Hindbrain
The hindbrain or rhombencephalon is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes. Metencephalon. Rhombomeres Rh3-Rh1 form the metencephalon. The metencephalon is composed of the pons and the cerebellum; it contains: Myelencephalon. Rhombomeres Rh8-Rh4 form the myelencephalon. The myelencephalon forms the medulla oblongata in the adult brain; it contains: Evolution. The hindbrain is homologous to a part of the arthropod brain known as the sub-oesophageal ganglion, in terms of the genes that it expresses and its position in between  the brain and the nerve cord. It has been suggested that the hindbrain first evolved in the Urbilaterian—the last common ancestor of chordates and arthropods—between 570 and 555 million years ago. Hindbrain diseases. A rare brain disease of the cerebellum is rhombencephalosynapsis characterized by an absent or partially formed vermis. Symptoms can include truncal ataxia. The disorder is a main feature of Gomez-Lopez-Hernandez syndrome.