Selected joint movements are used to test myotomes (Fig. 7.15B):
Abduction of the arm at the glenohumeral joint is controlled predominantly by C5.
Flexion of the forearm at the elbow joint is controlled primarily by C6.
Extension of the forearm at the elbow joint is controlled mainly by C7.
Flexion of the fingers is controlled mainly by C8.
Abduction and adduction of the index, middle, and ring fingers is controlled predominantly by T1.