Smooth muscle surrounding the bladder pushes urine out of the urethra.
The bladder.
The Blader contracting and the Prostate relaxing to allow urine to flow
Smooth muscle tissue is primarily found in the walls of hollow organs and structures within the body. This includes the gastrointestinal tract, blood vessels, the bladder, and the uterus. Unlike skeletal muscle, smooth muscle is involuntary and helps facilitate processes such as peristalsis, blood flow regulation, and the expulsion of urine.
it is the muscle tissue
ureter
sphincter
The Bladder Wall
You could test the urine to see if there are abnormally large numbers of proteins in the urine, this might tell you if muscle is being broken down.
Creatinine
Bones
never