatomy of the penis, and give you a brief introduction to each of its parts. We'll also go over the functions of the penis, as well as how they are achieved.

Though it looks fairly simple from the outside, the human penis is actually quite a complex organ, comprised of multiple parts and pieces

To add to this, we'll look into a few of the numerous congenital abnormalities, as well as infections and conditions, that can affect the penis. We've even put together a quick guide on how to keep your penis clean and healthy!

Whether you've got one, or are just intrigued by the topic, this is a great place to start if you're interested in taking a slightly deeper look into the human penis!

The anatomy of the human penis

human penis diagram

Source: Encyclopædia Britannica

There's a lot going on with the penis. Situated at the base of the pelvis, right above the scrotum, there are numerous parts that allow for its various functions. Not only is it used for sex and reproduction - after all, it is the male sex organ - it's also used for urination. Here's a quick rundown of what the penis is really made up of!

The glans penis

The glans is the head of the penis, which is located at the end of the shaft, or corpus. It is full of nerve endings - around 4000 - which make it very sensitive. In uncircumcised men, it's covered in mucosa - soft, pink tissue, which turns into dry skin if you are circumcised.

The meatus

This is the hole at the tip of the glans which allows semen or urine to leave your body.

The prepuce

This is the fold of skin that covers the glans, which is usually known as the foreskin. Men can have their foreskin removed through the process of circumcision.

The urethra

This is the tube inside the penis which is used for urination. It runs all the way from the bladder to the meatus, and crosses through the prostate gland on the way, collecting semen through the ejaculatory duct.

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The corpus cavernosum

These are two columns of tissue that are located and run along the underside of your penis. The tissue they are made from is spongey, which allows it to fill with blood and stiffen up during an erection.

The corpus spongiosum

Similar to the corpus cavernosum, this is also a column of spongey tissue - but this one runs along the top of the penis, and surrounds the urethra. During an erection, the corpus spongiosum also fills with blood, keeping the urethra open.

During an erection, the corpus spongiosum also fills with blood, keeping the urethra open

All these parts come together to form the penis. The glans, as well as the meatus and prepuce, are located at the end of the penis. The urethra, corpus cavernosum, and corpus spongiosum are wrapped in connective tissue - known as the fascia - and then skin, making up the shaft of the penis. Finally, the penis is held near the pelvic bone with suspensory ligaments which support the penis base. The penis also has a healthy supply of blood thanks to its blood vessels.

Main functions of the penis

As we mentioned earlier, the penis has two main functions, being used for both urination, and sexual reproduction.

Urination

Urination is the discharge of urine from the body, AKA, peeing. The spongey tissue that runs along the top of the penis - the corpus spongiosum - contains the urethra, which runs from the bladder to the meatus. When you pee, the detrusor muscle, located in the wall of the bladder, contracts, and urine is pushed through the urethra and out of the end of your penis. The release of urine can also be controlled with the external urethral sphincter muscle, which is between the bladder and the penis.

Sexual reproduction

There are actually two stages to the sexual function of the penis, those being erection and ejaculation.

Erection

When you get sexually aroused, through physical stimulation of otherwise, the spongy tissue that makes up the corpus cavernosum and corpus spongiosum fills with blood and stiffens up, making your penis rigid and erect - hence, erection.

What's going on here is your arteries widening, resulting in your penis becoming engorged

What's going on here is your arteries widening, resulting in your penis becoming engorged. This then puts pressure on and compresses the veins that would normally let blood flow out of the penis, which helps the erection last, as the blood is trapped inside.

Normally, an erect penis will be stiff and rigid enough to allow it to penetrate a partner for sexual intercourse. Intercourse or other sexual activities involving physical stimulation of the penis, often cause and result in orgasm and ejaculation.

Ejaculation

Ejaculation is when semen is discharged from the body and involves multiple simultaneous muscle contractions, all of which are involuntary.

A contraction in the vas deferens, or sperm duct, causes sperm to be sent from the testicles to the ejaculatory duct.

The prostate gland and seminal vesicle glands also contract, adding fluids to the sperm.

This fluid is what makes up most of the semen, which is then released from the body as the final of these simultaneous contractions occurs in the periurethral muscles, situated at the base of the penis.

Congenital abnormalities of the penis

Congenital abnormalities or disorders are conditions that you are born with, and are generally caused by something interfering with normal development prior to birth. The penis can be affected by numerous congenital abnormalities, which are often caused by a hormonal imbalance affecting how the penis develops.

Possible congenital abnormalities of the penis include:

Penile chordee

Penile chordee is a condition that causes the penis to be curved to a greater degree than what can usually be expected. It is usually most easily noticed during an erection. Chordee generally presents as an abnormal curve, a shortened urethra (the opening of which isn't in the usual location), and a dorsal penile hood.

