Final answer:
The male urethra features three divisions: the prostatic urethra, the membranous urethra, and the spongy (phallic) urethra, each having specific functions and associated structures for the transport of urine and semen.
Step-by-step explanation:
The male urethra is an essential structure for the transport of urine and semen out of the body. It measures approximately 20 cm in length on average and is divided into three main divisions: the prostatic urethra, the membranous urethra, and the spongy or phallic urethra.
The prostatic urethra is the portion that passes through the prostate gland and is the site for the ejaculation ducts and seminal vesicles to release sperm and seminal fluid during sexual activity. Following this is the membranous urethra, which passes through the pelvic floor muscles and is surrounded by the urethral sphincters that provide voluntary control over urination.
Lastly, the spongy urethra, also known as the phallic urethra, runs through the corpus spongiosum in the phallus and terminates at the external urethral orifice.
Mucous glands distributed along the urethra help protect it by secreting mucus to neutralize the acidic environment and provide lubrication. Innervation of the urethra in both males and females is similar, supporting the function of the internal and external urinary sphincters and the passage of urine.