Diencephalon: It is small and posterior part of fore brain, covered by cerebrum. It consist of thalamus, hypothalamus, epithalamus and metathalamus.

1. Thalamus:It is a major part of diencephalon and represents upper lateral wall. It accepts all sensory impulses from the all part of body (except olfaction) and send those to the cerebral cortex. Thus it acts as relay centre. In lower animals thalamus act as sensory centre because cerebral cortex is less develop.
2. Hypothalamus: It is called the master gland. It represents lower lateral wall of diencephalon. Pituitary gland is attached with its middle part. A web like structure is found on anterior surface of hypothalamus known as optic chiasma. In mammalian brain, corpus albicans is found on the posterior part of hypothalamus.
3. Epithalamus: It represents the roof of diencephalon. Pineal gland is found in this region.
4. Metathalamus: It represents the floor of diencephalon. It consist medial geniculate body (related to hearing) and lateral geniculate body (related to vision).

2. Mid Brain

It is small and contracted part of brain. Two longitudinal myelinated nerve fibres called cerebral penduclesor crura cerebrilocated at the anterior part of mid brain. Four spherical projections called optic lobe or colliculus are located at the posterior part of mid brain. Inferior optic lobes are related to acoustic reflex action.

3. Hind Brain

Cerebellum: It is second largest part of brain. Human cerebellum is made up of 3 lobes. Lateral lobes are large and spherical, called as cerebellar hemisphere. It control regulation and coordination of voluntary muscles.Cerebellumhelps to maintains the body balance of a person.
Medulla Oblongata: It is tubular and cylindrical in shape present at the posterior part of brain. It controls all the involuntary activities of the body e.g. respiration, metabolism, secretory actions of different cells etc.
Pons varolii: It is small spherical projection which is situated below the mid brain and upper to the medulla oblongata. It consists of many transverse and longitudinal nerve fibres. Transverse nerve fibers are joined with cerebellum, whereas longitudinal fibre are join cerebrum to medulla oblongata. It regulates the breathing reaction through pneumotaxic centre.