234 THE SALAMANDER 



whereby communication is established between the lateral and medial 

 brachial veins as well as with the V. anastomotica brachii. Directly 

 anterior to the insertion of the M. procoraco-humeralis the V. brachi- 

 alis lateralis joins the V. circumflexa scapulae to form the V. sub- 

 clavia as described above. 



The V. interossea arises on the dorsum of the hand by several factors 

 from the ulnar and middle regions of the arcus venosus dorsalis manus, 

 and from the several extensor muscles of that region. These factors 

 unite to form a single vessel at the proximal border of the carpus, just 

 mesial to the distal end of the ulna, and pass along the fore-arm on 

 the extensor side of the M. interosseus in company with the artery 

 and nerves. At the proximal end of the muscle it passes to the flexor 

 side of the limb and receives a large factor — the F. antibrachii ulnaris 

 — draining the flexor muscles of the ulnar side of the limb, as well as 

 the M. flexor primordialis communis, the MM. flex, accessorius 

 medialis and lateralis, and the M. pronator profundus. It may also 

 anastomose with the palmar factor of the V. super, radialis, but it is 

 uncertain whether this is constant. 



At the flexor side of the elbow the combined vein divides into 

 three. Of the two main limbs one fuses with the V. brachialis later- 

 alis, the other becomes the V. brachialis jnedialis (v.br.m.) and passes 

 along the ventral, or mesial side of the arm. The third branch, much 

 smaller than the other two, is the V. anastomotica brachii. Not infre- 

 quently the V. brachialis medialis and the V. anastomotica brachii 

 arise as a single vessel and divide later. 



As the V. brachialis medialis becomes superficial it receives one 

 or two large cutaneous veins — VF. cutaneae antibrachii mediales — from 

 the skin covering the ulnar side of the fore-arm. It also drains both 

 the extensor and flexor muscles of the arm. Near the shoulder it 

 receives a fairly large factor whereby it communicates, through the 

 plexus above mentioned, with the V. brachialis lateralis and V. anas- 

 tomotica. It then turns somewhat posteriorly, and, after receiving 

 another factor from the skin of the arm, it joins, or sends a large 

 branch to, the V. axillaris. In the latter case the remaining portion 

 passes antero-mesially beneath the scapula, ventral to the nerves of 

 the brachial plexus, and, after receiving a small twig or two from the 

 M. thoraci-scapularis, enters the post-cardinal vein close to the point 

 where it bends around the oesophagus. If the whole of the V. brachi- 

 alis medialis joins the axillary vein then a branch from the common 

 vessel thus formed passes to the post-cardinal. The relations in this 

 region are subject to a considerable amount of variation, and, in one 

 case, the vessel passing to the post-cardinal was so fine as to be almost 



