THE NECK. 149 



third or 5 cm. of the clavicle on its upper surface free from muscles. As the 

 incision is 7.5 cm. long this necessitates the division of 2.5 cm. (i in.) of muscle, 

 and as the middle of the incision is a little to the inner side of the middle of the 

 clavicle this will make it necessary to divide more of the clavicular origin of the 

 sternomastoid than of the trapezius. After the division of the deep fascia, fat and 

 veins are encountered. The scalenus anticus muscle has the subclavian vein in 

 front of it and the artery behind, therefore the vein must be attended to before a 

 search is made for the edge of the scalene muscle. The veins to be encountered are 

 the external jugular vein, which empties into the subclavian in front of or to the 

 outer side of the anterior scalene muscle, and its tributaries, the suprascapular and 

 transverse cervical veins, as well as the anterior jugular and a communicating branch 

 from the opposite side of the neck. The cephalic vein not infrequently sends a 

 communicating branch over the clavicle to empty into the external jugular. The 

 fat is to be picked away with forceps; the veins are to be held out of the way with a 

 blunt hook or ligated and cut. The suprascapular artery may be seen close to or 

 under the clavicle. The transverse cervical artery may perhaps be above the level 

 of the wound. The omohyoid muscle may or may not be seen, as its distance from 

 the clavicle is quite variable. The transverse cervical and suprascapular arteries 

 are not to be cut, as they are needed for the collateral circulation. As was 

 mentioned in speaking of the ligation of the external carotid artery, so also here it 

 is not always easy to distinguish between arteries and veins. The veins being 

 disposed of, the anterior scalene muscle is to be sought at the internal portion of the 

 wound. It runs somewhat like the lower portion of the sternomastoid, the posterior 

 edges of the two muscles coinciding. The phrenic nerve runs down first on the 

 anterior surface and then on the inner surface of the scalenus anticus. The edge of 

 the muscle being recognized, by following it down the finger feels the first rib. The 

 artery lies on the first rib immediately behind the muscle and the vein immediately in 

 front of the muscle. The tubercle on the first rib may not be readily felt because the 

 muscle is inserted into it. The prevertebral fascia coming down the scalenus anticus 

 muscle passes from it to the subclavian artery, forming its sheath; hence, as pointed 

 out by George A. Wright, of Manchester (Annals of Surgery, 1888, p. 362), the 

 edge of the muscle may not readily be distinguished and the brachial plexus is a 

 better guide. This is above the artery and the lower cord of the plexus lies directly 

 alongside of the artery. It is closer to the artery above and to its outer side than 

 the subclavian vein is below and to its inner side. The greatest care should be 

 exercised in passing the aneurism needle around the artery. The vein is not so 

 much in jeopardy as are the pleura and lowest cord of the brachial plexus, hence the 

 needle is passed from above down between the nerve and the artery and brought 

 out between the artery and vein. 



Wounding of the pleura may cause collapse of the lung and later a septic 

 pleurisy, while including the nerve will cause severe pain, etc. 



Collateral Circulation after Ligation of the Third Portion of the Subclavian Artery. 

 (i) Internal mammary with superior thoracic and long thoracic. (2) The poste- 

 rior scapular branch of the suprascapular with the dorsalis branch of the subscap- 

 ular. (3) Acromial branches of suprascapular with acromial branch of acromial 

 thoracic. (4) A number of small vessels derived from branches of the subclavian 

 above with axillary branches of the main axillary trunk below (Gray). 



Ligation of the Inferior Thyroid Artery. The inferior thyroid artery, unlike 

 the superior, lies deep from the surface, and it is a far more difficult vessel to reach. It 

 is a branch of the thyroid axis, the other branches being the transverse cervical and 

 suprascapular. The thyroid axis comes from the first part of the subclavian just a 

 little to the inner side of the edge of the scalenus anticus muscle. The inferior 

 thyroid artery ascends on the longus colli muscle, just to the inner side of the 

 scalenus anticus and almost in front of the vertebral artery. When it reaches about 

 the level of the seventh cervical vertebra it bends inward and behind the carotid 

 artery to reach the lower posterior edge of the .thyroid gland. The transverse 

 process of the sixth cervical vertebra, called the carotid tubercle of Chassaignac, is 

 above it. As it bends to go inward it gives off the ascending cervical artery. In 

 front of the artery are the internal jugular vein, common carotid artery, pneumo- 



