Pedicle origin and intervertebral compartment in the lumbar and upper sacral spine

Summary The osseous boundaries of the intervertebral compartment are described. Measurements of the pedicles demonstrate that their configuration determines the shape of the intervertebral compartment. The pedicles originate in the upper lumbar spine (L 1 and L 2) in a vertical direction from the posterior aspects of the vertebral bodies. In the caudal lumbar spine (L 4 and L 5) the origin of the pedicles is more oblique and thereby moves much more laterally and ventrally. As a consequence the horizontal extension of the pedicles is increasing in the lower lumbar spine. In the upper lumbar region the intervertebral compartment corresponds more to a foramen, in the lower lumbar spine more to a canal. The resulting clinical relevance for the length of the intervertebral compartment and the nerve root course is discussed.