736 NERVES OF THE SUPERIOR EXTREMITY. 



The median vein begins by branches from the palm of 

 the hand and wrist, ascends along the middle of the fore- 

 arm to the elbow, where it divides. One branch, the median 

 cephalic, joins the cephalic vein ; the other, the median 

 basilic., joins the basilic vein. (See Fig. 23*7.) 



The superficial veins all lie immediately beneath the 

 skin and upon the fascia. 



The deep veins correspond to the several arteries, and 

 have the same names as the arteries they accompany, each 

 artery having, however, two veins, called vence comites. 

 Hence we have radial, ulnar and interosseal veins, all 

 ascending beneath the fascia to the bend of the arm, where 

 they unite into the brachial vein, which is often double, 

 composed of two vense comites accompanying the brachial 

 artery, and receiving in their course the profunda and 

 anastomotic veins. The brachial vein at the lower margin 

 of the tendon of the teres major becomes the axillary vein, 

 which goes in front of the axillary artery, and receives in 

 its course the thoracic and circumflex veins, and finally 

 ends in the subclavian, already described among the ves- 

 sels of the neck. 



SECTION IV. 

 NERVES OF THE SUPERIOR EXTREMITY. 



The brachial or axillary plexus (Fig. 233) is the source of 

 nervous supply to the upper extremity. This plexus is 

 formed by the junction of the anterior branches of the four 

 inferior cervical, and first dorsal nerves. It extends from 

 the scaleni muscles to the neck of the humerus, in the 

 axilla, where they so interlace as to surround the axillary 

 artery. 



For further account of the brachial plexus, see Nerves of 

 the Neck. 



BRANCHES OF THE AXILLARY PLEXUS. 



Thoracic, Internal cutaneous, Median, 



Supra-scapular, External cutaneous, Ulnar, 



Sub-scapular, Circumflex, Kadial. 



