Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures.
Superficial dissection of brain-stem. Lateral view.
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 rhombencephalon, "rhombencephalosynapsis" is characterized by a missing vermis resulting in a fused cerebellum. Patients generally present with cerebellar ataxia.
The caudal rhombencephalon has been generally considered as the initiation site for neural tube closure.[1]
