The Study Of The Anatomical Features Of Thoracolumbar Nerve Roots By Cross-sectional Anatomic And CT, MRI Imaging

Part I : The study of MRI of thoracic-lumbar Nerve Root sheath andrelated structures in vertebral canalObjective: Through MRI study of cadaveric and/or normally organismalthoracic-lumbar root and its path, to establish the optimal methods of MRI to displaythe length, diameter, location of nerve roots and their surroundings and to determinethe MRI appearances of individual structures on routine or oblique scan.Materials and Methods: Four cadaver and two normal specimens were chosen toperform MRI of horizon-axial, coronal, sagittal plane for nerve roots. The MRIappearances of nerve roots were observed. Clinical relevance of the position of theganglia is discussed.Results:1.the length, diameter of thoracic nerve roots from T10 to T12 vary indistinctively,the average incline of nerve roots approach approximately right angle;the length,diameter of nerve root sheaths become gradually long from L1 to L3, however, theincline of nerve roots(acute angle) apparently reduced .2.the length, diameter and incline of left and right nerve root sheaths are symmetricalby and large.Conclusions:1. The nerve root sheath is easier to be damaged by the length and diameterbecoming bigger.2. The ventral and dorsal nerve roots have more chance to be damaged when they get across spinal dura mater, however, the distance between each of them becomes closer along with level-descending.3. Disc protrusion or herniation directed to medial plane, easy to compress junior(below-level) nerve root, if protruded to lateral plane, especially adjacent to intervertebral foramina, to tend to compress superior(same-level) nerve root.4. From upper to below, spinal nerve root' s length much longer, more approximately to perpendicularity, the origination point from spinal cord much higher.Part II : Three-dimensional reconstruction of thoracic-lumbar roots andother related contents by high resolution computed tomography.Objective: hi order to meet the needs of studies in spinal column surgery on three-dimensional spatial structure and morphology of thoracic-lumbar nerve root. Materials and Methods: Experimental models were selected by the authors using thoracic-lumbar specimens from six adult cadavers. Successive 1.25mm thick CTM screening was carried out from T10 to L3 intervertebral space without any intervals. The serial two-dimensional CT photographical pictures so obtained were inputted into a computer and the three-dimensional images were reconstructed through image analysis system.Results: The experimental results, which aims at investigating parameters of Intervertebral foramina, indicate that the three-dimensional images of reconstructed vertebral canal and nerve roots were life-like. These images could not only reveal their three-dimensional infrastructure and morphology, but also be cut and composed together at any direction and section by taming and transpositioning along X,Y andZ axes.The shape, location and adjacency relationship of individual structures were determined. The sagittal width of the thoracolumbar intervertebral foramen increased gradually from T10 to T12, decreased gradually from LI to L3;the height of intervertebral foramen gradually increased from T10 to L3, and were significantly greater than the corresponding sagittal width from T10 to L3;the length of intervertebral foramen increased gradually from T10 to L3;the spinal nerve roots were located in the superior part of the intervertebral foramen and the space between them were larger in vertical orientation, smaller in sagittal orientation. Conclusions: The visual effect expressed by three-dimensional images reconstructed from two-dimensional pictures can play important roles in stereomorphologic, biomechanical and other studies in fields of anatomy, image analysis and clinical medicine.Part III : The cross-sectional anatomic study of thoracolumbar Nerve Root.Objective: Through the methods of cross-sectional anatomy, to determine theshape, location and adjacency relationships of thoracolumbar nerve roots on coronal,sagittal and axial plane and to provide the cross-sectional anatomic evidence forsurgery path and operation quality.Materials and Methods: Three specimens of cadaveric thoracolumbar vertebraecolumn were divided into three groups. Coronal, sagittal and axial celloidin sectionswere made to observe the shape, location and adjacency relationships of individualstructures.Results:l.Cauda equina, zygapophyseal joint, spinous process, vertebral body or arch,endplate, connective tissues, venous plexus in epidural space, intervertebral discherniation, tumor in vertebral canal can be displayed intactly in axial planes.2.The length, diameter and incline of ventral and dorsal nerve root relative to spinalcord, morphologic changes of root ganglion, intervertebral canal can be observed incoronal planes.3.Intervertebral foramina ligament, filum terminale, intervertebral disc, anulusfibrosus, nucleus pulposus can be displayed in sagittal planes.Conclusions:1. Through the study of cross-sectional anatomy, the display effect about shape, location and adjacency relationships of individual structures of nerve roots and lumbosacral enlargement on coronal, sagittal and axial planes were determined to provide the cross-sectional anatomic evidences for correctly differentiating the individual structures on CT7MRI images or during the course of surgery.2. Through the study of cross-sectional anatomy, integrated with gross anatomy, systematic anatomy and topographic anatomy, the occurrence rate, location, shape, size, origin and insertion, course and adjacency relationships of individual structures of spinal nerve roots were determined. Through the study of anatomic orientation, angles, axes of individual structures with osseous marks were determined, so these structures can be intactly and correctly displayed on medical radiologic images. The description of nerve roots and lumbosacral enlargement, Intervertebral foramina can be helpful for radiologists and surgeons to further completely understand the clinical values of thoracolumbar vertebrae.3. Lesions of spinal nerve roots resulting from stenosis of intervertebral foramen occur more frequently in the lumbar region than in the thoracic region and areusually found in routine plane.