The spine is the central skeleton located in the cervicothoracic and lumbar back of the body and is the pillar that supports the body. The vertebrae are connected together by intervertebral discs, ligaments between vertebrae, and small joints to form the spine. The spine is composed of 26 vertebrae from top to bottom, including the cervical, thoracic, lumbar, sacral and coccygeal vertebrae. Inside the spine there is a longitudinally connected canal called the spinal canal, which houses the spinal cord. All the nerves that govern the body are derived from the spinal cord. Our spine is straight from the front, but from the side it is S-shaped with four physiological curves: cervical, thoracic, lumbar and sacral. The cervical and lumbar curves are convex to the front, and the thoracic and sacral curves are convex to the back. What is the role of these curvatures? Physiological curvature is suitable for people to maintain the stability of the center of gravity when walking upright, strengthen the stability of the posture, so that the spine is like a spring, the shock generated when walking, running, jumping weakened and disappeared, to prevent damage to the skull, brain and internal organs. What is the role of the physiological curvature of the spine The physiological curvature is an important structure of the normal human body. If people maintain incorrect posture or position for a long period of time or if they are overweighted or experience trauma, the physiological curvature disappears or changes, the protective effect of the physiological curvature on people is lost, and thus lumbar disc herniation, cervical spondylosis, and coccygeal disease occur, and neck, shoulder, lumbar, and leg pain and corresponding spine-related diseases occur.