230 The Subclavian Artery 



supine, with the shoulders raised and the head thrown back, the arm 

 being pulled down to the utmost, so as to lower the clavicle the base 

 of the posterior inferior triangle : when the clavicle is raised, as in 

 axillary aneurysm, ligation is rendered much more difficult. 



The land-marks are the clavicle, posterior border of sterno-mastoid, 

 and, possibly, the anterior margin of the trapezius, but this is not 

 generally defined. Perhaps the artery may be felt pulsating upon 

 the first rib. In a muscular subject the interval between the sterno- 

 mastoid and trapezius may be so small that much of the attachment 

 of the muscles may need section. 



The skin is well drawn down, and an incision is made through it, 

 the superficial fascia, and the platysma for about 2^ to 3 in. along 

 the middle of the clavicle, beginning at the posterior border of the 

 sterno-mastoid. Then, when the skin is released, the incision is 

 drawn up along the superior border of the clavicle. The external 

 jugular vein is seen as it is about to pass through the deep fascia ; if 

 it be much in the way it must be tied in two places and divided. 

 The deep fascia, which, being attached to the upper border of the 

 clavicle, is not drawn down with the skin and platysma, is then divided 

 above the clavicle, and the finger is passed through it into the connec- 

 tive tissue in the depths of the subclavian triangle. 



The first rib is then felt, and the scalene tubercle with the attach- 

 ment of the scalenus anticus the outer border of that muscle lying 

 behind that of the sterno-mastoid. As this tubercle is at the inner 

 border of the rib, and as the subclavian artery passes 'behind the 

 muscle, the finger must be directed outwards and a little backwards 

 over the first rib, in order to feel the artery. The lowest cords of the 

 brachial plexus are close behind the artery, and on a rather higher 

 plane, resting upon the sloping rib ; they are apt to be picked up in 

 mistake for the artery. But even in the cadaver it is easy to make 

 out the difference, for on rolling the artery with the tip of the finger 

 upon the rib it is felt to be hollow and collapsing, the nerve being solid 

 and cord-like. 



The artery having been freed by the cautious use of the director, 

 the aneurysm-needle is passed round it from behind, so that there 

 may be no risk of any of the plexus being enclosed in the loop. The 

 vein is well below the level of the artery, and behind the clavicle, and 

 is in but slight danger of being wounded. The operator does not 

 usually see the vein. Care must be taken that the point of the needle 

 is not thrust too much downwards, lest the dome of the pleura be 

 wounded. 



On one occasion in which I was performing this operation a large 

 and dusky lymphatic gland appeared in front of the artery, and at first 

 sight looked like the swollen vein. 



Some of the irregularities are mentioned on p. 180, the most 

 interesting of them being that in which the right subclavian is given off 



