VII 



MECHANICS OF THE HEART 



199 



border between the first costal and second intercostal space) or in 

 that of the pulmonary artery (left sternal border, at the level of 

 the second intercostal space). (Fig. 61, Ad and As.) 



(b) Presystolic murmurs, the diagnostic sign of stenosis of the 

 right or left auriculo-ventricular orifice, according as it is more or 

 less audible in the region of the right ventricle (external border 

 of sternum at the level of the fourth intercostal space), or in the 



FIG. 61. Semi-diagrammatic figure of topography of the heart and its .relations with the lungs 

 and thorax. Vd, Auscultation point of right ventricle ; Vs, auscultation point of left 

 ventricle ; AJ, auscultation point of aorta ; Ax, auscultation point of pulmonary ; A, aorta ; 

 P, pulmonary artery ; cs, vena cava superior ; i, /, innominate artery and vein ; .<?, *, subclavian 

 artery and vein ; c, c, carotid arteries ; g, g, jugular veins ; pe, dotted line to show limit of 

 lungs in inspiration ; pi, continuous line showing limit of lungs in expiration ; 1-10, 1st to 

 10th ribs. 



region of the left ventricle (left mamillary line in the fourth or 

 fifth intercostal space). (Fig. 61, Vd and Vs.) 



(c) Systolic murmurs, the diagnostic sign either of insufficiency 

 of the venous valves (bicuspid or tricuspid), or of stenosis of 

 the arterial orifices (aortic or pulmonary), according as it is 

 more conspicuous at one or other of these four points. Systolic 

 murmurs are distinguished from the preceding by their greater 

 accentuation, since they are produced by stronger vibrations, and 

 by the fact that the thoracic walls vibrate along with them 



