Finger abduction is associated with which nerve and muscles?

• A. C7, C8 - Radial nerve - Extensor digitorum
• B. C6, C7 - Biceps
• C. C5, C6 - Deltoid
• D. C8, T1 - Ulnar nerve - First dorsal interosseous and abductor digiti minimi

Answer: (D)

Finger abduction is driven by intrinsic hand muscles that move digits away from the middle finger, mainly the dorsal interossei and the abductor digiti minimi. These muscles are innervated by the ulnar nerve, with nerve roots C8 and T1. The first dorsal interosseous abducts the index finger, and the abductor digiti minimi abducts the little finger, both supplied by the deep branch of the ulnar nerve. That’s why the pairing of the ulnar nerve with these two muscles fits finger abduction.

In contrast, extending the fingers is done by the extensor digitorum (radial nerve), elbow flexion by the biceps ( musculocutaneous nerve), and shoulder abduction by the deltoid (axillary nerve), which are not about finger abduction.