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381. But is it lived constantly in the vir, then, Since the aorta cannot be carried into the lest ventricle, or the pulmonam arteryinto the right, the anterior artery, or ductus arteriosus, could beciosed; and the triangular foramen, which is analogous to the foramen ovale os embryo' could allow a passage Dom the lest ventriole to the right, but nos Dom the right to the lese. The reasonis, that tho blood is then constantly determined Dom the pulmonary vein to the lest ventricte, Dom the lest ventrictu to theriglis, and so into the great arte . It is determinen also Domench cava luto the right ventricte, then into the third or intermediate ventricte, and then into the lungs. Neither is there any flux of blood D in the right ventricle into the lest, because such a direction Would be contrary to the stream. Hence thevalves are probably opened in the direction Of the current, and the valvo whicli opens Dom the right to the lest, and is suspended Dom the septum Os the auricles, may be overspread Withthe larger, in accordance With the description gi ven of it. Andiliis, the rather, because the right fide of the heari is iiself also furnished With two other valves betWeen the Venous sinus and the right auricle. The casu is disserent Willi rogard to the lest
Lest theresere any confusion Ahould arise in the circulationos the blood, in consequence of the frequent changes caused by the animal living under Water and again in the air, Or test either circulation Ahould become successive, as in those cases Where the blood is conveyed through the foramen Ovale and ductus ar
thut the foramen ovale of the foetus opens Dom the lest auricle into the right. In tho heari With three ventricles, the ratio is the inverse of What it is in the lidari With tWo ventricies; sorbere the storia is not in the lest ventriclo, but in the right, toWhicli the blood is necessari ly carried Dom the lest. Nor againi3 the pulmonary artery in the right ventricte, but in an intermediate ventriclo, into whicli tho blood si Ws Dom the right
Ventricte : because there is no immediate exit hom the lest ventricle tuto any arter .
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383. ' this mechanism of the heart of the turile, we areturight that this animal en Dys the actine and fuit life of the
rior artery is closed that sextunds immodiately to the descendilignorta, Or to the inserior members of the body n. 377, 38I , then
the bratus und their medullae, Dom Whicli it goveriis the forces of the members of iis body. 384. me are likewise lauyhi, that an animal with such aheari, is stimulated by a kind of natural instinet to inhale the atrwith open nostriis, and frequently to plunoe inlo the water, bliniis fullino into the cupidily whi h the necessity of iis oryanization im-p08es. It is of the ulmost importance to iis lise, that the two ventricies of the heart should not unite into one, and that there Should be no entire collapse of the lungs, Whicli are excited by tho blood enclosed above the valves of the pulmonary artery, toreSpire as Osten as the heari performs iis diastole; also that non eos the other members should bo deprived of their motion by the continuat pulmonary dilatation. We thus see Why the animal, ignorant of the causes that excite ii as by a bliud impetus, is impelled to thu pursuit os these disserent modes of lise.
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387. LANC1s1. It is to be observed in the sirst place, that thecoronary artery, Whicli arises hom the aorta Mithin the pericardium, moSi generalty by tWo branches, very rareb by three, or by one, sis byone, it immediately asterWards divides into two,) is so placed as to forman acute angle Mith the section of the aorta that lies between ii and thelieari; and there re it may perhaps be thought, as the direction of themotion of the blood propelled by the systole of the heari, is not in the
fame line With the direction of the coronary arteries, but On the contra forms SO acute an angle With them,-that Only a very Smali quantity of the stream can flow at that time, and in that direction, into the coronary arteries. But On the contra , &c. yc. . . . It Should by nomeans be overtooked, that of the branches of the coronary arteries, With the exception of those that nature dispenses to the adipose sollicles of the heari, and to the trunks of the great arteries and vetiis,)the srsi are distributed to the auricles, and the subsequent branches tothe Ventricles : consequently the passage of the blood running throuithe coronary tWigs froin the storta to the auricles, is a litile shorterthan that of the blood running to the ventricies. . . . It is to be Ob- Served that the coronary arteries, by their larger branches, Whicli sermWonderses anastomoses With each other, creep Over the externat Sursace
not penetrate to the inner muscular substance of the heari excepi by the minutest twigs. It Seems also Worthy of remark, that the largerbranches, whicli Occupy the externat sursace of the heari, are covered
