Intervertebral disc: Two adjacent vertebrae are connected by an intervertebral disc. The intervertebral disc is composed of a hyaline cartilage plate, a fibrous ring and a nucleus pulposus. The external part is the annulus fibrosus and the internal part is the nucleus pulposus. The fibers are formed by hard, dense gelatinous fibers, surrounded by the nucleus pulposus. 1, transparent cartilage plate transparent cartilage plate that is the upper and lower cartilage surface of the vertebral body, as the upper and lower boundary of the nucleus pulposus. It is separated from the adjacent vertebrae. The size and shape of the cartilage plate is comparable to that of the upper and lower connected vertebrae. The hyaline cartilage plate is associated with the growth of the vertebral body height, and it has the function of preventing the nucleus pulposus from protruding into the cancellous bone of the vertebral body. If the cartilage plate is destroyed, the nucleus pulposus can protrude into the vertebral body and form a nodule of Hsu-Mo on the image. The cartilage plate above and below the vertebral body without blood vessels is like the articular cartilage of other joints, which can cushion the pressure to protect the vertebral body and prevent the vertebrae from being subjected to pressure, and as long as the cartilage plate remains intact, the vertebral body will not undergo resorption due to pressure. The cartilage plate can also be regarded as a semi-permeable membrane, under osmotic pressure, water can diffuse to the non-vascular intervertebral disc. 2, fibrous ring in the upper and lower transparent cartilage plate surrounded by a circle of strong fibrous tissue, consisting of collagen fibers and fibrocartilage, called the fibrous ring, tough and flexible, is the most important tissue to maintain the weight-bearing intervertebral disc, and the upper and lower cartilage plate and the spinal anterior and posterior longitudinal ligaments are closely connected. Fibrous ring is wide in front and narrow in the back, consisting of multiple layers of fibrocartilage rings arranged in a circular pattern as concentric layers, the direction of the fibers are interlaced with each other, the innermost layer of fibers and the intercellular matrix of the nucleus pulposus are fused without obvious boundaries, attached to the edge of the vertebral body, around the nucleus pulposus, the layers are intertwined, not only to help wrap around the nucleus pulposus, prevent the nucleus pulposus from protruding outward, under pressure, and in all directions can do a wide range of This is the reason why torsion is easy to cause injury. 3, the nucleus pulposus is an elastic semi-liquid gelatinous material, 85% of the water and degenerative remnants of the notochord, including chondrocyte nuclei collagen fiber network structure, and rich in protein mucopolysaccharide, so it has elasticity and expansion, accounting for about 50 to 60% of the disc surface, the nucleus pulposus is generally located in the middle of the annulus fibrosus, more posterior, not absolutely in the center. The nucleus pulposus changes its position and shape with external pressure and has the effect of moderating the impact, it is confined within the annulus fibrosus and has the tendency to expand outward when pressure is applied.