THE DEEP VEINS OF THE UPPER EXTREMITY 



737 



subclavian, receives the right vertebral vein, and, lower down, the right internal 

 mammary, right inferior thyroid, and sometimes the right thyroidea ima and the 

 right superior intercostal veins. 



The left innominate vein (v. anonyma sinistra), about two and a half inches 

 in length, and larger than the right, passes from left to right across the upper and 

 front part of the thorax, at the same time inclining downward, and unites with 

 the right innominate vein to form the superior vena cava. It is in relation, in 

 front, with the first piece of the sternum, from which it is separated by the Sterno- 

 hyoid and Sternothyroid muscles, the thymus gland or its remains, and some loose 

 areolar tissue. Behind it are the three large arteries arising from the arch of the 

 aorta, together with the vagus and phrenic nerves. This vessel is joined by the 

 left vertebral, left internal mammary, left inferior thyroid, left thyroidea ima, 

 and the left superior intercostal veins, and occasionally some thymic and peri- 

 cardiac veins. There are no valves in the innominate veins. 



LONGUS COLLI MUSCLE 



COMMON CAROTID 



ARTERY 



LEFT VAGUS 



NERVE 



VERTEBRAL ARTERY 



VERTEBRAL VEIN 

 THORACIC DUCT 



INTERNAL JUGULAR 



VEIN 



EXTERNAL JUGULAR 



VEIN 



ANTERIOR JUGULAR 



VEIN 



SUBCLAVIAN 



VEIN 



FIG. 514. The bend of the thoracic duct at its termination in the subclavian vein. (Poirier and Charpy.) 



Peculiarities. Sometimes the innominate veins open separately into the right auricle; in 

 such cases the right vein takes the ordinary course of the superior vena cava; but the left vein 

 the left superior vena cava, as it is termed after, communicating by a small branch with the 

 right one, passes in front of the root of the left lung, and, turning to the back of the heart, receives 

 the cardiac veins, and terminates in the back of the right auricle. This occasional condition 

 in the adult is due to the persistence of the early fetal condition, and is the normal state of things 

 in birds and some mammalia. 



The internal mammary veins (IT. mammariae internae), two to each internal 

 mammary artery, follow the course of that vessel, and receive tributaries corre- 

 sponding to the branches of the artery. The two veins unite into a single trunk 

 which terminates in the corresponding innominate vein. It receives the twelve 

 anterior intercostal veins from the upper six intercostal spaces of the corresponding 

 ,side six anterior perforating veins (rami perforantes] veins from the surface of 

 ithe sternum (rami sternales] muscular veins, and vessels from the mediastinum 

 and pleura. The internal mammary veins anastomose below with the venae 

 comites of the musculophrenic and superior epigastric arteries. The superior 

 phrenic vein (i. e., the vein accompanying the arteria comes nervi phrenici) usually 

 opens into the internal mammary vein. 



The vertebral vein (see p. 719). 



The inferior thyroid veins (vv. thyreoideae inferiores) (Fig. 515), two, frequently 

 Ithree or four, in number, arise in the venous plexus on the thyroid body (plexus 

 ttn/reoidcus impar\ communicating w T ith the middle and superior thyroid veins. 

 They form a plexus in front of the trachea, behind the Sternothyroid muscles. 



