1- Bladder and urethra anatomy

Question 1

What is the bladder trigone and what are its anatomical landmarks?

Answer 1

Triangular area of smooth bladder wall on posterior aspect.

Landmarks: 2 ureteric orifices and internal urethral meatus

Question 2

What is the main component of the bladder wall?

Answer 2

Detrusor muscle - fibres orientated in 3 directions to retain structural integrity when stretched. Mostly forms rugae (except at trigone).

Question 3

Name the 2 muscular sphincters located along urethra. What do they consist of and what is their function?

Answer 3

1. Internal urethral sphincter
   
   • males: circular smooth muscle fibres under autonomic control. Prevents seminal regurgitation during ejaculation.
   • females: inefficient sphincter formed by anatomy of bladder neck and proximal urethra
2. External urethral sphincter: skeletal muscle under voluntary control. Relaxes to allow urine flow during micturition.

Question 4

Why can bladder adenocarcinoma arise in some rare cases?

Answer 4

Small region at midline of bladder dome derived from embryonic mesoderm - urachus (remnant of allantois)

Question 5

Describe the arterial supply to the bladder.

Answer 5

• main supply from superior vesical branch of the internal iliac artery
• supplemented by inferior vesical artery in males and vaginal arteries in females

Question 6

Describe the venous drainage of the bladder

Answer 6

By vesical venous plexus which drains into internal ilia vein

Question 7

What type of epithelium lions the urethra?

Answer 7

Stratified columnar with mucus-secreting glands for protection from corrosive urine

Question 8

Name the 4 parts of the male urethra and the structures they run through

Answer 8

1. Pre-prostatic: from internal urethral meatus, through walls of bladder, to prostate
2. Prostatic: through prostate gland, receives drainage from ejaculatory ducts and prostatic ducts
3. Membranous: through pelvic floor and deep perineal pouch, surrounded by EUS
4. Spongy/penile: through bulb and corpus spongiosum of penis, ending at external urethral orifice, receives drainage from bulbourethral glands proximally

Question 9

What is the main difference between the male and female urethra?

Answer 9

Much shorter in female (4cm) than males (15-20cm)

Question 10

Into which area does the female urethral orifice open?

Answer 10

Vestibule (inferior to clitoris and superior to vaginal opening)

Question 11

Why is supra-pubic catheterisation often recommended in cases of bladder distension?

Answer 11

As bladder distends, it rises above level of pubis, and is exposed free of superficial peritoneum. Makes insertion of catheter possible without damaging peritoneum.

Question 12

Why must the penis be raised upwards during catheterisation?

Answer 12

Removes prepublication angle

Question 13

which structures lie anterior to bladder?

Answer 13

pubic bones and pubic symphysis