Assertion: urethra's sphincter | /r/HasProperty | voluntary
Facets:
Source sentences:
text: The internal urethral sphincter is involuntary and the external sphincter is voluntary.
text: Another sphincter, the external urethral sphincter, is skeletal (voluntary) muscle and encircles the urethra where it goes through the pelvic floor.
text: Since the external urinary sphincter is voluntary skeletal muscle, actions by cholinergic neurons maintain contraction (and thereby continence) during filling of the bladder.