VEINS OF THE UPPER EXTREMITY. 891 



Variations. — Unlike the basilic, the cephalic vein frequently presents variations which affect 

 principally its brachial portion. One of the most important of these is the complete absence of 

 this portion of the vein, the antibrachial portion emptying its blood into the basilic by means 

 of the median vein. In other cases it is only the uppermost part of the brachial portion that is 

 lacking, the lower part in such cases either making connection with the brachial veins or else 

 conveying its blood downward to the median vein, by which it passes to the basilic. 



Another interesting anomaly consists in the occurrence of a branch which is given off just 

 as the vein dips downward to pierce the costo-coracoid membrane. It is termed the jiigulo- 

 cephalic vein, and passes up over the clavicle to open above into the external jugular near its 

 communication with the subclavian. 



These variations find an explanation in the changes undergone by the superficial veins of 

 the arm during their development, both the absence of the brachial portion of the vein and the 

 occurrence of a jugulo-cephalic being the persistence of conditions normally passed through in 

 development. It would seem that three, or perhaps better four, stages are to be recognized in 

 the development of the superficial veins of the arm. In the first stage the basilic vein forms the 

 only great superficial trunk, extending up the inner side of the arm from the wrist to the axilla and 

 opening into the axillary vein above. Later, however, this condition is modified by the de- 

 velopment of the antibrachial portion of the cephalic, which increases in size at the expense of 

 the antibrachial portion of the basilic until it becomes the most important vein of the forearm. 

 At the bend of the elbow this vein receives a short transverse branch formed by the union of an 

 ascending and descending limb, and then bends obliquely inward to join the brachial portion of 

 the basilic. Higher up in the groove between the pectoralis major and deltoid muscles is a 

 small deltoid vein, which is unconnected with the veins already described. Such a stage as this 

 gives a clue to the variations in which the brachial portion of the cephalic is either absent or 

 only partially developed. The ascending limb of the transverse branch of the elbow, and this 

 branch itself, together represent what wifl later be the lower part of the brachial portion of the 

 cephalic, while the deltoid vein represents its upper part ; the descending limb of the trans- 

 verse branch represents the accessory cephalic vein, and the oblique portion of the antibrachial 

 cephalic, between the transverse branch and the basilic, represents the median vein. Indeed, 

 relics of this condition are to be seen even in the normal arrangement, for while the antibrachial 

 portion of the cephalic usually exceeds in size the corresponding portion of the basilic, the con- 

 ditions are reversed in the brachial portions of the two veins, the antibrachial portion of the 

 cephalic and the brachial portion of the basilic (connected by the median) forming the main 

 channel for the return of blood from the superficial portions of the arm. 



A third stage is brought about by the completion of the cephalic vein by the union of the 

 ascending limb of the transverse branch with the deltoid, the vein so formed being continued up 

 over the clavicle to open into the external jugular ; and, finally, the fourth or adult stage is pro- 

 duced from this by the degeneration of that portion of the cephalic which corresponds to what 

 is termed the jugulo-cephalic. 



The antibrachial portion of the cephalic is frequently termed the superficial radial vein, the 

 accessory cephalic being then the accessory superficial radial. Furthermore, it is to be noted 

 that quite frequently one or more strong longitudinal stems are developed in the superficial net- 

 work of the anterior surface of the forearm, and to one of these the term median vein has been 

 applied. This condition has generally been accepted by the English and French anatomists as 

 typical, and their description of the origin of the basilic and cephalic veins is as follows. The 

 median vein when it reaches the bend of the elbow divides into two divergent stems (Fig. 764) 

 which are termed the median basilic and median cephalic veins. The median basilic, which 

 corresponds with what has been termed above the median vein, unites with the superficial ulnar 

 to form the basilic vein, while the median cephalic, which represents the foetal transverse branch 

 of the elbow, similarly unites with the superficial radial to form the cephalic. Such an arrange- 

 ment is undoubtedly of frequent occurrence ; but since the median vein, as understood in such a 

 description, is so variable and so manifestly a secondary formation, and since the arrangement 

 taken above as typical is not only also of frequent occurrence, but furthermore follows more 

 closely the embryonic relations of the various vessels, it has been given the preference. 



Practical Considerations. — The Veins of the Upper Extremity. 



The Deep Veins. — The venae coniites of the radial artery have been said, 

 when distended, to alter, by presstire, the character of the pulse. The numerous 

 short anastomotic branches which unite the venae comites of the brachial artery 

 cross in front of that vessel and may have to be tied as a preliminary to ligation 

 of the artery. 



The Superficial Veins. — The Hand. — The veins of the dorsal surface are 

 subcutaneous," prominent, and, in order that the circulation may not be inter- 

 rupted during prehension, are much larger than those of the palmar surface. Like 

 the other superficial veins of the upper extremity, they are scantily supplied with 

 valves and are therefore easily distended by the effects of gravity or by any constric- 

 tion of the limb above. 



The Forearm. — The large size of the superficial veins in the forearm, their sub- 

 cutaneous position, the small number of valves they contain, and the fact that most 



