Nerve Supply of the Lower Extremity
The leg is supplied by two major nerves. The Femoral nerve supplies innervation to the front of the leg, while the Sciatic nerve innervates the back of the leg. The iliohypogastric and ilioinguinal nerves innervate the groin region and are sometimes the cause of groin pain, but more often hip dysfunction or disc problems are the cause of groin pain. The lateral femoral cutaneous nerve innervates the lateral leg. The Sciatic nerve splits into the Peroneal and Tibial nerves which innervate the side and back of the leg respectively. The Saphenous nerve is simply an extension of the femoral nerve. The real issue though is which nerve root is being compressed since all of these nerves are made up of multiple nerve roots. Thus, since the Sciatic nerve is made up of nerve roots from L5 to S3, it is usually the case that only one nerve root is compressed and therefore pain may not be in the entire back of the leg but only in part of this region.