392 ARTERIES. 



PLAN OF RELATIONS OF FIRST PORTION OF RIGHT SUBCLAVIAN ARTERY. 



In front. 



Integument and superficial fascia. 

 Platysma and deep fascia. 

 Clavicular origin of Sterno-mastoid. 

 Sterno-hyoid and Sterno-thyroid. 

 Internal jugular and vertebral veins. 

 Pneumogastric, cardiac, and phrenic nerves. 



Beneath. 

 Pleura. 



Behind. 



Recurrent laryngeal nerve. 

 Sympathetic. 



Longus colli. , 



Transverse process of seventh cervical vertebra. 



FIRST PART OF THE LEFT SUBCLAVIAN ARTERY (fig. 205). 



It arises from the end of the transverse portion of the arch of the aorta, oppo- 

 site 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, with the oesophagus, thoracic 

 duct, inferior cervical ganglion of the sympathetic, Longus colli, and vertebral 

 column. To its inner side, are the oasophagus, 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. f >. Outer side. 



(Esophagus. / o , L , eft - \ Pleura. 



J f Snhnlnvinn 



I rachea. 

 Thoracic duct. 



\ 



Behind. 



(Esophagus and thoracic duct. 

 Inferior cervical ganglion of sympathetic. 

 Longus colli and vertebral column. 



The relations of the second and third portions of the subclavian arteries are 

 precisely similar on both sides. 



The Second Portion of the Subclavian Artery lies between the two Scaleni 

 muscles ; it is very short, and forms the highest part of the arch described by that 

 vessel. 



