Rhombencephalon

Overview
The rhombencephalon (or hindbrain) is a developmental categorization of portions of the central nervous system in vertebrates.

The rhombencephalon can be subdivided in a variable number of transversal swellings called rhombomeres. In the human embryo we can distinguish eight rhombomeres, from caudal to rostral: Rh7-Rh1 and the isthmus (the most rostral rhombomere).

A rare disease of the rhomencephalon, "rhombencephalosynapsis" is characterized by a missing vermis resulting in a fused cerebellum. Patients generally present with cerebellar ataxia.

Myelencephalon
Rhombomeres Rh7-Rh4 form the myelencephalon.

The myelencephalon forms the medulla oblongata in the adult brain; it contains:
 * a portion of the fourth ventricle,
 * the glossopharyngeal nerve (CN IX),
 * vagus nerve (CN X),
 * accessory nerve (CN XI),
 * hypoglossal nerve (CN XII),
 * and a portion of the vestibulocochlear nerve (CN VIII).

Metencephalon
Rhombomeres Rh3-Rh1 form the metencephalon.

The metencephalon is composed of the pons and the cerebellum; it contains:
 * a portion of the fourth ventricle,
 * the trigeminal nerve (CN V),
 * abducens nerve (CN VI),
 * facial nerve (CN VII),
 * and a portion of the vestibulocochlear nerve (CN VIII).

Additional images
Rhombencephalon Rombencéfalo Rombencefalo Rhombencephalon Задний мозг