Anatomy of Male pelvic organs in a Nutshell

Male pelvic organs

Clinical: Nerve block in female:

• Through ischioanal fossa through fat
• Transvaginally
• Always administer near the ischial spine to block pudendal nerve.  This is preparation for childbirth.

Male pelvis: (350)

• Colon changes to rectum at S3
• Anteriorly (posterior to pubic symphysis) find the urinary bladder
• Rectum is also in midline.

Peritoneal reflections in the male pelvis: (348)

• Peritoneum encounters apex of urinary bladder and reflects / coats the superior aspect of the bladder.
• The loose connective tissue superior to pubis allows bladder to expand without stretching the peritoneum (loosely attached to abdominal wall)
• Peritoneum reflects slightly on posterior bladder wall, then goes on to reflect over the rectum.
• In female, refelections were made that created 2 pouches, in male, have only 1 pouch = rectovesicle pouch.
  • Between rectum and the bladder.
  • This is the lowest point in the peritoneal cavity in the male, not much clinical significance.
  • Piercing wall of rectum would cause infection from intestinal flora.  Fluids may collect in this pouch.
• Same level of relfection on rectum as in female (lower 1/3 vs upper 2/3).
• Favorite access to prostate gland was suprapubic incision (went below peritoneal sac).
  • Now, it is done trans-urethral using instruments up the urethra.
  • But, this shows that it is possible to enter cavity without injuring peritoneal cavity.

Male Urinary bladder: (353)

• Posterior aspect shows some accessory reproductive glands.
• Bladder is similar in male: trigone is present, have detrusser muscle. Peritoneum on superior surface, trigone is smooth etc.
• There is a sphincter in the neck of the urinary bladder that is involuntary (smooth muscle) = internal urethral sphincter.
  • This is in both sexes, is a circular arrangement of detrusser muscle.
  • This sphincter is under tonic contraction except during mituration.
  • Urination is a parasympathetic phenomena.
• In the region of the trigone controlling the internal urethral sphincter, parasympathetic fibers are inhibitory to the fibers.
  • This allows urine to leave.
  • Thus, inhibitory neurons are in the trigone region to control the internal urethra sphincter.

Male Urethra:

• Extending out of the bladder = Urethra.
• Passes through wall of bladder and enters into the prostate gland (largest accessory gland in male).
• The bladder rests on the prostate gland (in female, it rests on the pelvic diaphragm).  Prostate is walnut size gland, urethral goes through the center.  This is the prostatic urethra.

Prostate:

• Has thick fibrous capsule with smooth muscle fibers.
• Gland itself has rich smooth muscle cell component.  Thus has glandular component and smooth muscle component.
• Divided into lobes- some more muscular some more glandular.
• Smooth muscle is stimulated when secretions are to be released.
  • secretions are forced out into the prostatic urethra.
  • These are a component of semen.

(367) Posterior perspective of bladder:

• Some structures are between rectum and the bladder.
• A paired set of tubes coming down posterior wall from kidneys = ureters. They pierce the lateral wall and run oblique to wall before entering into corner of tirgone.
• Crossing laterally over the ureter– vas deferense from deep inguinal ring.
  • It desends into pelvis, crosses superiorly to ureter and is on the posterior aspect of bladder.
  • As it descends, it distends into region = ampulla.  Each vas deferens has ampulla of the vas deferens.
  • The two vas deferense come very close together and are parallel in the junction of bladder / prostate, but they do not fuse.
• Flanking the ampulla of the vas is another gland = seminal gland (lateral to ampulla) aka seminal vesicles.
  • Implies that it contains semen, it does not contain semen- only a component of semen.
  • Sperm cells never enter it.
  • The seminal vesicle has a duct = unite just external to prostate with terminal end of vas deferens, this combined duct (seminal vesicle + vas deferens) is the ejaculatory duct.
  • These duct go into prostate gland obliquely and empty into prostatic urethra.
  • Have 2 ejaculatory ducts.  They bring sperm (through vas deferens) and seminal vesicle secretions into urethra.

