How big is the central part in the Central Nervous System in human?

The human central nervous system comprises of the brain and spinal cord. The remainder of the nervous system is called the peripheral nervous system. In the average adult the mass of the human brain is about 1.3-1.4 kg and of a neonate (newborn) 350-400 g (0.35-0.4 kg). The dimensions of an adult human brain are approximately 140 mm wide, 167 mm long and 93 mm high (or deep). It represents approximately 2% of the weight of an average human adult. The volume of a human brain is about 1700 ml. It's estimated that there are approximately 100 thousand million neurones in the human brain.