520 



THE BLOOD-VASCULAR SYSTEM 



passes in the furrow between the ventricles toward the apex, near which it anastomoses with 

 branches derived from the left coronary artery. In this course the right coronary artery 

 supplies branches to the right atrium and roots of the pulmonary artery and aorta, as well as 

 one that descends near the margo acutus (right marginal), and a second (preventricular) to the 

 anterior wall of the right ventricle. It supplies both ventricles and the septum. 



The left coronary artery [a. coronarius sinistra] passes for a short distance forward, between 

 the pulmonary artery and the left auricle, and then divides into two principal branches, one of 

 which runs in the anterior longitudinal sulcus to the apex of the heart, the anterior descending 

 branch [r. descendens anterior], around which it sends branches to anastomose with the right 

 coronary; whilst the other, the circumflex [ramus circumflexus], winds to the diaphragmatic 

 surface in the coronary groove, to anastomose with the corresponding twigs of the right artery. 

 In this course it gives off a branch which follows the margo obtusus (left marginal) as well as 

 smaller branches to the left atrium, both ventricles, and the commencement of the aorta and 

 pulmonary vessels. 



Fig. 434. — Sterno-costal Surface op the Heart, showing its Arteries and Veins. 



(After Spalteholz.) 



Innominate artery 



Left subclavian artery 



— - Left common carotid artery 



Arch of aorta 



Superior vena cava — 



Aorta 



Right atrium - 



Anterior 

 cardiac veins 



Rightcoronary. 

 artery 



Anterior 

 cardiac vein 



Right ventricle 



_ _ Pulmonary artery 



— Conus arteriosus 

 Left auricle 



Great cardiac 

 vein 



-Anterior de- 

 scending 

 branch of the 

 left coronary 

 artery 



Anterior 

 ' longitudinal 

 sulcus 



1 Left ventricle 



The cardiac or coronary veins accompany the coronary arteries and return the blood from 

 the walls of the liniirt. 



The great cardiac vein [v. cordis magna], (fig. 434) runs in the anterior longitudinal sulcus, 

 passing round tlie left side of the heart in tlie coronary sulcus to terminate in the commence- 

 ment of the coronary sinus. Its mouth is usually guarded by two valves, and it receives in its 

 course the posterior vein of the left ventricle, with other smaller veins from the left atrium and 

 ventricle, all of which are guarded by valves. 



The middle cardiac vein (v. cordis media], sometimes the larger of tlic two chief veins, com- 

 nmnicates wiMi the foregoing at its commencement above the heart's apex. It ascends in the 

 posterior longitudinal grof)VC, receiving l)l<)od from the ventricular walls, and joins the coronary 

 sinus through an orifice guarded l)y a .single valve, close to its termination. 



