Thoracic Vertebrae:

There are 12 thoracic vertebrae in the upper back, between the base of the neck and the diaphragm muscle. These vertebrae articulate with the ribs, which in turn connect with the sternum or breastbone in the front of our chest, to form the thorax which is part of the axial skeleton. 

The ribs and sternum limit the range of movement available to the thoracic vertebrae, which tend to be less mobile than other parts of the spine, in most people.