Question:medium
A median nerve lesion at the wrist causes all of the following, except:
A median nerve lesion at the wrist causes all of the following, except:
Show Hint
Adductor pollicis is ulnar, not median; remember the LOAF muscles for the median nerve.
Updated On: Jun 24, 2026
- Thenar atrophy
- Weakness of adductor pollicis
- Weakness of 1st and 2nd lumbricals
- Weakness of flexor pollicis brevis
Show Solution
The Correct Option is B
Solution and Explanation
The cleanest way to solve this is to remember exactly which thumb and finger muscles the median nerve runs in the hand. The mnemonic LOAF captures them: the first and second Lumbricals, Opponens pollicis, Abductor pollicis brevis and Flexor pollicis brevis. Cut the median nerve at the wrist and every LOAF muscle loses power. So the thenar bulge, made of opponens, abductor pollicis brevis and flexor pollicis brevis, shrinks and wastes, explaining thenar atrophy and the weak flexor pollicis brevis. The first and second lumbricals also weaken. Three of the four options are therefore genuine consequences. The odd one out is the adductor pollicis, which is not on the LOAF list at all because it is wired to the deep branch of the ulnar nerve. A median lesion leaves it untouched, which is precisely why the Froment sign for adductor pollicis lights up in ulnar damage rather than median damage. The question asks for the false effect.
\[\boxed{\text{Weakness of adductor pollicis}}\]
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