On the surface
The surface of the cerebrum is composed of a thin area of gray matter and is called the cerebral cortex (cortex=bark) . The cortex consists of six layers of nerve cell bodies (cell bodies=the part which contains the cell's nucleus) , beneath which lies the cerebral white matter.
Gray matter and white matter
For the brain, the gray matter is the outer layer on the brain called the cerebral cortex. The white matter is found under it. In the spinal cord, the order is exactly opposite. The gray matter in the spinal cord travels in the center of the cord and is surrounded by white matter. The reason gray matter is called gray is because it contains nerve cell bodies which have a gray shade. White matter is white is made up extensions from the nerve cell bodies called axons - which are white in color. In the spinal cord , the group of axons for the branching spinal nerves.
The brain of an embyro
During embryonic division, when there is a rapid increase in brain size, the gray matter of the cerebral cortex enlarges much faster than the underlying white matter. As a result the cerebral cortex rolls and folds upon itself so that it can fit into the cranial cavity.
The brain's folds and creases
The folds are called gyri or convulations. Gyrus is the singular. The deep grooves between the folds are fissures; the shallow grooves are sulci. Sulcus is the singular. As you know the brain has the left half and the right half, the cerebral hemispheres. Between the hemispheres is a deep fissure called the lontitudinal fissure.
What holds the cerebral hemisphere together?
The hemispheres are connected by a large bundle of nerve fibers composed of white matter called the corpus callosum (corpus=body ; callosus=hard). This structure is larger in females that in males and scientists attribute this to the fact that females are the more emotional of the both. It appears that females us both hemispheres for emotions while males use only one side.
Related links
Brain Tour : Male Brain ; Female Brain
Brain structure differs between men and women. Do you see why men are from mars and women are from venus?
