Urethra

The urethra is a tube which carries urine from the urinary bladder to the outside of the body. In males, the urethra travels through the penis, and carries semen as well as urine. In females, the urethra is shorter, measuring between 3 and 4 cm in length; it runs almost vertical and emerges above the vaginal opening. In males, the urethra is much longer and measure between 18 and 20 cm long, with wide and narrow sections. The external urethral sphincter is a striated muscle that allows voluntary control over urination.