Where do most thrombi originate from?

Most thrombi originate from areas of turbulence in blood flow, particularly in veins and arteries. In the venous system, they commonly form in deep veins of the legs due to stasis, often associated with conditions like prolonged immobility. In arteries, thrombi frequently develop at sites of atherosclerotic plaques, where endothelial injury and turbulent flow occur. These conditions create an environment conducive to platelet activation and clot formation.