STRUCTURE OF HEART'S VALVES. 107 



form of bundles or columns the column carnea. These 

 columns are not all of them alike, for while some of them 

 are attached along their whole length on one side, and 

 by their extremities, others are attached only by their 

 extremities ; and a third set, to which the name musculi 

 papillares has been given, are attached to the wall of the 

 ventricle by one extremity only, the other projecting, 

 papilla-like, into the cavity of the ventricle (5, fig. 35)> an( i 

 having attached to it chorda tendinece. Of the tendinous 

 cords, besides those which pass from the walls of the ven- 

 tricle and the musculi papillares, to the margins of the valves 

 both free and attached, there are some of especial strength, 

 which pass from the same parts to the edges of the middle 

 pieces of the several chief portions of the valve. The 

 ends of these cords are spread out in the substance of the 

 valve, giving its middle piece its peculiar strength and 

 toughness; and from the sides numerous other more 

 slender and branching cords are given off, which are 



The right auricle has been thrown out of view, i, the two right pul- 

 monary veins cut short ; their openings are seen within the auricle ; 

 i', placed within the cavity of the auricle on the leftside of the septum 

 and on the part which forms the remains of the valve of the foramen 

 ovale, of which the crescentic fold is seen towards the left hand of i' ; 

 2, a narrow portion of the wall of the auricle and ventricle preserved 

 round the auriculo-ventricular orifice ; 3, 3', the cut surface of the walls 

 of the ventricle, seen to become very much thinner towards 3", at the 

 apex ; 4, a small part of the anterior wall of the left ventricle which 

 has been preserved with the principal anterior columna carnea or 

 musculus papillaris attached to it; 5, 5, musculi papillares; 5', the 

 left side of the septum between the two ventricles, within the cavity of 

 the left ventricle ; 6, 6', the mitral valve ; 7, placed in the interior of 

 the aorta near its commencement and above the three segments of its 

 semilunar valve which are hanging loosely together ; 7', the exterior of 

 the great aortic sinus ; 8, the root of the pulmonary artery and its 

 semilunar valves ; 8', the separated portion of the pulmonary artery 

 remaining attached to the aorta by 9, the cord of the ductus arteriosus ; 

 10, the arteries rising from the summit of the aortic arch. (From 

 Quain's Anatomy.) 



