Peripheral nervous system
The peripheral nervous system is an anatomically distinct portion of the nervous system containing the neurons and support structures on the periphery of the body. Essentially the peripheral nervous system contains any nervous tissue that is not part of the spinal cord or brain, tissue in these areas are defined as part of the central nervous system.
The peripheral nervous system is divided into two main sections, the somatic division and the autonomic division. The somatic division consists primarily of the sensory neurons that innervate the skin, muscles and joints. Information from the environment and several organ systems is detected by these neurons and follows the afferent path to the spinal cord. Some integration of sensory information takes places in the somatic division but most of that is handled by the central nervous system. The autonomic division controls visceral sensation, motor responses, and the exocrine system.
The autonomic system itself is divided in to the sympathetic system, parasympathetic system, and the enteric system. The sympathetic system responds primarily to stressful and salient events in the environment. It is sometimes colloquial described as the “fight or flight” system. The parasympathetic system is the opposite, and is designed to bring the body back to homeostasis and conserve energy and resources after a stressful response. The enteric system is primarily involved with controlling the smooth muscle of the gut.
- Martin, JH (2003). Neuroanatomy text and atlas 3rd ed., New York: McGraw-Hill.
- Sanes, Reh, Harris (2005). Development of the Nervous System, 2nd edition. Academic Press; ISBN 0-12-618621-9