Which assessment question would best help identify a peripheral nerve impairment affecting the hand, particularly the median nerve distribution?

Which assessment question would best help identify a peripheral nerve impairment affecting the hand, particularly the median nerve distribution?

• A. Do you have numbness on the plantar surface of the foot?
• B. Do you have weakness when trying to pinch with the thumb and index finger?
• C. Do you feel numbness in the posterior thigh?
• D. Can you raise your arm straight up without bending the elbow?

Answer: (B)

Testing the ability to pinch between the thumb and index finger directly taps into the median nerve’s motor role in the hand. The median nerve supplies the thenar muscles (such as abductor pollicis brevis and opponens pollicis) and the flexor pollicis brevis, along with the lateral two lumbricals, which are essential for a precise tip-to-tip pinch. When there is a peripheral nerve impairment in this distribution, these muscles weaken and the person often cannot maintain a strong tip-to-tip pinch, sometimes compensating with a pad-to-pad pinch. That change in pinch strength or pattern is a sensitive indicator of median nerve dysfunction in the hand. In contrast, numbness on the plantar surface of the foot points to a tibial or plantar nerve issue, numbness in the posterior thigh suggests a sciatic or posterior femoral cutaneous problem, and raising the arm straight up without bending the elbow mainly assesses shoulder or scapular–thoracic mechanics rather than intrinsic hand nerve function.

Testing the ability to pinch between the thumb and index finger directly taps into the median nerve’s motor role in the hand. The median nerve supplies the thenar muscles (such as abductor pollicis brevis and opponens pollicis) and the flexor pollicis brevis, along with the lateral two lumbricals, which are essential for a precise tip-to-tip pinch. When there is a peripheral nerve impairment in this distribution, these muscles weaken and the person often cannot maintain a strong tip-to-tip pinch, sometimes compensating with a pad-to-pad pinch. That change in pinch strength or pattern is a sensitive indicator of median nerve dysfunction in the hand.

In contrast, numbness on the plantar surface of the foot points to a tibial or plantar nerve issue, numbness in the posterior thigh suggests a sciatic or posterior femoral cutaneous problem, and raising the arm straight up without bending the elbow mainly assesses shoulder or scapular–thoracic mechanics rather than intrinsic hand nerve function.