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 a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee.1  1 Structure. Anterior cutaneous branches: The anterior cutaneous branches comprise the following nerves: intermediate femoral cutaneous nerve and medial femoral cutaneous nerve (Note the lateral femoral cutaneous nerve is a branch from the lumbar plexus.).