106 



ANATOMY FOR NUESES. 



[CHAP. IX. 



. , m yng 



heart. H, heart ; P. pericardium f P. C ' 



serous fluid. As their 

 opposing surfaces, owing 

 ? 5>. to the constant contrac- 

 tions of the heart, are 

 continually sliding one 

 upon the other, they are 

 admirably constructed to 

 protect the heart from any 



Fie, SO.-DIAGRAM OF HEART AND PERI- 1OSS f P Wei ' b ? fri ction. 

 CARDIUM. In .A, heart and pericardium lying The interior of the 

 separately. In B, pericardium lying around i, + v j i 



heart, //hparf. P , .,?. heart is lined by a deli- 



r- cate, smooth membrane, 

 called the endocardium. 

 This pavement membrane lines all the cavities of the heart, 



and is continued into 

 the blood-vessels, form- 

 ing their innermost coat. 

 The cavities of the 

 heart. The heart is 

 divided from the base 

 to the apex, by a fixed 

 partition, into a right 

 and left half. The two 

 sides of the heart have 

 no communication with 

 each other: the right 

 side always contains 

 venous, and the left 

 side arterial, blood. 

 Each half is sub- 

 divided into two 

 o cavities, the up- 

 per, called auri- 

 cle ; the lower, 

 ventricle. These 

 cavities com- 



F IG .81.-R IGHT S IDE o F H E AR, ^cavity of right ven- 

 tricle ; B, sup. vena cava ; C, inf. vena cava ; a, wall of right one another by 

 ventricle; 6, c, column carneae; d, pulmonary vein; e,f tri- mpan nf n 

 cuspid valve ; m, semilunar valve ; o, wall of left ventricle 

 P, q, v, ascending aorta, arch and descending aorta. ' Stricted Open- 



