nerve cord A large bundle of nerve fibres, running down the longitudinal axis of the body, that forms an important part of the central nervous system. Most invertebrates have a pair of solid nerve cords, situated ventrally and bearing segmentally arranged ganglia. All animals of the phylum Chordata have a dorsal hollow nerve cord; in vertebrates this is the spinal cord.

nerve cord The bundle of nerve fibres that runs along the longitudinal axis of the body. In most invertebrates there are two, solid nerve cords; in Chordata the nerve cord is hollow and in vertebrates it is the spinal cord.