A treatise on the blood, inflammation, and gun-shot wounds / by John Hunter ; with notes by James F. Palmer.

  • John Hunter
Date:
1840
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the blood, inflammation, and gun-shot wounds / by John Hunter ; with notes by James F. Palmer. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    166/618
    also elastic laterally [longitudinally?] from the direction of their fibres, which property shortens the artery when elongated by the blood, and I believe the muscles have little share in this action ; the whole of which tends to show that the elastic power is equal to the ask of producing, and really does produce, the natural state of the artery. What the direction of the muscular fibres may be 1 never could discover, but should suppose them oblique, because the de- gree of contraction appears greater than a straight muscle could produce, in which light a circular muscle is to be considered, as its effects are in the direction of its fibres ; for either the diameter or the circumference of the artery will decrease in the same propor- tion, but not the area, which will decrease in proportion to the square of the diameter. We should naturally suppose that, where the action of the heart is strong, elasticity is the best property to sustain its force; and that where the force and elasticity are well proportioned, no mischief can ensue. Where the force, therefore, of the heart is greatest there is the greatest degree of elasticity, which yields with reluctance, and constantly endeavours to oppose and counteract that force. From these active powers of an artery, together with a foreign power, viz., the blood, acting upon them and distending their parietes, in a manner somewhat similar to the common action of fluids in canals, we may perceive that there are three actions which take place, all of which operate in concert with each other, and produce one ultimate effect. . As the filling of the cavity of an artery produces an extension of its coats in every direction, the arteries are endowed with the elastic power, which, by contracting in all directions, brings them back again to their natural state. The action of the muscular power, being principally in a trans- verse direction, tends, when the artery is extended, to lessen its diameter, and assist the elastic power; but as its quantity of con- traction is superior to that of the elastic power, it does or may contract the artery beyond what the latter could effect. When the muscular action ceases, elasticity will be exerted to dilate the vessel and restore it to a middle state again, becoming the elongator or antagonist of the muscular coat, and by that means fitting it for a new action as described in other parts of the body. This will be most evident in the middle-sized vessels; for in the smaller, the proportion of elastic substance is not so considerable, and therefore it will contribute less to the dilatation of the vessel when the mus- cular coat relaxes. Yet we must suppose that no vessel even to its very extremity, is ever entirely collapsed; but that it possesses an elastic power sufficient to give it a middle state. Although these different structures do not always bear the same proportion to each other in arteries of the same size, yet we must conclude there is in these vessels a certain regular proportion preserved, and I am inclined to believe that the elasticity is in some degree in an inverse