Clinical: Prostate

• Prostate sometimes divided into lobes based on ducts: forms anterior, median, posterior lobes.
  • Ejaculatory duct divides median / posterior.
  • The median lobe is the one that tends to enlarge / hypertrophy than other lobes.
• The median lobe can cause clinical signs: as it enlarges, it enlarges into urethra and up into bladder.
  • It will impinge the prostatic urethra and narrow it, makes urine stream weak.
  • Superior enlargement will cause a ridge in floor of urinary bladder. Problem here is that urine will collect / stagnate in an area behind the ridgeà wont be voided, and so it cause infection.
  • Complaints: chronic UTI and weak urine flow.  They will claim an urgency to urinate (esp. at night) but they produce only a few drops.  Bladder is full / distended, but urethra is blocked.
  • These men have benign prostatic hyperplasia (BPH).  This is part of normal aging process.  Treatment is transurethra→ remove portion of prostate that impinges.  Clear out the prostatic urethra.
• Prostate is also often defined in lamellar (circumferential) pattern.

Features in prostatic urethra (353).

• In posterior wall, have ridge of mucus membrane that runs the whole length = prostatic crest.
• ½ way along length of this crest, have wide elevation = colliculus (seminal colliculus) = most prominent point of rest.
• (368). Urethral crest has seminal colliculusà on the crown of colliculus have 3 apertures.
  • Paired (proximal) are openings of ejaculatory ducts.
  • A single midline opening more distal that extends for short distance blindly into prostatic tissue.  This is prostatic utircle.
• This is vestigle vagina / utricle.
• It is a blind diverticulum that in female created the uterus and part of vagina.

1. • Have valleys off to the side of the crest.  In the valleys, have series of 12-20 pinhole openings = openings for secretions of the prostate gland = prostatic ducts.

Contribution to Semen:

• Down in deep pouch, see bulbourethral (cowper’s gland).
• Prostatic urethra is where semen is formed.
  • Sperm cells, seminal vesicle / prostatic secretions are all brought together.  When they are all mixed, semen is formed.
  • Bulbourethral glands are the first portion of ejaculate (as well as small portion of semen as it travels through urethra).

Sexual response in male: (female is lesser known and far more mysterious).

4 stages:

• Erection:
  • Mediated by the parasympathetic nervous system.
  • Occurs because venous tissues in the external genitalia (clitoris or penis) are engorged with blood. Mechanism is same for both sexes.
  • Prior to arousal, small arteries to erectile bodies (branches of deep artery of penis / clitoris) are coiled  = called helicine arteries.

1. 1. • They distribute to erectile tissue.
      • Smooth muscle cells in these vessels causes them to contract (sympathetic0 and coil).
      • Parasympathetic nerves override the symp, and cause helicine vessels to uncoil and release more blood into erectile tissue.

• • Venous escape is compressed between Buck’s fascia and tunica albuginea.
• Emission- The formation of semen.
  • Everything is brought together in the prostatic urethra.
  • Testicles, seminal vesicles, and prostate all mixed together.  This is done by sympathetic nervous system:
    • Also stimulates internal urethral sphincter in male to contract tightly to seal of bladder.
    • Underlying mechanism for closing it is so that semen cant go up into bladder, it has to go out through urethra.
• • Males know when emission occurs.  They can detect peristaltic waves. It occurs right before ejaculation.
• Ejaculation:
  • The prepulsion of semen along remainder of urethra and out.
  • It is controlled by parasympathetic nervous system.
• Detumescense (remission) – “when mom and dad come home”
  • Return of the organ to non-erect status.
  • This is sympathetically mediated.  In male takes 3-5 minutes, in female- 10 minutes.
  • He falls asleep, she says “hey!”.
• Erection and detumenescense are virtually the same in male / female.  The middle 2 parts are quite different between male / female.
• HANDOUT: All about semen
  • Seminal vesicle: 60% of total volume of semen

1. 1. • Mucoid consistency
      • Fructuose

• • • Citric acid and other nutrients

• • • Prostaglandins – help prepare female reproductive tract for sperm movement.
      1. They stimulate smooth muscle in fallopian tube to undergo reverse peristalsis to move sperm to egg.
      2. Sperm can reach distal tube in 5 minutes. By female smooth musculature→ especially in woman experiences orgasm.
    • Fibrinogen: clotting factor to retain mucoid consistency to hold semen in upper vagina.

1. • Prostate: 30% semen

1. 1. • Alkaline- thin, milky
      • Citrate

• • • Phosphate

• • • Calcium
    • Profibrinolysin- converted to fibrinolysin which, after some minutes, causes breakdown of protein in semenà mucoid clot is reduced to watery consistency.

1. • Sperm and secretions from testes and epididymus: 10%