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HEAD AND NECK 



the lower cervical transverse processes, and below, with the 

 apex of the pleura, the second part of the subclavian artery, 

 and its costo-cervical branch. The lateral border touches the 

 roots of the brachial plexus, and the medial border is in 

 relation with the thyreo-cervical artery, its inferior thyreoid 

 branch, and with the vertebral artery (Fig. 54). 



Serratus posterior 

 superior (insertion) 



Scalenus posterior 

 (insertion) 



Scalenus medius (insertion) 



Serratus anterior (origin) 



Serratus anterior 

 (origin) 



Scalenus anterior (insertion) 



Subclavius 

 (origin) 



Pectoralis minor (occasional or 



FIG. 84. Muscle-Attachments to the Superior Surface of the 



First Rib, and the Outer Surface of the Second Rib. 



A, First rib ; B, Second rib. 



Musculus Scalenus Medius. The scalenus medius is a 

 more powerful muscle than the scalenus anterior. It springs 

 from the posterior tubercles of all the cervical transverse 

 processes (with the exception, in some cases, of the first), 

 and it is inserted into a rough oval impression which marks 

 the upper surface of the first rib, between the tubercle of 

 the rib and the groove for the subclavian artery (Fig. 84). 



