436 Mr. W. P. Hemngham. 



Usual nerve supply. Muscles. 

 3rd, 4th, and 5th Levator anguli scapulae. 

 5 th. Rhomboids. 

 5th, or 5th and 6th. Supra- spinatus. Infra- spinatus. Teres minor. 

 5th and 6th. Subscapularis, Deltoid. 



Biceps. Brachialis anticus. 

 6th. Teres major. Pronator teres. Flexor carpi 



radialis. Supinator longus and . brevis. 

 Superficial thenar muscles. 

 5th, 6th, and 7th. Serratus magnus. 



6th or 7th. Extensores carpi radialis. 

 7th. Coraco-brachialis. 



Latissimus dorsi. 

 Extensors at back of forearm. 

 Outer head of triceps. 

 7th and 8th. Inner head of triceps. 



7th, 8th, and 9th. Flexor sublimis. 



Flexor profundus, carpi ulnaris, longus pollicis, 

 and pronator quadratus. 

 8th. Long head of triceps. 



Hypothenar muscles. 



Interossei. Deep thenar muscles. 



The pectoralis major receives from the 6th, 7tb, 8th, and 9th; the 

 minor from the 7th, 8th, and 9th. 



The question next arises upon what system are these muscles 

 innervated ? Is it a system of form or of function ? Are muscles 

 supplied by the same nerve because they act together or because they 

 lie near one another ? 



In the first place the movements of the arm are so varied that there 

 is hardly any combination of muscles unrepresented. In the com- 

 monest and most necessary of all acts, that of putting a piece of food 

 into the mouth, the food is grasped by the small muscles of the thumb 

 and the interossei, the carpus is flexed upon the forearm, the forearm 

 is half pronated and flexed upon the arm, and the pectoralis major 

 draws the limb forward across the chest. Doubtless many other 

 muscles take an unrecognised share also. But of those here mentioned 

 the anatomy of ordinary text-books shows that some, the flexors of 

 the elbow, are served by the outer cord, the 5th, 6th, and 7th, whilst 

 the interossei are supplied by the ulnar from the 8th and 9th. Ac- 

 cording to my dissections that one action is brought about through 

 every nerve in the plexus, and there is no action which does not 

 involve several nerves at once. 



Looking at the theory from another point of view, is it true that 

 muscles which cause the same movement, or which continually con- 



