The nerves running outside of the brain and spinal cord constitute the PNS (peripheral nervous system). These nerves are of two types: crania nerves (nerves originating from the brain) and spinal nerves (nerves originating from the spinal cord). These are 12 pairs of cranial nerves

Table: cranial nerve

31 pairs of spinal nerves arise from either side of the spinal cord. Each spinal nerve is a mixed nerve containing both sensory and motor nerve fibers running between the spinal cord and peripheral tissue.
Spinal nerves are classified into 5 groups – 12 pairs of thoracic nerves, 8 pairs of cervical nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and one pair of coccygeal nerves.

Peripheral nervous system (PNS)