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 supraorbital vein begins its course on the forehead, and it communicates with the frontal branch of the superficial temporal vein. The vein passes inferiorly, superior to the frontalis muscle and commonly joins the frontal vein at the medial angle of the orbital socket, to form the angular vein.