(n)the sphincter muscle of the urinary bladder; made up of a thickened muscular layer of bladder around the urethral opening, Syn.musculus sphincter vesicae
n. [ NL., fr. &unr_;&unr_;&unr_; to bind tight. ] (Anat.) A muscle which surrounds, and by its contraction tends to close, a natural opening; as, the sphincter of the bladder. [ 1913 Webster ]