The nervous system is the system that comprehends internal and external stimuli, evaluates them and manages the organism to give the necessary response. Nerve cells, called neurons, are the basic functional unit of the nervous system and are composed of a body and a large number of short and long extensions from this body. Anatomically, the nervous system consists of two parts: the peripheral and the central nervous system. The central nervous system consists of the brain, located inside the skull, and the spinal cord, located in the spinal canal. The brain and spinal cord are made up of three layers, with membranes surrounding the brain from the outside and spaces between them. From the outside to the inside, these membranes are called hard membrane, spidery membrane and inner membrane. These membranes protect the organs and are responsible for the secretion of CSF fluid and its absorption into the venous circulation. The brain is the highest center in the nervous system. The brain is divided into three parts. These are; rhombencephalon, mesencephalon, prosencephalon. The medulla oblangata is the second part of the central nervous system. The spinal cord is the unit that provides communication between the brain and peripheral structures and controls spinal reflexes. The peripheral nervous system is the system that provides communication between the brain and spinal cord and all other structures in the body.