voiding internal urethral orifice

voiding internal urethral orifice

[TA] the internal urethral opening when the bladder is being emptied of urine, when the trigonal muscles are relaxed and the detrusor muscle is contracting; during this stage the orifice occurs at a lower level and is bounded by a different portion of the mucosa than during filling and reserving.
See also: filling internal urethral orifice. Synonym(s): ostium urethrae internum evacuans [TA]