Thoracic Spine Anatomy and Upper Back Pain. The thoracic spine refers to the upper- and middle-back. It joins the cervical spine and extends down about five inches past the bottom of the shoulder blades, where it connects with the lumbar spine.
The thoracic spine is made up of twelve vertebrae, labeled T1-T12. While the cervical spine is built for flexibility (e.g. turning the head) and the lumbar spine is built for power and flexibility (e.g. lifting heavy objects, touching the toes), the thoracic spine is built for stability. This stability plays an important role in holding the body upright and providing protection for the vital organs in the chest.
The upper back is not designed for motion, and subsequently, injuries to the thoracic spine are rare. However, irritation of the large back and shoulder muscles or joint dysfunction in the upper back can produce very noticeable back pain.