THE CARDIAC OR CORONARY VEINS. 685 



Injection of the Veins. — To render the dissection and study of the veins more easy, they 

 ought to be filled with tallow or any other solidifiable matter, like the arteries. But to attain 

 this result the same mode of procedure cannot be employed as for them. Instead of causing 

 the injecting material to flow from the trunk into the branches, it is necessary to propel it 

 from the branches towards the trunk, because of the presence of the valves ; this is to be done 

 by successively fixing the cannula into several venous brandies. 



Four injections generally sufiice to fill the whole venous system in a satisfactory manner. 

 The first is made from the alveolar vein, beneath the masseter muscle; the second from a 

 digital vein of one or both anterior limbs, or from tlie side of the foot, after having destroyed 

 by a stylet the few valves which are sometimes found towards the point of union in this vein; 

 or from the side of the heart. The third, from the posterior digital veins, in the same way ; 

 the fourth, by an intestinal vein. If any important veins are empty after these four injectiona — 

 a case of frequent occurrence — they can be directly injected. 



CHAPTER II. 



Veins of the Lesser Circulation, or Pulmonary Veins (Fig. 349,/). 



The pulmonary veins comport themselves in a similar manner to the correspond- 

 ing arteries. They are lodged in the substance of the lung, and collect in from 

 four to eight trunks, which open into the roof of the left auricle, after emerging 

 from the pulmonary organ immediately above the origin of the bronchi. As 

 they are destitute of valves, they readily allow the blood to flow towards their 

 roots. It is they which carry to the left heart the blood thrown into the lungs 

 by the right ventricle, to be submitted to the revivifying action of the 

 atmosphere. 



CHAPTER III. 



Veins of the General or Systemic Circulation. 



These vessels bring to the right auricle the blood which has been dispersed in 

 the texture of organs, by the ramifications of the great arterial tree. 



They open into the auricle by forming three groups — the coronary or cardiac 

 veins, the anterior vena cava, and the posterior vena cava. 



The diaphragm establishes the exact limit between the domains of the 

 anterior and posterior vena cava. 



Aeticle I. — Caediac oe Coeonaey Veins. 



There are several small, and one large or great coronary vein. 



Small Cardiac Veins. — These are the almost insignificant vessels, un- 

 determined in number, which come from the walls of the right ventricle and 

 open directly into the corresponding auricle at the coronary groove. (Among 

 these may be included the debatable ve^ice Thehesii — a multitude of minute 

 venules said to arise in the structure of the heart, and open directly into its 

 cavities.) 



, Great Coronary Vein (Figs. 349, 5 ; 350, o, p). — This vein is formed 

 by two roots : one is lodged in the right ventricular groove, and accompanies 

 the cardiac artery of the sajne side ; the other follows, at first, the left ventricular 

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