216 THE NATURE AND TREATMENT OF 



blood, SO that it has no other channel than this which leads to 

 the lungs. 



The left auricle^ has scarcely any anatomical or structural 

 differences than those observed in the right, although its cavity 

 is smaller, and its walls are somewhat thicker than those found 

 on the right, it receives the blood from the lungs, after purifica- 

 tion, by means of the pulmonary veins, which have four openings 

 into this cavity, two proceeding from the right, and two from 

 the left lobes. The left, or arterial ventricle is the reser- 

 voir for arterial blood ; which is destined to re-animate, 

 replenish, and perpetuate the vital economy ; having a vastly 

 more important function to perform (which requires augmented 

 muscular mechanism), than its duplicate found on the right side ; 

 the thickness of its walls, must therefore necessarily, exceed 

 those of the right ; this is found to be the case, so that the 

 outer wall of this is about three times as thick as that found on 

 the other side, and this guide is useful to us, in determining, at 

 sight, after the heart is detached from the body, which is the 

 left ventricle and vice versa. 



The channel of communication between the left auricle and 

 ventricle is named as is the case on the opposite side, auriculo- 

 ventricular opening ; it is furnished however with only two, 

 instead of three, valvular openings termed valvula hicuspis or 

 mitralis. 



This ventricle is one of importance for our consideration from 

 the fact of the great aorta — the plastic hose, which seldom if 

 ever, requires cobbling or repair — here originating. Its margin 

 or outlet, is guarded by a complete set of valves, three in number, 

 termed semilunar, similar to those found at the origin of the 

 pulmonary artery. This ventricle is divided from the one on 

 the opposite side by a muscular and tendinous partition termed 

 septum ventriculorum. 



Form, situation, and attachment of the heart. — Its form 

 describes that simulating a cone having a body, base, and apex ; 

 its base being in a superior direction, it follows as a matter of 

 course, that its apex has an inferior insertion downwards and 

 backwards. 



