Classification of Nervous System The nervous system of vertebrates (including humans) is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The (CNS) is the major division, and consists of the brain and the spinal cord. The spinal canal contains the spinal cord, while the cranial cavity contains the brain. Classification of Nervous System | Source: www.thailandmedical.news 01. Peripheral Nervous System (PNS) The peripheral nervous system is divided into two main parts: ANS and SNS. Autonomic Nervous System (ANS): Controls involuntary bodily functions and regulates glands. The ANS is again divided to, sympathetic and parasympathetic. Sympathetic Nervous System: There are two kinds of neurons involved in the transmission of any signal through the sympathetic system: preganglionic and postganglionic. Parasympathetic nervous system: Your parasympathetic nervous system is a network of nerves that relaxes your body after periods of stress or ...