The existence of physiological curvature is a relative term, compared to the straightening of physiological curvature or the disappearance of physiological curvature, the existence of physiological curvature is a normal phenomenon and is not a pathological state. Under normal circumstances, the cervical, thoracic, lumbar and sacral vertebrae are called cervical curvature, thoracic curvature, lumbar curvature and sacral curvature, and different vertebral segments will bend in different directions. It is a normal curvature similar to the S-shape. The cervical and lumbar vertebrae have forward physiological curvature, but if these two physiological curvatures disappear or become straight, it means that there are pathological changes. Clinically, it is more common to see a straightening of the physiological curvature of the cervical spine or an inversion of the physiological curvature, indicating that cervical spondylosis is already present. The loss of physiological curvature of the lumbar spine is mostly due to changes in physiological curvature caused by a variety of diseases, such as severe acute lumbar sprain or painful stimulation of lumbar muscle strain. However, the examination of this kind of film and the judgment of the change of physiological curvature are a general understanding of the whole disease, and further examination is needed to clarify the characteristics of the disease according to the clinical symptoms or if necessary.