<prompt> The most common sourse of embolism -DVTTraumaInfectionSurgery  <response>: In greater than 95 of cases, venous emboli originate from thrombi within deep leg veins proximal to the popliteal fossa; embolization from lower leg thrombi is uncommon. Depending on size, a PE can occlude the main pulmonary aery, lodge at the bifurcation of the right and left pulmonary aeries saddle embolus, or pass into the smaller, branching aerioles . Rarely, an embolus passes through an atrial or ventricular defect and enters the systemic circulation paradoxical embolism Robbins Basic Pathology, 9 th edition, page 90 