Applied anatomy of lumbar nerve root canal stenosis and its clinical significance

Objective: To provide evidences for the image diagnosis and the selection of surgical approach of nerve root compression in lateral stenosis of the lower lumbar vertebral canal. Methods: The nerve roots were dissected and observed on 56 lumbosacral specimens. Results: The origins of compression were the medial margin of the upper facet and thickened ligamentum flavum in intraspinal area, the upper facet or/and bulging disc in foramina, the bulging disc or/and spur in extraforaminal area. In specimens without apparent bulging disc,the angles between the longitudinal axis of the dural sac and L4,5 nerve root were 40.4°±3.1° and 45.9°±3.7° respectively,while in 12 cadavers with bulging disc the angle were 67.0°±8. 2°and 69.6°±8. 1°respectively. Conclusion:The anatomical study is helpful for the explanation of abnormal manifestation of nerve root images and the understanding of compressive origins so that we can select appropriate approach and range of decompression during operation.