70 



ARRANGEMENT OF THE VENTRICULAR FIBRES. 



Fig. 19. 



Course of the ventricular muscular fibres A, On the anterior surface ; B, View 

 of the apex with the vortex (Henle); C, Scheme of the course of the 

 fibres within the ventricular wall ; D, Fibres passing into a papillary muscle 

 (C. Luclwig). 



outer longitudinal fibres are so arranged as to cross the inner longi- 

 tudinal layer at an acute angle. The tranverse layers lying between 

 these two form gradual transitions between these directions. At the 

 apex of the left ventricle, the outer longitudinal fibres bend or curve 

 so as to meet at the so-called vortex (Wirbct) B, where they enter 

 the muscular substance, and, taking an upward and inward direction, 

 reach the papillary muscles, D (Lower) ; although it is a mistake to 

 say that all the bundles which ascend to the papillary muscles arise 

 from the vertical fibres of the outer surface : many seem to arise 

 independently within the ventricular wall. According to Henle, 

 all the external longitudinal fibres do not arise from the fibrous rings 

 or the roots of the arteries. 



[The assumption that the muscles of the ventricle are arranged so as to form 

 a figure of 8, or in loops, seems to be incorrect ; thus, fibres are said to arise at the 

 base of the ventricle, to pass over it, and to reach the vortex, where they pass 

 into the interior of the muscular substance, to end either in the papillary muscles, 

 or high up on the inner surface of the heart at its base. Figs. C and D give a 

 schematic representation of this view.] 



A special layer of circular muscular fibres, which acts like a true 

 sphincter, surrounds the arterial opening of the left ventricle, and 

 seems to have a certain independence of action (Henle). 



