Nerve cord: a single hollow tract of nervous tissue that constitutes the centralnervous system of chordates and develops into the spinal cord andbrain in vertebrates.
Spinal cord:The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone where it passes through the foramen magnum, and meets and enters the spinal canal at the beginning of the cervical vertebrae.
Vertebral column: The vertebral column is protection of the spinal cord; it also provides stiffening for the body and attachment for the pectoral and pelvic girdles and many muscles. In humans an additional function is to transmit body weight in walking and standing.
Backbone:Backbone (Molecular Biology) Backbone, or main chain, is the general term used to describe the connecting chain in polymers. Different kinds of polymers have different chemical backbones. For example, in proteins the backbone is a polypeptide chain, but nucleic acids have a sugar phosphate backbone.