An Anatomical Study of Lumbar Posterior Rami Fibers and Their Bony Canals

Objective: To explore the anatomical structure of lumbar posterior rami fibers and their bony canals in order to provide solid data for clinical assessment of pain syndromes in the lower extremities and the establishment of the therapeutic regimen design for them. Methods: In 15 cadavers that met the criteria for this study,the lumbar posterior rami fibers were dissected,with the characteristic structure,distribution and the manner of branching of these nerve fibers,and their surrounding structures observed. The length,transverse and longitudinal diameters of the nerve fibers were measured using the sliding caliper. Results: The length of the lumbar posterior primary rami is( 6. 03 ± 1. 23) mm and the diameter is( 1. 18 ± 0. 09) mm. The diameters of the lumbar posterior primary rami and lateral branch are( 0. 83 ± 0. 21) mm and( 0. 46 ± 0. 57) mm,respectively. The lumbar posterior rami canal is the posterior extension of the bony opening for the lumbar posterior rami. The canal is formed as follows,the anterior border of the roof is the falciform margin of the intertransverse ligaments; the posterolateral portion is covered by the articular process of the superior interprocess ligament; the floor is the superior border of the hypostasy spondylous; the medial wall is the bone surface between the exterior margin of the hypostasy prezygapophysis and the root of processus transverses; the lateral wall is the medial margin of the intertransverse ligaments. The average length of lumbar posterior rami canal is( 5. 72 ±0. 94) mm. There are 3 shapes of exit for the lumbar posterior rami oval,elliptical and fissure. Conclusion: The lumbar posterior rami canal is narrow and solid; it functions to protect the lumbar posterior ramus that passes through it. The primary fibers as well as the branches of the lumbar posterior rami pass through the bony canal; any pathologic conditions affecting the shape of the canal will also induce compression on the nerve fibers. The distance between the lumbar posterior ramus and its bony canal and the posterior median line,and its depth from the body surface,can provide useful information for planning of such interventions as minimally-invasive internal fixation,small needle-scalpel procedure to relieve compression of the lumbar posterior rami fiber and selective procedures of fixed-point occlusion.