62 THE SUPERIOR EXTREMITY 



posterior belly of the omo-hyoid at the upper border of the 

 scapula. 



(2) Divide the dorsal scapular nerve and the descending 

 branch of the transverse cervical artery near the medial angle of 

 the scapula. 



(3) Pull the vertebral border of the scapula away from the 

 ribs to expose the posterior part of the serratus anterior on the 

 costal surface of the scapula. 



(4) Cut through the posterior part of the serratus anterior from 

 its upper to its lower border about one inch from the vertebral 

 margin of the scapula. 



(5) Pull the scapula still further away from the thorax and 

 divide the axillary vessels and nerves at the outer border of the 

 first rib. 



(6) Detach the anterior skin flap previously stitched to the 

 anterior wall of the thorax, and take the limb to the table 

 provided, where the further dissection is to be completed. 



Tie the divided axillary vessels and nerves to a piece of wood, 

 about 37.5 mm. (i inches) long, in their proper order (a piece of 

 a broken penholder will serve the purpose), and then by means 

 of a loop fix the wood to the coracoid process ; by that means 

 the vessels and nerves will be retained in their proper relation- 

 ships during the further stages of dissection, and they can be 

 released from the coracpid process when it is necessary to 

 examine anything which lies behind them. 



After the superior extremity has been separated proceed to 

 remove the whole of the skin which covers it whilst the sub- 

 cutaneous tissues are still in good condition, and in order that a 

 ?eneral view of the cutaneous veins and nerves may be obtained, 

 he main cutaneous veins carry blood to the axillary vein, and 

 the cutaneous nerves are either direct branches of the brachial 

 plexus or they spring from the main terminal branches of the 

 plexus. The following steps must be taken : (i) place the limb 

 on its posterior aspect ; (2) make an incision along the anterior 

 aspect from the region already denuded to the tip of the middle 

 finger (Fig. 5) ; (3) make a transverse incision at the wrist ; 



(4) -a transverse incision at the proximal ends of the fingers ; 



(5) an oblique incision from the middle of wrist to the tip 

 of the thumb; (6) incisions along the middle of the index, 

 the ring, and the little finger. Turn the lateral flaps 3 and 5 

 (Fig. 5) laterally, the medial flaps 4 and 6 medially round the 

 respective margins of the limb, and then dissect them from the 

 dorsal aspect. Treat the flaps 5 and 7 and those of the fingers 

 in the same way, and dissect flap 6 distally to the angle between 

 the thumb and the index finger. 



Take great care whilst removing the flaps not to injure the 

 cutaneous vessels and nerves which lie in the superficial fascia 

 immediately subjacent to the skin. 



Note that the skin is readily separated from the superficial 

 fascia in the arm and forearm and on the dorsal aspect of the 

 hand. It is slightly more adherent over the epicondyles of the 

 humerus and the olecranon. In the regions of the palm and the 

 volar aspects of the digits, the skin and superficial fascia are 

 closely adherent, for there the skin is bound to the deep fascia 

 by fibrous strands which pass through the superficial fascia. In 

 the ulnar part of the palm, about 25 mm. distal to the wrist, 



