The cranial and spinal nerves constitute the somatic peripheral nervous system. These nerves connect the brain and spinal cord to peripheral structures such as the skin surface and the skeletal muscles. The peripheral nerves measure approximately 93,000 miles (150,000 kilometers) in length.There are twelve pairs of cranial nerves in the human body. The cranial nerves are designated by Roman numerals and names. The Roman numerals indicate the order in which they emerge from the brain. The name indicates an anatomical feature of function. The trigeminal nerve is the largest, although not the longest, cranial nerve.
