Urethra is the channel that conducts urine from inside the bladder out of the body. It ends in the penis and is part of the urinary system, along with the kidneys and other urinary tract (ureter and bladder).
In men, the urethra also serves as a passage for sperm during ejaculation and measures about 16 cm. It extends from the bladder to the end of the penis and is divided into three parts:
Prostatic portion: It is near the bladder and inside the prostate. It is in this region that the urethra receives the sperm contents from vas deferens, prostatic ducts and seminal vesicles.
Membrane portion: area of the urethra surrounded by the urogenital diaphragm, which has a muscle layer that forms the urethral external sphincter (voluntary musculature).
Spongy portion: extends throughout the corpora cavernosa of the penis. In this area are the Littré glands, tiny glands responsible for the production of mucus that acts as a sexual lubricant. The ducts of the bulbourethral glands flow into this region, which ends in the urinary meatus.
