Which nerve provides primary motor supply to the abductor pollicis longus?

Which nerve provides primary motor supply to the abductor pollicis longus?

• A. Median nerve
• B. Ulnar nerve
• C. Musculocutaneous nerve
• D. Radial nerve

Answer: (D)

The abductor pollicis longus is a muscle of the posterior forearm that abducts the thumb, and its motor input comes from the posterior interosseous nerve, a branch of the deep division of the radial nerve. This means the radial nerve is the nerve providing the primary motor supply to this muscle (via the PIN). The other nerves listed don’t innervate this extensor compartment muscle: median nerve supplies many forearm flexors and some hand muscles, ulnar nerve handles most intrinsic hand muscles, and musculocutaneous nerve supplies the anterior arm. So the radial nerve is the correct source of motor innervation for the abductor pollicis longus.

The abductor pollicis longus is a muscle of the posterior forearm that abducts the thumb, and its motor input comes from the posterior interosseous nerve, a branch of the deep division of the radial nerve. This means the radial nerve is the nerve providing the primary motor supply to this muscle (via the PIN). The other nerves listed don’t innervate this extensor compartment muscle: median nerve supplies many forearm flexors and some hand muscles, ulnar nerve handles most intrinsic hand muscles, and musculocutaneous nerve supplies the anterior arm. So the radial nerve is the correct source of motor innervation for the abductor pollicis longus.