Antero-posterior organization of the central nervous system
A prominent feature of the central nervous system is its longitu-
dinal subdivision into distinct domains. Based on morphological
and embryological grounds, the vertebrate CNS is traditionally
subdivided in two major parts, the brain and the spinal cord, with the
brain itself being subdivided in an anterior (forebrain), an interme-
diate (midbrain) and a posterior (hindbrain) region (Fig. 2A). The
arthropodian CNS is subdivided in an anterior part, the cerebral
ganglion (also called brain), an intermediate part extending from
the oesophagus to the neck (suboesophageal ganglion) and a
caudal part, the ventral nerve cord made of a succession of
segmental ganglia (Fig. 2B).