http://www.copperjoint.com/sciatic-nerve-pain-better-explained/

Medical term: Sciatica is technically also known as radiculopathy. The technical definition of this term is that the nerve root in the lower back is being pinched or irritated either by a herniated disc, spinal stenosis or a lower back disorder. The nerve runs from the lower back through the back of each leg and goes to the other parts of the leg, foot and toes, which is the reason why pain is felt not just on the sciatic area but can crawl down to the buttocks, thigh, calf, foot and toes.