Thrombi usually originate in venous cysts or pouches, and at acute bends on the vessel, especially when these are situated in the vicinity of the knee, and are subjected to repeated injuries--for example in riding.
The commonest forms of embolus are portions of thrombi or of fibrinous formations on the valves of the heart, the latter being usually infected with micro-organisms.
Fibrinous thrombi are apt to form upon the roughened surface of the inner coat or upon the surface of the erosions.
The small, wartlike excrescences occurring sometimes in endocarditis may occasionally form a foundation on which a thrombi may develop.
Thrombi occur as the result of an injury to the wall of the vessel or may follow its compression or dilatation; they may result from some alteration of the wall of the vessel by disease or by the retardation of the circulation.
In worm aneurism we usually find large thrombi within the aneurismal dilatation of the artery, which sometimes plug the whole vessel or extend into the aorta.
Fatty degeneration and calcification of the middle and outer coats may occur, and large, hard, calcareous plates project inward, upon which thrombi may form or may exist in connection with atheroma of the inner coat.
Thrombi may form in any of the arteries, and doubtless have been the cause of many cases of lameness which could never be accounted for.
The danger of this is greatly increased by infection, which breaks down the thrombi in the veins and arteries.
Exposure of aorta and its branches, showing location of thrombi in numerous places.
Aorta and Its Branches Showing Location ofThrombi 210 Fig.
The shape of the older parietal forms is usually globular or pedunculate, owing to the growth in all directions except at the place of attachment; the obstructing thrombi are elongated.
Thrombi are also characterized by consistency and relative absence of moisture.
Thrombi from dilatation are met with both in dilated arteries and veins.
The thrombi thus formed are further enlarged by the deposition of micrococci, which multiply, block up individual capillary loops, and invade contiguous tissues.
Allied to the traumatic thrombi are those which arise {59} from acute inflammation of the intima extending from wounds or inflammatory processes in the vicinity of blood-vessels.
The vascularization of thrombi surrounded by unbroken walls is most likely to result from the extension into the thickened intima of new-formed branches of the vasa vasorum.
The formation of thrombi in the uterine and pelvic veins is sufficiently common during the puerperal period.
The most frequent mechanical disturbance from the non-obstructing parietal thrombi of the heart and arteries results from the detachment of fragments and their transfer as emboli to remote parts of the body.
The fibrinous and fibrino-cellular products of the inflammation of serous surfaces are favorable positions for the deposition of calcium salts, as are thrombi arising from the walls of blood-vessels.
With the co-existence of abnormal endothelium and stagnant blood, thrombi form with greater frequency and become more voluminous in a given interval of time.
The thrombi are occasionally observed as firm fibrinous clots, but they may be likewise found in the rapidly fatal cases to have undergone suppurative changes.
Disturbances of the circulation, in the brain or elsewhere, may proceed from thrombi or emboli and give rise to complications which will render fatal an otherwise mild form of the disease.
Phlebitic thrombi do not necessarily break down, and may in that case act as a barrier to the progression of septic germs into the circulation (Spiegelberg).
Thrombi from compression are frequently formed in veins, in the vicinity of growing tumors.
The brain is usually normal; fluid may be in the subarachnoid space, and thrombi in the cerebral sinuses.
The former consist of pericarditis, endocarditis, and myocarditis; the latter embrace deposition of fibrin on the valves, temporary incompetence of the mitral or tricuspid valves, and the formation of thrombi in the cavities of the heart.
Ammonia--the carbonate and solution of the acetate--is indicated, and should be given for the purpose of dissolving thrombi and emboli.
Emboli may be lodged in the liver from thrombi formed in the peripheral distribution of the portal vein, or from distant parts of the systemic circulation, as in bone diseases.
Emboli derived from venous thrombi are sometimes carried into the pulmonary artery or its branches.
Thrombi may complicate the drainage, and if none can be obtained from several of the larger veins, tap the heart as a last resort.
When degeneration takes place, softening follows, and sometimes particles become dislodged and float off to set up thrombiin other viscera.
If thrombi have lodged in any of the larger arteries, the circulation to the part reached by the branches of the artery will be affected.
Such thrombi are found also in areas where extravasation has not taken place, and conversely, hemorrhages occur where no thrombi are demonstrable, so that a mutual causal relationship cannot be proved.
Thrombosis of vessels is found both in the neighborhood of hemorrhage and elsewhere, the thrombi at times completely occluding the vessels and giving rise to typical wedge-shaped infarcts.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "thrombi" in a variety of sentences. We hope that you will now be able to make sentences using this word.
