The somatic nervous system (SoNS or voluntary nervous system) is the part of the peripheral nervous system associated with skeletal muscle voluntary control of body movements.The SoNS consists of afferent nerves and efferent nerves.esides these, thousands of association nerves are also present in the body. Thus somatic nervous system consists of three parts: 1  Spinal nerves: They are peripheral nerves that carry sensory information into and motor commands out of the spinal cord.