| [Objectives]1 Morphological measurements of anterior branches of lumbosacral nerve 4, 5 and lumbosacral trunk, as well as adjacent relationship between nerves and sacroiliac joint, with the aim of providing anatomical evidences for lumbosacral plexus injury in clinic.2 On the basis of the technique of three-dimensional reconstruction, three-dimension(3D) graphics of anterior branches of lumbosacral 4, 5 and lumbosacral trunk, as well as pelvis are reconstructed , which can be demonstrated lively, directly and concretely and applied to clinical teaching conveniently.[Materials and methods]1 Anatomical investigation: 20 adult cadavers fixed and instillated with formaldehyde solution were dissected. In order to expose iliac fossa, psoas major muscles and inferior lumbar vertebraes, anterior wall of abdomen were dissected and turned over upward along superior borders of pubis and iliac bones. Then iliacus muscles were dissected from iliac fossa and psoas major muscles were resected. During these procedure, nerves and soft tissues connected to pelvis should be protected and must make them located originally. When sacroiliac joint was oxposed clearly, a Kirschner-wire wasinserted into front sacroiliac joint as a landmark. Then horizontal distances between anterior branches of lumbar nerves 4, 5, lumbosacral trunk(LST) and sacroiliac joint were measured with a caliper, as well as that of the width and thickness of nerves.2 Three-dimensional reconstruction: After exposing nerves and sacroiliac joints with methods above-mentioned in a specimen, mixture composed of Titanium powder and adhesive was smeared on the surface of nervus major branches of L4, L5, LST , obturator nerves and fermoral nerves. As soon as mixture solidifying, specimen was scanned by spiral computer tomography with 3mm thickness each slide. Finally, 159 two-dimension sectional images were acquired and processed with 3D-DOCTOR. Datas were analysed statistically. [Results]1 (1)The distance between the anterior branches of lumbar nerve 5 as it exits from the intervertebral foramen and the sacroiliac joint, the distance between anterior branches of lumbar nerve 4 branch and the sacroiliac joint at the level where the lumbar nerve 5 exits the intervertebral foramen, the distance between the beginning of the LST and the sacroiliac joint , the proximity of the LST to the sacroiliac joint at the promontorium and the proximity of the LST to the sacroiliac joint at the pelvic brim were as follows:(23.4+4.0) , (17.8+4.8) , (13.3 + 2.8) , (11.8 + 3.2) and (9.6+3.6) mm. (2)Among these distances, the shortest distance between the nerve and the joint is the one between the LST and the sacroiliac joint at the pelvic brim. (3) During dissection of the nerves, anterior branches of the lumbar nerves 4, 5 and the LST were found to be fixed relatively well to the sacral bone with fibrous connective tissue. (4) Anterior branches of lumbar nerves 4, 5 did not merge into the LST before entering the lesser pelvis separately in 3 cadavers (6 sides), with 15% its occurrence rate.2 Three dimension reconstructional investigation: (1)three dimentional images about L4. L5 LST and pelvis can be demonstrated lively, directly and concretely and can be rotated at random.(2)The distances between nerves andpelvis, width and depth of nerves measured on the two-dimensional images of spiral CT are: 25.4mm; 18.3mm; 14.5mm; 12.7mm; 9.3mm; 2.63mm; 1.32mm; 6.96mm; 2.84mm; 8.73mm; 2.86mm.All results measured on the two-dimensional images of spiral CT are in accordance with those from measurement. (Conclusions]1 To follow anterior branches of L4, L5, LST' migrating lateral and inferior, distance between the nerve and the joint became shorter at different levels. The shortest distance between the nerve and the joint is the one between the LST and the sacroiliac joint at the pelvic brim. Therefore, during the exploration and operation for fracture of posterior pelvic ring with or without injury of nerves nearby, extreme care should be taken to identify the L... |
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