AXILLARY SPACE 



29 



a similar connecting twig not infrequently passes upwards, in 

 front of the neck of the second rib, from the second to the 

 first thoracic nerve. The manner in which these great nerves 

 join to form the plexus is very constant. The fifth and sixth 



Scalenus anterior and longus cc 

 Scalenus medius and posterior 



-Phrenic nerve 

 Seal. ant. and longus colli 

 Seal. med. and post. 



Seal. ant. and longus colli 

 Seal. med. and post. 



Scalenus ant. and longus colli 

 Scalenus med. and post. 



T3 



FIG. 13. Diagram of the Brachial Plexus. (After Paterson.) 



cervical nerves unite to form an upper trunk ; the seventh remains 

 single and proceeds distally as a middle trunk ; whilst the 

 eighth and first thoracic nerves join, close to the intervertebral 

 foramina, to constitute a third or lower trunk. A short 

 distance above the clavicle each of the three trunks splits 

 into an anterior and a posterior division. Raise the three 

 anterior divisions on the handle of the knife, and it will be 



