74 THOMPSON YATES LABORATORIES REPORT 
The distribution of the root was found to include the following muscles : — 
The dorsal primary division innervated the following, as tested by experimental excitation : — • 
erector spince. 
transverso-spinales. 
The ventral primary division as given below : — 
scaleni (not always). 
teres major. 
teres minor. 
rhomhoidei. 
serratus magnus. 
pectoralis major. 
deltoideus (apparently the whole of the muscle). 
supraspinatus. 
infraspinatus. 
suhscapularis. 
biceps caput longum. 
biceps caput breve. 
brachialis anticus. 
coraco-brachialis, 
supinator longus. 
supinator brevis. 
extensor carpi radialis longior. 
extensor carpi radialis brevior (slightly). 
pronator radii teres (slightly). 
flexor carpi radialis (slightly). 
latissimus dorsi. 
diaphragma (especially the portions nearer the vertebral column and lateral part 
attached to lowest ribs). 
longus colli, 
triceps. 
In one experiment, a part of the outer head of triceps contracted feebly but distinctly. 
In two experiments, the distribution was further examined by tracing microscopically the 
Wallerian degeneration in the nerve twigs of the limb twenty days subsequent to section of the 
motor root of the inside of the vertebral canal. 
