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.
1 Limited flexibility. 2  The rib cage is connected to each level of the thoracic spine. 3  One rib is connected firmly on each side of each thoracic vertebra, with one pair extending from either side of T1, another pair from T2, and so on.