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sors, they are seund to be marhed on the inside by minute irregularrugae ; and on this account admit os being eastly distended and enlargod both in longili and breadth. . . . Agian it is to be observed, that thecoronary arteries have no Valves at their immissaries ;' although Thomas Bartholin, because he happened tO meet Mith valves once or tWice, as Ιmyself lihewise have done,) presumes that they are to be found alWays. And indeod arteries of this kind require no valvular barriers to prevent the bicod Dom regurgitating into the aorta; Since the constant pressureand struggle of the blood in the aorta, is poWersul enough on every Sideessectualty to colanteraci the return of the bl od se m the mouilis of the coronary arteries. But this does not hold in the lesser branches of thocoronaries, which dip deeply into the muscular substance of the heari audauricles; sor here Me snd litile sphincters and valves beautifully and abundantly distributed. me Motu Cordis, &c., lib. i., prop. 39.) Aster attempting in vain by the introduction os a probe, and by other meanS, tofind any valves either in the orifices, or the larger branches, of the coronary arteries, it occurred to us to examine Some of the tWigs proceed-ing Dum them, after haring previolasty opened them With a lancet. Into these then me inserted a brisile, and on pushing it in the direction of the larger branches, we met With an obstruction. In Order to prove to Ocular demonstration What it Was that impeded the further progress of the brisue, and prevented iis entrance along the cavlty Of the branches, and to ascertain whether it Was a Valve, or anything elSe, We proceeded
Stance of the heari, together With the segment of the porta stom whichthey issued. These we delached with their large, tesser, and least and most delicate branches, to as great an extent as We could ; and we thenplaced the whole tree of vesseis in a basin os Water. Having done this, we observed ali the extreme vesseis, both by reason Os their minutenessand of the air they enclosed, spread about in every direction, and float-ing on the water, So as to present a beautis ut appearance, like portions of WindWeed, anise, or sennel; and we remarhed both in the larger and leSSer series of tubes a variety of phenomena. We observed first, that the great Stems of the coronary arteries, whicli surround the base of the heari, and reach to iis apex, ctoated in a spirat ordor and With a Spirat motion, and aster they Were taken out of the water, they couldbe extended to a much greater tength than when they adhered to thelieart. On injecting mercury into the coronary artery, it WaS curiOHSto See the larger branches hecome corrugated, and the Smaller Strangu-
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lated, as is by nervous threads . . . . When we stit up the trunks of the coronary arteries, and the larger branches proceeding DOm them, Refound the interior membrane much Whiter and thielior than in the other
arteries, sin whieli the arachnoid membrane is plainly seen) ; and Somuch SOfter, that When we attempted to puli it oss, it followed the fingors With more facili ty than in the case of any other artery. Itappestred that this Mas the case, because nowhere in the body arethe arteries placed in greater and more violent motion than in the heari; sor Whicli reason the externat membrane, as weli as the intermediate muscular membrane, falling as they do, So osten and So strongly, into contraction and distraction, are in a manner disjoined and separated froni the internat membra ne ; while the innermost membrane runs intonumeroUS rugae, Whicli in Some meastare persorm the Ostice of valves, and prevent the return of the blood into the aorta, as Weli as iis reaction Or reSistance a ferso. We Observed branches proceeding hom thetrunks of the coronary arteries, and tWigS DOm the branches, proportionalty more numerous and abundant than in the arteries of any othermuscle ; and not Without reaSon, for Since the muscular planes and DS-cipe are far more abundant in the heari than in any other muscle, it is necessary that each line and curve thereos, each bundie, and each fibre,
should be trached by litile arteries of iis own. We caresully noted theskill of nature in placing at the mouilis of each of the larger coronaryarteries, where they divided into the Suialter, a Lind of circular marginor border, and as it Were a delicate sphincter. . . . But at the litile mouilis of the lesser and least arteries that are distributed through, and buried within, one Or Other of the muscular planeS, We SaW ValVeS OP- posed, Whicli in faci prevented the regress of the blood from the lesserarteries into the larger. This arra gement seems to me to conduce ina remarkable Way to the systole of the heart. For When iis fleshyfibres begin to be stret hed, they are at the fame time increased in buth; . . . and lienee we find that Water injected into the coronary arteries, and diffused through the substance of the heari, never runs bach eVenwhen the heari is compressed; the contrary being the case in the Velias, through the mouilis of Which any liquid that is thrown in, SOOn regurgitates. But in order to See these valves olearly, we must Select thesmali arteries, and introduce into them a fine probe, or a brisile, gentlydriving it the wrong Way of the Vesseis, that is, toWard the largerbranches; for near each of the litile mouilis that open toWard thetrunks, We shali Observe even With the naked eye, that the membranes of the valves are raised, and the potnt of the probe or brisile impededand entangled. But is we stili pusti on the probe, we shali find it Hothed and covered With the membrane of the valve, Whicli is thus eX-
