Here is your answer:
Skeletal system: is the system that contains the bones, bone marrow, and tissue. Also the skeletal system is used to support the structure of the body.
Muscular system: is the system contains the muscles, and helps circulates blood throughout the body, it also helps you move, walk, run, or just to move period.
Nervous system: is the part of the body that helps keep your body safe, so lets say you touch a hot stove when it hurts your body your nervous system sends a message to your brain telling it that it hurts and you quickly move your hand out of the way it all happens under one second.
All systems play a vital role and work together to get and keep your body functioning correctly.
Hope this helps!