Ugh. The Webster 1913 definition does not do justice to what an embolus is.

In medical terms, an embolus occurs when a small fragment of something breaks off and gets carried away in the blood stream, ending up lodged somewhere else in the body.

Septic emboli occur when bits of bacteria get carried from one part of the body to another. These classically occur when there are bacterial vegetations growing on the heart valves, which can throw off small clumps of bacteria which then can start growing in other parts of the body, especially well perfused ones like the kidney.

Malignant emboli are little bits of malignant tissue (bits of a cancer) that get carried by the bloodstream, lodging in different parts of the body as metastases. Secondary metastases in the brain are almost invariably caused by emboli.

Thrombotic emboli can be either arterial or venous. In the venous circulation, deep venous thromboses can give off emboli that lodge in the pulmonary circulation, leading to pulmonary embolus. In the arterial system, thrombi arising in the atria of the heart or carotid arteries can throw off emboli to the brain, resulting in stroke.

Fat emboli occur when there is significant trauma, usually in a fracture of a long bone, and pieces of fat get carried around, blocking vessels in distant places.

Em"bo*lus (?), n.; pl. Emboli (#). [L., fr. Gr. pointed so as to be put or thrust in, fr. to throw, thrust, or put in. See Emblem.]


Something inserted, as a wedge; the piston or sucker of a pump or syringe.

2. Med.

A plug of some substance lodged in a blood vessel, being brought thither by the blood current. It consists most frequently of a clot of fibrin, a detached shred of a morbid growth, a globule of fat, or a microscopic organism.


© Webster 1913.

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