While 35 million Americans suffer from back pain, CT and MR are effective in diagnosing only a fraction of cases of back pain and sciatica. Painful conditions of the disc and facet joints, and some cases of central and lateral spinal stenosis are likely underdiagnosed by conventional CT, MR and radiographic studies. The aims of this project have been to improve the diagnostic usefulness of CT and MR by means of precise anatomic/tomographic correlations. The correlations have identified signs by which various defects in the anulus fibrous, nucleus pulposus, ligamentum flavum and facet joints can be demonstrated with tomographic imaging. The most valuable contribution of the work to date, according to previous reviews, was the use of biomechanical techniques to model the changes produced in the spinal canal and neural foramina by loads and stresses that may be produced by normal activities. The hypothesis of this study is that central and lateral spinal stenosis are underestimated in CT and MR because patients are recumbent during the acquisition of the images. We propose in the renewal to model extension, flexion, lateral bending and rotation of the spine in cadaveric specimens. Loads will be applied with biomechanical techniques to the spine to simulate movement of the spine, displacements will be measured with kinematic techniques, and changes in anatomic relationships of the discs, facet joints, ligamentum flavum, transforaminal ligaments, and nerve roots will be studied by means of CT, MR, and cryomicrotomy. The loads and displacements and anatomic situations which result in spinal stenosis will be identified. The study is likely to provide information on the causes of radiculopathy. Except in our studies of the spinal canal and neural foramen, the transforaminal ligaments, which reduce the space available for the spinal nerves, have been disregarded. Specifically, patho-anatomic changes in the neural foramina and spinal canal will be identified in which stresses such as upright position, weight bearing, and other activities may critically narrow the neural foramina or affect spinal nerves.