THE RIGHT AURICLE. 



357 



part of the atrium is a slight groove, the sulcus terminalis of His (fig. 308), which 

 runs from the front of the termination of the superior to the right of the inferior 

 vena cava, and marks off the portion of the atrium formed by the dilated end of 

 the venous trunks (saccus reuniens of the embryo) from that belonging to the 

 primitive auricle. 



When opened, the interior of the right auricle presents a smooth and even surface 

 over the inner and posterior wall of the atrium, but the appendix is ridged vertically 

 with closely set reticulated muscular bands, and upon the right wall_of_the atrium 



^~^,^rt-pubn'- wb 

 t^x rt.pubn. veins 



pidm.vein, 



Mr mr/yJj* 



ovaMs 



f\ 



^^ mttrnl 



-"' 'vcdue 



cunt, papillary 

 muscle ' 



moderator 

 'ban^ 



v\ 



papillary 

 muscles 



Fig. 310. THE INTERIOR OP THE HINDER PORTION OP THE HEART, FROM BEFORE, SHOWING THE CON- 

 FORMATION OF THE INTERAURIOULAR AND INTERVENTRICULAR SEPTA, THE CRISTA TERMINALIS AND 

 MUSCULI PECTINATI OF THE RIGHT AURICLE, &C. (His.) f 



*, portion of the septum between the right auricle and left ventricle, continued below into the 

 septal flap of the tricuspid valve. 



similar bundles are seen, here running more parallel with one another, like the teeth 

 of a comb, whence they are named musculi pectinati. The musculi pectinati end 

 posteriorly on a vertical ridge, the crista terminalis of His (fig. 310), corresponding 

 to the sulcus terminalis externally. 



The posterior wall corresponds with the partition between the two auricles 

 (septum auricularum}. At its lower part, and just above and to the left of the 

 orifice of the inferior vena cava, is an oval depression, the fovea or fossa ovalis (fig. 



