THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The urethral sphincter can be used to control micturition. Voiding urine begins with voluntary relaxation of the external sphincter muscle of the bladder. Parasympathetic impulses induce contractions of the bladder and relaxation of the internal sphincter [18].

Detailed explanation-2: -Contraction of internal urethral sphincter stops the flow through the internal urethral orifice preventing the flow of urine from the bladder. The internal urethral sphincter is made of a layer of smooth muscle that is surrounded by striated muscle.

Detailed explanation-3: -The primary function of the detrusor muscle is to contract during urination to push the urine out of the bladder and into the urethra. The detrusor muscle will relax to allow the storage of urine in the urinary bladder.

Detailed explanation-4: -Thus allowing outflow of urine into the urethra. This process is involuntary, however the flow of urine can be voluntarily stopped by contraction of the external urethral sphincter. At an appropriate time and place, the external urethral sphincter can then be voluntarily relaxed, allowing the passing of urine.