Some ages of license are actually higher than the age of majority. For example, the age of license to purchase alcoholic beverages is 21 in all U.S. states. Another example is the voting age, which prior to the 1970s was 21, while the age of majority was 18 in most states.
The nervous system is composed of the brain and spinal cord, together known as the central nervous system, and a vast array of peripheral nerves that transmit information to and from these central structures. The nervous system may be damaged by infection, injury, vascular problems, inflammation, and degeneration.
To break this down even further, individual nerve cells consist of an axon (the inner pathway whereby information is transmitted) and a myelin sheath (a fatty outer covering that protects the nerve cell and helps transmit information). An injury or irritation to any part of nerve structure can cause nerve pain.