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wariis in the middie of their course, and bind the spirat fibres here and there. . . . But When the Spirat fibreS reach the apex, they maho asingle and lo se turn upon themSelves, and are carried inWards, and beautis ully constitute the inmost Sursace of the Ventricles, and especiallyof the lest ventricte, together With their tricuspid valves, so that it is doubiful whether this order of fibres is spetit on the internat substance of the auricles, vetiis and arteries, Or Whether it arises from that sub- Stanee . . . . For it iS evident enough, that the internat paris of the ventricles, and the tendinous cords of the above valve, ariSe DOm the Samesbres of Whicli the externat sursace of the ventricles is constituted. The second and much more Wonderfui mode of Weaving the fibres fortite production of the ventricles, is that whieli We observe is coveredand concealed as a treasure by nature, betWeen the bes ore mentionedbands of spirat fibres, Which We have described as mahing up srst theexternat, and then, by a further production, the internat sursace of thelieart. For other layers of many Linds of fibres, Whicli occupy the centre of the thichness of the walis, particularly of the lest ventricte, aro held closely Within the doubled bag of these fasciae. These layersos fibres talie a direction more or less inclined to the longitudinat diameter of the heari; so that some of them forni With it an acute
angie, SOme almost a right angie. But these as it Were bound fibres,do not run So as to pasS through the apex tuto the cavities, but they runbach sor the most part in arilly, but a litile inferioriy, to the circulartendolis placed at the base of the heari, from Whicli they arose exterioriy, but a litile superioriy. . . . The last and most beautis ut contriv-ance by Whicli the fleshy substance of the ventricles resisis the distractionand dissolution threatened by iis own motioris, is that rare Wicher-Work
Septum, are cunningly supported at the fame time that they are distinguiShed . . . . TheSe cysis, Whicli haVe a doubie cavlty separated by a partition, are so framed, that the Osier tWigS, to purSue the comparison, Which have begun to constitute the right Sinus, for instance, When they have reached the septum, are there tWisted, implicated and decussaled, not in Order to remain there, but to be prolonged onWardsto the opposite fide, and lo Weme and environ the lest eavity. . . . That nature has adopted the fame Liud of Wicker-Work in compacting the fibrous structure of the ventricles, is attested also by the columnar mus-cle like the chain We use in supporting houses) that is found within theright ventricle of the heari in certain quadrupeds, and especialty in the
OX. This muscie runs transversely frona the septum to the externat anil
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Ibid , prop. 3l.) We sp id above, that the lidari has four principallendonS, and these os a circular forin ; although the two that join theauricles With the ventricles, do not appear to euelOSe an eXa et circle. For aS those segments of them that a re connected with the arches of the auricles are truly tendinous in structure, so the inferior segmentS, hich
tendinous Substance of the tricuspid valves. We have labored assidu- OuSty to unWeave by ari, the structure of the circular tendonS, SO clOSelyWOVen RS it is by nature . . . . It occurred to us to macerate the beari in Vinegar, Whicli succe0ds well, provided it be the heari os a robustyOUth, . . . but not SO in the hearis of old men, Where the tendoris particularly that stand at the heads of the great arteries, are eXtremely
and are With the greatest difficulty unravelled. . . . By the term tendonwe are uot to understand a Something that is not muscular. For a ten- don iS a Very compaci adhesion and intertexture of attenuated fleshysi bres, more Or less strengthened by the addition os transverse villi;
rOW channeis of their Vesseis stud pores, and are theres ore in generalrather White than otherwise . . . . To return then to the Subjeci; thecircular tendoris we have spolien os, are formed by the prolongati0n, attenuation, and greater condensation of the fibres, of Whicli the wholemass both of the heari and great vesseis is made up . Thus is the fibres disposed upon the ventricles be regarded be re they are produced to the auricles and heads of the vetus, or contrari ise, ... We Shali clearly see that they form by a most beautis ut interweaving circular tendonS, but Whicli more closely approximate to the muscular texture. LikeWiSethat fibres are sent froin the ventricles to the large arteries, after form-ing the very 1irin and strong texture of the other two tendoris. Andalthough the structure of the four circular tendolis consists of Various fleshy sibi es, both mutuatly superimposed, and interWOven more Or leSStightly and crossWise; of the fleshy 1ibres of the beatis of the vetiis, and of the auricles, whicli pass into the ventricles, and So into the great arteries ; yet We ought to mention that the weaving of the circular ten- dolis in the confine belween the auricles and ventricles, is Someri lintdisserent froni that of the two other tendolis conjoining the VentricleSWith the great arteries ; for the sirst is more simple, redder, and leSSStrong, and hende but litile disserent in texture from a muscie ; but theother i S more compotinii, compaci, White and robust, and in a Word, iS
