738 



THE VASCULAR SYSTEMS 



From this plexus a left vein descends and joins the left innominate trunk, am 

 a right vein passes obliquely downward and outward across the innominate arter 

 to open into the right innominate vein, just at its junction with the superior venj 



cava. The thyreoidea imi 



-.Anterior jugular. 



Superior thyroid. 



Middle thyroid 



External jugular. 



Trunk of 

 thyroid and 

 pericardiac. 



FIG. 515. The vence cava? and azygos veins, with their fprinative 

 tributaries. 



vein (v. thyreoidea ima 

 passes downward in fron 

 of the trachea and termi 

 nates in the left innomi 

 nate vein. These vein 

 receive tributaries from tin 

 tracheal veins (vv. trache 

 ales), from the cesophagea 

 veins (vv. oesophageae) 

 from the inferior laryngea 

 veins (v. laryngea inferior] 



The superior intercos 

 tal Veins (right and left 

 drain the blood from tw< 

 or three of the intercosta 

 spaces below the first 

 The right superior inter 

 costal vein (v. intercostali 

 suprema dextrd) passe 

 downward and inward an< 

 opens into the vena azygo 

 major; the left superio 

 intercostal vein (v. intercos 

 talis suprema sinister) run 

 across the arch of th 

 aorta and opens into th 

 left innominate vein. I 

 usually receives the lef 

 bronchial and left superio 

 phrenic vein, and commu 

 nicates below with th< 

 vena azygos minor supe 

 rior. The vein from th 

 first intercostal space open 

 directly into the corre 

 spending vertebral or in 

 nominate vein. 



The superior vena cavi 

 (precava; v. cava superior 

 (Fig. 515) receives th< 

 blood which is conveye< 

 to the heart from th< 

 whole of the upper half o 

 the body. It is a shor 

 trunk, varying from tw< 

 inches and a half to thre< 

 inches in length, forme( 

 by the junction of the tw< 

 innominate veins. It com 

 mences at the level of th< 



