ON THE MOTIONS AND SOUNDS OF THE HBART. 275 



Second Report of the Dublin Sub-Cotnmittee on the Motions 

 and Sounds of the Heart. (See vol. iv. p. 243.) 



§ I. — The Dublin Committee for investigating the motions 

 and sounds of the heart, re-appointed by the British As- 

 sociation at their last Meeting, have considered tlie following 

 questions submitted to them by the General Committee of the 

 Association. 



1. Whether the muscular fibres of the columnae carnese con- 

 tract at the same precise moment as the mass of muscular fibres 

 of the ventricle ? 



2. What is the precise mode in which the tricuspid and mitral 

 valves prevent the reflux of blood ? Are they floated up and 

 stretched across the auriculo- ventricular orifices, or drawn to- 

 gether to a point within the cavity of the ventricle by the action 

 of the columnae carneae ? 



In order to solve the former of these questions the Committee 

 have several times repeated the experiment of opening the heart, 

 either while within the body of the newly killed animal, or sud- 

 denly removed from it and placed in tepid water, in the expec- 

 tation that the movements of the fleshy columns and of the 

 general mass of the ventricles might be compared by inspection 

 and their relations as to time thus ascertained. But in every 

 instance it was found that the injury thus inflicted upon the 

 heart caused its death so rapidly that no satisfactory conclusion 

 could be drawn from these experiments. 



Independently of any direct experiment on this subject there 

 are many considerations which, in the opinion of the Committee, 

 serve to prove that the question now under view should be an- 

 swered in the afiirmative. 



The fleshy columns which are attached to the valves, and 

 which have, for the sake of distinction, been called by some 

 ^'papillary muscles," differ from the other fleshy columns in the 

 circumstance of being connected to the svibstance of the ven- 

 tricle only at one of their extremities, while the otheris conjoined 

 to the " chordae tendineae," but their fibres are, equally as those 

 of the ordinary fleshy columns, continuous with the fibres of the 

 general mass of the ventricles. That the ordinary fleshy columns 

 contract simultaneously with the systole of the ventricles there 

 can be no doubt, as the shortening of those columns is neces- 

 sary to the completeness of the systole ; and as the papillary 

 muscles resemble the ordinary fleshy columns in the continuity 

 of their fibres with those of the ventricles, it is reasonable to 



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