Fig. 41-1. Median section of the vertebral column, showing the different levels of the vertebral bodies, myelomeres, and spinous processes. The spinal cord ends at the Ll/2 vertebral level and the subarachnoid space at S1/2 level. Cisternal, lumbar, and epidural punctures are shown. As an example of a spinal nerve, the S1 nerve can be seen arising from myelomere S1 opposite the T12 vertebra, descending (as part of the cauda equina), and emerging from the first sacral foramen. Click for high resolution image.