<P> Rostrally to the spinal cord lies the brain . The brain makes up the largest portion of the central nervous system, and is often the main structure referred to when speaking of the nervous system . The brain is the major functional unit of the central nervous system . While the spinal cord has certain processing ability such as that of spinal locomotion and can process reflexes, the brain is the major processing unit of the nervous system . </P> <P> The brainstem consists of the medulla, the pons and the midbrain . The medulla can be referred to as an extension of the spinal cord, and its organization and functional properties are similar to those of the spinal cord . The tracts passing from the spinal cord to the brain pass through here . </P> <P> Regulatory functions of the medulla nuclei include control of the blood pressure and breathing . Other nuclei are involved in balance, taste, hearing and control of muscles of the face and neck . </P> <P> The next structure rostral to the medulla is the pons, which lies on the ventral anterior side of the brainstem . Nuclei in the pons include pontine nuclei which work with the cerebellum and transmit information between the cerebellum and the cerebral cortex . In the dorsal posterior pons lie nuclei that have to do with breathing, sleep and taste . </P>

The cns is comprised of the brain spinal cord and ventral body cavity