| Objective: it is well known that nerve root compressed by lumbar herniated interveterbral disc can induce clinical symptoms such as numbness, pain and muscle weakness. So effective decompressions for pressed nerve root are very important. There are many decompression methods such as disctomy, foraminotomy, vertebral lamina resection and facetectomy. The results of long follow-up was excellent, however, some patients recovered slowly. Some reasons can explain for this, among them, hypertension inside nerve root existed after removing the compression outside of nerve root was an important reason. So based on the intervertebral disc extraction, many scholars incised the endonurium of nerve root. After a long time follow-up, they got satisfied results. However, there is not much anatomic information for this surgeon, so we studied the L3-S1 nerve root in order to provide more morphological data for the surgeon.Material and Methods: (1) Twenty-five cadavers, aged 58-72 years, without prior spinal surgeon or deformity, were studied. First remove the erector spinae behind the lamina, expose the lamina and the facet. Then cut the interspinal ligaments to count the number of vertebrae. Next cut thespinous process and lamina of L3-S1 expose dura. (2) Use vernier calliper to measure the length, diameter of nerve root on both sides. (3) Incise the epineurium of nerve root with sharp knife, then measure the length of nerve root and the thickness of epineurium. (4) Split the durra from the midline behind, measure the length of arachnoid ligaments. (5) Separate the nerve root from the surrounding tissue, measure the intraforaminal ligaments. (6) Cut the nerve root on both sides then draw the dura up and measure Hoffmann ligaments. (7) Use HE methods to stain introforaminal ligaments, use FOOT, VG, WEIGERT methods to stain nerve root.Results: Anatomic Study: (l)The average length of L3-Sl nerve root was 17.5 +0.7mm ,21.1 ?0.8mm, 22.5 ?l.lmm and 25.4?.6mm respectively, the average diameter was 3.4 ?.1 mm, 3.9 ?0.2mm ,4.5 ?0.2mm and 2.9 + 0.2mm respectively . There was no stastical difference between nerve root on both sides. (2) The average length of L3-S1 nerve root sleeve was 2.6 +0.5mm, 3.8+1.0mm, 4.4 + 0.8 and 4.9+ l.lmm respectively; the average thickness of endonurium was 0.26 ?0.02mm, 0.29 +0.02mm, 0.28 + 0.02mm and 0.24 +0.01mm respectively. There was no stastical difference between nerve roots on both sides. (3) Arachnoid ligaments fixed nerve root inside dura. There were several kind of arachnoid ligaments included continuous kind, incontinuous kind and net-like kind, the continuous kind hadthe largest number of 108(64%), the number of incontinous kind was 56(28%), and the net-like ligament had only 1(4%); the average length of arachnoid ligaments was 13.5 ?2.2mm, the longest one was 28.68mm, the shortest one was 5.36mm, most of them was between 15-20mm, one of the cavers had no arachnoid ligaments at all. (4) Introrforaminal ligaments existed in every intervertebral foramen. They run certain angle with nerve root from the distal to the proximal. There were four ligaments which fixed nerve root to intervertebral disc, facet joint capsule and surrounding pedicles. Usually, the ligaments, which connected the nerve root with posterior capsule, were the most thickness one (97%). There were no ligaments surrounding SI nerve root, but there were some fibers connect SI nerve root with sacrum. (5) Hofmann ligaments stretch between the dura and superficial layer of the PLL. They originated from the axilla where the nerve root puncture the dura, attached to the PLL. There were usually two at each level. The average length of L3-L4, L4-L5, L5-S1 Hoffmann ligaments was 13.5?1.6mm,21.6?2.1mm,20.3?.2mm respectively. At L5-S1 level, they were very narrow, almost thread like, and they got wider as dissect cranially, at L3-L4, L4-L5 level they were 8.9 ?1.3mm and 5.7 +1.2mm respectively. (6) There were also some fibers connecting nerve root to dura, which could form a triangle; we called them nerve root trian... |
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