Urinary system



The male urethra is a brawny pipe ( 18-22 curium retentive ) that conveys urine from the internal urethral orifice of the urinary bladder to the external urethra orifice, located at the tip of the glans penis in males. The urethra besides provides an exit for semen ( sperm and glandular secretions ) .
Prostatic part of urethra (Pars prostatica urethrae); Image: Samantha ZimmermanMembranous part of urethra (Pars membranacea urethrae); Image: Samantha ZimmermanSpongy part of urethra (Pars spongiosa urethrae); Image: Samantha ZimmermanExternal orifice of urethra (Ostium urethrae externum); Image: Samantha Zimmerman
prostate contribution of urethra
Pars prostatica urethra

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Urethra prostatica

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In the flaccid ( none rear ) express, the urethra has a double curvature. For descriptive purposes, the urethra is divided into four parts .

  • The intramural (preprostatic) part (0.5 – 1.5 cm long)
  • The prostatic urethra (3 – 4 cm long)
  • Intermediate (membranous) part (1 – 1.5 cm long)
  • The spongy urethra (approximately 15 cm long)

The intramural part of the urethra ( preprostatic urethra ) varies in diameter and length, depending on whether the bladder is filling ( bladder neck is tonically contracted then the home urethral orifice is little and high ; the filling inner urethral orifice ) or emptying ( the neck is relaxed therefore the orifice is wide and low ; the emptying internal urethral orifice ) .
The most big feature of the prostatic urethra is the urethral crest, which is a medial ridge between bilateral grooves, then prostate sinuses. The secretory ducts of the prostate, the prostatic ducts, open into the prostatic sinuses. The seminal colliculus is a round eminence in the middle of the urethral cap with a slit-like orifice that opens into a small cul-de-sac, the prostatic utricle. The prostate utricle is the vestigial end of the embryonic uterovaginal canal, the surrounding walls of which, in the female, constitute the primordium of the uterus and a function of the vagina. The ejaculatory ducts open into the prostate urethra via moment, slit-like openings located adjacent to and occasionally equitable within the orifice of the prostate utricle. Thus urinary and generative tracts merge at this point.

Blood supply and lymphatics

The male urethra is chiefly supplied by prostatic branches of the inferior vesical and middle rectal arteries. It is drained by the prostatic venous plexus, while its lymphatic vessels pass chiefly to the internal iliac lymph nodes ; a few lymphatic vessels drain into the external iliac lymph nodes .


Its innervations are derived from the prostatic plexus ( mix sympathetic, parasympathetic nervous system, and visceral sensory nerve fibers ). The prostate plexus is one of the pelvis plexuses ( an inferior extension of the vesical plexus ) arising as organ-specific extensions of the inferior hypogastric plexus .

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