Composed of twelve vertebrae, the thoracic spine is the longest part of your back. It is often referred to as the middle back or torso back. One way to identify these vertebrae is to realize that each of one has a rib attached to it.
The nerves that are protected by the vertebrae in the thoracic spine control muscles, surface tissue, and internal organs. These nerves also control the arms from the elbow down, hands, fingers, the muscles of the middle back, the chest, and the ribcage.
Nerves passing through the spinal canal of the thoracic spine also control crucial parts of the sympathetic nervous system including the heart, lungs, bronchial tubes, gallbladder, liver, stomach, small intestines, kidneys, pancreas, and kidneys.