The Male urethra Flashcards
Describe the male urethra
It is a long muscular tube, 18-20 cm long and it conveys urine from the bladder to exterior via the external urethral orifice located at the tip of the glans penis.
It also provides an exit for semen.
The male urethra has 4 parts what are they
Preprostatic urethra
Prostatic Urethra
Membranous urethra
Spongy Urethra
Describe the prostatic urethra
It is 3-4 cm long.
It begins at internal urethral orifice at the apex of trigone.
It descends via prostate and ends by piercing superficial fascia of urogenital diaphragm.
It is the widest and most dilatable partof the urethra.
Describe the membranous urethra
It is 1.5cm long.
It pierces the external urethral sphincter and the fascia perineal membrane that covers the superficial part of the sphincter.
It is the least dilatable part of urethra
Describe the spongy urethra
It is 15 cm long.
It traverses the corpus spongiosum of the penis.
It lies below the pubic symphysis and then in its flaccid statebends downwards and forwards.
It is at this point that semen or urine is expelled.
Remember that blood supply covers arterial supply and venous drainage
Arterial supply to the urethra
Inferior vesical and middle rectal arteries.
Venous drainage of urethra
Prostatic venous plexus
Blood supply to the urethra
This is via inferior vesical and middle rectal arteries and drained by the protstic venous plexus.
Nerve Supply
Pudendal nerves
Efferents from pelvic splanchnic nerves
Lymphatic drainage of Urethra
Lymph vessels pass to :
Sacral lymph nodes
Internal iliac lymph nodes
Deep inguinal lymph nodes
Describe the prepostatic urethra
It extends vertically from the internal urethral meatus to superior aspect of prostrate.
It is surrounded by the internal urethral sphincter
Clinical Correlates
Rupture of the Urethra: Where the urethra passes beneath the pubis is a common site of its rupture .
Trauma to urethra caused by an injury results to penile urethra in the perineum.
Extravasation of urine occurs as it enters anteriorly into the loose CT of scrotum and then to anterior abdominal wall
