Subclavian Artery 229 



Behind are the recurrent laryngeal nerve, the sympathetic cord, 

 the longus colli, and a little of the pleura. 



Below are the pleura and the recurrent laryngeal ; above, the verte- 

 bral branch is given off, and, below, the internal mammary. 



The fact of the lung and pleura being somewhat behind the first 

 part of the right subclavian, but in front of the left, is explained by the 

 left artery not arising until the second part of the aortic arch had 

 passed well back. 



legation of the first part of the right subclavian is performed by 

 raising a triangular flap, as in tying the innominate artery (p. 1 82). When 

 the sterno-mastoid and sterno-hyoid and thyroid are divided and 

 raised, the common carotid is to be followed down to the innominate, 

 and the first part of the subclavian is then to be denuded. 



The aneurysm-needle is passed from before backwards. 



The operation is difficult and dangerous, not only on account of 

 the depth at which the vessel is placed, but also on account of the 

 important structures which risk being wounded, namely, the internal 

 jugular and vertebral veins, the pleura and the apex of the lung, and 

 the pneumogastric, recurrent laryngeal, and phrenic nerves. If the 

 procedure be resorted to, the common carotid should also be tied, so 

 as to cut off most of the collateral supply and to diminish the risk of 

 recurrent haemorrhage. 



Ligation of the first part of the left artery is well-nigh impracticable ; 

 the vessel is closely surrounded by important veins and nerves, whilst 

 the thoracic duct and the pleura are in the immediate neighbourhood. 



The second part of the subclavian artery lies behind the sca- 

 lenus anticus, additional anterior relations being the clavicular origin 

 of the sterno-mastoid, the subclavian vein, and the phrenic nerve. 



Behind are the apex of the pleura, and the scalenus medius. 



Above are the cords of the brachial plexus, emerging between the 

 origins of the anterior and middle scalenus, and below is the pleura. 



The second part may ba tied by cutting through the clavicular 

 origin of the sterno-mastoid, turning inwards the phrenic nerve, and 

 dividing the origin of the anterior scalene. There is, however, so 

 great a risk of damaging the phrenic nerve, the internal jugular vein, 

 and the pleura that the operation is very rarely resorted to. 



The third part of the subclavian artery is comparatively 

 superficial in the posterior inferior triangle (p. 9). It rests upon the 

 first rib. 



Above it are the omo-hyoid, and the cords of the brachial plexus. 



In front are the platysma and the cervical fascia; the external 

 jugular, supra-scapular, and transverse cervical veins ; the subclavian 

 vein, though on a lower plane ; the clavicle and subclavius, and the 

 supra-scapular artery. Behind are the scalenus medius and the lowest 

 nerves of the brachial plexus. 

 ; migration of the third part of the subclavian. The patient lies 



