The peripheral nervous system (PNS is made up of all the other parts of the nervous system excluding the brain and the spinal cord which are parts and segments of the central nervous system (CNS) (Noveguide.com 1-3). The peripheral nervous system (PNS) is divided into two main categories which are: 1) the sensory-somatic nervous system and 2) the autonomic nervous system (Novelguide.com 1-3). The sensory-somatic nervous system serves as the sensory entrance between the environment or surroundings outside the human body and the CNS. The responses made by the body in this part of the PNS are inclined to be conscious (Noveguide.com 1-3). The sensory-somatic nervous system is composed of 31 pairs of spinal nerves and 12 pairs of cranial nerves. Other pairs are only for sensory neurons which are mainly engaged in the senses for smell, vision, hearing and balance (Novelguide.com 1-3). The other pairs are made up of motor neurons that affect movements (example: swallowing, movement of head and shoulders). Other pairs are comprised of a combination of sensory and motor neurons that work together. All the spinal neurons have both sensory and motor neurons. this and the other pairs contained therein allow the spinal neuron to function and work correctly serving as the means to transmit signals from any stimuli that are normally followed by a response (Novelguide.com 1-3). The autonomic nervous system (ANS) is subdivided into three parts: 1) the parasympathetic nervous system. 2) the sympathetic nervous system and the enteric nervous system.