242 FRANKLIN P. MALL 



ventricle, which ends in itself. My own dissections of the mus- 

 cle wall of the left ventricle, as well as MacCallum's, show that 

 all of the muscle bands arise in tendons either at the base of the 

 heart or in the papillary muscles which in turn are attached to 

 the tendon of the base through the valves. 



Returning now to the two main muscle bands which form the 

 horns of the vortex, it is found by separating them that the cavity 

 of the left ventricle is opened, as shown in fig. 4. This figure shows 

 that where the two main bundles lock there is a third bundle — 

 the so-called circular fibers of the heart. In order to separate the 

 bundles at this point it is necessary to remove this third layer 

 which is shown in fig. 7, BS\ as arising from the left side of the 

 left ostium and then passes into the septum through the posterior 

 longitudinal sulcus. It forms the deep bulbo-spiral band. In 

 fig. 8 a piece of the deep bulbo-spiral band, BS", is cut out to show 

 the course of the superficial bulbo-spiral band, BS, as it passes 

 through the septum. In studying this figure it is to be remembered 

 that the cut edge of the bundle marked X does not belong to the 

 deep bulbo-spiral bundle but to the superficial bulbo-spiral which 

 passes around the heart and enters at the apex. The position of 

 this cut is shown by the straight line X in fig. 6. It is also to be 

 observed that the deep bulbo-spiral band passes under the longi- 

 tudinal bundle of the right ventricle (figs. 8 and 9, LRV, which 

 arises from the aortic septum just below the medial cusp of the 

 tricuspid valve. 



The superficial layer of the deep bulbo-spiral band is shown in 

 fig. 9. The view is exactly the same as in fig. 8 with part of the 

 origin of the longitudinal bundle, LRV, from the aorta to the 

 right ventricle removed. It is also noticed in fig. 9 that the bundle 

 arises on the opposite side of the aorta marked as a cut end, 0, 

 in the figure (See also fig. 10, BS'). The course of the fibers is 

 also given which reminds us somewhat of Krehl's figures. 



In fig. 10 the large flap of muscle which is turned back is the 

 portion of the bulbo-spiral band marked A and B in figs. 5-7. It 

 encircles the apex in fig. 10, enters the septum, fig. 8, and passes 

 below the deep bulbo-spiral band, figs. 8, 10 and 12. 



