250 



The B me J rial Plextis 



The reason of there being a brachial plexus is probably this : 

 Certain muscles habitually work together. Thus, for example, the 

 biceps, brachialis anticus, and supinator longus bend the elbow. The 

 motor fibres for them arise together in the cervical enlargement, but 

 anatomically it may not be convenient for the fibres to reach all of 

 them by the musculo-cutaneous nerve ; some, therefore, are * switched 

 off' by the musculo-spiral. By adapting this theory to the different 

 groups of muscles the need appears for a great primary interlacement 

 at the root of the upper extremity. 



The branches given off above the clavicle are twigs to the 

 scaleni, the levator anguli scapulas, rhomboids, longus colli, and sub- 



.FROM 41!! 



-CLAVIAN 



UPRA-SCAPULAR 



BH5 TO LONG 

 US COLLI 

 SCALEN 



1ST DORSAL 



EXT: ANT: THORACIC 



UPPER SUB-SCAPULAR 



.SUB*- SCAPULAR 

 CIRCUMFLEX 



Plan of brachial plexus. (GKAV. 



