VEINS, LYMPHATICS, ARTERIES, AND NERVES 73 



cords of the brachial plexus (C) which arise from vertebral 

 nerves T.I, and C.VIII, and C.VII. 



A. VEINS AND LYMPHATICS OF THE LEFT SUPERIOR 



LIMB 



(Fig. 27) 



The blood of the superior limb is returned by two venous 

 systems, the cephalic, or superficial, and the basilic, or deep 

 veins essentially as in man. The basilic system parallels, with 

 some modifications, the brachial artery and its branches, but 

 there is no artery in the arm comparable to the cephahc vein. 

 These two venous systems are united by anastomosis of a num- 

 ber of smaller veins, especially in the forearm and hand. The 

 cephalic empties into the axillary vein, which is merely the 

 continuation of the brachial, and is known as the subclavian 

 after entering the body cavity. 



The cephalic vein originates in the dorsum of the hand from 

 digital branches of three interosseous veins which unite on the 

 mid-dorsum of the metacarpus, between the second and third 

 metacarpals, and between the skin and tendons of the extensor 

 digitorum communis m. (23). Thus is formed a subcutaneous 

 venous arch which is the beginning of the main branch of the 

 cephahc vein. A fourth interosseous vein from the pollex and 

 index finger joins the cephahc on the mid-dorsum of the carpus. 

 A large palmar branch passes along the radial side of the fore- 

 arm and joins the cephalic in the concavity of the elbow. There 

 is no typical vena mediana cubiti, connecting the cephalic 

 and brachial systems at the concavity of the elbow as in man. 

 Thus, in its subcutaneous course the cephahc vein passes 

 along the cranial side of the superior limb from the venous arch 

 to the middle of the humerus, then by a wide spiral over the 

 lateral surface of the brachium, along the acromiodeltoid 

 muscle and at the metacromial process passes between the long 

 and lateral heads of the triceps m., caudad of the humerus, to 

 join the brachial vein. At this point it receives an anastomos- 



