Peripheral Nervous System

T he peripheral nervous system consists of those parts of the nervous system which lie outside the central nervous axis (the brain and the spinal cord), and includes the cranial and the spinal nerves, their associated ganglia, and the peripheral parts of the autonomic nervous system. In essence it provides the nervous links between the central nervous system and the other organ systems of the body. Its constituent neurons may be broadly grouped into two categories: afferent , which carry into the central nervous system nervous impulses generated by the stimulation of one or other of a wide variety of receptor organs; and efferent , which carry away from the central nervous system nervous impulses which activate one or other of a number of effector organs. The receptor organs include organs of special sense (the eye, the ear, and the organs of smell and taste), the organs of cutaneous sense, receptors in the viscera including the cardiovascular system, and organs which monitor the position and movements of the body. The effector organs are limited, in Man, to striated, cardiac and smooth muscles and to glands.