576 



ANGIOLOGY 



First Part of the Right Subclavian Artery (Figs. 505, 520). The first part cf 

 the right subclavian artery arises from the innominate artery, behind the upper 

 part of the right sternoclavicular articulation, and passes upward and lateralward 

 to the medial margin of the Scalenus anterior. It ascends a little above the clavicle', 

 the extent to which it does so varying in different cases. 





Fio. 520. Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries. 



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

 the clavicular origin of the Sternocleidomastoideus, the Sternohyoideus, and Sternothyreoideus, 

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

 by the vagus nerve and the cardiac branches of the vagus and sympathetic, and by the sub- 

 clavian loop of the sympathetic trunk which forms a ring around the vessel. The anterior jugular 

 vein is directed lateralward in front of the artery, but is separated from it by the Sternohyoideus 

 and Sternothyreoideus. Below and behind the artery is the pleura, which separates it from the 

 apex of the lung; behind is the sympathetic trunk, the Longus colli and the first thoracic vertebra. 

 The right recurrent nerve winds around the lower and back part of the vessel. 



