Central nervous system
The peripheral nervous system refers to parts of the nervous system outside the brain and spinal cord. It includes the cranial nerves, spinal nerves and their roots and branches, peripheral nerves, and neuromuscular junctions. The anterior horn cells, although technically part of the central nervous system (CNS), are sometimes discussed with the peripheral nervous system because they are part of the motor unit. In the peripheral nervous system, bundles of nerve ﬁbers or axons conduct information to and from the central nervous system. The autonomic nervous system is the part of the nervous system concerned with the innervation of involuntary structures, such as the heart, smooth muscle, and glands within the body The nervous system consists of two main parts: the central nervous system and the peripheral nervous system: 1  The central nervous system is made up of the brain and spinal cord. The brain sends messages through the spinal cord and nerves of the peripheral nervous system to control the movement of the muscles and the function of internal organs. The basic working unit of the nervous system is a cell called a neuron. 1 Peripheral nervous system (PNS): a part of the nervous system which includes all the nerves outside of the brain and spinal cord. 2  Sympathetic nervous system: The part of your nervous system that unconsciously controls your organs and glands when you're excited or frightened. The brain and spinal cord are inside your skull and vertebrae (the vertebrae make up your backbone). These bones protect the CNS when you get into accidents. The other part of the nervous system is the Peripheral Nervous System (or PNS). The PNS consists mainly of the nerves that go to and from the CNS. “Peripheral nerve” is a term used synonymously to describe the peripheral nervous system. The peripheral nervous system is a network of 43 pairs of motor and sensory nerves that connect the brain and spinal cord (the central nervous system) to the entire human body. These nerves control the functions of sensation, movement and motor coordination The CNS consists of your brain and spinal cord. The brain and spinal cord are inside your skull and vertebrae (the vertebrae make up your backbone). These bones protect the CNS when you get into accidents. The other part of the nervous system is the Peripheral Nervous System (or PNS). The PNS consists mainly of the nerves that go to and from the CNS. Unlike the CNS, though, there is no bony protection for the PNS. Have you ever hit your funny bone?. That odd feeling was you pinching one of the nerves in your arm The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system; some textbooks also include sensory systems. The cranial nerves are part of the PNS with the exception of cranial nerve II, the optic nerve, along with the retina. The main function of the PNS is to connect the central nervous system (CNS) to the limbs and organs, essentially serving as a communication relay going back and forth between the brain and the extremities. 1 The central nervous system is made up of the brain and spinal cord. 2  The peripheral nervous system is made up of the nerve fibers that branch off from the spinal cord and extend to all parts of the body, including the neck and arms, torso, legs, skeletal muscles and internal organs. The brain sends messages through the spinal cord and nerves of the peripheral nervous system to control the movement of the muscles and the function of internal organs. The basic working unit of the nervous system is a cell called a neuron. Peripheral nervous system: The portion of the nervous system that is outside the brain and spinal cord. Abbreviated PNS. The nerves in the PNS connect the central nervous system (CNS) to sensory organs, such as the eye and ear, and to other organs of the body, muscles, blood vessels, and glands. The peripheral nerves include the 12 cranial nerves, the spinal nerves and roots, and the autonomic nerves. All the nerves and nerve cells outside your central nervous system make up your peripheral nervous system. Its task is to relay information from your brain and spinal cord to the rest of your body and from your body to your brain and spinal cord. 
http://emedicine.medscape.com/article/1948687-overview https://www.nichd.nih.gov/health/topics/neuro/conditioninfo/Pages/parts.aspx https://askabiologist.asu.edu/parts-nervous-system http://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/peripheral_nerve_surgery/conditions/peripheral_nerve_system.html https://askabiologist.asu.edu/parts-nervous-system https://en.wikipedia.org/wiki/Peripheral_nervous_system https://www.nichd.nih.gov/health/topics/neuro/conditioninfo/Pages/parts.aspx http://www.medicinenet.com/script/main/art.asp?articlekey=8258 http://www.bbc.co.uk/science/humanbody/body/factfiles/peripheralnervoussystem/peripheral_nervous_system.shtml
peripheral nervous is part of what system