The famous term sciatica is commonly used to describe the unpleasant pain that travels along the sciatic nerve. The sciatica is a symptom caused by a disease that occurs in the lumbar spine. The sciatic nerve is the largest nerve in the body, about the diameter of a finger.
The sciatic nerve fibers of the call begin at the 4th and 5th lumbar vertebrae (L4, L5) and the first few segments of the sacrum. The nerve passes through the sciatic foramen below the Piriformis muscle (rotates the thigh laterally), passes through the posterior hip and bottom of the Gluteus Maximus (muscle in the buttock, thigh extension). Then, the sciatic nerve extends vertically downward and the back of the thigh, anterior to the knee branching into the hamstring muscles (calf) and further down to the feet.