Anatomic Observation And Its Significance Of L4-L5 Intervertebral Disc,Intervertebral Foramen And L4 Spinal Nerve

[Objective] observe the configuration and traits of L4- 5intervertebral disc and foramen,and the L4 spinal nerve,in order to clarify the spatial relationship and significance between the three,so it can be a reference for diagnosis of L4-5 lumber intervertebral disc herniation, providing morphological data for operation planning of the percutaneous lumbar vertebral disc centesis. [Method] Measurement and macroscopic investigation were performed on the region between L4 and L5 intervertebral body from 15 embalmed cadaver specimens. Dissect the L4-5 intervertebral foramen region. Ascertain the position of L4 spinal nerve root at the out orifice plane, regarded as a clock, which belongs to the intervertebral foramen. Remove the back wall of the following part of T12 intervertebral body of spine. Divide the targeted intervertebral disc into four parts averagely with three transverse planes. Measure the maxima of transverse and sagittal diameters, perimeters and area of the intervertebral disc and nucleus pulposus at different planes, also the width of anterior and posterior longitudinal ligament. Measure relative angles of L4 nerve root. Determine the distance form the back edge of nucleus pulposus to L4 nerve root. Simultaneously, measure the sectional area of the spinal nerve at the out orifice,the plane area of the out orifice and the area the safe triangle. Observe the puncturing plane,angle and depth.[Result] there is no statistical significance of the maxima of transverse and sagittal diameters, perimeters, areas and width of anterior longitudinal ligamentum between the superior, median and inferior sections. The area of nucleus pulposus is 35%~50% of that of intervertebral disc. The maximum is at the medial plane. The back edge of nucleus pulposus is near to L4 nerve root at the intervertebral foramen. The angles between nerve root and spinal dura mater are from 2.6o to 51o. The clock position of L4 nerve roots are 7:00-7:30 on the left and 4:30-5:00 on the right. The puncturing plane,angle and depth: puncturing by a needle, we adopt a direction that forms a 40o-45o with the coronal in horizontal, locate the point of the needle at the center of the intervertebral disc in coronal plane, at the 2/5 point from the back edge of it in sagittal plane.[Conclusion]1.The safe triangle that is composed of the low edge of L4 spinal nerve, the above edge of the down pedicle of vertebral arch and its superior articular process is the main anatomical structure of puncturing canal in PLD. In the research, we adopt the colock distribution type to observe the tracing route of L4 spinal nerve at the out orifice. So we can ascertain the probable area of the safe triangle, furthermore the area of the safe triangle that we got is 93.25±7.4mm2,it can guide PLD.2. In PLD,we adopt a direction that forms a 40o -45o with the coronal in horizontal, locate the point of the needle at the center of the intervertebral disc in coronal plane, at the 2/5 point from the back edge of it in sagittal plane. This research will improve the accuracy of puncturing and reduce the complication of PLD.3.In the connection between the back edge of nucleus pulposus and the spinal nerve, the direction distance of the back edge of nucleus pulposus to out orifice and inner orifice of intervertebral foramen are less than that of the back edge of nucleus pulposus to the spinal nerve transverses the spinal dura mater. This is the cause that the spinal nerve is often pressed at the orifice.