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 anterior tibial vein forms a small network anterior to the tibia and collects blood from the tissues of the shin. The plantar venous arch sends its blood into the leg through the medial and lateral plantar veins into the posterior tibial vein, which ascends along the leg posterior to the tibia.