Peripheral nervous system

The peripheral nervous system or PNS, is a subsystem of nervous system of the nervous system, and consists of the nerves and neurons that reside or extend outside the central nervous system--to serve the limbs and organs, for example. Unlike the central nervous system, however, the PNS is not protected by bone or the blood-brain barrier, leaving it exposed to toxins and mechanical injuries. The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system. It consists of the cervical spinal nerves C1-C4, brachial plexus (C5-T1), thoracic spinal nerves, lumbar spinal nerves, sacral spinal nerves and coccygeal spinal nerves.