Three major parts of brainstem are midbrain, pons and medulla oblongata. Pons is present between midbrain and medulla oblongata. Medulla controls breathing, blood pressure and heart rate. Pons has tracks for signals to transfer fron cerebellum to the cerebrum. Mid brain controls vision and hearing. The three major parts of diencephalon are thalamus, hypothalamus and epithalamus. Thalamus is the egg shaped structure. Hypothalamus is called the master gland. Pineal gland is part of epithalamus. Solution Three major parts of brainstem are midbrain, pons and medulla oblongata. Pons is present between midbrain and medulla oblongata. Medulla controls breathing, blood pressure and heart rate. Pons has tracks for signals to transfer fron cerebellum to the cerebrum. Mid brain controls vision and hearing. The three major parts of diencephalon are thalamus, hypothalamus and epithalamus. Thalamus is the egg shaped structure. Hypothalamus is called the master gland. Pineal gland is part of epithalamus..