The two hemispheres of the brain are connected by a thick band of nerve fibers called the corpus callosum. The corpus callosum is the main white matter tract between the two cerebral hemispheres, consisting of about 200 million axons. It allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side. Each hemisphere controls muscles and glands on the opposite side of the body.