388. "We found nature often variable and inconstant with respect to the immissaries of the coronary arteries; we have now to observe that the same may be said of the emissaries of the coronary veins, which in fact open in the heart without following any ascertained law. Thus although they generally open within the sinus of the right auricle, near the cava, by two mouths, one superior, and the other inferior, yet sometimes they open only by one orifice, and this of large size, which immediately after separates into two; and not seldom they open by three orifices, which are always found proportionally somewhat smaller. We say proportionally, for there are certain fine and minute orifices of the coronary veins, many in number,... which vomit chiefly the blood returning from the roots of the larger veins and arteries, from the auricles, and from the base of the heart near and within a certain little venous canal,...[which is like an oblong valve placed upon many together of the little mouths of the veins]. 1
We can assert that we have very frequently seen three large trunks of the coronary veins running to the right auricle, and eructating their fluids through the before mentioned orifices; two of the trunks occupying the posterior parts of the heart, and one of them ascending from the apex in a right line, the other creeping from the left auricle, and from the adjoining walls of the left ventricle especially. The third trunk we found occupying the anterior surface of the heart, and bringing back the blood from the bundles of fibres belonging to the right ventricle. Nor is there a frequent diversity only in the number and situation of the orifices and branches; but also, and to a very great extent, in the valve, which Eustachius describes as like a new moon in shape, the larger orifice of the coronary vein being covered with it as a lid. And although it is for the most part single and solitary, and shields and defends either one, or two together, of the mouths of the veins, yet it is sometimes wanting entirely, the large orifice of the coronary vein lying quite naked and open.... And not only is one lunular or crescentic valve sometimes seen, but sometimes two, to correspond to the two orifices of the vein one valve being comparatively large, the other small, according to the size of the area of the orifices by which the trunks of the coronary veins open into the auricle.... The coronary veins distributed over the surface of the heart, appear to be somewhat more numerous than the arteries.... Those coronary veins that come from the fibres of the auricles, are shorter than those that come from the muscular texture of the ventricles, so that by the same law by which the blood runs through the coronary arteries into the parietes of the auricles, sooner than into the parietes of the ventricles, it returns through the veins from the auricles sooner than from the ventricles.... We seldom find valves in the larger trunks of the coronary veins, but always in the smaller branches, as we found to be usual in the arteries. (Ibid., prop. 42.)
"I am aware that the most celebrated anatomists of the present day, and especially Thebesius,... have shown that the passages and tubules that convey the blood from the larger coronary veins into the ventricles, assist these veins necessarily, either always, or when occasion requires.... We seriously affirm, that the first gleam of light on this obscure subject, broke in upon us about nineteen years once, in dissecting the heart of a mastiff. In this case, having opened the right ventricle lengthwise, and sponged it clear of blood, we happened to grasp the left ventricle in our hand, and to press strongly against the septum; and we saw very minute and slightly red drops of ichor issue slowly from certain little mouths in different parts of the septum and its vicinity. This immediately led us to doubt, whether nature had not opened obscure passages for the transit of the blood, from the left cavity to the right, and vice versa. But when afterwards I found, on opening the left ventricle, that the same thing occurred in it also, near the apex, as well as in other internal segments of the heart when strongly compressed, and especially where the veins had been secured, I was immediately roused to suspect the true nature of these diverticula. They are best shown by the injection of liquids into the coronary veins.... If mercury be injected into the arteries of the heart in a healthy state, it is seen to pass through the pores and minutest openings of the ventricles, but it does not so plainly issue by little jets as if thrown in through one of the trunks of the coronary veins.... The open diverticula of the veins are conspicuous within the cavities of the heart, and the attentive anatomist will easily detect them, if, through the different mouths or emissaries of the coronary veins that open into the right auricle and into the top of the vena cava, he gently throw in either air or colored water (for the trunks of the coronary veins have no valves); when he will soon perceive the injection not only oozing into the right and left cavities, in the form of bubbles and little drops, as it were of sweat, but sometimes gushing out in little jets. We selected more than once ... the lesser mouth of a coronary vein, which appears under the larger mouth generally near the root of the cava, and which is framed to receive the blood returning from the posterior parts of the heart, and thus from the middle septum especially. The water gently injected into this orifice by the syringe, much to our admiration, was seen to pass under the columns themselves towards the apex of the left ventricle. In like manner, when air was thrown into another vein occupying the external and posterior part of the heart, we immediately observed the columns in the left ventricle tremulous and vibrating, and bubbles rising in different parts. We selected also a third posterior vein, the liquor thrown in through which, came out by certain most minute roundish openings existing in the internal tunic of the right ventricle, towards its apex and middle septum. Neither did we neglect the other branches of the veins, for we threw in liquids through the anterior coronary veins also, and saw the right ventricle evidently moistened, and the transverse column particularly, or the fleshy beam, bedewed with drops. So that I could no longer doubt the existence of an intimate communication between the coronary veins and the two ventricles. We chose for experiment the hearts of horses, or else of oxen, such as had been slaughtered.... But we must candidly confess, that in the human heart we have seldom been able to see (as some have verbally described, and even represented in plates) the liquids injected through the twigs, issuing from the foramina of the ventricles. In the hearts of oxen and horses, however, we have observed it very conspicuously.... We ought not here to omit to mention, that on the internal surface of the left auricle, certain small foramina occur, which are diverticula of those veins that creep alone from the external surface of this auricle towards the sages, and diverticula, leading from the coronary veins into each of the four cavities of the heart, and that the blood makes use of these as outlets. (Ibid., prop. 44.) It is to be observed, that the orifices of the diverticula, which are numerous in both auricles and ventricles, are protected by no valves, but open freely and nakedly; so that others as well as myself have readily injected liquids with a syringe through these foramina, which liquids were diffused through the substance of the heart, or rather through the veins, and when they could not escape in any other way, regurgitated through the same orifices.... That the blood alternately goes in and out, with a kind of ebb and flow, through the before mentioned diverticula of the veins, seems to be proved by what we have observed in regard to the lips of these orifices. For these lips are not rough, uneven, or edged, but always smooth and polished; making it probable, that the liquids smooth down the margins of these little mouths by their alternate passage to and fro, as it were by the chafing of a fine and delicate pumice. (Ibid., prop. 46.)
"When we injected mercury through the coronary arteries of the heart of a dog, we not only found the larger, smaller, and capillary branches that ramified over the external surface filled with the injection; but in dissecting the ventricles, and the left especially, we saw the lacerti, columns, and cords of the internal surface, beautifully distended by the mercury, so that they shone like silver, and presented the appearance of transparent tubules, which, although perfectly sound, yet sweated all over with minute drops of mercury, and when cut into, let out the mercury in large quantities. (Ibid., prop. 52.) The nerves are applied to, implicated with, and inserted in, the coronary vessels in a wonderful manner.... But although it should not appear from their anatomy, that the nerves surround the coronary vessels with an ivied twine, and are applied to, implicated with, and affixed to them in six hundred different ways, and thus assist in the alternate protrusion of the blood from the external to the internal parts, and from these to the interior passages, nevertheless ... experiments would most clearly demonstrate that such is really the case.... If we take the heart of a man, dog, or sheep, we shall find it generally relaxed and flaccid, or as it were in a state of diastole, with the coronary arteries and veins very large and conspicuous. And if we slightly moisten it on the outside with boiling water, and inject it with the same, we shall immediately see it pass from diastole into strong systole, and the external coronary vessels become smaller and in a manner obliterated, while the nerves that more especially accompany and envelop the arteries, appear more conspicuous, and strive as it were against the coronary arteries." (Ibid., prop. 53.)
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