30 



TOPOGRAPHICAL ANATOMY OF THE 



The cavities of the heart. 



Atrium^ dextrum. — As an examination of the exterior of the heart 

 has already shown, each atrium is divisible into a main part in- 

 timately connected with the other atrium and the ventricle of its own 

 side, and a freer part or auricle (auricula cordis). 



Like all the cavities of the heart, the right atrium has a smooth 

 glistening lining, the endocardium; but the wall of the auricle is 



V. azygos. 

 Branches of a. pulmonalis. 



Aorta 



Truncus brachiocephalicus. 



' Vena cava cranialis. 



I 



I 



\ 



Vv. 

 Pulmonales. 

 Fossa ovalis. 

 Intervenous tvibercle ^'' 

 Vena cava caudalis.- 



Coronary sinus.'" 

 Chordae tendineae 



V. cordis media. _A^ 



A. coronaria dextra 

 (ramus descendens) 



Auricle of right atriui 

 Tricuspid valve. 



Conus arteriosus. 

 Papillary muscle. 



-Transverse muscle. 



Pig i3_The heart and great blood-vessels viewed from the right, with the 

 interior of the right atrium and right ventricle exposed. In taking 

 away the wall of the ventricle, one of the cusps of the tricuspid valve 

 was also removed. 



rendered uneven by the presence of reticulated muscular ridges of vary- 

 ing height, the muscidi pedinati} The ridges end at a semilunar 

 crest (crista terminalis), which corresponds in position to a shallow and 

 often very imperfectly defined groove, the sidcus terminalis, on the 

 exterior of the atrium. 



1 Atrium [L.], antechamber, the hall or principal room in a Roman house. 



2 Pecten [L.], a comb. From the comb-like arrangement of the muscular ridges. 



