Embolism from mural thrombus in the thoracic aorta.

Mural thrombus in the internal carotid artery is a source of emboli to the retinal and cerebral arteries, causing transient or permanent blindness and hemiplegia (Gunning et al., 1946b); thrombi in subclavian arteries damaged by cervical ribs form emboli which lodge in the digital arteries, inducing ischaemia of the fingers and thickened intima (Gunning et al., 1964a). Emboli from mural thrombi in the popliteal artery have been implicated in gangrene of the great toe (Ross, 1936). Mural thrombi on plaques of nodular arteriosclerosis are common in the abdominal aorta, but the frequency with which they form emboli to the abdominal or leg arteries is unknown, the paucity of published cases suggesting the event is either uncommon or unrecognized. Gross examples of a phenomenon are important because they