The peripheral nervous system consists of the nervous tissue outside of the central nervous system, mainly ganglia and nerves. Ganglia are the grouping of the cell bodies of the neurons, and the nerves are the grouping of the axon fibers. There are 12 pairs of cranial and 31 pairs of spinal nerves originating from the CNS. They are present and evenly distributed throughout the entire body to allow the proper flow of electrical signals, and to provide communication between the peripheral and central nervous systems. The nerves of the PNS can be classified according to which type of neuron axons they contain: Motor, sensory or mixed (both motor and sensory). Structurally, the PNS can be divided into:

Figure 1: Central and Peripheral Nervous System