686 THE VEINS. 



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 entrance of the posterior vena cava. 



In their course, the two branches of the coronary vein receive branches from 

 the auricular and ventricular walls. 



The bronchial veins, ramifying on the bronchi Uke the arteries, the satellites 

 of which they are, also open into the great coronary vein, very near its entrance, 

 after becoming a single vessel, which sometimes passes directly into the auricular 

 cavity. 



Article II.— Anterior Yena Cava (Figs. 349, r ; 350, d ; 389). 



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

 ing 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 comprised between 

 the two layers of the anterior mediastinum, and lies below the trachea, to the 

 right of the anterior aorta. 



Four large vessels — the ftao jugular and tico 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. 389). 



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. 389). 



Superior Cervical Vein. — Exactly resembles the artery the name of which 

 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. 349, w ; 389). 



Great Vena Azygos (Figs. 349, x ; 350, e ; 389).— This is a long single 

 vein, which commences at the first lumbar vertebra, and extends forward on 

 the right of the anterior 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 entrance 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 vertebra by means of the parietal pleura ; it runs alongside the outer 

 border of the thoracic duct, which separates it from the aorta. ^ The terminal 



' Sometimes the azygos is situated between the aorta and the thoracic duct. When the 

 latter lies to the left side, it is in direct contact with the posterior aorta. 



