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ANGIOLOGY 





The sternocostal surface (Fig. 492) is directed forward, upward, and to the left. 

 Its lower part is convex, formed chiefly by the right ventricle, and traversed near 

 its left margin by the anterior longitudinal sulcus. Its upper part is separated f rom 

 the lower by the coronary sulcus, and is formed by the atria; it presents a deep 

 concavity (Fig. 494), occupied by the ascending aorta and the pulmonary artery. 



The diaphragmatic surface (Fig. 491), directed downward and slightly backward, 

 is formed by the ventricles, and rests upon the central tendon and a small part of 

 the left muscular portion of the diaphragm. It is separated from the base by 

 the posterior part of the coronary sulcus, and is traversed obliquely by the posterior 

 longitudinal sulcus. 



The right margin of the heart is long, and is formed by the right atrium above 

 and the right ventricle below. The atrial portion is rounded and almost vertical; 

 it is situated behind the third, fourth, and fifth right costal cartilages about 



Azygos vein 



Left pulmonary veins 



Oblique vein qfleftairium 

 Great cardiac vein 

 Left marginal vein 



Posterior vein of left ventricle 



Right pulmonary 

 veins 



Small cardiac vein 



Middle cardiac vein 



FIG. 491. Base and diaphragmatic surface of heart. 



1.25 cm. from the margin of the sternum. The ventricular portion, thin and sharp, 

 is named the acute margin; it is nearly horizontal, and extends from the sternal 

 end of the sixth right costal cartilage to the apex of the heart. 



The left or obtuse margin is shorter, full, and rounded: it is formed mainly by 

 the left ventricle, but to a slight extent, above, by the left atrium. It extends 

 from a point in the second left intercostal space, about 2.5 mm. from the sternal 

 margin, obliquely downward, with a convexity to the left, to the apex of the heart. 



Right Atrium (atrium dextrum; right auricle}. The right atrium is larger than 

 the left, but its walls are somewhat thinner, measuring about 2 mm.; its cavity 

 is capable of containing about 57c.c. It consists of two parts: a principal cavity, 

 or sinus venarum, situated posteriorly, and an anterior, smaller portion, the auricula. 



Sinus Venarum (sinus venosus). The sinus venarum is the large quadrangular 

 cavity placed between the two vejise cavse. Its walls, which are extremely thin, 



