Peritonitis is defined as inflammation of the peritoneum. The inflammatory response involves vasodilation, exudation of protein-rich fluid, cellular infiltration, pain and, chronically, formation of fibrous adhesion. The disease can be classified into primary and secondary cases.
It begins in the venous plexus along the medial side of the foot, and it runs up the medial side of the leg and knee, alongside the saphenous nerve. In the thigh, the long saphenous vein continues up the medial surface, accompanying the medial femoral cutaneous nerve.
The femoral nerve is the major nerve that serves the tissues of the thigh and leg, including the muscles and skin. While the much larger sciatic nerve also passes through the thigh on its way to the lower leg and foot, only the femoral nerve innervates the tissues of the thigh.