874 



THE VASCULAE SYSTEM. 



aperture. Above and anteriorly it is in relation with the ascending aorta, and 

 from the junction of this aspect with the right lateral boundary the right 

 auricle is prolonged anteriorly and to the left. Its right side forms the right 

 margin of the heart, and is in relation with the right phrenic nerve and its accom- 

 panying vessels, and with the right pleura and lung, the pericardium intervening. 

 On the left the right atrium is limited by the oblique septum which separates it 

 from the left atrium. The sulcus terminalis is a shallow groove on the surface of 

 the right atrium, which passes from the front of the superior vena cava to the 

 front of the inferior vena cava. It indicates the junction of the primitive sinus 

 venosus with the atrium proper. 



The interior of the right atrium is lined with a glistening membrane, the endo- 



Vena cava superior 



Upper right 

 pulmonary vein 



Lower right 

 pulmonary vein 



Musculi pectinati 



Limbus fossse ovalis 

 Fossa ovalis 



Valve of vena cava JftJ 



Aorta 

 Pulmonary artery 



- Right auricle 

 Conns arteriosus 



Vena cava inferior 



Anterior cusp of 

 tricuspid valve 



Chordae tendineae 



Moderator band 



Coronary valve 



Musculi papillares 



FIG. 753. THE CAVITIES OF THE RIGHT ATRIUM AND EIGHT VENTRICLE OF THE HEART. 

 From a formalin fixed heart. 



cardium; its walls are smooth, except anteriorly and in the auricle whe 

 muscular bundles, the musculi pectinati, form a series of small vertical columi 

 The musculi pectinati terminate, above, in a crest, the crista terminalis, which corr 

 sponds in position with the sulcus terminalis on the external surface. 



At the upper and posterior part of the cavity is the opening of the super! 

 vena cava, devoid of a valve. At the lower and posterior part is the orifice 

 the inferior vena cava, bounded, anteriorly, by the rudimentary valve of the ve 

 cava (O.T. Eustachian) ; and immediately anterior and to the left of this val' 1 

 between it and the atrio-ventricular orifice, is the opening of the coronary sin^ 

 guarded by the unicuspid coronary valve. The atrio-ventricular aperture, guard 

 by a tricuspid valve, is known as the tricuspid orifice. It is situated in the infer ' 

 part of the anterior boundary, and admits three fingers. A number of small fosf , 

 foramina venarum minimarum, are scattered over the walls, and into some i 

 them the venae cordis minimae open. In the septal wall is an oval depression, 1 J 

 fossa ovalis, bounded, above and anteriorly, by a raised margin, the limbus fos J 

 ovalis, which is continuous, inferiorly, with the valve of the vena cava ; the fo i 



