472 



ARTERIES. 



of either of these structures might lead to the most dangerous consequences. Again, the artery 

 is in contact, below, with the pleura, which must also be avoided ; and, lastly, the proximity of 

 so many of its larger branches arising internal to this point, must be a still further objection to 

 the operation. If, however, it has been determined to perform the operation in this situation, 

 it should be remembered that it occasionally happens that the artery passes in front of the 

 Scaleus Anticus, or through the fibres of that muscle ; and that the vein sometimes passes with 

 the artery behind the Scalenus Anticus. 



In those cases of aneurism of the axillary or subclavian artery which encroach upon the outer 

 portion of the Scalenus muscle to such an extent that a ligature cannot be applied in that situa- 

 tion, it may be deemed advisable, as a last resource, to tie the first portion of the subclavian 

 artery. On the left side, this operation is almost impracticable; the great depth of the artery 

 from the surface, its intimate relation with the pleura, and its close proximity to so many import- 

 ant veins and nerves, present a series of difficulties which it is next to impossible to overcome. 1 

 On the right side, the operation is practicable, and has been performed, though not with success. 

 The main objection to the operation-in this situation is the smallness of the interval which usually 

 exists between the commencement of the vessel, and the origin of the nearest branch. This 

 operation may be performed in the following manner : The patient being placed on the table in 

 the horizontal position, with the neck extended, an incision should be made parallel with the 

 inner part of the clavicle, and a second along the inner border of the Sterno-mastoid, meeting 

 the former at an angle. The sternal attachment of the Sterno-mastoid may now be divided on 

 a director, and turned outwards ; a few small arteries and veins, and occasionally the anterior 

 jugular, must be avoided, and the Sterno-hyoid and Sterno-thyroid muscles divided in the same 

 manner as the preceding muscle. After tearing through the deep fascia witli the finger-nail, the 

 internal jugular vein will be seen crossing the subclavian artery; this should be pressed aside, 

 and the artery secured by passing the needle from below upwards, by which the pleura is more 

 effectually avoided. The exact position of the vagus nerve, the recurrent laryngeal, the phrenic 

 and sympathetic nerves should be remembered, and the ligature should be applied near the 

 origin of the vertebral, in order to afford as much room as possible for the formation of a coagu- 

 lum between the ligature and the origin of the vessel. It should be remembered, that the right 

 subclavian artery is occasionally deeply placed in the first part of its course, when it arises from 

 the left side of the aortic arch, and passes in such cases behind the ossophagus, or between it 

 and the trachea. 



Collateral Circulation. After ligature of the third part of the subclavian artery, the collateral 

 circulation is mainly established by three sets of vessels, thus described in a dissection : 



" 1. A posterior set, consisting of the suprascapular and posterior scapular branches of the 

 subclavian, which anastomosed with the infrascapular from the axillary. 



"2. An internal set produced by the connection of the internal mammary on the one hand, 

 with the short and long thoracic arteries, and the infrascapular on the other. 



' 3. A middle or axillary set, which consisted of a number of small vessels derived from branches 

 of the subclavian, above ; and passing through the axilla, to terminate either in the main trunk, 

 or some of the branches of the axillary, below. This last set presented most conspicuously the 



peculiar character of newly-formed, or, rather, di- 

 lated arteries," being excessively tortuous, and 

 forming a complete plexus. 



" The chief agent in the restoration of the axil- 

 lary artery below the tumor, was the infrascapular 

 artery, which communicated most freely with the 

 internal mammary, suprascapular, and posterior 

 scapular branches of the subclavian, from all of 

 which it received so great an influx of blood as to 

 dilate it to three times its natural size."^ 



Fig. 282. Plan of the Branches of the 

 Eight Subclavian Artery. 



BRANCHES OF THE SUBCLAVIAN ARTERY. 



These are four in number. Three aris- 

 ing from the first portion of the vessel, the 

 vertebral, the internal mammary, and the 

 thyroid axis ; and one from the second 

 portion, the superior intercostal. The ver- 

 tebral arises from the upper and back part 



of the first portion of the artery ; the thyroid axis from the front, and the in- 

 ternal mammary from the under part of this vessel. The superior intercostal 



1 The operation was, however, performed in New York, by Dr. J. K. Eodgers, and the case is 

 very briefly mentioned in Mott's Translation of Yelpeau, vol. ii. p. 365. 



2 Guy's Hospital Reports, vol. i. 1836. Case of axillary aneurism, in which Mr. Aston Key 

 had tied the subclavian artery on the outer edge of the Scalenus muscle, twelve years previ- 

 ously. 



