Licence: Public Domain Mark
Credit: Heart / by John Reid. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![(ralves are approximated in this manner appears to me to be the much more probable opmioii; for when we examine the uniform position and course of the musculi papillares and chorda; . tendinea;, more particularly those of tlie left \ventricle; that the chordae tendineae pass from teach musculus papillaris to both lips of the ;mitral valve, occasionally crossnig each other; ;iand that the posterior or smaller lip, though it may be drawn inwards so as to meet the larger and more moveable, is so bound down as to be scarcely capable in most cases of being rfloated up on a level with the orifice; and [ further, when we also remember that the mus- iculi papillares contract at the same time with I the other fibres of the heart, we can scarcely rresist coming to this conclusion. Besides, if [the lips of the valves were floated up to the (.orifice, a greater quantity of blood would regur- •.gitale into the auricles during the systole of the wentricle than in all likelihood takes place; (for as the lips of the valve must be widely > separated from each other when the systole I commences, it is evident that a less quantity ' of blood must have passed through the orifice i before the lips are sufficiently approximated to k obstruct its further passage when these are ; assisted by an active force, than when they are I merely passively brought together by the cur- ; rent of blood passing in that direction. It has, I however, been supposed that the musculi ] papillares do not contract with the other fibres (of the ventricles. Haller states* that on laying I open the heart he has seen the muscles of the ' valves contract during the systole of the heart. It may be objected to this experiment that the 1 unusual stimulus applied to the heart in cutting i its fibres across may have deranged the usual I order of its contractions. I have repeatedly ( opened the heart in rabbits and waited until its I contractions had ceased, and on renewing its ; movements by irritating the inner surface at a 1 distance from the cut edges, I have observed I that the columnse carneae acted simultaneously ' with the other muscular fibres of the heart.f I • was also satisfied that the musculi papillares ' were proportionally more shortened during their I contraction than the heart itself taken as a ■ whole, which is nothing more than what we ■ would expect when we remember that the fibres ■ of the musculi papillares are so far free and run longitudinally, while by far the greater part of the other fibres run in a spiral manner. Haller, in relating his observations on the contraction of the musculi papillares, makes another statement, which, however, is decidedly adverse to this opinion. The chordae tendineae appeared to him to be relaxed during the con- traction of the musculi papillares. It is difficult to make satisfactory observa- tions upon the effects of the contractions of the * Elementa Physiolog. torn. i. p. 390. Sur le Mouvcment dii sang, p. 129. Memoires sur la Nature sensible, torn. i. p. 379. t [The observations of the London Committee appointed by the Britioh Association to examine into the motions and sounds of the heart confirmed this view of the simultaneity of contraction of the lunina; caracaa and ventricular fibres.—Ed.I musculi papillares upon the tension of the chordae tendineae. In several animals upon which we attempted to ascertain this, it was only when the heart was acting languidly that we could observe what was likely to be the effect of the contraction of the musculi papil- lares on the chordffi tendineae when they were placed as far as possible in their natural rela- tion to each other. We could never observe that they contracted sufficiently to move the valves, but they certainly rendered some of the chordas tendinece more tense. When, however, we take into account, that in an experiment of this kind, the valves are not thrown out widely from the orifices of the auriculo-ventricular orifices, the ventricle is not distended with blood, the chordae tendinea consequently not put so far on the stretch as occurs at the com- mencement of the systole, and that the con- tractions of the musculi papillares are languid, we can easily perceive how, in the natural systole of the heart, these contractions of the musculi papillares should be sufficient to move the valves inwards, though not to such an extent as to apply them closely to each other. The con- traction of these musculi papillares apparently sets the valves in motion, and they are subse- quently applied to each other by the currents of blood. It may be supposed that if the con- traction of these musculi papillares can render the chordae tendineae sufficiently tense to move the valves, this would prevent the subsequent elevation of them to obstruct the auriculo- ventricular opening. We believe, however, that it is only at the commencement of the systole that they are sufficiently tense to move the valves, for as the contraction proceeds the capacity of the heart is so much diminished, both in its transverse and longitudinal dimen- sions, that they become relaxed. Besides, if we could suppose that these musculi papillares are capable of contracting through a sufficient space to draw the valves together, this would be all that is necessary to prevent the regurgita- tion of the blood through the auriculo-ventri- cular opening.* So convinced, indeed, were the older anato- mists and physiologists that the chorda tendinea are relaxed during the systole of the heart, and of the necessity of an accompanying diminution of the length of the ventricles themselves to effect this, that this argument adduced by Bassuel appears to have been principally instrumental in deciding the once keenly controverted ques- tion whether or not the heart was elongated during its contraction.^ * All these experiments upon the action of the cohimniB carneae were finished and the article forwarded to London about the middle of June, 1836. t Mr. T. W. King in an elaborate essay (Guy's Hospital Reports, No. iv. April 1837,) has pointed out what he conceives to be a safety-valve func- tion in the right ventricle of the human heart. This view is founded upon the fact which he be- lieves that he has ascertained, that the tricuspid valve, naturally weak and imperfect, closes less and less accurately, according to the increasing degrees of the ventricular distention. From this he is r.unvinced that, iu all cases in which the](https://iiif.wellcomecollection.org/image/b21908503_0029.jp2/full/800%2C/0/default.jpg)
