Circulatory system the areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels empty into the right atrium of the heart. The heart itself is supplied with oxygen and nutrients through a small "loop" of the systemic circulation and derives very little from the blood contained within the four chambers. The general rule is that arteries from the heart branch out into capillaries, which collect into veins leading back to the heart. Portal veins are a slight exception to this. In humans the only significant example is the hepatic portal vein which
Patellar network Patellar network The patellar network (circulatory anastomosis around the knee-joint, patellar anastomosis, genicular anastomosis, articular vascular network of knee or rete articulare genus) is an intricate network of vessels around and above the patella, and on the contiguous ends of the femur and tibia, forming a superficial and a deep plexus. The arteries which form this plexus are the inferior medial and superior medial genicular arteries, the inferior lateral and superior lateral genicular arteries, the descending genicular artery, the descending branch of lateral femoral circumflex artery, and the anterior tibial recurrent artery. The genicular anastomosis provides collateral circulation to supply