384 CARDIAC VEINS. 



CARDIAC VEINS. 



The veins returning the blood from the substance of the heart, are 

 the 



Great cardiac vein, 

 Posterior cardiac veins, 

 Anterior cardiac veins, 

 Venae Thebesii. 



The Great cardiac vein (coronary) commences at the apex of the 

 heart, and ascends along the anterior ventricular groove to the base 

 of the ventricles ; it then curves around the left auriculo- ventricular 

 groove to the posterior part of the heart, where it terminates in the 

 right auricle. It receives in its course the left cardiac veins from the 

 left auricle and ventricle, and the posterior cardiac veins from the pos- 

 terior ventricular groove. 



The Posterior cardiac vein, frequently two in number, commences 

 also at the apex of the heart, and ascends along the posterior ventri- 

 cular groove, to terminate in the great cardiac vein. It receives the 

 veins from the posterior aspect of the two ventricles. 



The Anterior cardiac veins collect the blood from the anterior sur- 

 face of the right ventricle ; one larger than the rest runs along the 

 right border of the heart and joins the trunk formed by these veins, 

 which curves around the right auriculo- ventricular groove, to terminate 

 in the great cardiac vein near its entrance into the right auricle. 



The Venae Thebesii are numerous minute venules which convey the 

 venous blood directly from the substance of the heart into its four 

 cavities. Their existence is denied by some anatomists. 



PORTAL SYSTEM. 



The portal system is composed of four large veins which return the 

 blood from the chylopoietic viscera ; they are the 



Inferior mesenteric vein, 

 Superior mesenteric vein, 

 Splenic vein, 

 Gastric veins. 



The Inferior mesenteric vein receives its blood from the rectum by 

 means of the haemorrhoidal veins, and from the sigmoid flexure and 

 descending colon, and ascends behind the transverse duodenum and 

 pancreas, to terminate in the splenic vein. Its haemorrhoidal branches 

 inosculate with the branches of the internal iliac vein, and thus 

 establish a communication between the portal and general venous 

 system. 



The Superior mesenteric vein is formed by branches which collect 



