HEART. 



601 



valves are approximated in this manner appears 

 to me to be the much move probable opinion; 

 for when we examine the uniform position and 

 course of the musculi papillares and chordae 

 tendineae, more particularly those of the left 

 ventricle ; that the chordae tendineae pass from 

 each musculus papillaris to both lips of the 

 mitral valve, occasionally crossing each other; 

 and 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 

 floated up on a level with the orifice; and 

 further, when we also remember that the mus- 

 culi papillares contract at the same time with 

 the other fibres of the heart, we can scarcely 

 resist coming to this conclusion. Besides, if 

 the lips of the valves were floated up to the 

 orifice, a greater quantity of blood would regur- 

 gitate into the auricles during the systole of the 

 ventricle than in all likelihood takes place; 

 for as the lips of the valve must be widely 

 separated from each other when the systole 

 commences, it is evident that a less quantity 

 of blood must have passed through the orifice 

 before the lips are sufficiently approximated to 

 obstruct its further passage when these are 

 assisted by an active force, than when they are 

 merely passively brought together by the cur- 

 rent of blood passing in that direction. It has, 

 however, been supposed that the musculi 

 papillares do not contract with the other fibres 

 of the ventricles. lialler states* that on laying 

 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 

 unusual stimulus applied to the heart in cutting 

 its fibres across may have deranged the usual 

 order of its contractions. I have repeatedly 

 opened the heart in rabbits and waited until its 

 contractions had ceased, and on renewing its 

 movements by irritating the inner surface at a 

 distance from the cut edges, 1 have observed 

 that the columns 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 

 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 

 Mouvement du sang, p. 129. Memoires sur la 

 Nature sensible, torn. i. p. 379. 



t [The observations of the London Committee 

 appointed by the British Association to examine 

 into the motions and sounds of the heart confirmed 

 this view of the simultaneity of contraction of the 

 columnar earner and ventricular fibres. ED.] 



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 chordae 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 

 chordae tendineae 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 tendineae 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 chordae tendineae 

 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 argumentadduced 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 .f 



* All these experiments upon the action of the 

 columns 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 tf 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 " convinced that, in all cases in which the 



