Peripheral Nervous System
The peripheral nervous system is divided into two major parts: the somatic nervous system and the autonomic nervous system.
The somatic nervous system consists of peripheral nerve fibers that send sensory information to the central nervous system AND motor nerve fibers that project to skeletal muscle.
The cell body is located in either the brain or spinal cord and projects directly to a skeletal muscle.
The autonomic nervous system is divided into three parts: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system. The autonomic nervous system controls smooth muscle of the viscera (internal organs) and glands.
This picture shows the general organization of the autonomic nervous system. The preganglionic neuron is located in either the brain or the spinal cord. This preganglionic neuron projects to an autonomic ganglion. The postganglionic neuron then projects to the target organ. Notice that the somatic nervous system has only one neuron between the central nervous system and the target organ while the autonomic nervous system uses two neurons.
The enteric nervous system is a third division of the autonomic nervous system that you do not hear much about. The enteric nervous system is a meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, gall bladder).