This is neuralgia of the sciatic nerve. These are the two largest nerves in the body, composed of the tibial and common perineal nerves, bound together and containing elements of the lowest two lumbar and upper three sacral spinal cord nerves. Sciatica is felt as severe pain from the buttocks, down the back of the thighs, often radiating to the inside of the leg, even to the point of parasthesia or prickly numbness. Although tumours can cause the problem, far and away the most common causes are a lower back subluxation (responding to adjustment) or pelvic congestion and edoema (responding to laxatives, exercise, and decreasing portal vein and lymphatic congestion).