Pelvic spinal nerves. Historical anatomical artwork of the spinal nerves (white) in the human pelvic region. This side view (front of the body at right) is obtained by removing the buttock and other major muscles to show the sacrum (base of the spine, upper left). Bones (yellow), ligaments (white) and muscles (red) are also seen. The holes in the sacrum allow nerve branches to emerge from the spinal cord, but the thick white areas are mostly the spinal ligaments. One of the thick white areas (at lower centre, running vertically down into the leg) is the sciatic nerve, the largest nerve in the body. Artwork from The Nerves of the Human Body (Ed. Jones Quain, London, 1839).