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panded by sorce. Ali these appearances are best seen in the heart of thohorse; ... sor here the VHVeS that hinder the passage of the probe, aroraised in every one of the SectionS Or origins of the smaller trutilis, tintilthey are either ruptured by larce, or elSe Opening out in a contra direction, give Way and Sheathe the probe. In like manner Smali sphinctersare here and there clearly observed in the twigs of the litile arteries, likellitie knois, whicli are Seen even in the last ramifications, so sar as themicroscope mill ensile us to solioW them. Ibid., prop. 40). Nature isso variable and inconstant in locating the mouilis of the coronary arteries, that a sew dissections only, especialty is made in the human subjeci,are Suffcient to present us Mith many VarietieS. . . . In thOSe perSODSWho during life had a strong pulse, We generalty found the orifices above the margins of the valves : in thOSe Who had a moderate pulse, We Observed them in the confines of the valves, or One Orifice placed above the valves , and the other below, as Morgagni also has noticed : Whilo in those Who had had a smali pulse, and particularly in Women, We found them for the most part opening bellind the margins of the valves. We have observed something Similar, but much more evidently, in brutes ;
immissaries ori a levet with the borders of the valves ; the animais in these cases being gentie of temper and domestic. In StoW-sooted, languid animal s, Such as Oxen and Sheep, We saW the orifices buried belowthe margins of the valves. But Whether any, and What, Variely, in the motion and flow of the blood through the coronary arteries, is produced by the variety of Siluation in the orifices, is a question Os Do
muScular, moveabie, and in great pari free, but nevertheless attachedio, and continuous with, the base of the heari, and in three places continuous with the parietes of the great artery. Thus when the heari salis into systole, these membraneS, aS partS of it, are neceSSarily ali ille contracted, and beoo me Shorter, as far as they can, both in tengiliand breadth, c. . . . In the vivisection of mastis 's, which have thoorifices of the coronaries above the margins of the valves,) When thethorax is opstned and the pericardium divided, We have Seen the corO- nary artery pulsating at the Same time mitti the storta, both belligexpanded and constricted simultaneousty ; and in like manner When punctured, the j et os blood froni both, and the interval between the j eis, Was Synchronous. But in Sheep, Which have the immissaries of the coronary arteries placed under the valves, Me SaW the aorta begin
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388. We Dund nature osten variable and inconstant With respectio the immissaries of the coronary arteries ; We have noW to ObSerVethat the fame may be said of the emissaries of the coronary VeinS, Whichin faci open in the heart without sollowing any ascertained law. Thus although they generalty open Within the sinus of the right auricle, nearthe cava, by tWo mouilis, one Superior, and the Other inserior, yet Sometimes they Open Only by one orifice, and this Of large sige, Whichimmediately after separates into tWo ; and not seldom they open by three orifices, Whicli are alWays 1 und proportionalty SomeWhat Smaller. We say proportionalty, for there are certain fine and minute orifices of the Coronary Veii S, many in number, . . . Whicli Vomit chiesty the blood returning froin the roots of the larger Veins and arteries, from the auricles, and se in the base of the heari near and within a certain litile VenouS canat, . . . Whicli is like an oblong Valve placed upon many to-gether of the litile mouilis of the vetus. ' We can asseri that we have very frequently seen three large truntis of the coronary Veius running to
the right auricle, and eructating their fluids through the be rementioned orifices; tWo of the trutilis occupying the posterior paris of the heari, and one of them ascending Doui the apex in a right line, theother creeping Dom the lest auricle, and from the aloining walis of thelest ventricle especially. The third trunk We found occupying the anterior sursace of the heari, and bringing bacti the blood Dom tho bundies of fibres bolonging to the right ventricie. Νor is there a frequent diversity only in the number and siluation of the orifices and branches ; butalSo, and to a Very great eXtent, in the valve, Whicli Eustachius describes as like a DeW moon in Shape, the larger orifice of the coronary
but somelimes tWO, to correspond to the two orifices of the vetii ; one valve being comparatively large, the other smali, according to the fige of the area of the orifices by Whicli the trunks of the coronary Veinsopen into the auricle . . . . The coronary Veins distributed Over the sur- face of the heari, appear to be SomeWhat more numerous than the nrterieS. . . . ThOSe coronary Veins that come Dom the fibres of the auricles, are shorter than those that come Dom the muscular texture of
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THE CORONARY VES SELS OF THE HEART, ETC.
