244 



THE HEART. 



arteries and veins with lymphatic vessels and nerves, imbedded in 

 fatty tissue. 



CAVITIES OF THE HEART, 



■ The heart, as before remarked, contains four chambers or compart- 

 ments, a right and a left auricle and a right and a left ventricle. 



166. 



Fig. 166.— View OK THE HEvni 

 AND Gkeat Vessels from 

 BEHIND (R. Quain). 



1, posterior surface of the 

 right ventricle ; 2, the same 

 of the left ; 3, the right iral- 

 monary arttry near the division 

 of the primary trunk ; 3', 

 branches of the right pulmonary 

 artery passing into the root of 

 the right lung ; 3", the same of 

 the left ; 4', arch of the aorta ; 

 4", descending thoracic aorta ; 5, 

 right auricle ; 6, is placed on the 

 division between the right and 

 left auricles ; 7, superior vena 

 cava ; 7', left vena innominata ; 

 8, trunk of the inferior vena 

 cava ; 9, right large hej)atic 

 vein ; 10, 11, 12, right pul- 

 monary veins ; 13, 14, left 

 pulmonary veins ; + , + , i^os- 

 terior bi-anches of the right and 

 left coronary arteries. 



The right auricle (fig. 1(15, 5) is best broug'.t into view on turning 

 the heart somewhat to the left side ; it is then seen to occupy the right 

 and anterior portion of the base of the organ. When thus viewed the 

 auricle appears of a quadrangular form, the superior and inferior 

 venaa cavse (fig. 167, 1, 2), occupying respectively the upper and 

 lower posterior angles, while a tongue-shaped portion, the auricular 

 appendix or auricle proper, * is seen to project from the anterior and 

 upper angle and to turn to the left over the root of the aorta. The 

 main part of the auricle, that into which the great veins directly pour 

 their blood, is commonly named simis venosus or atrium, to distinguish 

 it from the auricular appendix. When opened, the interior of the right 

 auricle presents a smooth and even surface, except in the appendix 

 which is ridged vertically with closely set reticulated muscular bands, 

 and upon the anterior wall of the sinus, where similar bundles are seen 

 extending, but here running parallel with one another, like the teeth 

 of a comb, and thence termed musculi pectinali. 



The posterior wall corresponds with the partition between the two 

 auricles (septum auricular urn). Near its lower part and just above and 

 to the left of the orifice of the inferior vena cava is an oval depression, 

 the fovea or fossa oralis (fig. 167, 3'), the remains of the foramen ovale 

 {vestigium foraminis oralis), which is an open passage in the foetal heart 

 from the right to the left auricle. The fossa oralis is bounded above 

 and at the sides by a prominent border, deficient below, the annulus 



* So termed from its resemblance to the external ear of some animals. 



