Nerve Cord

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nerve cord

[′nərv ‚kȯrd]
(invertebrate zoology)
Paired, ventral cords of nervous tissue in certain invertebrates, such as insects or the earthworm.
(zoology)
Dorsal, hollow tubular cord of nervous tissue in chordates.

Nerve Cord

 

a structure within the central nervous system of annelids and arthropods. The nerve cord is situated on the ventral side of the body, under the gut. It is connected to the cerebral ganglia. The nerve cord consists of a pair of partially fused longitudinal nerve trunks, called connectives, and of pairs of segmental ganglia that innervate each of the body segments. The primitive form of the nerve cord, which occurs in some primitive annelids, polychaetes, and onychophorans, is scaliform, having widely spaced trunks and long commissures between the ganglia.