VESSELS AND NERVES OF THE HEART 



521 



The posterior vein of the left ventricle [v. post, ventriculi sinistri], lies upon the posterior 

 surface of the ventricle and, receiving branches from it, passes upward to terminate directly 

 in the coronary sinus. 



The anterior cardiac veins [w. cordis anteriores] consist of several small branches from the 

 front of the right ventricle, which vary in number and either open separately into the right 

 atrium or join the lesser cardiac vein (fig. 434). 



The small cardiac vein [v. cordis parva] is a small vessel which receives branches from both 

 the right atrium and ventricle, and winds around the right side of the heart, in the coronary 

 sulcus, to terminate in the coronary sinus. 



The coronary sinus [sinus coronarius] (fig. 435) may be regarded as a much dilated terminal 

 portion of the great cardiac vein. It is about 2.5 cm. (1 in.) in length, is covered by muscular 

 fibres from the atrium, and hes in the coronary sulcus below the base of the heart. Its cardiac 

 orifice, with the coronary (Thebesian) valve, has already been described. Besides the tributary 

 veins already named, a small oblique vein [v. obhqua atrii sinistri] of the left atrium may some- 



FiG. 435. — Base axd Diaphragmatic Surface of the Heart, showing its Arteries and 



Veins. (After Spalteholz.) 



Right pulmonary artery 



Aorta 



Left pulmouary artery — 

 Left atrium "-- 



Left pulmonary .,.---', 

 vein 



Oblique vein of the 



left atrium -~^ 



Great cardiac 

 vein 



Posterior 

 vein of the 



left V e n - 



tricle 



Coronary 

 sinus ' 



- / Superior vena cava 



\ -^^ Right pulmonary veins 



-■Right atrium 



Inferior vena 

 cava 



Left ventricle— 



Vena minima 



Right 



ventricle 



Middle cardiac vein 



Posterior descending 

 branch of the right 

 coronary artery 



Posterior longitudinal sulcus 



times be traced, on the back of the left atrium, from the hgament of the left vena cava (Marshall) 

 to the sinus. This httle vein, which is not always pervious or easy of demonstration, never 

 possesses a valve at its orifice, and, like the coronary sinus, formed a part of the left superior 

 vena cava of earlj- foetal hfe. 



The smallest cardiac veins [vv. cordis minimse] drain blood from septum and lateral walls 

 of the atria, particularly the right; also from the conus arteriosus. They open directly into the 

 right atrium. 



Although anastomoses occur between the two coronary arteries, these are by no means 

 extensive, and are not sufficient to allow of the estabhshment of a satisfactory collateral cir- 

 culation in the case of the blocking of one coronary artery. Consequently such interference 

 with the cardiac circulation produces rapid pathological "changes in the heart musculature, 

 provided it is sudden in occmrence. If the obhteration of the artery take place gradually, 

 however, some rehef may be afi'orded by the estabhshment of a collateral circulation through 

 the vense minimse, which open out from both the atrial and ventricular cavities and communicate 



