The central nervous system (CNS) is made up of the brain and the spinal cord. It is to collect information from all the nerves in the body and sending out responses. There are 86 main nerves branching off the Nervous system. The spinal nerves are the 31 pairs of nerves. This CNS sends out messages to more than 640 muscles around the body. Outer layer of brain is called Cortex. A human brain has a cerebral cortex four times bigger as a Chimpanzee, 20 times as big as Monkey’s and 300 times bigger as Rat`s.