The nervous system is made up of two major parts - the brain and spinal cord. The brain is composed of the cerebrum, cerebellum, and medulla oblongata. The cerebrum is responsible for complex sensory and neural functions and voluntary activity. The cerebellum regulates fear, pleasure responses, and some cognitive functions. The medulla oblongata controls involuntary functions. The spinal cord connects to the medulla and runs down the spinal column, carrying information between the brain and body and controlling muscle movement. Nerve cells form networks to receive and transmit messages throughout the nervous system.