i8o THE SURGICAL ANATOMY OF THE HORSE 



The Veins of the Forearm 



The Median or Internal Subcutaneous Vein. — This is a vein of consider- 

 able size. It is the direct upward continuation of the internal meta- 

 carpal vein. It ascends the forearm, as its name would imply, immediately 

 under the skin, and superficially therefore to the fibrous aponeurosis of 

 this region. Beginning at the inner aspect of the knee, it takes a course 

 upwards and forwards, crossing the shaft of the radius obliquely. 

 Towards the upper end of the forearm it terminates by splitting into 

 two large divisions. The more anterior of these divisions is termed the 

 Cephalic Vein, and this passes across the aponeurotic insertion of the 

 biceps muscle to reach the groove between the mastoido-humeralis 

 and pectoral muscles. Up this groove it ascends, and communicates 

 ultimately with the jugular vein. In the groove mentioned the vein 

 is placed alongside the descending division of the inferior cervical artery. 

 The posterior division of the median is termed the Basilic Vein, and this 

 vein becomes more deeply seated by piercing the posterior superficial 

 pectoral muscle from without inwards. It terminates above the elbow by 

 uniting with the ulnar and posterior radial veins to form the brachial vein. 

 Owing to its size and superficial position, the median vein is readily 

 located in the living animal, for it forms a prominent surface-marking on 

 the inner aspect of the limb. On account of its being so easily accessible, 

 it was frequently selected for the performance of phlebotomy when that 

 operation was commonly practised. The degree of obliquity which its 

 course takes across the radius varies, so that occasionally when perform- 

 ing the operation of median neurectomy we find this vein running right 

 across the seat of our cutaneous incision, thus causing a slight modification 

 in our method of procedure. This point is referred to in dealing with 

 median neurectomy. 



The Anterior Subcutaneous or Radial Vein. — This is very much smaller 

 than the median vein. It begins at the carpus and runs up the front of 



