You are asked to see a 60 y.o. male 2 days following a cervical laminectomy because he has new new neurological symptoms in his right arm. The surgical team think these may be due to poor patient positioning. The sign that would most help differentiate c C8-T1 nerve root injury from an ulnar nerve injury is
A. loss of sensation in the index finger
B. loss of sensation in the little finger
C. weakness of the abductor digiti minimi muscle
D. weakness of the abductor pollicis brevis m
E. weakness of the first dorsal interosseous m.
Answer: D