Which nerve is responsible for abduction and adduction of the fingers?

• A. Ulnar
• B. Radial
• C. Median
• D. Axillary

Answer: (A)

Abduction and adduction of the fingers are controlled by the interosseous muscles in the hand. The dorsal interossei spread the fingers away from the middle finger, while the palmar interossei bring them toward the middle finger. These intrinsic hand muscles are innervated mainly by the deep branch of the ulnar nerve (C8–T1). That’s why the ulnar nerve is the correct answer. The radial nerve powers many extensor muscles, the median nerve supplies most of the thenar muscles and lateral lumbricals, and the axillary nerve supplies the deltoid and teres minor, none of which govern finger abduction/adduction.