Simple, the central nervous system, which is composed of the brain and the spinal cord. The central nervous system communicates with the rest of the body by sending messages from the brain through the nerves that branch off of your spine which then connects to the peripheral nervous system. These are the millions of nerves throughout your body and convey messages to your central nervous system and vice versa. The chemical and electrical impulses, through contractions of your skeletal muscles, result in the movement of your body. Hope that answers your question!