Spinal column nerve stimulator. Coloured X-ray showing the wires (red/yellow) of a nerve stimulator in the spine of a paraplegic patient. The wires lead to a stimulator (not seen), implanted under the lowest rib. They enter the spinal canal through a hole cut between the 4th (L4) and 5th (L5) lumbar vertebrae of the spine (blue/purple, top left to lower left). L5 is directly above the pelvis (lower right), and below L4. The wires attach to the nerve roots of the sacral vertebrae S2-4 in L5. An external radio transmitter restores bladder, bowel and erection control. The kidney (upper right) is also seen.