• Yao-Sen Wu, Yan Lin, Xiao-Lei Zhang, Nai-Feng Tian, Liao-Jun Sun, Hua-Zi Xu, Yong-Long Chi, and Zhi-Jun Pan.
• Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
• Spine. 2012 Sep 15;37(20):E1232-7.

Study DesignA cadaver and radiological study.ObjectiveTo investigate the projection of nerve roots on the posterior aspect of the spine from T11 to L5.Summary Of Background DataUnderstanding the projection of nerve roots on the posterior lamina will help to determine the decompressing areas of lamina and avoiding unnecessary bony resection. It can prevent segmental instability and postoperative scar formation. No studies regarding this subject are available.MethodsFifteen formalin-preserved spine specimens were used for this study. After exposing the dural sac and bilateral nerve roots, small pieces of stainless steel wires were placed along the root sleeves from their points of origin, and then standard anteroposterior and lateral radiographs were taken. Parameters were measured directly on radiographs using the picture archiving communication system. Measurements included: (1) take-off angles of the nerve roots at the coronal (CA) and sagittal planes (SA); (2) distance from the origin of the root sleeve to the posterior midline (DM); (3) distance from the origin of the root sleeve to the superior (DS) and inferior margin (DI) of its corresponding lamina; and (4) distance between the origins of neighboring nerve roots (DR).ResultsThe CA statistically decreased from T11 (52.4° ± 3.13°) to L5 (25.8° ± 3.10°). An opposite variation tendency was observed in SA. The DS increased from 1.8 ± 0.32 mm for T11 to 5.84 ± 1.05 mm for L5. No consistent change was found at DI. The DR was largest at the L1-L2 interval (33.9 ± 1.40 mm) and it decreased progressively to L4-L5 (25.5 ± 2.40 mm). DM statistically increased from T11 (8.9 ± 1.51 mm) to L1 (10.9 ± 1.11 mm) and then progressively decreased until it reached a minimum at L5 (8.1 ± 0.83 mm).ConclusionThe precise projection of nerve roots to the posterior aspect of spine and intraspinal take-off angles at the sagittal plane have been presented. Surgical interventions of the lumbar disc and nerve root may benefit from this quantitative anatomical study.

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