FUNCTIONAL ANATOMY OF CARDIAC PUMPING 



7 6 5 



Auricula 



sinistra 



Basis cordis 

 Ati nun sinistrum 



\'. pulmoaalis dextra 



V. cava superior 



! A + 



Sinus coronarius 



Septum ventru ul< muo 



Ostium vcn 

 sinistrum /- 



\ in - ill,: 



dextrum 



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(c. 



fig. 5. Superficial muscle layers of the 

 maximally contracted human heart, viewed 

 from the caudal aspect after separation of the 

 atria (above) from the ventricles (below). 

 The ostia of the contracted ventricles can be 

 compared with their state in the relaxed 

 ventricles (dashed lines). The changes in 

 ventricular configuration during relaxation 

 are also indicated by dashed lines. [From 

 Spalteholz (148).] 



Apex cordis 



cells. These intermediate cells contain an increasingly 

 larger number of myofibrils as they approach the 

 true myocardial cells. Merely judging from morpho- 

 logical evidence, they must contribute to some 

 extent to the over-all contractile process. 



Architecture of the Ventricular Myocardium 



Since the ventricles perform more pumping action 

 than the atria, the architecture of the ventricular 

 myocardium has attracted most of the attention of 

 functionally oriented anatomists. Despite extensive 

 description by MacCallum (108), Mall (111), 

 Monckeberg (114), Benninghoff (10), Robb & 

 Robb (136), Spalteholz (148), and Lev & Simkins 



(97), much confusion still prevails. Opinions vary 

 because it is difficult to dissect clearly the complexly 

 arranged, intertwined and crisscrossing discrete 

 muscle bands. Consequently, it is even harder to 

 derive from the anatomic findings a picture of the 

 direction of maximal pull of each muscular compo- 

 nent, not to mention the concerted action of several 

 components. 



Many of the muscle bands encircle both left and 

 right ventricles. According to the most commonly 

 accepted terminology, one distinguishes four different 

 muscles, the course of which can be best understood 

 from semischematic drawings: the superficial bulbo- 

 spiral (fig. 7), superior sinospiral (fig. 8), deep sino- 

 spiral (fig. 9), and deep bulbospiral muscle (fig. 10.) 