Usually, surgery is not recommended to correct chordee unless the penis has a very significant bend, or the condition is affecting the stream of urine. It's important to note that even though chordee has a similar effect to Peyronie's Disease, the cause is entirely different.

Penile torsion

Penile torsion is where the penis seems to be rotated as opposed to curved. This rotation is usually in a counterclockwise direction. Though it is commonly associated with other penile anomalies such as chordee, it happens on its own in around 1/4 of cases.

Similarly to chordee, unless the case is severe and affects the quality of life, surgery is not recommended to correct the condition.

Hypospadias and Epispadias

These conditions both affect the position of the opening of the urethra. With hypospadias - which is one of the most common penile congenital abnormalities - the opening is located on the underside of the penis, as opposed to the top of the penis, which is what happens with epispadias.

For these conditions, surgery is usually recommended for cases found in young children, despite there being a risk of long-term complications such as difficulty urinating, and a higher chance of developing urinary tract infections. Hypospadias often presents along with chordee or penile torsion, but these abnormalities can sometimes happen on their own.

Micropenis

Sometimes babies are born with an abnormally small penis - a micropenis. When stretched, a micropenis is far smaller what is normal at that point in a child's development. For adults, a micropenis is a penis that, when stretched, is less than 3.67 inches long.

In the USA, around 1.5 out of every 10,000 male babies are born with a micropenis. It is theorized to occur when a pregnant woman produces an unusually low quantity of androgens - male hormones.

Aphalia

Aphalia - the congenital absence of a penis - is a very rare abnormality. Commonly occurring alongside congenital abnormalities of the heart or digestive tract, only one in every 30 million births is thought to be affected, with the number of reported cases currently sitting at less than 100 (though this number may have increased since the research was published). Currently, there is no known cause of Aphalia.

Common infections and conditions of the penis

As with most body parts, the penis is not immune to infections or other conditions which can affect both how it works, as well as how it looks. As we've established, there are numerous parts to the penis, and as such, various areas can have issues. These issues include:

Infections

Balanitis

Balanitis causes the glans to become inflamed, tender, and painful.

Balanoposthitis

Balanoposthitis is a case of balanitis that also involves the foreskin, and as such, only affects uncircumcised men.

Urethritis

Urethritis causes the urethra to become inflamed and can cause painful urination as well as penile discharge. It is often caused by gonorrhea or chlamydia.

Gonorrhea

Gonorrhea is a sexually transmitted infection (STI) that usually results in urethritis and the symptoms that come with it.

Chlamydia

Another STI, which also causes urethritis and the associated symptoms. However, a fairly large 40% of male chlamydia cases are symptomless.

Syphilis

Syphilis is an STI that is usually signified by the formation of a chancre - a painless ulcer - on the penis. Syphilis is quite uncommon.

Herpes

Herpes is an STI that causes blisters and ulcers to form on the penis, which reoccurs over time.

Penis warts

Penis warts can be caused by human papillomavirus - HPV. These warts spread during sex, and are very contagious.

Conditions

Erectile dysfunction

Erectile dysfunction is a condition where the affected person is unable to get or maintain an erection, to the point where it hinders sexual satisfaction, and the ability to have intercourse.

Erectile dysfunction has many causes, which can be both physical and emotional. Common causes include heart disease, diabetes, and certain medications, as well as mental health issues such as stress, anxiety, and depression. Usually, it can be effectively treated, with the specifics of the treatment depending on the cause.

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Priapism

Priapism is a painful erection that lasts an abnormally long time - up to and even longer than four hours. It can happen when the blood that causes an erection isn't able to drain out again and is not always the result of being aroused.

People of any age can suffer from priapism. It is more common in people with blood diseases such as leukemia, or sickle cell disease. Priapism requires quick treatment, as if left untreated it can cause scarring, as well as permanent erectile dysfunction.

Phimosis and paraphimosis

Sometimes the foreskin is too tight, making it difficult and sometimes impossible for it to be pulled back over the glans - this is known as phimosis. Phimosis is actually normal in young children, but can sometimes be caused by scarring in older children.

Generally, unless phimosis is particularly severe and causing symptoms, it isn't necessarily a problem

Generally, unless phimosis is particularly severe and causing symptoms, it isn't necessarily a problem. However, if a foreskin is too tight, it can get stuck when pulled back, in a condition known as paraphimosis. Paraphimosis requires emergency treatment as it can cause tissue death if left for too long.

Peyronie's Disease

Peyronie's Disease is a condition in which the formation of scar tissue - usually due to an injury - causes the penis to develop an abnormal curve. While not a particularly common condition, the risk of being affected by it is thought to increase with age.

Unfortunately, Peyronie's Disease isn't fully understood yet, and can sometimes occur for unknown reasons. However, it is known that in certain severe cases, it can be a cause of erectile dysfunction.

