How the Penis Works

The penis is a primary male sexual and reproductive organ. The average size of the penis is about nine centimeters when not erect and about 13 cm when erect.

The penis is located just above the scrotum (which holds the testes, or testicles) in the pelvic area and consists of three main parts: base, shaft, and glans. Its two key functions are passing urine and ejaculating (releasing semen).

Penises sometimes have anatomical variations, including differences in urethral opening location and abnormal curvature. The most common conditions that affect penises include erectile dysfunction and sexually transmitted infections (STIs).

Anatomy of the Penis

The penis is a complex organ with multiple purposes, including allowing the release of urine from the body, becoming erect during intercourse, and allowing for the release of sperm during orgasm and reproduction.

Structure

The penis has three parts: base, shaft, and glans. People who have not been circumcised may also have foreskin.

• Base: Attaches the penis to the inside of the body
• Shaft: The main part of the penis (the elongated tube)
• Glans: The tip of the penis, also where the urethral opening (where urine or semen leaves the body) is located

The shaft of the penis has several components. Corpora cavernosa tissue is erectile tissue. The corpus spongiosum surrounds the urethra and also aids in erection. Other components of the penis include nerve tissues, blood vessels, and fat tissue. The urethra runs from the bladder through the bulb and shaft of the penis and ends at the urethral opening.

Location

The penis is located in the pelvic region of the body. It rests just above the scrotum, where the testes (testicles) are located. The testes are two male reproductive organs that produce sperm and testosterone.

Inside the body, the penis forms a connection with the scrotum and bladder. A tube called the vas deferens transports semen from the testes into the urethra (urine channel) of the penis during ejaculation. Likewise, the urethra connects the bladder to the penis and allows urine to be released out of the ureteral opening at the head of the penis.

Anatomical Variations

Some people are born with anatomical variations of the penis. These may include:

• Chordee: The penis has a downward curve to it
• Peyronie disease: The penis curves when erect
• Epispadias: The urethra (opening of the penis) is on top or side of the penis instead of the tip
• Hypospadias: The urethra opening is found on the underside of the penis
• Palmatus: The penis is surrounded by the scrotum (a webbed penis)
• Buried penis: The penis is concealed by a fat pad
• Micropenis: An underdeveloped penis

What Does the Penis Do?

The penis has two primary functions: to release urine from the body and to aid in reproduction via sexual intercourse. Penises also serve as centers for sexual pleasure.

Reproduction and Intercourse

During sexual activity or stimulation, the penis becomes erect as blood flows to it. This erection allows the penis to penetrate the vagina if intercourse occurs.

Once orgasm is reached, semen is released from the penis via ejaculation. Semen comes from the testes via the vas deferens and exits the body through the urethra.

If intercourse and male orgasm has occurred, semen is deposited in the vagina, where it can travel and potentially fertilize an egg. Penises are also a significant source of sexual pleasure, both during and before ejaculation. After ejaculation, the penis becomes flaccid (soft) again.

Urination

The second main function of the penis is to allow urine to pass out of the body. Here's how it works:

• The kidneys filter waste and fluid from the bloodstream, and it collects in the bladder.
• When the bladder is full, it signals the body to urinate.
• The urethral sphincter relaxes, which allows urine to pass from the bladder, through the urethra located inside the penis, and out of the body via the urethra opening at the tip of the penis.

Associated Conditions

Several conditions can affect penises. The most common associated conditions include:

• Erectile dysfunction: Difficulty getting or maintaining erections
• Balantis: Inflammation in the head of the penis, which usually occurs in people who have been circumcised
• Priapism: A painful erection that doesn’t end
• Peyronie's disease: A bump (plaque) in the tissues of the penis that causes the penis to bend during an erection
• Penis cancer: Rare and has a high cure rate if found in the early stages

Sexually transmitted infections (STIs) can also affect penises. STIs are caused by viruses, bacteria, and parasites and may include infections like:

• Genital herpes
• Syphilis
• Chlamydia
• Gonorrhea
• Human papillomavirus (HPV)
• Pubic lice

People with STIs can have mild or more noticeable symptoms. If you have a STI, you may experience unusual discharge from your penis or painful or more frequent urination.

Diagnostic Testing

Erectile dysfunction and other sexual conditions are some of the most common reasons you might seek medical care for your penis. You might seek care if you were exposed to an STI or have signs of an STI. Inflammation of the penis, unusual penis shape during erection, painful erections, and difficulty urinating are other reasons you may visit a healthcare provider.

A healthcare provider will usually start by taking a full medical history. This will include asking about your symptoms, when they started, and any other health conditions you have. They may ask you questions about your condom use or hygiene. Next, they will likely examine your penis, along with the rest of your pelvic and genital area.

Depending on the cause, diagnostic tests might include:

• Blood tests to check for diabetes (which can contribute to erectile dysfunction) or other conditions
• Swabs of the penis to check for STIs, urinary tract infections (UTIs), and yeast infections
• Imaging tests, such as ultrasounds, to check blood flow and anatomical abnormalities, including bladder emptying

Tips for Keeping Your Penis Healthy

The key to keeping your penis healthy is to engage in good penis hygiene, protect yourself from STIs and other infections, and engage in healthy lifestyle choices. Here are some recommendations:

• Wash your penis properly to help reduce the chances of inflammation or infections
• Don’t use harsh soaps (water is often enough)
• Gently move the foreskin and wash under it if you are uncircumcised—but never pull back on the foreskin of a child
• Wear clean underwear—preferably gentle fabrics like cotton
  

It's important to take steps to prevent STIs. This can include asking your partner about their sexual history and STI history. It also includes engaging in sex safely, such as consistent condom use. You might consider getting vaccinated for STIs like HPV.

Engaging in healthy lifestyle choices can also support penis health and avoid dysfunction that can increase with aging, such as erectile dysfunction. This may include the following:

• Stay physically active
• Eat a nutrient-rich diet
• Avoid smoking

A Quick Review

The penis is one of the main male reproductive organs. It’s also involved in urination.

Conditions affecting penises include erectile dysfunction, inflammation, STIs, and painful erections. Maintaining hygiene practices and healthy lifestyle habits can support penis health.

Reach out to a healthcare provider if you have any questions or concerns about your penis.