Cerebrum

The cerebrum accounts for about 80 percent of total mass of the brain. It consists of the right and left cerebral hemispheres that are divided (though not completely) by a longitudinal fissure. Internally, portions of the two hemispheres are connected by large tract of white matter called the corpus callosum. Each hemisphere fits into the dome of the cranial vault of the skull. The cerebrum comprises a surface layer referred to as the cerebral cortex that is composed of grey matter and below this, a thick layer of white matter. The cerebral cortex features numerous folds and grooves that are called convolutions which form during fetal development. These convolutions allow for a larger area of grey matter that is made up of nerve cell bodies. The elevated fold of the convolutions are called gyri and the depressed groves are called sulci