Sciatica is the name given to pain which originates in the lower back and radiates to the buttocks and down the legs due to irritation of the Sciatic nerve. Sciatica is one of the most common causes of lower backache.
The sciatic nerve is one of the most important and big nerves affecting to the back and lower limbs. It emerges from the openings in the sacral vertebral bone (tail bone) and supplies muscles in the back and lower limbs. In sciatica, the openings in the sacral bone through which the sciatic nerve emerges, is narrowed, causing pressure on the sciatic nerve and resulting pain along its course. As this nerve supplies back and lower limb, there is backache and pain running down the legs.