504 



THE CIRCULATORY APPARATUS. 



Fig. 260. 



summit, into which are implanted the tendinous cords (chordce tendince) 

 proceeding from the auriculo-ventricular valve ; those of the second order 

 are free in their middle part, and attached by their extremities to the walls 

 of the heart ; while the third description adhere throughout their length to 

 the cardiac tissue, on which they stand as if sculptured in relief. 



In the right ventricle, two columns of the first order, rarely three, are 



met with : one on the anterior wall, 

 the other on the posterior. The 

 columns of the second order num- 

 ber two or three principal ones, ex- 

 tending from one wall to the other, 

 or attached to two different points 

 of the same wall. There also ex- 

 ist a considerable number of small 

 ones intermixed with those of the 

 third order. The latter are par- 

 ticularly abundant in the angles 

 formed by the union of the two 

 faces, where they interlace and give 

 rise to more or less complicated 

 areolae. 



Apex. The apex of the right 

 ventricle does not descend to the 

 point of the heart, being distant 



RIGHT SIDE OF THE HEART LAID OPEN. fl ' m ** ab Ut 1 2 ^llCS. 



1, Cavity of right auricle ; 2, Appendix auri- Base -This IS pierced by two 



culse, with musculi pectinati ; 3, Anterior large onnces the annculo-ven- 

 vena cava opening into the upper part of tricular opening and the pulmonary 



the right auricle ; 4, Posterior vena cava ; 

 5, Fossa ovalis, surrounded by the annul us 

 ovalis ; 6, Eustachian valve ; 7, Opening 

 of the coronary sinus ; 8, Coronary valve ; 



opening. 



Auriculo-ventricular opening. 

 Placed on a level with the con- 



), Entrance of auricular-ventricular open- striction which divides the right 



ing. a, Right ventricle ; 6, Its cavity ; c, 

 Conus arteriosus, or infundibulum ; d, Pul- 

 monary artery; <?, /, Tricuspid valve; g, 

 One of the musculi papillares to which 

 the curtains of the tricuspid valve are 



heart into two superposed compart- 

 ments, this orifice, widely open and 

 almost a regular circle, forms the 

 communication between the auricle 



attached by chordae tendinse ; h, Columnar and ventricle. It is provided with 



a valvular fold that exactly closes 

 the orifice when the ventricle con- 



carneae ; ', Two musculi papillares of val- 

 vular curtain ; , /, Chordae tendineae ; m, 

 Semilunar valves of pulmonary artery ; 

 n, Apex of left appendix auricula ; o, Left tracts to propel the blood into the 

 ventricle. l un g s and which is termed the 



tricuspid (having three points) valve, 



in consequence of its form. This valve offers : 1, A superior border, attached 

 to the entire margin of the auriculo-ventricular opening ; 2, An inferior 

 opening, free, cut into three festoons by three deep notches, and fixed to 

 the ventricular walls, principally on the summits of the fleshy columns, by 

 means of tendinous cords which ramify on reaching the valve. One of these 

 festoons, more developed than the others, is placed on the limit of the 

 auriculo-ventricular and pulmonary openings ; thereby constituting a kind of 

 vertical partition which divides the ventricular cavity at its base into two 

 compartments : a right or auricular, and a left or arterial. The other 

 festoons are applied to the anterior and posterior walls of the ventricle; 

 3, An external face, which receives the insertion of a great number of 



