ABSTRACT
Due to the difference in the rate of development of the vertebral column relative to the spinal cord, the spinal cord segments do not always correspond to the vertebral levels. In general, the rule of 2 applies to the vertebral levels T1-T10. In other words, the injured spinal segments are determined by adding 2 to the level of the affected vertebrae. Spinous processes of the T11-T12 vertebrae correspond to the lumbar spinal segments. Accordingly, the cervical spinal nerves exit above their corresponding vertebrae, while the remaining spinal nerves emerge from the vertebral column below the corresponding vertebrae. When the dorsal and ventral roots of the lower lumbar and sacral segments assume a longer course around the conus medullaris to reach the corresponding intervertebral foramina, the cauda equina is formed (Figures 3.1 and 3.2).
