Median nerve motor function includes which actions?

Median nerve motor function includes which actions?

• A. Lumbricals to digits 1-3 and thumb opposition
• B. Ulnar deviation of the wrist
• C. Thumb opposition only
• D. Elbow extension

Answer: (C)

Thumb opposition is the defining motor action of the median nerve because it innervates the thenar muscles—opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis—that turn the thumb toward the palm and across the hand to meet the other digits. This opposition enables a precision pinch and is a classic sign of median nerve function. Other options don’t fit median nerve motor control. Ulnar deviation of the wrist is mainly produced by the flexor carpi ulnaris (ulnar nerve) and extensor carpi ulnaris, not the median nerve. Elbow extension is primarily carried out by the triceps via the radial nerve. Regarding the lumbricals, the first and second lumbricals (to digits II and III) are median-innervated, while the later lumbricals are ulnar-innervated; there isn’t a lumbrical to the thumb, and the phrasing about digits 1-3 is anatomically inaccurate.

Thumb opposition is the defining motor action of the median nerve because it innervates the thenar muscles—opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis—that turn the thumb toward the palm and across the hand to meet the other digits. This opposition enables a precision pinch and is a classic sign of median nerve function.

Other options don’t fit median nerve motor control. Ulnar deviation of the wrist is mainly produced by the flexor carpi ulnaris (ulnar nerve) and extensor carpi ulnaris, not the median nerve. Elbow extension is primarily carried out by the triceps via the radial nerve. Regarding the lumbricals, the first and second lumbricals (to digits II and III) are median-innervated, while the later lumbricals are ulnar-innervated; there isn’t a lumbrical to the thumb, and the phrasing about digits 1-3 is anatomically inaccurate.