HEART OF BIMANA. 



>31 



Inner layers of heart-flbres. cxlxxxviii" 



414 



The interruption of such deep layers is frequent, both by change 

 of direction, as at 4 ; and by the decussation of fibres to form the 

 great mammillary columns, as shown in the section of such at CC, 

 fig. 413. The right layer 

 of septal fibres, though 

 continuous mainly with 

 the parietal fibres of the 

 right ventricle, curve with 

 their concavity toward the 

 left ventricle, and aid in 

 its compression. 1 



A conception of the 

 plan of arrangement of 

 the muscular fibres of the 

 ventricles may be helped 

 by the diagram, fig. 414. 



The course of the superficial fibres, round both ventricles, is 

 indicated by the band, Cpcaaa, from the arterial rings over the 

 fore part of the ventricles, 

 and by the band Cacc, over 

 the back part : both combine 

 to form the whorl CRC and 

 R, and gain the interior of 

 the ventricles forming the 

 septum, s, and the carneae 

 columnar, cc : the deeper 

 layers surrounding the left 

 ventricle, lv, are indicated 

 at rr, CpcaaaaC, and 

 Cpca. Traced from within 

 outward, the fibres from the 

 funicular fasciculus or 'rope,' 

 r, combine with others con- 

 tinued from the two great 

 carneae column ae, cc, of the 

 left ventricle, LV, to form 

 the inner series, CRC, which, 

 twining round the apex, 

 close the ventricular cavity, 

 and become superficial : then sweeping spirally from left to right 

 divide into two bands : the longer one first encircles the left ven- 



1 The fibres of the heart have attachments to fixed points in parts of their course, 

 rather than at definite beginnings or endings : and variations of description may bo 



m m 2 



Ideal type of arrangement of ventricular fibres; 

 Human heart, cxlxxyiii". 



