THE HEAD AND NECK. 65 



front of it are the skin, superficial fascia containing the platysma myoides, the 

 clavicular head of the sterno-cleido-mastoid muscle, the sterno-hyoid and sterno- 

 thyroid muscles. The phrenic nerve, the cardiac branches of the sympathetic 

 nerve, the vagus nerve, the vertebral and internal jugular veins, cross this artery. 

 Behind the artery is the neck of the first rib and the longus colli muscle and the 

 recurrent laryngeal nerve ; below the artery is the pleura, against wounding which 

 the greatest precautions should be taken in operations in this locality. 



The left subclavian artery is longer than the right ; it does not arch outward 

 like the artery of the opposite side, but ascends vertically to the inner border of 

 the scalenus anticus muscle and is situated more deeply in the thorax. In front 



PostSfu.ntii 

 AnlSfunai 



FIG. 36. SCHEME FOR HEAD AND UPPER EXTREMITY. 



of the artery are the lung and pleura, the vagus, phrenic, and cardiac nerves, the 

 left common carotid artery, internal jugular and vertebral veins, and left brachio- 

 cephalic vein, the sterno-hyoid, sterno-thyroid, and sterno-cleido-mastoid mus- 

 cles Behind the artery are the oesophagus, thoracic duct, inferior cervical gang- 

 lion, longus colli muscle, anH vertebral column. To the outer side of the artery 

 is the pleura ; to the inner side are the trachea, thoracic duct, and oesophagus. 



Branches of the subclavian artery : 



The internal mammary to anterior thoracic and abdominal walls. 



The vertebral to the brain and spinal cord and vertebrae. 



The superior intercostal to the first and second intercostal spaces. 



