Figure 1 : Schematic illustration of the human brain.

From: A mechanical model predicts morphological abnormalities in the developing human brain

Figure 1

The cross section of the brain illustrates its characteristic convoluted surface with ridges called gyri and grooves called sulci. The outer layer of gray matter, which forms the cortex, is made up of neuronal cell bodies including the cell nuclei. The inner core of white matter, which forms the subcortex, consists primarily of neuronal axons. Cortical folding maximizes the surface-to-volume ratio to increase the number of nuclei and decrease the relative distance between them.