the ventricles, so that by the fame law by Whicli the blood ruris throughthe coronary arteries into the parieteS Of the auricles, sooner than into the parietes of the ventricles, it returns through the vetiis from the auricles sooner than DOm the Ventricies. . . . We seldom find valves in thelarger trunks of the coronao vetiis, but always in the Smaller branches,as we found to bo usual in the arteries. Ibid., prop. 42.) I am aWare that the most celebrated anatomisis of the presentday, and especialty Τhebesius, . . . have Shewn 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 OceaSion requireS. . . . We SeriouSty affirm, that the firsi gleam of light on this obscure Subjeci, brohe in upon us about nineleen years since, tu diS-
secting the heari os a mastiss. In this case, having opened the right ventricle tengthWise, and sponged it clear of blood, me happened tografp the lest ventricle in Our haud, and to press Strongly against the Septum; and We SaW Very minute and Stightly red drops of ichor issueslowly from certain litile mouilis in disserent paris of the septum andiis vicinity. This immediately led us to doubi, whether nature hadnot opened obscure passages for the transit of the blood, from tho test cavlty to the right, and vice verasi. But When asterwarda I sound, onopening the lest ventricte, that the fame thing occurred in il also, nearthe apeX, as Weli as in other internat segments of the heart when Strongly compressed, and especialty Where the vetiis had been secured, I Was immediately roused to suspeet the true nature of thesediverticula. They are best shewn by the injection os liquids into the coronary VeinS. . . . Ιs mercury be injected into the arteries of thelieari 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 byllitie jets as is thrown in through one of the trunks of the coronaryVeinS. . . . The Open diverticula of the Veins are conspicuous Within thecavities of the heari, and the attentive anatomist Will eastly deieci them, is, through the disserent mouilis or emissaries of the coronary Vein S that open into the right auricle and into the top of the vena cava, he gently throw in either air or colored Mater, for the trunks of the coronary Veins have no valves) : When he Will soon perceive the injection not only oozing into the right and test cavities, in the forni of bubbles and litile dropS, as it Were of sweat, but somelimes gushing out in litile
Vein, Whicli appears under the larger mouth generalty near the root of the cava, and whicli is framed to receive the bl od returning si om theposterior paris of the heari, and thus from the middie Septum eSpecially. The Mater gently injected into this orifice by the Syringe, much to Our
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admiration Was seen to pass under the columns themselves toWards theapex of the lest ventricio. In like manner, When air Was thrown intonnother Vein occupying the externat and posterior part of the heari, We immediately observed the columns in the lest ventricle tremulous and vibrating, and bubbles rising in disserent paris. We selected also athird posterior vein, the liquor thrown in through whicli, came out bycertain most minute roundisii openings existing in the internat tunic of the right ventricte, togards iis apex and middie septum. Nei thor didWe neglect the other branches of the vetus, sor We throw in liquidsthrough the anterior coronary Veius also, and saW the right ventricle evidently moistened, and the tranSVerSe column particularly, Or the
verbalty described, and even represented in plates) the liquids injected through tho tWigs, isSuing from the foramina of the ventricies. In theliearis of hors es and OXen, hOWever, We have observed ii very conspicu-OUSty. . .. We ought not here to Omit to mention, that on the internalsursace of the lest auricle, certain Smali foramina occur, Whicli are diverticula of those vetus that creep along from the externat sursace of this auricle toward the right auricie. It is evident, theresere, frona avariety of well-conducted eXperimenis, that there are meanderS, Windirigi assages, and diverticula, leading froin the coronary vetiis into each of the four cavities of the heari, and that the blood malles use of these asouitets. Ibid., prop. 44.) It is to be observed, that the orifices of the diverticula, Whicli are numerous in both auricleS and ventricles, are protected by no valves, but Open freely and nakedly; so that Others asweli as myself have readily injected liquids With a syringe through these foramina, Whicli liquids were disrused through the substance of the heari, Or rather through the vetiis, and when they could not escape in
any other Way, regurgitated through the Same OrificeS. . . . That theblood alternately goes in and oui, With a Lind of ebb and 1l0W, throughthe bes rementioned diverticula of the veins, seems to be proved by What Ue have observed in regard to the lips of these orifices. For theselips are not rough, uneven or edged, but alWays sinooth and potished; mahing it probabie, that the liquids sm oth down the margins of thesellitie mouilis by their alternate passage to and fro, as it Vere by the chasing of a fine and delicate pumice. Ibid., prop. 46). When we injected mercury through the coronary arteries of thelieari os a dog, we not only found the larger, sinalter and capillata