600 THE VEINS. 



the cardiac artery of the same side; the other follows at first the left 

 ventricular groove, ascends nearly to the pulmonary artery, and is then 

 inflected backwards by placing itself in the coronary groove, along with the 

 horizontal branch of the left cardiac artery. Turning round the base of the 

 posterior ventricle, it joins the right root, near the upper extremity of its 

 groove. The common trunk resulting from this junction, after a short course, 

 opens into the right auricle, below and within the embouchure of the posterior 

 vena cava. 



In their track, the two branches of the coronary vein receive branches 

 which escape from the auricular and ventricular walls. 



The bronchial veins, ramifying on the bronchi like the arteries, whose 

 satellites they are, also open into the great coronary vein, very near its 

 embouchure, after becoming a single vessel, which is sometimes thrown 

 directly into the auricular cavity. 



ARTICLE II. ANTERIOR VENA CAVA. (Figs. 258, r ; 259, d ; 293.) 



This is a voluminous trunk, which ought to be considered as the corres- 

 ponding vein of the anterior aorta. It extends from the entrance of the 

 chest to the right auricle, into the roof of which* it is inserted. It is com- 

 prised between the two layers of the anterior mediastinum, and lies 

 below the trachea, to the right of the anterior aorta. 



Four large vessels the two jugular and two axillary veins opening in 

 common in the space comprised between the two first ribs, constitute the 

 roots of this vessel. 



COLLATERAL AFFLUENTS. The affluent vessels which the anterior vena 

 cava receives in its course are : the internal thoracic, vertebral, superior 

 cervical, and dorsal veins, and the great vena azygos. 



INTERNAL THORACIC (OR INTERNAL MAMMARY) VEIN. A satellite of the 

 artery of the same name, this vein opens into the anterior vena cava, at its 

 origin (Fig. 293). 



VERTEBRAL VEIN. It accompanies the corresponding artery in the canal 

 formed by the foramina in the transverse processes of the cervical vertebra, 

 and joins the vena cava at the origin of that artery (Fig. 293). 



SUPERIOR CERVICAL VEIN. Exactly resembles the artery whose name 

 it bears. 



DORSAL VEIN. This vessel follows the dorso-muscular artery, and, like 

 it, presents a subcostal branch. On the left side, this branch is designated 

 the small vena azygos, and is often prolonged to the eleventh or twelfth rib ; 

 it receives the intercostal veins of the spaces it crosses. 



It may be remarked that the vertebral, superior cervical, and dorsal 

 veins of the right side, are nearly always thrown separately into the vena 

 cava, while on the left side they constantly unite to form a single trunk 

 (Figs. 258, u ; 293). 



GREAT VENA AZYGOS (Figs. 258 ; x- 259, e-, 293). This is a long 

 single vein, which commences at the first lumbar vertebra, and extends 

 forward on the right of the thoracic aorta, beneath the bodies of the dorsal 

 vertebrae to about the sixth, when it is inflected downward to terminate in 

 the anterior vena cava, near the embouchure of that vessel, or even directly 

 into the right auricle. 



In its course, the great vena azygos is maintained against the bodies 

 of the dorsal vertebrae by means of the parietal pleura ; it runs along- 

 side the outer border of the thoracic duct, which separates it from the 



