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Abstract
The mammalian nervous system is divided into two major divisions. The central nervous system consists of the brain and spinal cord. The peripheral nervous system includes twelve pairs of cranial nerves and a varying number of paired spinal nerves. The autonomic nervous system is part of the peripheral nervous system and is subdivided into para- sympathetic (craniosacral) and sympathetic (thora columbar) systems (Langley, 1903). Simply stated, the autonomic nervous system innervates cardiac muscle, smooth muscle and glandular tissue. Thus the autonomic system deals with the viscera or internal environment of the body. The remainder of the nervous system, for the most part, deals with response to the external environment.
The sympathetic system consists of a series of nerve ranglia lying along either side of the vertebral column. These ganglia are interconnected by a nerve chain. Further, the chain ganglia are connected to the spinal cord usually in the thoracic and lumbar regions. The chain ganglia also communicate with the spinal nerves.
