The nervous system includes the brain, the spinal cord, and all the nerves in the body. Nerves carry information through the spinal cord to the brain about what is happening inside and outside of the body, and the brain processes the information and sends messages back through the nerves that control how muscles and other organs respond.

The nervous system is divided into the brain and the spinal cord (which are together known as the central nervous system) and the nerve cells that lead away from the brain and the spinal cord to the rest of the body (peripheral nervous system). The nervous system controls:

• Sight, hearing, taste, smell, and feeling (sensation).
• Voluntary and involuntary motor functions, such as movement, balance, and coordination, and it regulates the actions of most of the other body systems, such as blood flow and blood pressure.
• The ability to think. The nervous system allows a person to be conscious, to have thoughts and memories, and to use language.