Características anatómicas del origen de las arterias intercostales posteriores y lumbares y su relación con los síndromes de isquemia de la médula espinal.

Abstract

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It has been studied, in 27 individuals of both sexes died an age ranging between 37 and 82 years, the initial course of the segmentary arteries of the aorta descendens and the alterations that the atheromatous plaques of the dorsal wall of aorta produce at the openings of such blood vessels. The twisted initial stretch of the segmentary arteries and the total or partial closure of the aortic openings seem to be major factors in the production of ischemia in the spinal cord. The angle formed by the segmentary arteries with the aorta ranges between 100 and 150º. The more cephalic the vessel, the more obtuse the angle is. The histologic study of the intramural course of the segmentary arteries reveals that these vessels do not form an angle with the aorta but an elbow-like arch which is almost 90º. Having this and the diameter of the vessels in mind, the blood pressure, calculated according to the Reynolds' formula, shall range in these vessels between 8 and 10 cm. Hg. In addition, if the atheromatous plaques on the dorsal wall of aorta partially block the opening of the segmentary vessels, then the pressure would probably attain levels below the capillary-pressure values and thus the circulation would interrupted or at least it would slow dow considerably in these vessels. In all the cases of this report the dorsal wall of the aorta was found to be an elective place for the atheromatous plaques. In the elderly cases, it was found that all the openings of the segmentary arteries present its contour altered in greater or lesser degree by the atheromatous plaques. On some occasions it was found that these plaques blocked completely some of the openings. The most intensely affected are usually the low-thoracic and upper-lumbar segments.