ventral nerve cord
The pair of closely united ventral longitudinal nerves with their segmental ganglia that is characteristic of many elongate invertebrates (as earthworms)[BTO]. A large process bundle that runs along the vental mid-line extending from the ventral region of the nerve ring[WB]. The ventral cord is one of the distinguishing traits of the central nervous system of all arthropods (such as insects, crustaceans and arachnids) as well as many other invertebrates, such as the annelid worms[GO].