Applied anatomy of the lateral approach to the vertebral lamina for treating extreme lateral lumber dsic herniation

Objective: To research the surgical approach in treatment of extreme lateral lumbar disc herniation from the view of microsurgery anatomy. Methods: Twenty adult cadavers fixed by formalin were selected. Thicknesses of intertransverse ligament were measured, and the distribution of anterior branches from lumber nerve and vessel were observed. Results: The thickness of intertransverse ligament was about 0.60~1.39 mm. More than 90 percent of segmental arteries and the accompanying veins from L3 to L5 were located ventrally in the superior portion of the intertransverse ligament. A branch from lumber artery permanently located in the middle of postero-lateral intertransverse ligament. The angle between the anterior branch of lumber nerve root and the midline sagittal plane was about 18.9°~39.2°. The distance from the inferior accessory process to the anterior branch of lumber nerve was about 5.63~8.05 mm, and from the lateral margin of vertebral arch isthmus to the anterior branch of lumber nerve was 1.73~3.64 mm. Conclusions: Intertransverse ligament is a reliable landmark for the surgical approach in treatment of extreme lateral lumber disc herniation, and the applied anatomy play an important instructive role in treating extreme lateral lumbar disc hemiation.