Figure 39-12 Electrode placement for stimulation of the ulnar nerve and for recording of the compound action potential from three sites of the hand. A, Abductor digiti minimi muscle (in the hypothenar eminence). B, Adductor pollicis muscle (in the thenar eminence). C, First dorsal interosseus muscle. (Courtesy of Datex-Ohmeda, Helsinki, Finland.)