CIRCULATION OF THE BLOOD 



others are columns attached by either extremity and free at the central 

 portion ; and others are papillae, giving origin to the chordae tendineae, 

 which are attached to the free borders of the auriculo-ventricular valves. 

 These fleshy columns interlace in every direction and give the inner 

 surfaces of the cavities a reticulated appearance. This arrangement 



9,! 



Fig. 19. Left cavities of the heart (Bonamy 

 and Beau). 



I, left ventricular cavity ; 2, mitral valve; 

 3, 4, columnce carnece ; 5, aortic opening ; 6, aorta ; 

 7, 8, 9, aortic valves ; 10, right ventricular cavity ; 

 ii, interventricular septum ; 12, pulmonary ar- 

 tery ; 13, 14, pulmonic valves ; 15, left auricular 

 cavity ; 16, 16, right pulmonary veins, with 17, 17, 

 openings of the veins ; 18, section of the coronary 



Fig. 20. Right cavities of the heart (Bonamy 

 and Beau). 



i, right ventricular cavity ; 2, posterior cur- 

 tain of the tricuspid valve ; 3, right auricular 

 cavity ; 4, columnce carnece of the right auricle ; 

 5, section of the coronary vein; 6, Eustachian 

 valve ; 7, ring of Vieussens ; 8, fossa ovalis; 

 9, superior vena cava; 10, inferior vena cava; 

 ii, aorta; 12, 12, right pulmonary veins. 



facilitates the complete emptying of the ventricles during their con- 

 traction. 



The walls of the left ventricle are thicker than those of the right 

 side. The average thickness of the right ventricle at the base is two and 

 a half lines (5.25 millimeters), and the thickness of the left ventricle at 

 the corresponding part is seven lines (14.7 millimeters), or a little more 

 than half an inch. 



