892 



HUMAN ANATOMY. 



cephalic vein 



Musculo- 

 cutaneous nerve 



Tendon of biceps-^ 



Median 



cephalic vein 



Basilic vein 



Accessory basilic vein 

 Brachial artery 

 Median ner\-e 

 Brachial vein 



Internal 



cutaneous nerve 



Basilic vein 



Median basilic vein 



of the venous blood of the limb is returned by them, make circular constriction of 

 the arm or forearm — as in cases of poorly applied splints — especially dangerous. 

 Swelling and oedema distal to the constriction are sure to result speedily and, if the 

 pressure is continued, to be followed by ulceration or gangrene. 



On the extensor surface of the forearm the superficial veins are less conspicuous 

 than on the flexor, and between the olecranon and the level of the pronator teres 

 insertion are almost completely lacking. This is the surface most exposed to trau- 

 matism, and along it main arteries and nerve-trunks are also absent. 



The Elbozv. — The vein given of! by the median vein when it reaches the bend of 

 the elbow, and known by the English and French anatomists {vide supra) as the 

 median basilic, is of the greatest practical importance among the veins at the bend of 

 the elbow. The M-like figure made by the superficial ulnar and superficial radial in 

 uniting respectively with the median basilic and median cephalic to form the basilic 



and cephalic veins is by 

 l^iG. 764. j^Q means constant, but is 



present in only from one-half 

 to two-thirds of all cases 

 (Treves). Even, however, 

 if the basilic and cephalic 

 veins do not originate in 

 this way, the median vein 

 (if from the cephalic), the 

 median basilic (if from the 

 median) , will be found begin- 

 ning a short distance below 

 the elbow, to the outer side 

 of the biceps tendons, and 

 crossing the tendon, the 

 brachial artery, the brachial 

 veins, and the median nerve, 

 from all of which it is 

 separated by the bicipital 

 aponeurosis, the inner of the 

 two lower biceps tendons of 

 the old anatomists. The 

 vein may, however, run 

 either more transversely or 

 more vertically and so have 

 different relations to the 

 artery and nerve ; it is 

 usually the largest of the 

 anticubital veins, but may 

 be smaller than the median 

 cephalic, which is commonly the second in size, followed by the median, ulnar, and 

 radial, in the order mentioned. 



For reasons explained above, abnormalities and even absence of the cephalic 

 and radial veins are more frequent than those of the basilic. 



For this reason, and on account of its large size, the greater quantity of blood 

 it carries — as it is above the entrance of the deep median vein, and thus receives 

 blood from the deep veins of the forearm — its superficial position, its prominence, 

 and its relative fixation to the bicipital fascia by cellular tissue, the median basilic is 

 the vein selected for either intravenous transfusion or phlebotomy. In opening the 

 vein, certain dangers are to be avoided: (i) Wound of the brachial artery, if it 

 results in a direct communication between the vein and artery, will cause an aneu- 

 rismal varix ; if it results in the formation of an intervening sac in the perivascular 

 connective tissue, through which the blood from the artery flows before entering the 

 vein, it will cause a varicose aneurism. (2) A septic wound may cause a lymphan- 

 gitis from infection of the lymph-vessels accompanying the vein, and may result in 

 axilary abscess. (3) Unnecessary damage to the filaments of the internal cuta- 



Cephalic vein 



Bicipital fascia 



Median vein 



Superficial dissection of region of elbow, showing 

 relation of veins and nerves. 



