<P> The peripheral nervous system ( PNS ) is one of the two components of the nervous system , the other part is the central nervous system ( CNS ) . The PNS consists of the nerves and ganglia outside the brain and spinal cord . The main function of the PNS is to connect the CNS to the limbs and organs , essentially serving as a relay between the brain and spinal cord and the rest of the body . Unlike the CNS , the PNS is not protected by the vertebral column and skull , or by the blood -- brain barrier , which leaves it exposed to toxins and mechanical injuries . The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system . In the somatic nervous system , the cranial nerves are part of the PNS with the exception of the optic nerve ( cranial nerve II ) , along with the retina . The second cranial nerve is not a true peripheral nerve but a tract of the diencephalon . Cranial nerve ganglia originated in the CNS . However , the remaining ten cranial nerve axons extend beyond the brain and are therefore considered part of the PNS . The autonomic nervous system is an involuntary control of smooth muscle and glands . The connection between CNS and organs allows the system to be in two different functional states : sympathetic and parasympathetic . </P>
explain the function of the peripheral nervous system
to connect the CNS to the limbs and organs , essentially serving as a relay between the brain and spinal cord and the rest of the body