The hemispheres are connected by a tract of nerve fibres called corpus callosum. The outer portion of cerebrum is called the cerebral cortex that makes up the grey matter of the cerebrum. Beneath the grey matter there are present millions of medullated nerve fibres which give an opaque white appearance, hence are collectively called white matter. Each cerebral hemisphere is divided into four lobes: frontal
(monitors complex thoughts, actions and ideas and
controls intellectual ability), parietal (registers sensory perception and takes in information from environment organises it and communicates it to rest of the brain), temporal (decodes and interprets sound, smell, memory and emotion) and occipital lobes (decodes and interprets visual information, shape and colour).
Diencephalon is completely covered by cerebral hemispheres. Its main parts are epithalamus, thalamus and hypothalamus Epithalamus is thin and its anterior part is folded to form anterior choroid plexus and just behind it, there is pineal stalk which has pineal body. Thalamus, is major coordinating centre for sensory and motor signalling and is composed primarily of grey matter. Hypothalamus lies at the base of the thalamus and contains a number of centres which control body
temperature, urge for eating and drinking, growth and sexual behaviour, etc. Hypothalamus is an important link between neural and endocrine system (neuroendocrine role).
