Final answer:
The external urethral sphincter in males surrounds the membranous urethra, providing voluntary control over urination.
Step-by-step explanation:
The external urethral sphincter in males surrounds the membranous urethra. The male urethra is divided into four regions with the membranous urethra passing through the deep muscles of the perineum where it is controlled by the overlying urethral sphincters. This sphincter allows for voluntary control over the flow of urine. The other structures mentioned, such as the bulbourethral gland (or Cowper's gland) and the prostate gland, have significant roles in the male reproductive system rather than being directly associated with the control of urination.