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 Joint Dysfunction. 2  Pain caused by joint dysfunction, where the ribs attach to the spine at each level of the thoracic spine, can cause pain. 3  Herniated or degenerative discs. 4  While less common in the thoracic spine, degenerative disc disease or a thoracic herniated disc can be a source of pain.here are several features of the thoracic spine that distinguish it from the lumbar and cervical spine: 1  Limited flexibility. 2  The ribs connected to T11 and T12 at the bottom of the thoracic spine do not attach the sternum in front, but do provide protection for the kidneys in the back of the body.