Neuromuscular disorders affect the nerves that control your own voluntary muscles. Voluntary muscles are the ones which we can control by our self like in your arms and legs. Your nerve cells also called as neurons, send the messages that control these muscles. When the neurons become delicate or die, communication between your nervous system and muscles breaks down. As a result, your muscles weaken and waste away this weakness can lead to twitching, cramps, aches, pains, and joint and movement problems. Frequently it also affects heart function and your ability to breathe.