THE SCBCLAVIAX ARTERIES. 577 



FIRST PART OF THE RICHT SUBCLAYIAN ARTERY (Figs. 344, 359) x 



The right subclavian artery arises from the arteria innominata, opposite the 

 right stern '-clavicular articulation, and passes upward and outward to the inner 

 margin of the Scalenus anticus muscle. In this part of its course it ascends & 

 little above the clavicle, the extent to which it does so varying in different cases. 

 It is covered, in front, by the integument, superficial fascia. Platysma, deep fascia, 

 the clavicular origin of the Sterno-mastoid, the Sterno-hyoid, and Sterno-thyroid 

 muscles, and another 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 the phrenic nerve. Beneath, the artery is invested by the 

 pleura, and behind, it is separated by a cellular interval from the Longus colli, 

 the neck of the first rib, and the cord of the sympathetic nerve; the recurrent 

 laryngeal nerve winds round the lower and back part of the vessel. The subclavian 

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



PLAN OF RELATIONS OF FIRST PORTION OF THE RIGHT SUBCLAVIAN ARTERY. 



In front. 



Skin, superficial fascia. 



Platysma. 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. 

 Neck of first rib. 



FIRST PART OF THE LEFT SUBCLAVIAN ARTERY (Fig. 344). 



The left subclavian artery arises from the end of the arch of the aorta, 

 opposite the fourth dorsal vertebra, and ascends nearly vertically to the inner 

 margin of the Scalenus anticus muscle. This part of the vessel is. therefore, 

 longer than the right, situated more deeply in the cavity of the chest, and directed 

 nearly vertically upward, instead of arching outward like the vessel of the 

 opposite side. 



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

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

 internal jugular and vertebral veins, and the commencement of the left innominate 

 vein : and is covered by the Sterno-thyroid, Sterno-hyoid. and Sterno-mastoid 

 muscles : it has the left carotid in front of, but not in contact with, it ; 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, vertebral, and innominate veins. 

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



