What are the causes of the onset of lumbar disc herniation? There are many reasons why this disease develops, such as due to long-term strain, or some other reasons, in short, there are many causes of lumbar disc herniation, the following two aspects from the internal and external causes to understand. (a) internal factors 1, anatomical factors: the lumbar intervertebral disc fiber ring is weak, the posterior longitudinal ligament longitudinal length of the spine, strengthening the back of the fiber ring, but since the first lumbar plane below, the posterior longitudinal ligament gradually narrowed, to the 5th lumbar vertebra and the 1st sacral vertebra, the width is only half of the original. The lumbosacral region is the part that bears the greatest dynamic and static forces, so the narrowing of the posterior longitudinal ligament creates a weakness in the natural structure, making the nucleus pulposus easily protrude to the posterior sides. 2, intervertebral disc degeneration and developmental defects: the intervertebral disc can have different degrees of degeneration with the growth of age. After the age of 30, degeneration begins significantly, due to increased opportunities for weight bearing and spinal movement, the intervertebral disc is often subjected to extrusion, tension and torsional stress from all sides, thus making it easy for the intervertebral disc to dehydration, fibrosis, atrophy, decreased elasticity, resulting in imbalance in the internal and external mechanical balance of the spine, decreased stability, and finally due to trauma, strain, cold and other external factors resulting in the rupture of the fibrous ring from the inside out. This is the main reason for the occurrence of this disease. (B) external causes 1, injury and strain: especially cumulative injury, is an important factor causing the disease. Because the lumbar vertebrae are arranged in a physiological convexity, the intervertebral disc is thick in the front and thin in the back, when people bend over to carry heavy objects, the nucleus pulposus produces strong resistance tension due to the influence of weight, muscle and ligament tension, in this case, such as excessive lumbar weight or sprain, it is likely that the nucleus pulposus will break through the fibrous ring and protrude to the side and back, causing irritation or compression symptoms of the spinal nerve root, cauda equina or spinal cord. The intervertebral disc is deformed when bending or under pressure, at which point the disc’s ability to absorb water is reduced until the pressure is lifted, and the deformation and ability to absorb water can only be restored. If long-term bending work, or lumbar cumulative strain injury, resulting in long-term filling of the nucleus pulposus, the nutrient supply of the fibrous ring is also long-term shortage, coupled with increased muscle tension in the lumbar back, resulting in increased pressure in the intervertebral disc, so a slight external force can also cause the fibrous ring to rupture and cause the nucleus pulposus to protrude. 2, cold stimulation: long-term cold stimulation, so that the lumbar back muscles, vascular spasm, contraction, affecting the local blood circulation, which affects the intervertebral disc nutrient supply. At the same time, due to muscle tension spasm, resulting in increased pressure in the intervertebral disc, especially for the degenerated intervertebral disc, can cause further damage, resulting in herniated nucleus pulposus.