The murmur of mitral regurgitation is heard principally in three locations, namely, about the point of maximum impulse, over the upper portions of the chest to the left of the sternum, and over the back of the thorax in the region about the lower angle of the scapula. The discussion started by Naunyn1 in 1868 regarding the cause of the murmur in the second left intercostal space, and continued by Curschmann,2 Balfour,3 Russell,4 Bramwell,5 Gibson6 and Mackenzie7 has been reviewed by G. A. Gibson.
In the back, explanations of the presence of the murmur have been offered by Duroziez8 and also, among others, by Hirschfelder.9
At the apex, however, where the propagation is opposite to the direction of the regurgitant stream, though there has been much speculation, no serious experimental proof has been adduced to explain the clinical findings.
De SAUTELLE WT, GREY EG. THE RELATION OF THE PAPILLARY MUSCLES TO MITRAL REGURGITANT MURMURS. Arch Intern Med (Chic). 1911;VIII(6):734-746. doi:10.1001/archinte.1911.00060120020002