SUBCLAVIAN. 469 



layer of the deep fascia. It is crossed by the internal jugular and vertebral 

 veins, and by the pneumogastric, the cardiac branches of the sympathetic, and 

 phrenic nerves. Beneath, the artery is invested by the pleura, and behind, it is 

 separated by a cellular interval from the Longus Colli, the transverse process 

 of the seventh cervical vertebra, and the sympathetic ; the recurrent laryngeal 

 nerve winding around the lower and back part of the vessel. The subclavian 

 vein lies below the subclavian artery, immediately behind the clavicle. 



PLAN OF RELATIONS OF FIEST PORTION OF EIGHT SUBCLAVIAN ARTERY. 



In front. 



Clavicular origin of Sterno-mastoid. 

 Sterno-hyoid and Sterno-thyroid. 

 Internal jugular and vertebral veins. 

 Pneumogastric, cardiac and phrenic nerves. 



Beneatli. 

 Pleura. 



Behind. 



Recurrent luryngeal nerve. 

 Sympathetic. 

 Longus Colli. 

 Transverse process of seventh cervical vertebra. 



FIRST PART OF THE LEFT SUBCLAVIAN ARTERY. (Fig. 272.) 



The left subclavian artery arises from the end of the transverse portion of 

 the arch of the aorta, opposite the second dorsal vertebra, and ascends to the 

 inner margin of the first rib, behind the insertion of the Scalenus anticus muscle. 

 This vessel is, therefore, longer than the right, situated more deeply in the 

 cavity of the chest, and directed almost vertically upwards, instead of arching 

 outwards like the vessel of the opposite side. 



It is in relation, in front, with the pleura, the left lung, the pneumogastric, 

 phrenic, and cardiac nerves, which lie parallel with it, the left carotid artery, 

 left internal jugular and innominate veins, and is covered by the Sterno-thyroid, 

 Sterno-hyoid, and Sterno-mastoid muscles ; behind, it is in relation with the 

 oesophagus, thoracic duct, inferior cervical ganglion of the sympathetic, Longus 

 Colli, and vertebral column. To its inner side are the oesophagus, trachea and 

 thoracic duct ; to its outer side, the pleura. 



PLAN OF RELATIONS OF FIRST PORTION OF LEFT SUBCLAVIAN ARTERY. 



In front. 



Pleura and left lung. 



Pneumogastric, cardiac, and phrenic nerves. 

 Left carotid artery. 



Left internal jugular and innominate veins, 

 Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles. 



Inner side. 



(Esophagus. / sni.mvian \ Outer side. 



Trachea. \ Artery. J . Pleura. 



Thoracic duct. 



\ 



Behind. 



(Esophagus and thoracic duct. 

 Inferior cervical ganglion of sympathetic. 

 Lon^us Colli and vertebral column. 



