THE CARDIAC I'AV.V.v. 677 



oesophageal opening, and then curves downward and backward between the folds 

 of the lesser omentum, to end in the vena port*. 



The Portal Vein is formed by the junction of the superior mesenteric and 

 splenic veins, their union taking place in front of the vena cava and behind the 

 upper border of the great end of the pancreas. Passing upward through the right 

 border of the lesser omentum to the under surface of the liver, it enters the trans- 

 verse fissure, where it is somewhat enlarged, forming the sinu* of the portal vein, 

 and divides into two branches which accompany the ramifications of the hepatic 

 artery and hepatic duct throughout the substance of the liver. Of these two 

 branches, the right is the larger, but the shorter, of the two. The portal vein is 

 about three or four inches in length, and. whilst contained in the lesser omentum. 

 lies behind and between the hepatic duct and artery, the former being to the right, 

 the latter to the left. These structures are accompanied by filaments of the hepatic 

 plexus of nerves and numerous lymphatics, surrounded by a quantity of loose 

 areolar tissue (-<ij}*u?e of G-fasoti), and placed between the layers of the lesser 

 omentum. The vena port* receives the gastric and cystic veins : the latter vein 

 sometimes terminates in the right branch of the vena port*. Within the liver the 

 portal vein receives the blood from the branches of the hepatic artery. 



THE CARDIAC VEINS. 

 The veins which return the blood from the substance of the heart are the 



Anterior Cardiac Vein. Right Cardiac Veins. 



Posterior Cardiac Vein. Right or Small Coronary Sinus. 



Left Cardiac Veins. Left or Great Coronary Sinus. 



Ven* Thebesii. 



The Anterior Cardiac Vein (sometimes called Great Cardiac l^ein) is a vessel 

 of considerable size which commences at the apex of the heart and ascends along 

 the anterior interventricular groove to the base of the ventricles. It then curves 

 to the left side, around the auriculo-ventricular groove, between the left auricle 

 and ventricle, to the back part of the heart, and opens into the great coronary 

 sinus, its aperture being guarded by two valves. It receives, in its course, tribu- 

 taries from both ventricles, but especially the left, and also from the left auricle ; 

 one of these, ascending along the thick margin of the left ventricle, is of consider- 

 able size. The vessels joining it are provided with valves. 



The Middle Cardiac Vein commences by small tributaries at the apex of the 

 heart, communicating with those of the preceding. It ascends along the posterior 

 interveutricular groove to the base of the heart, and terminates in the great coro- 

 nary sinus, its orifice being guarded by a valve. It receives the veins from the 

 posterior surface of both ventricles. 



The Left or Posterior Cardiac Veins are three or four small vessels which col- 

 lect the blood from the posterior surface of the left ventricle, and open into the 

 lower border of the great coronary sinus. 



The Bight or Anterior Cardiac Veins are three or four small vessels which col- 

 lect the blood from the anterior surface of the right ventricle. One of these (the 

 f G<il> n}. larger than the rest, runs along the right border of the heart. 

 They open separately into the lower part of the right auricle. 



The Right or Small Coronary Sinus runs along the groove between the right 

 auricle and ventricle, to open into the right extremity of the great coronary sinus. 

 It receives blood from the back part of the right auricle and ventricle. 



The Left or Great Coronary Sinus is that portion of the anterior cardiac vein 

 which is situated in the posterior part of the left auriculo-ventricular groove. It 

 is about an inch in length, presents a considerable dilatation, and is covered by 

 the muscular fibres of the left auricle. It receives the veins enumerated above, 

 and an oblique vein from the back part of the left auricle, the remnant of the 

 obliterated left innominate trunk of the foetus, described by Mr. Marshall. The 



