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.
The word thoracic means pertaining to the chest, and the thoracic spine (also called the upper back or mid-back) is the portion of the spinal column that corresponds to the chest area. Twelve vertebrae in the middle of the spine with ribs attached make up the thoracic spine.