The forebrain or prosencephalon (supratentorial portion of the brain) comprises the telencephalon (the two cerebral hemispheres and the midline structures connecting them) and the diencephalon. The midbrain or mesencephalon lies between the fore brain and the hind brain. It passes through the tentorium cerebelli. The hindbrain or rhombencephalon (infratentorial portion of the brain) comprises the pons, the medulla oblongata (almost always called “medulla” for short), and the cerebellum. The mid brain, pons, and medulla together make up the brain stem.