THE SUPERIOR VENA CAVA. 



473 



ii^£ 



the parts, and will be more fully refen-ed to at p. 485, in connection with the 



description of the great cardiac vein. The superior vena cava in one case has 



been seen to he joined by one of the pulmonary 



veins (Meckel). In several cases two superior Fig. 302. 



venjE cavEe have been found, a right and a 



left, the left always opening into the left \^\( 



auricle, and in one case being joined hy a \w^ 



pulmonary vein. (Hj-iil, Gruber, Luschka.) \ 



Fig. 302. — Sketch of the Principal Yexous 

 Trunks, togethek with the Thoracic Duct. I 



a, the basilar i^rocess of the occipital bone, 

 through which and the temporal bones a trans- 

 verse incision has been made so as to lay open the 

 jugular foramen on both sides ; h, tbe fifth cervi- 

 cal vertebra ; c, the first rib ; d, the sixth ; e, tlie 

 twelfth; /, the fifth lumbar vertebra; 1, vena 

 cava superior divided at the place of its entrance 

 into tbe right auricle ; 2, right, 2', left subcla- 

 vian veins ; 3, right internal jugular vein ; 3', 3', 

 lower part of the lateral sinuses of the dura 

 mater ; that of the right side shows at its junction 

 with the juguhxr vein the bulb which lies in 

 the jugular depression of the temporal bone ; 4, 

 right, and 4', left external jugular veins ; 5, right, 

 and 5', left vertebral veins, anastomosing with 5", 

 external vertebral veins, before joining the sub- 

 clavian veins ; 6, placed on left subclavian vein 

 below the ojiening of the last, and of the thoracic 

 duct; below 6, the inferior thyroid veins ; 7, 7', the 

 internal mammary veins ; 8, the left superior 

 intercostal vein joining tbe left brachio- cephalic 

 vein, and anastomosing below with intercostal veins 

 which join the trunk of the azygos ; the right 

 superior intercostal vein is seen joining the azygos 

 vein ; 9, main or right azygos vein ; 0', the left 

 azygos, repi-esented here as crossing the vertebral 

 column on the eighth vertebra ; 10, the thoracic 

 duct ; 11, trunk of the inferior vena cava at 

 tlie place of junction of the renal veins ; the vena 

 cava is seen dividing on the fourth lumbar vertebra 

 into the two common iliac veins ; 12, the union 

 of the left azygos vein with the left renal vein ; 13, 

 on the right side, the commencement of the right 

 azygos vein in the lumbar region, joined by several 

 lumbar veins ; 13', the commencement of the 

 azygos vein of the left side, joining similar veins 

 on that side ; 14, 14', the external ihac veins ; 

 15, placed on the promontory of the sacrum, points 

 on either side to the prolongation of tbe lower 

 branches of the right and left lumbar veins into 

 the pelvis, and their union with sacral and other 

 branches of the internal iliac veins. 



'O^ 



l-A. 



_3W 



INNOMINATE OE BEACHIO-CEPHaLIC 

 VEINS. 



The blood returned from the upj3er 

 hmbs through the subidavian veins, and 

 from the head and neck by the jugular 

 veins, is poured into two trunks, named 

 the brachio-cephalic or innominate veins. 



14" 



^U 



These vessels, resulting from 



