The forced urethral muscle refers to the muscular fibers of the bladder wall, which are composed of smooth muscle fibers. The bladder wall is composed of three layers of tissue, the inner mucosal layer, the middle muscular layer, and the outer tunica albuginea. The bladder muscle and the internal urethral sphincter, by the body of the sympathetic nerve and parasympathetic nerve innervation, in the sympathetic nerve excitation can make the bladder muscle relaxation, is conducive to the temporary storage of urine. Under the action of the parasympathetic nerve, the bladder muscle contraction, the internal urethral sphincter relaxation, urine from the bladder discharge. After the urine is temporarily stored in the bladder and reaches a certain capacity, it forms a stimulus to the detrusor receptors on the bladder wall, causing an active voiding nerve reflex, contraction of the vesicourethral muscle causes the bladder to contract, and relaxation of the sphincter muscle discharges the stored urine out of the body through the urethra.