Penis care tips: How to keep your penis clean and healthy

Keeping your penis clean and healthy is simple, and can easily be incorporated into your regular routine of hygiene. When it comes to cleaning, your penis needs to be cleaned regularly, but avoid using abrasive products as they can cause irritation - water and gentle soap is the best option. If you're not circumcised, make sure to wash under your foreskin as well as your glans - but again, only use water and mild soap, as to avoid irritation.

Cleaning your penis is also a good time to make sure there isn't anything that looks abnormal or different about it, such as lumps. Make sure to check your testicles for the same thing.

Good penis hygiene is also important for penis health. Without regular cleaning, an oily, irritating, and bad-smelling substance called smegma can build up beneath the foreskin. A build-up of smegma can cause inflammation and balanitis if left uncleaned. Inflammation and balanitis can still occur in circumcised men even without the build-up of smegma.

Maintaining a healthy penis isn't just about avoiding STIs, though that is important as well

Maintaining a healthy penis isn't just about avoiding STIs, though that is important as well. Using a condom during sex is the best and only way to reduce your risk of getting an STI unless you're in a monogamous relationship where you know you and your partner are both free of them. If you want to have unprotected sex, it's important that you and your partners get regular STI tests.

It's also worth noting that rough sex can sometimes damage your penis. It's possible to tear your foreskin if it is pulled back too harshly or suddenly. It's also possible to fracture your penis if it is bent too much, despite the penis not containing bones - it's actually the lining of the corpus cavernosum or corpus spongiosum that can rupture and result in a fracture. The idea of that should be enough to encourage any man to be careful and remain aware of what's going on down there during sex!

general health tips can also be good for your penis - if you're healthy, your penis should be too

Finally, general health tips can also be good for your penis - if you're healthy, your penis should be too. Eating a healthy, balanced diet, getting regular exercise, and staying well hydrated are all important for your health. Avoiding harmful substances such as alcohol, tobacco, and other drugs is also useful. Furthermore, maintaining good mental health is also essential, so don't be afraid to seek help if you're struggling with stress, or symptoms of anxiety, depression, or any other mental health issue.

Human Penis FAQs

What determines the size of the human penis?

There is a multitude of factors that can affect penis size. Genetics plays a large role. Cisgender men have one X chromosome and one Y chromosome - it's the Y chromosome that determines the development of the penis and testicles. However, the Y chromosome might not always carry the gene for penis length and girth - after all, the X chromosome contains far more genes.

It's possible for hormone imbalances during pregnancy to affect a fetus' genitals, as well as imbalances in the fetus

There are a few other factors as well. It's possible for hormone imbalances during pregnancy to affect a fetus' genitals, as well as imbalances in the fetus. Epigenetics may also play a role - this is when a person's environment affects the expression of their genes, which can have effects such as influencing hormones. Nutrition is another factor - malnutrition at any point can affect hormones and development and can even delay puberty, which can contribute to a smaller penis and testicles.

Certain factors can obscure the penis and make it appear to be smaller. Both body fat and pubic hair can make a penis seem to be smaller than it truly is. To add to this, cold temperature exposure can cause the penis' blood vessels to constrict, shrinking the penis temporarily.

cold temperature exposure can cause the penis' blood vessels to constrict, shrinking the penis temporarily

You may have also heard myths about other factors affecting penile length and girth, such as too much masturbation, as well as height, and the size of you feet. These are all urban legends that aren't actually true, so you can rest assured none of them will contribute to the size of your penis!

What is the average penis size?

While there isn't necessarily a 'normal penis size' (though certain conditions, such as micropenis, are abnormalities), the nature of research and statistics means there are a few 'averages' for adult penile length and circumference.

Research into erect penis size has found the average erect penile length to be between 5.1 and 5.5 inches. However, since the topic means volunteers may be inclined to exaggerate, it's believed that the average is actually closer to the lower end. Similar but slightly older research found that the average girth for erect penises is around 4.59 inches. It also found that when it comes to flaccid penis size, the average flaccid penis length is thought to be around 3.61 inches, with the average girth being 3.66 inches.

Though penis size is quite a concern amongst human males, it's important to remember that your penile dimensions really don't matter all that much

Though penis size is quite a concern amongst human males, it's important to remember that your penile dimensions really don't matter all that much. Whether you have a smaller penis, bang-on average penis, or larger penis, it's all the same really - size simply doesn't affect penis function, health, and even desirability. Additionally, the stress caused by worrying about penis size can contribute to erectile dysfunction - which is all the more reason to embrace what you've got.

I have pain in my penis, should I see a doctor?

You should visit a doctor if you have penis pain, no matter what the cause may be. There are numerous causes of penile pain, including STIs, phimosis, and priapism (prolonged, painful erections), among many others. Treatments for penis pain vary depending on the cause, but can often reduce the pain, and address the problem.

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