SUBCLAVIAN ARTERIES. LIGATURE. 1009 



Before concluding the remarks on the third division of the artery, it should 

 be mentioned that the suprascapular or transverse cervical artery may be 

 met with in the operation, which in other cases may be complicated by the 

 occurrence of a branch, or, however rarely, of branches, taking rise beyond 

 the scalenus muscle. 



The second division of the subclavian artery is the part which rises highest 

 in the neck, and on this account it may be advantageously selected for the 

 application of a ligature when the vessel is difficult of access beyond the 

 muscle. The chief objection to operating on the artery in this situation 

 arises from the contiguity of the large branches. Care is necessary in 

 dividing the scalenus muscle to avoid the phrenic nerve and the internal 

 jugular vein. Moreover, the fact of the entire of the subclavian artery 

 being in apposition with the pleura, except where it rests on the rib, must 

 be borne in mind. 



Some difficulty may arise from a change in the position of the artery, as 

 when it lies between the fibres of the anterior scalenus, or when it is in 

 front of that muscle ; but such cases are of very rare occurrence, and the 

 knowledge of the fact that the vessel may be thus displaced, will assist the 

 surgeon in the event of difficulty arising from this cause. 



Before it reaches the scalenus muscle the left subclavian artery [plate 2] 

 may be said to be inaccessible for the application of a ligature, in consequence 

 of its depth and its close connection with the lung and other structures cal- 

 culated to create difficulty in an operation, among which may be mentioned 

 the internal jugular and left innominate veins. To the difficulties resulting 

 from the manner of its connection with the parts now named, must be 

 added the danger of performing an operation in the neighbourhood of the 

 large branches. 



On the right side, though deeply placed and closely connected with im- 

 portant parts, the first division of the subclavian artery may be tied with- 

 out extreme difficulty. But inasmuch as the length of the vessel, between 

 its three large branches on the one hand, and the common carotid on the 

 other, ordinarily measures no more than an inch, and often less, there is 

 little likelihood of the operation in question being successfully performed in 

 any case ; and the probability of success must be held to be still farther 

 diminished when it is considered that the length of the free part of the 

 artery is sometimes lessened by one of the large branches arising nearer than 

 usual to its commencement. 



In order to place a ligature on the portion of the right subclaviau artery 

 here referred to, it is necessary to divide by horizontal incisions the 

 three muscles which cover it, together with the layers of fascia between and 

 beneath them [plate 17, fig. 1]. While the muscles are being divided, a 

 branch of the suprascapular artery will probably require to be secured 

 [plate 16]. The position of the inner end of the clavicle and of the trachea, 

 and the effect of pressure with the finger on the circulation in the aneurism 

 or in the limb, will assist the surgeon in finding the artery without dissect- 

 ing the surrounding parts to an unnecessary and injurious extent a pre- 

 caution of importance in all cases. In the farther steps of the operation, 

 the exact position of the internal jugular vein, the vagus nerve, and the 

 pleura, are to be well remembered. 



The right subclavian artery is occasionally somewhat more deeply placed 

 than usual in the first part of its course : and this occurs when it springs 

 from the left side of the arch, or, more frequently, when it separates from 

 the innominate behind the carotid [plate 20, fig. 4], 



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