Urethra
 |
Female anatomy |
In
anatomy, the
urethra is a tube which connects the
urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass
urine to the outside, and also a reproductive function in the male, as a passage for
sperm.
The external
urethral sphincter is a smooth muscle that allows voluntary control over
urination.
Men have a longer urethra than women. This means that women tend to be more susceptible to infections of the bladder (
cystitis) and the urinary tract. The length of a male's urethra, and the fact it contains a number of bends makes
catheterisation more difficult.
In the human female, the urethra is about 1-1.5 inches (2.5-4 cm) long and opens in the
vulva between the
clitoris and the
vaginal opening. In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the
penis.
The urethra is divided into four parts in men, named after the location:
*The pre-prostatic
* The
prostatic urethra crosses through the
prostate gland. There is a small opening where the
vas deferens enters.
* The
membranous urethra is a small (1 or 2 cm) portion passing through the
external urethral sphincter. This is the narrowest part of the urethra.
* The
spongy (or
penile) urethra runs along the length of the penis on its ventral (underneath) surface. It is about 15-16 cm in length, and travels through the
corpus spongiosum.
The
epithelium of the urethra starts off as transitional cells as it exits the bladder. Further along the urethra there are stratified columnar cells, then stratified squamous cells near the external meatus (exit hole).
There are small
mucus-secreting urethral glands, that help protect the epithelium from the corrosive urine.
*
Hypospadias and
epispadias are forms of abnormal development of the urethra in the male, where the opening is not quite where it should be (it occurs lower than normal with hypospadias, and higher with epispadias). In a severe
chordee, the urethra can develop between the penis and the
scrotum.
* Infection of the urethra is
urethritis, said to be more common in females than males. Urethritis is a common cause of
dysuria (pain when urinating).
* Related to urethritis is so called
urethral syndrome* Passage of
kidney stones through the urethra can be painful and subsequently it can lead to
urethral strictures. If you use urethra toys, make sure to clean them well, sexual pleasure from a urethra toy is not fun unless you are safe.
Endoscopy of the bladder via the urethra is called
cystoscopy.
The male urethra is well-known as the conduit for sperm during
sexual intercourse.
*
Vulvovaginal health*
Urethral sponge*
G-spot*
Urethral sounding*
Urethrotomy
