Surgical anatomy of urethra

The male urethra is an 15-22 cm long muscular tube that conveys urine from urinary bladder to external opening in the perineum. It also provides an exit for semen during ejaculation. The urethra is contained within the corpus spongiosum, which lies in a groove below the two corpora cavernosa. The inside of the urethra is lined with stratified squamous epithelium

Parts of the urethra

Prostatic urethra

Begins as a continuation of the bladder neck and passes through the prostate gland. Receives the ejaculatory ducts and prostatic ducts. It is the widest and most dilatable portion of the urethra.

Membranous urethra

Passes through the pelvic floor and the deep perineal pouch. It surrounded by the external urethral sphincter which provides voluntary control of micturition. It is the narrowest and least dilatable portion of the urethra.

Penile (bulbous) urethra

Passes through the bulb and corpus spongiosum of the penis, ending at the external urethral orifice (the meatus). It receives the bulbourethral glands proximally. In the glans penis, the urethra dilates to form the navicular fossa.