A Natural Spine Curve is an important part of healthy spinal anatomy because a normal spine is not perfectly straight. Its gentle curves help the body balance, move, carry weight, and absorb everyday forces. Here is how the cervical, thoracic, lumbar, and sacral curves fit together, and when a curve may need medical evaluation. Updated for a U.S. audience in 2026. If you look at a healthy spine from the side, it usually forms a…