CH. XVIII.] 



THE HEART. 



205 



The interior is smooth, being lined with the general lining of 

 the heart, the endocardium, and into it open the superior and 

 inferior vense cavse, or great veins, which convey the blood from 



<^iA^ 



Fig. 208. The right auricle and ventricle opened, and a part of their right and anterior 

 walla removed, BO as to nhow their interior. J. i, superior vena cava ; 2, inferior 

 vena cava : 2', hepatic veins cut short ; 3, right auricle ; 3', placed in the fossa ovalis, 

 below which is the Eustachian valve ; 3", is placed close to the aperture of the coronary 

 vein; -f -f, placed in the auriculo-ventricular groove, where a narrow portion of the 

 adjacent walls of the auricle and ventricle has been preserved ; 4, 4, cavity of the right 

 ventricle, the upper figure is immediately below the semilunar valves ; 4', large columna 

 carnea or musculus papillaris; 5, 5', 5", tricuspid valve; 6, placed in the interior of 

 the pulmonary artery, a part of the anterior wall of that vessel having been removed, 

 and a narrow portion of it preserved at its commencement, where the semilunar valves 

 are attached ; 7, concavity of the aortic arch close to the cord of the ductus arteriosus ; 

 8, ascending part or sinus of the arch covered at its commencement by the auricular 

 appendix and pulmonary artery ; 9, placed t>etween the innominate and left carotid 

 arteries; 10, appendix of the left auricle; n, n, the outaide of the left ventricle, the 

 lower figure near the apex. (Allen Thomson.) 



all parts of the body to the heart. The opening of the inferior 

 cava is protected and partly covered by a membrane called the 

 Eustachian valve. In the posterior wall of the auricle is a slight 

 depression called the fossa ovalis, which corresponds to an opening 



