320 GENERAL ACCOUNT OF THE GREAT VEIN OF THE ARM. 



The Basilic Vein. 



This vessel passes down, deeply seated, to the bend of the 

 elbow. It becomes superficial near the internal condyle, and 

 divides into several branches. One of these, called median 

 basilic, generally proceeds to join the median branch of the 

 cephalic, and from the union of these two branches is formed 

 the median vein, which passe* down near the middle of the 

 anterior part of the fore-arm. This vein generally sends off a 

 branch which proceeds internally, see fig. 179, and anasto- 

 moses with the deep-seated radial veins of the fore-arm. 

 This venous branch, which establishes a direct communica- 

 tion between the superficial and deep-seated veins at the bend 

 of the arm, is called the vena communicans, and is deserving 

 of particular attention on the part of the student. It is the 

 channel through which the blood is chiefly made to flow by 

 the action of the flexor muscles of the fingers, commonly put 

 in motion during venesection, from the deep-seated to the 

 superficial veins, so as to facilitate the withdrawal of blood in 

 that operation. It is provided with valves, which open in a 

 direction so as to prevent a return of blood toward the deep- 

 seated veins ; a direction which is different from that of any 

 other branch that I have yet noticed, connected with the deep- 

 seated system of the veins of the arm. In my own dissections 

 I have more frequently seen this vein open into the median 

 basilic, than into the median vein, as represented in fig. 179, 

 p. 319. The former therefore I look upon as the normal arrange- 

 ment. Occasionally it has opened into the median cephalic. 

 It passes from within outwards, through the fascia, at the outer 

 side of the tendon of the biceps, and between the pronator radii 

 teres, and supinator radii longus muscles. 



In some instances that rarer form of aneurysm at the bend 

 of the arm called aneurysmal varix, is produced not by a 

 direct communication made by an unhealed puncture from a 

 lancet through both coats of the median basilic vein and the 

 anterior wall of the artery by which the blood seems to get into 

 the superficial venous branch but by one of the deep-seated 



