456 



DISSECTION OF THE THORAX. 



Cardiac 



veins. 



Coronary 

 sinus : 



extent ; 



veins join- 

 ing it ; 



valves. 



Large coro- 

 nary vein. 



Small coro- 

 nary vein. 



Posterior 



cardiac 



veins. 



Anterior 



cardiac 



veins. 



communicate on the surface of the heart, but their anastomoses 



are very fine. 



The VEINS OF THE HEART (fig. 167) differ in their arrangement 



from the arteries, and are for the most part collected into one large 



trunk the coronary sinus. 



The coronary sinus (') will be seen on raising the heart to be 



placed in the sulcus between the left auricle and ventricle. About 



an inch in length, it is joined at the left end by the great cardiac 



vein ( 4 ) ; and at the right 

 end it opens into the right 

 auricle. It is crossed by 

 the muscular fibres of the 

 left auricle. Inferiorly and 

 at its right end it receives 

 posterior cardiac branches 

 from the back of the ven- 

 tricles (|), and at its left 

 extremity another small 

 vein ( 2 ), the oblique vein 

 (Marshall), which descends 

 to it along the back of the 

 left auricle. 



On slitting up the sinus 

 with the scissors the 

 openings of its different 

 veins will be seen to be 

 guarded by valves, with 

 the exception of the oblique 

 vein ; and at its right end 

 is the Thebesian valve of 

 the right auricle which will 

 be seen later when the 

 auricle is opened. 



The left coronary or great 

 cardiac vein ( 4 ) begins in 

 front near the apex of the 

 heart, ascends in the inter- 



FIG. 167. BACK OF THE HEART WITH ITS 

 VEINS AND THE CORONARY SINUS. 

 (MARSHALL). 



A. Right auricle. 



B. Left auricle, with the appendix, o. 



1. Coronary sinus. 



2. Oblique vein. 



3. Right coronary vein. 



4. Left or great coronary vein. 



ft Posterior cardiac veins ; the larger 

 one on the right is the middle cardiac vein. 



ventricular groove, and 

 then turns to the back in 

 the sulcus between the left 



auricle and ventricle, to open into the coronary sinus (*). It receives 

 branches, mainly from the left side of the heart, in its course ; and 

 its ending in the sinus is marked by a double valve. 



The right coronary vein ( 3 ) is of small size, and runs in the hinder 

 part of the right auriculo-ventricular groove to the right end of the 

 coronary sinus. 



The posterior cardiac veins (||) ascend on the back of the left 

 ventricle to the coronary sinus '; and one larger vessel, the middle 

 cardiac vein, lies in the posterior interventricular furrow. 



The anterior cardiac veins are three or four in number, and run 



