An Anatomic Study of the Lumbosacral Region in Relation to Low Back Pain and Sciatica

Abstract

FOR MANY YEARS the syndrome of low back pain with associated sciatic nerve radiation has been a subject for investigationi. The complex anatomy of the lumbosacral and sacro-iliac regions, combined with nlumerous anatomic variations, has complicated the problem of etiology of this clinical entity.Two etiologic factors are now generally accepted as the basis for low back pain and sciatica. It has been conclusively shown that pain may arise in the joinits, ligaments and muscles of the lumbosacral region and be referred throughout the distribution of the sciatir-nerve. Pain may also arise from compression or irritation of the sciatic nierve at its roots. This may occur in the spinal canal, in the intervertebral foranmina where tlle nerve roots are in contact with the intervertebral jOintS, or alonig the course of the nerve after its exit from the spinal canal.This latter factor of compression of the nerve comiiponlenits has, in recent years, been emphasized by the widespread advocation of the theory of herniation of the intervertebral disk into the spinal canal. It is a fact, however, that compression or irritation of the nerves may as readily take place in the intervertebral foramina where the nierve roots anid ganglia are confined in a relatively smaller space. The anlatomy and relationships of the sciatic nerve comiiponients to the structures comlposing the intervertebral foramlina predispose to compression when patlhologic changes occur in this region.It was this fact which led Us to take tip the study of anlatomic anid patlhologic changes in the lunbosacral joints and foramina. Ten unselected lumbosacral spines were obtainied at autopsy, and dissected to determine the variations in anatomy and pathology which mlay affect the spinal nerves as they course througlh the foraminia. The fourth anid fifth lumbar intervertebral foramina were studied to determiinie: (i) The relative size of the nerves to the foramina; (2) the effect of swelling and effusion in the intervertebral joint capsules on the nerves and ganglia; and (3) the effect onl the nerves of variations in ligamentous or osseous structures in the region of the foramina.The fourth and fifth lumbar spinal nerves emerge obliquely from the spinal canal (Fig. i ). The nerve with its ganglion as it lies in the foramen is bounded above and below by the pedicles of the adj acent vertebrae, anteriorly by the body of the vertebra and intervertebral disk, posteriorly by the capsular ligamentum flavum. The capsular ligamentum flavum forms the 892

Butterfly vertebra. A case report and a short review of the literature

“…Cadaveric dissections performed by Larmon [10] proved that congenital malformations of S1 can be an independent cause of low back pain and sciatica by compromising the L5 or S1 nerve roots at the intervertebral foramen. He described 2 variants of S1.…”

“…He described 2 variants of S1. The first characterised by projections emerging from the posterior margin of vertebral body, causing impingement on the nerve root; the second characterised by a deep groove on the limit between the body and the transverse processes of S1, causing sharp bending and entrapment of L5 nerve root due to ligamentous fibres [10].…”

Intervertebral foraminal ligaments of the lumbar spine: anatomy and biomechanics

“…The earlier observations published [3,8,11,12,13] indicated that the ligaments occur in a random pattern and were distributed arbitrarily in nonsymmetrical patterns. In this study, the authors claimed that these ligaments were not anomalous and were probably developmental in origin.…”

Human osseous intervertebral foramen width

“…The osteometric assessment of the intervertebral foramen is just an approximate estimation of its in vivo size, which depends on soft-tissue and dynamic components (Bose and Balasubramaniam, 1984;Cinotti et al, 2002;Crock, 1981;Epstein et al, 1962;Fujiwara et al, 2001;Hoyland et al, 1989;Larmon, 1944;Lee et al, 1988;Lu et al, 2000;Magnuson, 1944;Mayoux-Benhamou et al, 1989;Stephens et al, 1991;Swanberg, 1915;Vital et al, 1983;Yoo et al, 1992;Yoshida et al, 1992). The lack of any soft tissue (which for this region includes nerves, lymphatic vessels, venous plexus, and arteries) could not be overcome in our study.…”