282 SUBCLAVIAN ARTERY RELATIONS. 



perpendicularly to the inner border of that muscle. The second 

 portion curves outwards behind the scalenus anticus ; and the third 

 portion passes downwards and outwards beneath the clavicle, to the 

 lower border of the first rib, where it becomes the axillary artery. 



Relations. The first portion, on the right side, is in relation in 

 front with the internal jugular and subclavian vein at their point of 

 junction, and is crossed by the pneumogastric nerve, cardiac nerves, 

 and phrenic nerve. Behind and beneath it is invested by the pleura, 

 is crossed by the right recurrent laryngeal nerve and vertebral vein, 

 and is in relation with the transverse process of the seventh cervical 

 vertebra. The first portion on the left side is in relation in front with 

 the pleura, the vena innominata, the pneumogastric and phrenic 

 nerves (which lie parallel to it), and the left carotid artery. To its 

 inner side is the ossophagus ; to its outer side the pleura ; and behind. 

 the thoracic duct, longus col.li, and vertebral column. 



Plan of the relations of the first portion of the Right Subclavian Artery. 



In Front. 



Internal jugular vein, 

 Subclavian vein, 

 Pneumogastric nerve, 

 Cardiac nerves, 

 Phrenic nerve. 



Right Subclavian Artery. 



Behind and beneath. 

 Pleura, 



Recurrent laryngeal nerve. 

 Vertebral vein, 

 Transverse process of 7th cervical vertebra. 



Plan of the relations of the first portion of the Left Subclavian Artery. 



In Front. 

 Pleura, 



Vena innominata, 

 Pneumogastric nerve, 

 Phrenic nerve, 

 Left carotid artery. 



Inner Side. 

 (Esophagus. 



Left Subclavian Artery. 



Outer Side. 

 Pleura. 



Behind. 

 Thoracic duct, 

 Longus colli, 

 Vertebral column. 



The Second portion is situated between the two scaleni, and is 

 supported by the margin of the first rib. The scalenus anticus 

 separates it from the subclavian vein and phrenic nerve. Behind it 

 is in relation with the brachial plexus. 



The Thyroid portion is in relation, in front with the subclavian vein 

 and subclavius muscle; behind with the brachial plexus and scalenus 

 posticus; below with the first rib; and above with the supra-scapular 

 artery and platysma. 



