I apologize if my reply is too long-winded. There are two sciatic nerves, one going to each leg. Actually, these are nerve bundles composed of many fibers feeding out from the lower spine. The components of each sciatic nerve join to form a large nerve-trunk that supplies the buttocks, thighs and lower legs. When nerves are irritated, they malfunction.
Sciatic nerves are no exception.
The sensory nerves not only send pain messages to the brain, but they also transmit information about heat, cold and body position. Ordinarily, the motor consequences indicate a much more serious prognosis. If the inflammation or nerve-pressure is not relieved, permanent nerve damage may result and the victim may become handicapped. Irritation of the sciatic nerve may occur at any point along the course of the nerve. Sometimes viral infections can cause sciatica, but any tissue can rub against the nerve to cause symptoms.