This chapter discusses the brain and nervous system from the basics, starting from the structure of neurons. Neurons are organized within the brain to form white matter and gray matter. Gray matter consists of neuronal cell bodies. White matter consists of axons and support cells. The brain also contains a number of hollow chambers termed ventricles. There are conventional directions for navigating around the brain, just as there is a north, south, east, and west for navigating around maps. Anterior and posterior refer to directions toward the front and back of the brain. The hollow chambers of the brain that contain cerebrospinal fluid. The thalamus consists of two interconnected egg-shaped masses that lie in the center of the brain and appear prominent in a medial section. The basal ganglia and limbic system comprise a number of anatomical structures in subcortical gray matter and are involved, respectively, in the control of action and adapting the organism to its environment (memory, emotion). <\/p>\n\n\n\n