104 



HAISTD-BOOK OF PHYSIOLOGY. 



On examination of the external surface the division of the heart into 

 parts which correspond to the chambers inside of it may be traced, for a 

 deep transverse groove called the auriculo-ventricular groove divides the 

 auricles which form the base of the heart from the ventricles which form 

 the remainder, including the apex, the ventricular portion being by far 

 the greater; and, again, the inter-ventricular groove runs between the 



FIG. 92. The right auricle and ventricle opened, and a part of their right and anterior walls re- 

 moved, so as to show their interior. %. 1, 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; +, +, 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 por- 

 tion 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 cov- 

 ered at its commencement by the auricular appendix and pulmonary artery; 9, placed between the 

 innominate and left carotid arteries; 10, appendix of the left auricle; 11, 11, the outside of the left 

 ventricle, the lower figure near the apex. (Allen Thomson.) 



ventricles both front and back, and separates the one from the other. 

 The anterior groove is nearer the left margin and the posterior nearer the 

 right, as the front surface of the heart is made up chiefly of the right 

 ventricle and the posterior surface of the left ventricle. In the furrows 

 run the coronary vessels, which supply the tissue of the heart itself with 

 blood, as well as nerves and lymphatics imbedded in more or less fatty 

 tissue. 



