VEINS. 



475 



direct continuation with the lateral sinus. It conveys all the blood from the 

 brain that is distributed to this organ by the circle of Willis. This internal jugu- 

 lar vein, by its confluence with the subclavian vein, forms the innominate on 

 each side. In the neck the vein accompanies the internal carotid and common 

 carotid arteries, in the upper and lower parts respectively. At the jugular fora- 

 men the vein is in relation with the ninth, tenth, and eleventh cranial nerves, 

 which also emerge from this jugular foramen. This vein has a pair of valves two 

 inches above its terminus. 



THE INNOMINATE VEINS. 



Explain fully tlie innominate or brachio-ceplialic veins on the right and left sides. 



These veins are formed by the confluence of the subclavian and internal 

 jugular veins. (Fig. 150.) The left innominate is much the longer of the 

 two. It crosses all the branches of the second part of the arch of the aorta, 

 both pneumogastric nerves, the trachea, and the oesophagus. Tributary to it are 

 both inferior thyroid veins. This vein meets the innominate of the right side to 

 form, with the vena azygos major, the descending vena cava. 



VEINS OF THE UPPER EXTREMITIES. 



These are both deep and superficial. The deep veins in the forearm are the 

 radial and ulnar, two for each artery, called radial and ulnar venae comites respec- 

 tively. They are connected by transverse branches, one to the other. The deep 

 veins of the forearm unite in the retiring angle of the elbow (cubital fossa) to 

 form the brachial vein or veins. 



The Brachial Vein or Veins. This vein extends from the bend of the 

 elbow to the lower border of the latissimus dorsi tendon i. e., from the cubital 

 fossa to the base of the axillary space. Where there are two veins on each side 

 of the artery they communicate freely with each other and with the superficial 

 veins opposite to them in the superficial fascia. Sometimes the brachial receives 

 the basilic vein. 



The axillary vein is the continuation of the brachial through the axillary 

 space. This vein has a valve in its lower one-third. It is in very close relation 

 with two axillary glands, on account of which this vein is of great surgical im- 

 portance in the operation for the removal of infiltrated axillary lymphatic glands. 

 This vein conveys nearly all the blood of the upper extremity. The axillary vein 

 is noted for the following large and important tributaries which it receives : 



1. The circumflex (anterior and posterior). 



2. The three subscapular veins. 



3. The long thoracic vein. 



4. Small and numerous alar thoracics from the axillary glands. 



5. Short thoracic veins, the highest in the axillary space. 



6. The long thoracic or external mammary vein. 



7. The acromio-thoracic or thoracic axis vein of Morris. 



The subclavian vein is the upward continuation of the axillary vein. It 

 unites with the internal jugular vein behind the sterno-clavicular articulation to 

 form the innominate or brachio-cephalic vein. On the outer surface of the first 

 rib it lies in a depression, and is separated from the subclavian artery by the 

 scalenus anticus muscle. In front of the vein are the clavicle and the subclavius 

 muscle. Tributaries are the cephalic and the external and anterior jugular veins. 

 On the left side, the thoracic duct opens into the beginning of the innominate, 

 between the subclavian and internal jugular ; on the right side the right lym- 

 phatic duct opens into a corresponding point of the right innominate vein. 



The superior vena cava is formed by the confluence of the two innominate 

 veins. It begins near the junction of the sternum and first rib on the right side. 



