The periphery, the spinal cord and the brain itself. The periphery is made up of all the nerve endings and sensory neves that are where information begins and ends in the body. If information is gathered here or this is the destination of a message to do something, that is likely to be a part of the periphery. The many sections of the periphery are complex and widely varied and beyond the scope of this primer. The spinal cord communicates between the periphery and the brain.
Sensory nerves enter it, bringing information to the brain about our world.
Motor nerves exit carrying messages to the muscles and organs informing them how to operate. In cross section, the central part of the spinal cord is vaguely h-shaped. This is where information travels up to the brain. Each segment of spinal cord communicates with a particuluar section of the body and with the segments directly above and below it. An important part of the spinal cord is what is known as the reflex arc .