Cerebellum, brainstem and diencephalon. Illustration of a midline sagittal section through three structures found at the rear base of the brain. At centre is the brainstem. At left is the cerebellum. At upper right is the diencephalon, one of the first part of the forebrain to form during embryogenesis. The diencephalon includes the thalamus and hypothalamus. The brainstem consists of the midbrain (mesencephalon, upper centre), pons (centre), and medulla oblongata (bottom). The brainstem deals with subconscious functions, such as breathing and blood pressure. The cerebellum controls balance, posture and muscle coordination.