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internat, Strongest, and manifeStly tendinouS membrane) the tendonsiliat are continuous With the auricles and ventricles, bo held up to tholight, their structure appears like a Web, compOSed of various planos offlaments going oss in disserent directions. Thus On One sursace thesibres ruit froin the right of the auricles to the lest os the ventricies ;biit on the other frum the lest of the auricles to the right of the ventricles ;' While many again pass semicircularly, or are otherWiSe dispersed in Various Ways, Without Observing any ascertained laW, and Supportand strengthen the proximate planes. Wheres re these tendoris do Dotappear to differ in texture froni the ventricies or auricles, excepi in the comparative sueness of the fibriis, and their mutuat interlacernent anil adhesion. But the case is other ise With the texture Of the round tendoris, Whicli are between the heari and the large arteries, and whicli asit is stronger, so is it more indistinet than the texture of the ten-d iis be rementioned. I Will, however, candidly state the result of myobserVations aster repented experiments. The fibres, then, of Whichthe disserent planes multifariousty applied to the Ventricles are Composed, are collected into sinali and numerous bundies of an evidently tendinous character, and proceed to sortii these tendons ; and these blandies, orrather litile coriis, ever becoming smaller, are Wondersulty implicated With oach other by various decussations, and SO closely adhere together, and are so tWisted or contorted, that they have the appearance of tow,sorming an inextricabie farrago os fibres, Whicli is very Strong at theorifice of the aorta, but less robust at that of the pulmonary artery;tili the fame cords, emerging froin the tendonS, are in lOoser contactwith each other, and bee me more distinet in the texture of the arteries.. . . Nor muSt We Omit to mention, that certain Very Strong fascicles offibres from the ventricles, climb over the tendonS in decussating rows, and are inserted externalty into the larger arteries principalty in those places that ansWer directly to the subjacent adhesions of the semilianarvalveS. ΜOreoVer, as far as We have yet been able to See, these fasci-cles of fibres seem to penetrate deeply, and to inosculate With the othors that bind the abovementioned valves to the internat cavities of the arteries. Ibid., prop. 32.) Morgagni haS Openly aSSerted, that the semi- lunar valves are Strengthened at the very border With tendinous fibros, and are furnished below With numerous fleshy sbres. This We sonte time ago observed Very clearly in children, particularly in those Who haddidit aster attacks of hectic severi in Whom We 1 und these valves in-
Ex dextera auricularum in Sinistrum ventriculorum, altera vero e sinistru in dexterum, &C.
' See an allusion to this above, P. 372.- Tr.9
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crea sed to the fullest fige of Whicli their fibres and the Vesseis Uere susceptible. . . . In the po3t mortem examination of children, We foundeach connexion of tWo of the valves together, With the aorta, exhibitingR Very analogous appearance to the clitoris in female abortioris, for raisedand crested oblong sutures adhered to the arteries, with Whicli they were united by frui anil strong bands of carneo-tendinous fibres, conVeniently placed in each of the curvilinear angies of the valves; the loose bOrders of the valves boing thereby attached to the more solid walis of the arteries. But these fibrous bauds are produced further, and j0ined Withthe fascicles of sibres that . . . constitute the circular tendons. It is further to be observed, that the semiiunar valves have evidently tendinous bases rising a litile above the orisce of the heari, and circularly emboSsed as it Were by nature. Each of them likewise is furnishod in the middie of iis hordei as Arantius first remarhed, and MorgagniasterWarils shewed more clearly in an excellent figure) With certain roundisii nodules, whicli are Often cartilaginous and even Osseous in oldsubjecis. As they begin to harden, they appear about the fige of those tubercles called sties or hordeola, that grow in the corners of the eyes. . . . The tendinous teXture of the mitral and tricuspid valves, is more eastly shewn than that of the semiiunar valves ; since the former go tothe columns from nearly cylindrical muscies placed within the ventricles, and aster they arise, are dilaten and opened out into thin margins, Whichthey Who are unacquainted With the ultimate structure of animais, callmembranes, although they are true tendoris, Since they have a carneOmuScular Origin, and terminate in White cords, that contieet the orifices
