12 THE SUPERIOR EXTREMITY 



been noted the nerves and vessels which pass through it to 

 the skin must be sought for. They are : 



Nervi Cutanei. 



Supraclavicular, from the cervical plexus. 



Anterior cutaneous) from the anterior (intercostal) rami of the thoracic 

 Lateral cutaneous / nerves. 

 Arterize Cutanese. 



Cutaneous twigs from the branches of the thoraco-acromial artery : 



From the clavicular branch. 



From the acromial branch. 



From the deltoid branch. 



Perforating branches of the internal mammary artery. 

 Branches form the lateral thoracic artery. 

 Branches form the transverse scapular artery. 



Dissection. Cut through the superficial fascia to the deep 

 fascia along the lateral margin of the sternum. The level of 

 the deep fascia will be recognised by the increased resistance 

 offered to the knife, and by its bluish-white colour when it is 

 exposed. As regards the difference of resistance the dissector 

 must educate his fingers to recognise the different " feel " of the 

 various structures. As the edge of the knife touches them, 

 superficial fascia, deep fascia, nerves, vessels, muscles, they all 

 cause a different sensation, recognisable by the educated touch, 

 which can only be acquired by attention and practice. 



As soon as the level of the deep fascia is reached raise the 

 cut margin of the superficial fascia with the forceps or fingers 

 and, with the edge of the scalpel, sever the strands which attach 

 the deep surface of the superficial fascia to the deep fascia, 

 cutting against the deep fascia and removing the whole of the 

 superficial fascia. As the separation proceeds pull the detached 

 superficial fascia away from the sternum, and as soon as the 

 anterior ends of the intercostal spaces are reached look for the 

 anterior cutaneous nerves and the perforating branches of the 

 internal mammary artery, which pierce the deep fascia near the 

 margin of the sternum. If the arteries are well injected one 

 should be found in each of the upper six intercostal spaces. It 

 is not probable that a nerve will be found in the first space, but 

 one should be found in each of the other five spaces. The 

 arteries will be recognised by the red injection which they 

 contain ; each is accompanied by a small vein. The nerves 

 are whitish threads, not unlike thin white thread. They are 

 much firmer to the touch, and much stronger than the blood- 

 vessels. 



Trace both the vessels and nerves as far laterally as possible. 

 When the anterior cutaneous nerves and the accompanying 

 vessels have been secured look for the supraclavicular nerves; 

 to find them cut through the fibres of the platysma along the 

 upper border of the clavicle from the sternum to the shoulder, 

 and turn the lower part of the severed muscle and fascia down- 

 wards, detaching it from the fascia beneath with the edge of 

 the scalpel. As this is done look for the nerves which appear 

 as whitish strands running downwards across the clavicle and 

 passing from the deeper into the more superficial layer. Two 

 or three should be found about the middle of the clavicle, one 



