The urethra is a mucosa-lined tube leading from the bladder to the outside of the body. The urethra allows the discharge of urine, as well as semen in males. In females the urethra's orifice lies between the vaginal opening and clitoris. In males it passes through the prostate gland and penis, and opens at the tip of the glans.
The urethra contains many nerves. Because of the sensitivity of the urethra, many males and females enjoy urethral stimulation via sounding.