THE MALE URETHRA Anatomy

THE MALE URETHRA Anatomy

The male urethra is a fibromuscular tube that extends from the bladder neck to the meatus. Functionally the urethra allows transport of urine from the bladder and semen from the ejaculatory ducts through the penis. The male urethra is subdivided into the following parts. The meatus is a vertical slit-like opening at the tip of the glans penis. The glandular part of the urethra is called the fossa navicularis. The penile urethra extends from the meatus to the penoscrotal junction. The bulbar urethra extends from the penoscrotal junction to the bulbomembranous junction. The penile urethra and bulbar urethra are surrounded by corpora spongiosa. The membra nous urethra extends from the bulbomembranous junction to the verumontanum. It is surrounded by the voluntary external sphincter, which consists of both the smooth muscle external sphincter and the striated rhabdosphincter. It is innervated by the pudendal nerve, originating from spinal segments S2–4. The prostatic urethra extends from the bladder neck to the verumontanum and is surrounded by the prostate. The bladder neck contributes to the maintenance of continence in the male. Its main role is to act as a genital sphincter that closes at the time of ejaculation. The bladder neck and external sphincter can independently maintain continence in men. The urethral lining changes from transitional cell epithelium proximally to stratified squamous cell epithelium distally .