140 The Allif^ator and Its Allies 



the serratus superficial is and the hinder regions 

 of the collo-thoraci-suprascapularis profundus 

 muscles, unites with the tenth nerve just after 

 giving off the small thoracicus inferior nerve 

 to the costo-coracoideus muscle. After uniting 

 with the tenth nerve the ninth nerve immediately 

 divides into two branches that form loops with 

 branches of the eighth nerve, the whole making a 

 very complicated plexus. 



X. The tenth nerve, as noted above, is one of 

 the two largest nerves of the brachial plexus. 

 After giving off a single nerve to the ventral 

 musculature, this nerve unites with the eleventh 

 nerve; it then gives a branch to the costo-coracoid- 

 eus muscle and forms a loop with the ninth nerve. 

 After giving off a couple of nerves it again divides 

 into two equal branches which unite with similar 

 branches of the eighth nerve. 



XI. The eleventh nerve is next to the smallest 

 of the plexus. Besides branches to the trunk 

 musculature it gives a fine twig to the integument 

 of the axilla and unites with the tenth nerve in the 

 brachial plexus. This is the last nerve that enters 

 into the brachial plexus. 



The distribution of the nerves of the brachial 

 plexus is as follows (Fig. 31): (a) supracoracoideus 

 to the muscle of that name and to the integument 

 of the breast; (b) thoraci inferiores nerves (loa) — • 

 a complex of nerves from the eighth, ninth, and 

 tenth spinal stems — lead to the costo-coracoideus 



