Leading Causes of Sciatica and Sciatic Nerve Pain
Sciatica is the name of the pain from when something—usually a herniated disc, but other causes are possible, too—compresses, irritates, or inflames the sciatic nerve or one of the nerve roots that eventually link up with the sciatic nerve. Translation: pain up and down your leg—you might feel it anywhere from your buttocks to your ankle.
Source: HealthCentral