46 THE SUPERIOR EXTREMITY 



the neck, from the brachial plexus, by three roots. The upper 

 two roots (one from the fifth cervical and the other from the 

 sixth cervical nerve) pierce the scalenus medius, and, uniting 



Coraco- 

 brachialis and 

 Biceps brachii 

 (short head) Pectoralis minor 



Omo-hyoid 



Triceps 

 (long head) 



FIG. 24. Costal aspect of the Scapula with the Attachments 

 of Muscles mapped out. 



into one stem, give off branches to the upper part of the 

 serratus anterior. The third root takes origin from the seventh 

 cervical nerve, passes in front of the scalenus medius, and runs 

 downwards for a considerable distance on the surface of 



