o Formed in rapidly-flowing blood of aeries & hea o Coronary (most common), cereberal & femoral aeries o Due to endothelial injury by turbulence o Usually mural not occluding the lumen completely o In retrograde direction o Grey white o Distinct lines of Zahn composed of platelets, fibrin , RBC & WBC o Ischemia leading to infarcts e.g., of brain, hea o Less common o More common Venous thrombi o Formed in slow moving blood in veins. o Superficial veins of lower limb, deep veins of lower limb --> femoral, popliteal & iliac. o Due to stasis o Almost invariably occlusive o In antegrade direction towards the hea. o Red-Blue o Lines of Zahn are not so distinct (mainly RBCs) o Edema, ulcer, poor wound healing Also know about the following terms. o Lines of Zohn Characteristic of thrombi that is formed in hea or aoa. They have visible and micoscopic laminations produced by alternating pale layer of platelets mixed with fibrin and darker layer containing red blood cells. Their presence implies thrombosis at a site of rapid blood flow. In veins or smaller aeries, where flow is not rapid, they are less apparent. o Mural thrombi --> When aerial thrombi arise in hea or aoa, they usually adhere to the wall of underlying structure and are termed as mural thrombi.">