1. The four curvatures in human spine are cervical, lumbar, thoracic and sacral curvatures.
2. The cervical and lumbar curvatures are secondary and convex whereas the thoracic and sacral curvatures are primary and concave.
3. Importance: Curvatures help in maintaining balance in upright position.
They absorb shocks while walking and also protect the vertebrae from fracture.
