[An observation on the micro-structure and form of annulus fibrosus of lumbar interverbral disc 4, 5].

We observed the structure and form of adult annulus fibrosus of lumbar intervertebral disc at the fibrous layer level. The annulus fibrosus of lumbar interverbral disc was delaminated by using microsurgical technique. 8 testing points were taken in each layer and the angles between their fibers going and horizontal plane were measured. The results showed that the fiber going angle at each measurement point continually increased with the increase of fibrous layer from outside to inside along the radial direction in horizontal plane. The least fiber going angle was 25 degrees - 30 degrees. The fiber going angle at the same layer gradually increased from front to back. The fiber going angle was 70 degrees - 90 degrees at the middle of the back of annulus fibrosus of lumbar interverbral disc. The fiber going was consistent with the posterior longitudinal ligament going. Through the normalized equation and normalized line, the fiber going angle at any point in any layer could be obtained conveniently. We also observed that the annuli fibrosus were interlaced in the front, left and right of annulus fibrosus of lumbar intervertebral disc. And there were more interlaced areas in local sides of lumbar intervertebral disc, but there was no interlaced areas between layers near the middle of posterior annulus fibrosus. So we came to the conclusion: Annulus fibrosus of lumbar intervertebral disc has a special micro-structure in adaptation with its function.