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HANDBOOK OF PHYSIOLOGY. 



furrows or grooves run the coronary vessels, which supply the tissue of 

 the heart with blood, as well as nerves and lymphatics imbedded in 

 more or less fatty material. 



The Chambers of the Heart. The interior of the heart is divided 

 by a longitudinal partition in such a manner as to form two chief cham- 

 bers or cavities right and left. Each of these chambers is again sub- 



Fig. 147. The right auricle and ventricle opened, and a part of their right and anterior walls 

 removed, so as to show their interior. ^. 1, Superior vena cava ; 2, inferior veua 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 

 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 add pulmonary artery ; 9. placed between 

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

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



divided transversely into an upper and a lower portion, called respect- 

 ively, as already incidentally mentioned, auricle and ventricle, which 

 freely communicate one with the other; the aperture of communication, 

 however, is guarded by valves, so disposed as to allow blood to pass 

 freely from the auricle into the ventricle, but not in the opposite direc- 



