Urethra

The urethra is a tube that connects the reproductive system and bladder to the outside of the body to transport urine and sperm. All mammals have it. It allows the removal of urine from the body. There is a muscle (the urethral sphincter) which controls urination.

Female urethra and male urethra

In male mammals, the urethra is also a part of the reproductive system, because males use it as a tube for sperm during sex. The urethra joins together with the ejaculatory duct in the prostate to meet the reproductive system.

Human anatomy

Main article: Anatomy

See also: Urinary system

Human male and female urinary bladders and urethras

In human anatomy, a male person has a longer urethra than a female person. This means that the latter have bladder infections more often because their bladders are closer to the outside. Because the male urethra is longer and is not straight, inserting a catheter (tube to help urination) is more difficult for a male person.

Male

In male anatomy, the urethra is about 20 cm (8 in) long and its opening goes to the outside of the body. It ends at the opening of the penis. For a male person, the urethra goes through the penis. The section that goes through the prostate is about 3-4 cm long.

The male urethra has three sections:

A male urethra cut open along on all its length with urinary bladder and penis structure

• The prostatic urethra crosses the prostate gland. The vas deferens also opens into the urethra in this section.
• The membranous urethra is a short section that goes through the urethral sphincter. It is 1 or 2 cm long and is the narrowest (least wide) part of the urethra.
• The spongy or penile urethra goes through the penis on its lower side. This section is 15-16 cm (6 in) long and goes through the corpus spongiosum.

Female

In female anatomy, the urethra is 3-4 cm (1.5 in) long. The opening to the outside of the body here is part of the vulva (the female area between the legs). The female urethra is between the clitoris and the opening to the vagina.

The female bladder can get infections more often because the bladder is closer to the outside. The female urethra is straight.

Detailed view of a human vulva (with anatomical features): 1 - Clitoral hood, 2. Clitoris, 3. Labia majora, 4. Urinary opening, 5. Labia minora, 6. Anus, 7. Vaginal opening, 8. Perineum

Medical problems

• Urethritis is an infection of the urethra. It often causes pain when urinating.
• Kidney stones that go through the urethra can cause a lot of pain.