172 



THE CIRCULATION OF THE BLOOD 



to-left direction. At the apex they extend up into the deeper tissue. If 

 the superficial muscles are dissected off, there is left a great central core of 

 muscle, which is described by MacCallum as running more transversely 



* 



FIG. 139. 



FIG. 140. 



FIG. 139. Diagram of the Course of the Superficial Muscle Layers Originating in the 

 Right and Left Coronary Sulci and in the Posterior Half of the Tendon of the Conus. 

 C, Anterior papillary muscle. (After MacCallum.) 



FIG. 140. Diagram of the Course of the Superficial Muscle Layers Originating in the 

 Anterior Half of the Tendon of the Conus. A, Posterior papillary muscle; B, papillary 

 muscle of the septum. (After MacCallum.) 



FIG. 141. 



FIG. 142. 



FIG. 141. Diagram of the Course of the Layer Superficial to the Deepest Layer of the 

 Muscle of the Left Ventricle, which is shown in outline. The deepest layer is also shown. 

 A, Posterior papillary muscle; B, papillary muscle of the septum. (After MacCallum.) 



FIG. 142. Diagram of a Layer still more Superficial to that Shown in Fig. 141, and 

 Ending in the Anterior Papillary Muscle. The deeper layers are represented in dotted 

 lines. A, Posterior papillary muscle; B, papillary muscle of septum; C, anterior papillary 

 muscle. (After MacCallum.) 



around the wall of one ventricle, then through the septum and around the 

 other in a reverse scroll, figure 141. 



The Valves of the Heart. The valves of the heart are arranged so 

 that the blood can pass only in one direction. These are the tricuspid 



