Urogynaecology

Question 1

Which nerve/s (and from what divisions of the NS) control the filling/storage phase of the bladder cycle?

Answer 1

Hypogastric nerve: contraction of internal urethral sphincter and smooth muscle in the urethra

Pudendal nerve: contraction of external urethral sphincter

Bladder distension (filling phase) 
--> SYMPATHETIC outflow --> hypogastric --> contraction of internal urethral sphincter and smooth muscle in the urethra
\+
--> SOMATIC NS --> + pudendal nerve --> contraction of external urethral sphincter

Question 2

What nerve/s (and from what division of the NS) control the voiding phase of the bladder cycle?

Answer 2

Pelvic nerve: contraction of detrusor muscle + inhibition of the pudendal and hypogastric nerves => relaxation of sphincters and urethral smooth muscle => urine voiding

PARASYMPATHETIC outflow –> pelvic nerve