Neuroanatomy kaplanbr br The human brain is hugely interconnected but three major components can be identified: the cerebrum, the cerebellum and the brain stem.br br The brainstem which includes the medulla, the pons and the midbrain, controls breathing, digestion, heart rate and other autonomic processes, as well as connecting the brain with the spinal cord and the rest of the body.br br The cerebellum plays an important role in balance, motor control, but is also involved in some cognitive functions such as attention, language, emotional functions (such as regulating fear and pleasure responses) and in the processing of procedural memories.br br The cerebrum (or forebrain), which makes up 75 of the brain by volume and 85 by weight, is divided by a large groove, known as the longitudinal fissure, into two distinct hemispheres. The left and right hemispheres ("left" and "right" refer to the owner's point of view, not an outside viewer's) are linked by a large bundle of nerve fibres called the corpus callosum, and also by other smaller connections called commissures.br Most of the important elements of the cerebrum, are split into symmetrical pairs in the left and right hemispheres. Thus, we often speak of the temporal lobes, hippocampi, etc (in the plural), although this website generally follows the convention of speaking of the temporal lobe, hippocampus, etc (in the singular), which should therefore be taken to mean both sides, within both hemispheres. The two hemispheres look similar, but are slightly different in structure and perform different functions.