Consultant UrologistKing Abdulaziz National Guard

HospitalAlhofof

• The anatomy of the male urethral sphincter has not been stable since it was first described more than 150 years ago.

Henle 1866:

• urethral sphincter is composed of a smooth and a skeletal muscle component.

• Classified the sphincter as stripped fiber sphincter vesicae externus to distinguish it from the smooth fiber sphincter vesicae internus

• German

Holl 1897:• named diaphragma urogenital.• confirmed that the muscle fibers behind the

membranous urethra end in the Perineal Body.

• sphincter urethrae membranaceae joins sphincter urethrae prostaticae and cover the anterior surface of the prostate.

German

Kalischer 1900: • in children the skeletal urethral sphincter

forms a distinctly marked muscle cap on the prostate, whereas in adults the muscle fibers are partially atrophied and dispersed among the smooth muscles of the prostate.

German

Kalischer

• He concluded that:the prostatic part of the skeletal sphincter is too weak to act as a urinary sphincter and it is mainly concerned with sexual function.

•Rhabdosphincter urogenitalis

–Rhabdosphincter prostaticus

–Rhabdosphincter infraprostaticus

–Rhabdosphincter diaphragmaticus,

• It soon was forgotten in the english books 1876 and 1877 the French authors Paulet7 and Ca-diat,

• sphincter externe de la vessie ( external urethral sphincter )

• Franco-Prussian war

Manley 1966 • confirmed the findings of Kalischer

that in adults the skeletal muscle fibers decrease in size and become separated by smooth muscle fibers while the bladder is approached proximally.

English

Oelrich 1980

• The skeletal sphincter is formed embryologically before the development of the prostate.

• At puberty accelerated prostate growth causes invasion and thinning of the sphincter resulting in isolated segments of the sphincter which partly overlap the prostate and contained within it.

Smooth Muscle Component

• The presence of annular sphincter fibers passing from the bladder to the urethra was denied 1836 by Guthrie, 1958 by Clegg12 and 1960 by Woodburne.

• 1854 Kohlrausch was the first to introduce the concept of an internal sphincter.

Smooth Muscle Component

• 1866 Henle: the muscle fibers of the sphincter as independent of the bladder musculature and identified it as the sphincter vesicae internus.

• 1897 Versari: internal sphincter is an anatomical entity.

• 1900 Kalischer: It is derived from the musculature of the urethra.

• The urethra as well as the trigone is provided with many elastic fibers, which are missing in the bladder “sphincter trigonalis”.

Very recent revisit • These findings were recently confirmed by

computer generated 3-dimensional reconstruction of the male pelvis that showed the trigone to migrate at the bladder neck anterior to the urethra and continue down the front of the prostate as the anterior fibromuscular stroma, forming with it a single unit in continuity.

• the trigone, while flattening during bladder filling, can act as a sphincter.

Recent anatomy !• Near the bladder

neck, the detrusor muscle is clearly separable into the three layers

• inner longitudinal, middle circular, and outer longitudinal

layers

Recent anatomy !• The inner

longitudinal fibers pass through the internal meatus continued with the inner longitudinal layer of smooth muscle in the urethra

Recent anatomy !• The middle circular and

inner longitudinal muscles extend down the prostatic urethra as a preprostatic sphincter.

• That is responsible for continence at the level of the bladder neck.

• Can save continence when striated urethral sphincter is destroyed.

Recent anatomy !• The outer longitudinal

fibers are thickest posteriorly at the bladder base.

• Most of the fibers blend with the fibromuscular tissue of the prostatic capsule

• insert into the apex of the trigone

• provide a strong trigonal backing

Recent anatomy !• Laterally, the

fibers from this posterior sheet pass anteriorly and fuse to form a loop around the bladder neck.

• participate in continence at the bladder neck

Recent anatomy !• Some anterior fibers

course forward to join the puboprostatic ligaments in men and the pubourethral ligaments in women.

• contribute to bladder neck opening during micturition.

Recent anatomy !• In female: the

inner longitudinal fibers pass downward as the inner longitudinal layer of the urethra.

• existence of middle circular layer has been denied “Gosling, 1979, 1985; Williams et al, 1989”.

Recent anatomy !

• Differs from male:– little adrenergic innervation.– sphincteric function is limited.– 50% of women,

urine inters theurethra with cough.

Ureterovesical Junction and the Trigone

• fibromuscular sheath (of Waldeyer)

• Intramural ureter• Intravesical ureter• Superficial trigone.• detrusor layer • Deep trigone.

Anti reflux.

Recent anatomy !

• The External Sphincter!

Is it the right term?

• The Distal Closure Complex!

• The striated sphincter corresponds to the location of peak urethral closing pressure.

• Located between the 2 layers of the endopelvic fascia which covers the pelvic diaphragm. At the level of the membranous urethra.

The striated sphincter is actually omega shaped, broad at its base and narrowing as it passes up through the levator ani to meet the apex of the prostate.

The striated muscle is composed of :

•The urethral sphincter or rhabdosphincter. •The periurethral striated muscles of the pelvic floor.

•

• urogenital diaphragm composed from

– Transversus perinei– ischiocavernosi

• Blocking striated sphincter activity has variable effects and may reduce urethral tone, but rarely by more than 40%, suggesting that the smooth muscles are important.

• Blocking sympathetic tone with α-adrenoceptor blockers may also reduce urethral pressure by about 30%, suggesting that the striated muscles are important.

– The external urethral sphincter is composed of two parts.

– The periurethral striated muscle of the pelvic floor contains both fast-twitch and slow-twitch fibers.

– The striated muscle of the distal sphincter mechanism contains predominantly slow-twitch fibers.

– In the male, 35% fast-twitch and 65% slow-twitch fibers

– In the female, 13% fast-twitch and 87% slow-twitch.

• The striated periurethral muscles of the pelvic floor are adapted for the rapid recruitment of motor units required during increases in abdominal pressure. It has been speculated that the successful treatment of stress incontinence by pelvic floor exercises or electrostimulation is caused by the conversion of fast-twitch to slow-twitch striated muscle fibers.

Conflict again

• Levator Ani Muscles do NOT meet ventrally. They arise separately from the pubis.

• The space between the external sphincter and the pubis is filled with vascular network.

• Levator Ani Muscles are almost vertical.

Vesico-prostatic angle

Urine Storage Micturition

Urine Storage

• External sphincter contraction (somatic nerves)

• Internal sphincter contraction (sympathetic nerves)  

• Detrusor inhibition (sympathetic nerves)  

•  Sacral parasympathetic outflow inactive

Micturition

• Inhibition of external sphincter activity

• Inhibition of sympathetic outflow  • Activation of parasympathetic

outflow to the bladder  • Activation of parasympathetic

outflow to the urethra

Summary

Continence• Innervation• Bladder neck musculature

angle hammok• Distal closure complex!

Sealing• Mucous secretion• Vascular cushion• Elasticity of urethra