The human brain is well protected by the skull. Inside the skull, the brain is covered by cranial meninges consisting of an outer layer called dura mater, a very thin middle layer called arachnoid, and an inner layer called pia mater which is in contact with the brain tissue.

The brain can be divided into three major parts: (i) forebrain, (ii) midbrain, and (iii) hindbrain.

The forebrain consists of cerebrum, thalamus and hypothalamus. The cerebrum forms the major part of the human brain. A deep cleft divides the cerebrum longitudinally into two halves called the left and right cerebral hemispheres, which are connected by a tract of nerve fibres called corpus callosum. The hypothalamus controls body temperature, eating and drinking.

The midbrain receives and integrates visual, tactile and auditory inputs. The hindbrain comprises pons, cerebellum and medulla.

The layer of cells covering the cerebral hemisphere is called cerebral cortex, which is thrown into prominent folds. It is referred to as grey matter due to its greyish appearance. The cerebral cortex contains motor areas, sensory areas and association areas responsible for complex functions like intersensory associations, memory and communication. The inner parts of cerebral hemispheres and associated deep structures form the limbic system, which is concerned with olfaction, autonomic responses, regulation of sexual behaviour, expression of emotional reactions, and motivation.