This part of your spine is your upper back. It is made up of 12 vertebrae. The rib cage of the chest is attached to the thoracic spine at each level. This gives a great deal of stability and support to the upper body. This in turn, limits the back's movement at the chest level.
Because the upper back isn't designed for movement, it is uncommon to have injuries of the thoracic spine. However, irritation of the large muscles of the back and shoulder or joint problems in the upper back can be very painful.