THE INNOMINATE VEINS. 609 



The Brachial Veins are placed one on each side of the brachial artery, receiving 

 tributaries corresponding with the branches given off from that vessel; at the 

 lower margin of the Subscapularis, they join the axillary vein. 



These deep veins have numerous anastomoses, not only with each other, but 

 also with the superficial veins. 



The Axillary Vein is of large size, and is the continuation upward of the 

 basilic vein. It commences at the lower border of the tendons of the Teres major 

 and Latissimus dorsi, increases in size as it ascends, by receiving tributaries cor- 

 responding with the branches of the axillary artery, and terminates immediately 

 beneath the clavicle at the outer border of the first* rib, where it becomes the sub- 

 clavian vein. This vessel is covered in front by the Pectoral muscles and costo- 

 coracoid membrane, and lies on the thoracic side of the axillary artery, which it 

 partially overlaps. Near its termination it receives the cephalic vein. This vein is 

 provided with a pair of valves opposite the lower border of the Subscapularis muscle ; 

 valves are also found at the termination of the cephalic and subscapular veins. 



Surgical Anatomy. There are several points of surgical interest in connection with the 

 axillary vein. Being more superficial, larger, and slightly overlapping the axillary artery, it is 

 more liable to be wounded in the operation of extirpation of the axillary glands, especially as 

 these glands, when diseased, are apt to become adherent to the vessel. When wounded there 

 is always a danger of air being drawn into its interior, and death resulting. This is due not only 

 to the fact that it is near the thorax, and therefore liable to be influenced by the respiratory 

 movements, but also because it is adherent by its anterior surface to the costo-coracoid membrane, 

 and therefore if wounded is likely to remain patulous and favor the chance of air bein^ sucked 

 in. _ This adhesion of the vein to the fascia prevents its collapsing, and therefore favors the 

 furious bleeding which takes place in these cases. 



To avoid wounding the axillary vein in the extirpation of glands from the axilla, no sharp 

 cutting instruments should be used after the axillary cavity has been freely exposed, and care 

 should be taken to use no undue force in isolating the glands. Should the vein be so embedded 

 in the malignant deposit that the latter cannot be removed without taking away a part of the 

 vein, this must be done, the vessel having been first ligated above and below. 



The Subclavian Vein, the continuation of the axillary, extends from the outer 

 border of the first- rib to the inner end of the clavicle, where it unites with the 

 internal jugular to form the innominate vein. It is in relation, in front, with the 

 clavicle and Subclavius muscle ; behind and above, with the subclavian artery, 

 from which it is separated internally by the Scalenus anticus muscle and phrenic 

 nerve. Below, it rests in a depression on the first rib and upon the pleura. 

 Above, it is covered by the cervical fascia and integument. 



The subclavian vein occasionally rises in the neck to a level with the third part 

 of the subclavian artery, and in two instances has been seen passing with this vessel 

 behind the Scalenus anticus. This vessel is usually provided with valves about 

 an inch from its termination in the innominate, just external to the entrance of the 

 external jugular vein. 



Tributaries. It receives the external arid anterior jugular veins and a small 

 branch from the cephalic, outside the Scalenus, and on the inner side of that 

 muscle the internal jugular vein. At the angle of junction Avith the internal 

 jugular the left subclavian vein receives the thoracic duct, while the right sub- 

 clavian vein receives the right lymphatic duct. 



The Innominate or Brachio-cephalic Veins (Fig. 331) are two large trunks, 

 placed one on each side of the root of the neck, and formed by the union of the 

 internal jugular and subclavian veins of the corresponding side. 



The Right Innominate Vein is a short vessel, an inch in length, which com- 

 mences at the inner end of the clavicle, and, passing almost vertically downward, 

 joins with the left innominate vein just below the cartilage of the first rib, close to 

 the right border of the sternum, to form the superior vena cava. It lies superficial 

 and external to the innominate artery ; on its right side is the phrenic nerve, and 

 the pleura is here interposed between it and the apex of the lung. This vein, at 

 the angle of junction of the internal jugular with the subclavian, receives the 

 right vertebral vein, and, lower down, the right internal mammary, right inferior 

 thyroid, and sometimes the right superior intercostal veins. 



39 



