928 



THE ORGANS OF CIRCULATION 



Tiie grooves are placed near the borders of the heart, so that the right ventricle 

 is mainly anterior, and the left i)osterior. 



Of the four cavities into which the heart is divided, the right auricle and 

 ventricle constitute its venous side, whilst the left auricle and ventricle belong to 

 its arterial side. 



The riglit auricle receives the venous blood of the body through the two venae 

 cavfe, and of the heart through the coronary sinus, and transmits it into the right 

 ventricle. The right ventricle in turn transmits the venous blood to the lungs 

 through the pulmonary artery. From the lungs it is returned arterialised to the 

 left auricle of the heart by the pulmonary veins. From the auricle it passes into 



Fig. 547. — Sno^mNG the Position of the Heart and its Valves in Relation to the 



Chest Walls. 



(Reduced from Hensman and Fisher's Anatomical Outlines.) 



(The rightauricle ami ventricle, with the puhiionary .semilunar and tricuspid valve?, are outlined in blue tints; 



whilst the left auricle and ventricle, with their corresponding valves, are indicated in red.) 



the corresponding ventricle, and thence through the aorta and its branches to all 

 parts of the body, including the heart itself. 



The right auricle, — The right auricle forms the upper and right part of the 

 heart; below it is the right ventricle; to the inner side anteriorly it embraces the 

 root of the i)ulmonary artery, and posteriorly it is separated from the left auricle 

 by the interauricular septum, and it is in relation with the right inferior pulmo- 

 nary vein. It is lined by a smooth and delicate membrane, the endocardium, 

 wliich is continuous with the inner coats of the l)l(K)d-vessels. It ])r('sents a large 

 (juadraiigular cavity, the' sinus venosus or atrium, and one nuich smaller within 

 the auricular appendix. The auricle forms the right and fore part of the base of 

 the heart. 



