part of part of intersects midsagittal plane of in taxon Chordata ventral nerve cord WBbt:0005829 EFO:0000896 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]. MIAA:0000339 BTO:0002328 The ventral nerve cords make up the nervous system of some phyla of the invertebrates, particularly within the nematodes, annelids and the arthropods. It usually consists of cerebral ganglia anteriorly with the nerve cords running down the ventral ('belly', as opposed to back) plane of the organism. This characteristic is important in qualifying the difference compared to the chordates, which have a dorsal nerve cord. Ventral nerve cords from anterior to posterior (the thoracic and abdominal tagma in the arthropods) are made up of segmented ganglia that are connected by a tract of nerve fibers passing from one side to the other of the nerve cord called commissures. The complete system bears some likeness to a rope ladder. In some animals the bilateral ganglia are fused into a single large ganglion per segment. This characteristic is found mostly in the insects. NLX:146329 A cluster of neurons that extends posteriorly from the embryonic and larval brain and is surrounded by a connective tissue sheath. ventral cord FBbt:00005097 UBERON:0000934 MAT:0000339 Wikipedia:Ventral_nerve_cord primary nerve cord ventrum