383 ANATOMICAL TECBNOLOGT. 



Then make a transverse incision 2-3 cm. long, from the beginning 

 of the longitudinal incision, dextrad. Then, commencing at a point 

 opposite the 1st rib, cut through the skin along the caudal {upper 

 in present posture) side of the arm to the elbow. After the nerves are 

 studied in the brachium, the longitudinal incision on the caudal 

 side of the arm will be continued to the pad in the palm of the hand. 



Reflect the skin just across the ventrimeson by grasping the cut 

 edge and tearing it from the structures which it covers. Grasp the 

 corner of the cephalic flap and tear the skin from the arm and 

 shoulder, exposing as much as is shown in Fig. 105. Reflect the 

 skin from the dorsal side of the arm in the same way, because, if 

 done in this manner, any nerves entering it can be readily seen, 

 whereas if the scalpel is Used freely, they will be cut with the con- 

 nective tissue. 



After the skin is reflected, make an incision through the muscles 

 2 cm. from the ventrimeson, commencing and ending as for the skin. 

 It is necessary to proceed ^vith extreme caution, to avoid cutting the 

 vessels and nerves entad of the muscles. In the neck the cut should 

 divide only the muscles covering the carotid artery, the tagus 

 and sympathic nerves (Fig. 101). It is best to uncover these struc- 

 tures at the beginning of the incision and keep them in view. In 

 cutting the pectoral muscles, one should proceed in the same man- 

 ner. When the muscles are divided, the mesal edge should be 

 grasped by the hand and turned mesad, taking care not to break 

 any of the nerves entering them. The lateral ends of the muscles 

 should likewise be turned laterad with the same caution. Finally, 

 separate carefully the MM. epitrochlearis and biceps to the elbow, 

 cutting, however, just deep enough to expose the internal cutaneous 

 and median nerves (Fig. 105). The above incisions will expose the 

 brachial plexus and the principal branches arising therefrom. 



Commencing as near the meson as possible, with tracer, fine for- 

 ceps and fine scissors, remove fat and connective tissue from the 

 vessels and nerves. Fat is moderately tender, and both it and con- 

 nective tissue are more easily torn than either blood vessels or 

 nerves ; the nerves too>may be recognized as directed above (§ 1008) ; 

 the arteries, being filled, will serve as landmarks. The axillary 

 vein should be removed, great care being used so that no nerves 

 are cut in the operation. 



§ 1018. N. thoracicus anterior (Fig. 105, 106 ; Quain, A, I, 684 ; 

 Gray, A, 672). — The anterior thoracic nerve passes ventrad from the 



