Straightening of the physiological curvature of the cervical vertebrae C4-C6 may be caused by cervical degenerative disease, ankylosing spondylitis, spinal deformity and other factors. 1. Degenerative lesions of the cervical spine: due to ageing, or long-term poor posture such as frequent head-down or desk work can cause neck muscle fatigue, and gradually appear cervical disc herniation, intervertebral space narrowing, osteophytes and other lesions, which can be caused by cervical spine curvature straightening. 2. Ankylosing spondylitis: rheumatic immune disease, is a chronic inflammatory lesion, the main lesion site for the sacroiliac joints, spine and peripheral joints, etc., can cause spinal joints hyperplasia and degeneration fusion, caused by the cervical spine physiological curvature straightening. 3. Spinal deformity: congenital spinal deformity such as cervical fusion, scoliosis, etc. can cause the cervical spine’s physiological curvature to become straight. Patients with cervical vertebrae C4-C6 cervical vertebrae physiological curvature straightening, if accompanied by neck pain and other symptoms, it is recommended to go to the hospital in time for examination, to clarify the cause of the disease and then standardized treatment.