The thoracic spine, guarded by the rib cage and the sacrum, is not as mobile as the other parts of the back. Keep in mind that your spinal column supports the head and allows the entire torso to bend and twist. The spinal column also protects the spinal cord, which houses a bundle of nerves, or ganglia, that connect our brain to our body. The interdependent relationship between the spinal column and the spinal cord is a wondrous, complex marvel that few of us ever think about. Each section of the spine has a natural curve.
Natural curves are important.
Without these curves the spine would not have the strength and resilience to act as a shock absorber during movement. The back's curves are designed to absorb shock and to facilitate the full range of motion throughout the spinal column. The natural curves act as a coiled spring to absorb force or jarring during activity. Jogging or jumping rope would be impossible without these curves. The yielding curves are the pillars of strength, resilience, and flexibility in the spine.