

THE HEART 



are connected below with the right ventricle, and medially with the left atrium, 

 but are free in the rest of their extent. 



Auricula (auricula dextra; right auricular appendix). The auricula is a small 

 conical muscular pouch, the margins of which present a dentated edge. It projects 

 from the upper and front part of the sinus forward and toward the left side, over- 

 lapping the root of the aorta. 



Ant. desc. branch of left 

 coronary artery 



Right coronary 

 artery 





FIG. 492. Sternocostal surface of heart. 



The separation of the auricula from the sinus venarum is indicated externally 

 >y a groove, the terminal sulcus, which extends from the front of the superior vena 

 cava to the front of the inferior vena cava, and represents the line of union of the 

 sinus venosus of the embryo with the primitive atrium. On the inner wall of the 

 atrium the separation is marked by a vertical, smooth, muscular ridge, the terminal 

 crest. Behind the crest the internal surface of the atrium is smooth, while in front 

 of it the muscular fibers of the wall are raised into parallel ridges resembling the 

 teeth of a comb, and hence named the musculi pectinati. 



Its interior (Fig. 493) presents the following parts for examination: 



Superior vena cava. 



Openings 



Inferior vena cava. 

 Coronary sinus. 

 Foramina venarum 



minimarum. 

 Atrioventricular. 



Valves 



J Valve of the inferior vena cava. 

 1 Valve of the coronary sinus. 



Fossa ovalis. 

 Limbus fossa? ovalis. 

 Intervenous tubercle. 

 Musculi pectinati. 

 Crista terminalis. 



The superior vena cava returns the blood from the upper half of the body, and 

 opens into the upper and back part of the atrium, the direction of its orifice being 

 downward and forward. Its opening has no valve. 



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