The phylum Chordata is a taxonomic group. All animals which have a  spine, or backbone, are classified in the phylum Chordata. There  are three subphylums in Chordata: Uroch â¦ ordata (tunicates),  Cephalachordata (lancelets), and Vertebrata (vertebrates).
The 12 vertebrae in the upper back make up what is known as the thoracic spine. They curve outward and inward to provide structure for the rib cage. The bones provide structure and flexibility for the body, while protecting the spinal colu... Read More.
12 pairs (24). 8-12 rib pairs are called false ribs. Our thoracic cage or rib cage is composed of 12 pairs of ribs, sternum, cartilages and thoracic vertebrae. Of the 12 pairs of ribs, the first 7 pairs (1-7) are attached to vertebrae posteriorly and sternum anteriorly (with costal cartilage). These rib pairs are called true ribs.