we have hitherio suid of the circular tendons, must also, We thinh, beunderstood of the broad tendoris, denominated valves. Thus both themitral and tricuspid, and the semiiunar valves, are so sermed, that when laid bach they allow the blood to pass, but When ratSed, preVentit froni returning. The mitral and tricuspid valves, with their cords and reticular and scabrous bases, Whicli reniter nearly the whole internalsursace of the ventricles irregular and uneven,) are so directed, that Wheu the cardiae machine acquires a tension, and exercises a degree Of impetus at nearly ali potnts of iis cavities, . . . they the valves) m0Staccurately mingle the old cruor or blood with the refluent lymph, Miththe influent chyle, and with the air, or With those particles that are Secerned from the air. Ibid. , prop. 34.) We observe also that certain adipose bands are found disposed upon the coronary artery, and aroland
the four circular tendoris of the heart. . . . Nor must We Omit tonotice certain adipose sollicles, whieli, under the form os cinereOUS SPOtS,
here and there dapplo the internat tunios, both in the lest ventricle os
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strong and adult hearis, and in the beginning of the storta. Whon these follicles are priched With a lancet, Ue have found them containsat; and indoeil in the body of an illuStrious duke, . . . WhO died of inflammation of the natural and spiritual viscera, brought on by indolent habiis and high living, We saW them degeneraled into litile steatomota. For in the heart of this subjeci, both Within the right and test sinuses, there hung from the lacertuli of the columns, tubercles of a sub-cinereous hue, Whicli on being cut into, gere soland to contain concreteil sat. Ibid., prop. 35.) The fibres that invest the domes orarches of the auricles, are entirely muscular, and the nearer they are tot he d ors of the ventricles, the more they RSSume a tendino S character. In like maniter the auricles are larger in the scutal than in the insantheari; so that the right auricle is constantly broader than the lest . . . .
anceS, unless he lay doWn the folloWing anatomical postulates. I. Thatthe auricles placed at the fides of the base of the heari, are alternatelyrelaxed and contracted, and when relaxed, are filled With the blood descending froin the heads of the vetus. . . . II. That the aurieleS Rre almost the inverse of the ventricles in their siluation, and in the prO- duction aud direction of their fibres. For the ventricles have their baseand tendinous pari above, toWards the throni, and their apex Or muScular pari below ; While the auricles have their tendons below, or attho base of the heari, but their muscular paris Or domeS abOVe, Or to-wariis the throni. Thus it happens that every time the Whole quadri- cave muscle of the heari is strained and constricted, the auricles areseen to be depressed toWard the base, and to descend; and the ventricles to be elevated toWard the base, and to ascend ; so that the body of the heari, Which besore Was oblong, beeomes nearly round and spherical. . . . Finalty, We Should, Ι think, reminit the reader, that anatomisisare weli agrestit, that the blood moves sonteWhat more SioWly throughthe Vena cava towards the right auricle and ventriete, than through the pulmonary veiris into the lest auricle and ventricie. Ibid., prop. 37.)Harvey has observed, that in s me meri, that is, in those Who are ofhardy frame and Strong constitution, the right auricle is so robust, and so admirably furnished on the inside With sineWy cor Is and various iis- sues of fibres, that it seems to rival the ventricies of other subjecis ;and I Was sui priged,' says he, that there Should be so great a disseretice in disserent persons.' ' And again he says, With stili greater clearness: All these paris, constituting the praecordia,) constantly maintain a proportion to each other, for the more pOWerfui, muScular, and hardy the person, and the more robust, thicli, dense and fibrous
Exercitatio Anutomica de Motu Cordi8, caP. XVii.
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the heari, the more thicli anil strong in proportion are the auricles audaxteries ' Ibid., prop. 38.) Borelli' proves that the momentum os the force of the heari overcomes a pressure equat tO IS, 000 pouni S.
