Bladder and ureter function

Question 1

Which nerve/input is the main cause of bladder contraction?

Answer 1

Parasympathetic nerves innervate the detrusor muscle causing contraction

Question 2

Which nerve/input causes constriction of external urethral sphincter?

Answer 2

Pudendal nerve (S2, S3, S4, origin at Onuf’s nucleus)

Question 3

Which nerve supplies primary sympathetic input to the bladder?

Answer 3

Hypogastric nerve (L1, L2, L3)

Question 4

Which nerve supplies primary parasympathetic input to the bladder?

Answer 4

Pelvic nerves (S2, S3, S4)

Question 5

Which nerve supplies primary voluntary motor input to the bladder?

Answer 5

Pudendal nerve (S2, S3, S4)

Question 6

What type of lesion can cause atonic bladder? How does atonic bladder cause overflow incontinence?

Answer 6

1. Sensory nerve fibers from bladder to spinal cord 2. No micturition reflex since sensory signals from bladder are missing - bladder does not empty periodically and overflows a few drops at a time

Question 7

What type of lesion can cause automatic bladder? Do symptoms of automatic bladder appear immediately after the lesion?

Answer 7

1. Spinal cord damage above the sacral region 2. No - eventually appear

Question 8

What is the immediate effect of spinal cord damage above the sacral region on the bladder?

Answer 8

Initial suppression of micturition reflex

Question 9

What are the possible causes and symptoms associated with uninhibited neurogenic bladder?

Answer 9

1. Causes - partial damage in spinal cord or brain stem that interrupts most of the descending inhibitory signals but leaves descending facilitory signals intact 2. Symptoms - hyperexcitability - even a small amount of urine elicits an uncontrollable micturition reflex