Week 19 - GUT

Question 1

The right and left ejaculatory ducts empty into the:

• a) Prostatic urethra
• b) Membranous urethra
• c) Spongy urethra
• d) Trigone of the bladder
• e) Peripheral zone of prostate

Answer 1

• a) Prostatic urethra
• b) Membranous urethra
• c) Spongy urethra
• d) Trigone of the bladder
• e) Peripheral zone of prostate

Question 2

In which zone of the prostate gland does benign prostatic hyperplasia (BPH) typically occur?

Answer 2

= The transition zone

Histological division of the prostate into three zones (according to McNeal):

• Central zone – surrounds the ejaculatory ducts, comprising approximately 25% of normal prostate volume.
  
  • The ducts of the glands from the central zone are obliquely emptying in the prostatic urethra, thus being rather immune to urine reflux.
• Transitional zone – located centrally and surrounds the urethra, comprising approximately 5-10% of normal prostate volume.
  
  • The glands of the transitional zone are those that typically undergo benign hyperplasia (BPH)
• Peripheral zone – makes up the main body of the gland (approximately 65%) and is located posteriorly.
  
  • The ducts of the glands from the peripheral zone are vertically emptying in the prostatic urethra; that may explain the tendency of these glands to permit urine reflux.
    
    • The peripheral zone is mainly the area felt against the rectum on DRE.

The fibromuscular stroma (or fourth zone for some) is situated anteriorly in the gland. It merges with the tissue of the urogenital diaphragm. This part of the gland is actually the result of interaction of the prostate gland budding around the urethra during prostate embryogenesis and the common horseshoe-like muscle precursor of the smooth and striated muscle that will eventually form the internal and external urethra sphincter.

Question 3

Adenocarcinoma is the most common form of prostate cancer. Where do these most commonly arise?

Answer 3

= Peripheral Zone

Question 4

Which of the following muscles is the most integral in maintenance of the anorectal angle?

• a) Coccygeus
• b) Puborectalis
• c) Iliococcygeus
• d) Pubococcygeus
• e) Bulbocavernosus

Answer 4

= b) Puborectalis

Question 5

Name the important communication that facilitates metastatic invasion of prostate cancer into the lumbar vertebrae.

Answer 5

Venous drainage of the prostate is via the prostatic venous plexus, draining into the internal iliac veins.

However, the prostatic venous plexus also connects posteriorly by networks of veins, including the Batson venous plexus, to the internal vertebral venous plexus.