465. What Nicholas Steno relates that he has seen in experimentSupou rabbiis, namely, that the motion Os the superior caVa, Wheneven the heari and auricles had censen to move,) was stili Lept up by the mere pressure of the finger, and that the auricle Was moved by it,
we also have taken the palus to observe in the ViVisection Os horSeS. . . . FOr as both venae cavae in the horse are White, and ns Solid in appenrance as the aorta in the dog, their motion is beller feen than in other animais; provided that as sOon as the Sternum is remOVed, the peri- cardium be laid open. For in this case, the Vena cava is Sometimessound stili moving spontaneously, or is not, the application Of the warm fingers, or the waruith of the breath, is sufficient to restore it in a shortlime to iis natural temperature aud molion. Sometimes When Onlypunctured with a needle or With the potui os a lancet, the intermitted motion is again reneWed : and When the experiment Succeeds, the cava
moving like the intestines) mahes reciprocul peristestic constrictions and vibrations toWard the heari four or sive times, While the right auricle
ing iis bestis When priched With a needle, or stimulated by the application Of a Warm body, talies place also equalty in every part of thelieari, in the auricles as Weli as ventricies ; a single pricli, or the fresti contact of a Warm body, being sufficient to cause irregular palpitations and fluctuations there also; providen alWays that the heari has notgrOWn colit and Stiss. . . . During eXperiments made UpOn rabbiis, in the monti, of June, three bours after they had been operied, and Whenthe motion of the auricle had ceased, we saw the cava stili moving, and when iis branches were tied, and bl od Was let out through a puncture in the right ventricte, the motion of the two cavae Within the ligatures immediately ceased. But as SOOn as the ligatures Were loosened, and the blood was again admitted, We plainly saw the usual motion retiaruin the branches of the cavae, and this, both above, and belo towariis the right auricle. . .. We ought not to Omit to mention, that in theviviseetion Os s Wis, We SaW a vermicular motion in the branches of the cava frequently recurring, follo ed at length by a SlON contraction, Orfluctuation, of the ample right auricle and ventricte, although theruWaS no Spontaneous Stroke Or pulse in the lest auricle ; and when tho
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lest ventricle was laid bach, We could observe no motion in iis posterior Wali; although the segments of the heari moveil When punctured witha neeille; a sussicient proo that the occasionat cause as they say) of spontaneous tension in the right auricle and ventricte, consisted in thepowerfui pressure of the blood, Which Was urged toWariis the right chambers of the beari by the branches of the cava periStalti catly contracting. . . . Νearly ali the four Liniis of biriis,' have branches of the vena cava, Uust as Os the aorta,) that open into a Very Shori trunk, or as it may rather be considered, into the ample vestibule of the right auricie. In fossis, is the vivisection be rapidly done, We See as distinctly os possibie a motion towariis the auricle not only in ali thobranches of the cava, but also of that coronary Vein that ruris longitudinalty froin the cono Ι mean the apex) towariis the base of the heari,
so that the concussion os iis tunic seems to begin from the apex, andio continue Onwariis to the base. Ibid., prop. 56. 466. SΤΕ No. In a semate rabbit . . . di SSected in August . . . Imade Various observations t uching the motion of the auricles and cava
branches, and after tWo or three pulsations of the cava, the auricle moved once, but not always in the fame way: for Sometimes the motioncrepi in the border of the auricle, froni the luserior corner toWard the Superior; SOmetimes the fame border Was moved in the contrary direction, Or froin the Superior corner to the inferior; somelimes When theborder Was entirely at rest, a contraction Was observed in the middie planeas it Were of the auricle. In the heart of the pigeon I have also seena moti0n proceeding from One corner of the auricle to the opposite one.)When the three branches of the cava Uere tied, and ali the blood that was Within the ligature, in the cava and right auricle and ventricte, Was tot out through a litile opening made With a fine nostille in the bot-tom of the right ventricte, ali motion censed at orice, and One Would have suid that the whole of the paris were dead. But this state os restdid not continue long, since the fresti blood issued froni the vetus of
the heari, and stightly distending the collapsed tunius, produced a fresti
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began to languisti, the beats of the auricles as weli as Of the cava couldbe clearly distinguished froin that of the lidari: in faci, the motions Ofati three were distinct in psint of time. But When ine lieari Stopped,
the part of the auricle nearest the vena cava furvived sor a long time; and when the auricle also was quite motionless, the cma alone beatbelow the heari, exhibiting two entirely distinct motioris, one of WhichWaS Seen On the Oulside, in the remoter pari, the Other On the inside, in the pari nexi to the heart. What most excited my Surprige, as Iliave not observed it in any other subjeci, Was the circum Stanee that heu the right ventricte Was laid open, and emptied of blood, a motion stili continued in the coats of the velit, although noW completely collapSed, and the transverse fibres, one aster another, Were Stightly ele-Vnted thereby, SO as to present the appea rance of a thread carried tranSVerSely OVer the Vein, and proceeding towariis the heari: this motion had not ceased at two O'cloch in the asternoon, although I be-gan the vivisection ut uine O'cloch in the morning. I homoe Bartholini Aela Mediea et Philosophica Namnien8ia, Vol. it., an. 1673, n. HVi.
