Cerebrum forms a major part of the human brain. A deep cleft divides the cerebrum longitudinally into two halves, which are termed as the left and right cerebral hemispheres. The hemispheres are connected by a tract of nerve fibres called corpus callosum. Corpus callosum is a broadband of nervous tissue that connects two cerebral hemispheres. It consists of 300 million fibres and is present only in mammals.