467. According to the observations os severat Writers, is the hearis os birds, Dogs, and other animais, be priched Mith any potnted instrument after death, Or even after being cut in pieces, they Will in acertain manner stili contract. The apex of the heari appears to bo a Very moVeable pari, as alSo the right auricle particularly, Whicli beatson being touched With a needle, and somelimes tahes On a peculiar vibration ; one portion frequently not vibrating With the portion contigvous to it, but the vibration somelimes solioWing in another and remoterpart. And a constrictile action may likewise be excited simply byWarnith, breuthing up0n the pari, or handi ing it between the fingersand palin. The motion Of the hestri may to a certain extent be recalledas ter death by throwing blood, Or Warm Mater, into the Vena CaVa, Orinto the jugular or subclavian vetiis, Or into the thoracic duci. Theheari may be eastly made to palpitate by agitating the vena cava neartho auricle : in Whicli case the auricle begius to palpitate, and Soon aster the ventricle also. And it has been observed, that Where the current
of blood through the lungs is interrupted, the right auricle has palpi
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addition to What has hitherio been suid respecting the blood, the
arteries and vetus, the primitive structure of the heari, theproper and coronary Vesseis of the fame, and the foetat circulation,-that We should e quire into the cause of the action Os thonerVes, as Weli as of the ganglia generat ly; and into the cause of the action of the intercostat nerve and par vagiam, Specificatly ; and into the cause of the action of the great cardiae pleXus, and the Derves that depend upon it, particularly; and moreOVer into the cause of the action os the muscies; for thelieari in ali respecis is a muSele. Aster a due consideration of these subjecis, We Shali learn, that the proximate cause of tho heari's diastole, is the continuat pressure and action Of the blood of the two venae cavae tapon theright auricle; and that the proximate cause of the beari S Systole is the extension of the nervolas fibres : so that When theblood acis, the nervous fibre yields; and When the nervous fibre
The cardiae machine is so constructed, that iis alternate motion depends upon, and is determined by, the auricles, and particularly the right auricle, as iis Wheel and lever; ConSequently Upon, and by, the intumescence of this auricie, Whenthe blood presses, acis, and floWs in; and upon, and by, iis detumeScence, When the nerves are extended. All the other
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Paris are So mutuatly connected, iliat Whichever comes intomotion, contributes to iis reciprocation. ConSequently eaeli,
together With the wholo, is Lept in sucti perfeci equilibration, that the smallust thing in veris tho hingo of the motion, and theresistance, Whicli in the natural state is very slight, is casily
Again, When the fame subjecis are rightly considered, Welearn What are the remoto efficient causes of the henrt's motion, namely, that the lungs, the cerebrum, the medulla oblongata, the medulla spinalis, and the cerebellum, ure sucii causes. The
Iungs, Since they admit and transmit tho. blood of the right sideos the heari, and Leep the praecordia in the universat motion. The cerebrum, since it propeis iis biood toWariis the jugularvulus by iis o u proper force, and Sprinlites into it the spiritu-
Ous fluid, and acts moreOver tapon the muscies of the body. The cerebellum, since it rolis doWn the blood, also by iis oWn properforce, and SO DOm a living Duntain, into the Superior Vena caUR; aud silis and animates the cardine nerves, und the nerves of the arteries nud vetus, With spirituous suid. The medulla oblongata and medulla spinalis, since thor transmit tho blood intoboth venae cavae, and through the agygos particularly, into the Superior Vena cava. And it is not necessary, that the moments of animation in any of these paris should coincide With the alternate moments of the heart.
Since then these are the remote efficient causes, it sollOWs, that the motion of the heari may be continued sor a time Without the assistance of any of them; but this time Will be longeror Shorter in proportion as the ubovementioned bodies are in theseries and connection os causes : in fine, just so long as thenervous fibres of the heari cau be maintained in their integrityand poWer of acting, to preserve them in Whicli is the peculiarossice of the cerebellum; and so long as the blood can be poured from tho living Duntain into the vena CRUR. FrOm these ground s, in connecti ou With those laid d0wn in