How do you test motor and sensory function of the median nerve?

How do you test motor and sensory function of the median nerve?

• A. Abduct/Spread fingers against resistance; Sensory: little finger
• B. Flexing thumb distal phalanx against resistance; Sensory: tip of index finger
• C. Extension of wrist and fingers; Sensory: Dorsum of thumb
• D. Flexing ring finger; Sensory: Thenar eminence

Answer: (B)

Testing the median nerve involves checking both its motor and sensory components. For motor function, having the patient flex the thumb’s distal phalanx against resistance specifically engages the flexor pollicis longus, a muscle innervated by the median nerve via the anterior interosseous branch. If the patient can’t actively flex the thumb IP joint against resistance, this suggests impairment of median nerve motor supply to that muscle. For sensory function, assessing sensation at the tip of the index finger targets the median nerve’s cutaneous distribution in the palmar hand. Normal feeling there supports intact median nerve sensation in that area. The other tests point to different nerves or distributions: extending the wrist and fingers tests the radial nerve; abducting the fingers against resistance and sensing the little finger assess ulnar nerve distribution; testing ring finger movement and thenar area sensation mixes non-median functions.

Testing the median nerve involves checking both its motor and sensory components. For motor function, having the patient flex the thumb’s distal phalanx against resistance specifically engages the flexor pollicis longus, a muscle innervated by the median nerve via the anterior interosseous branch. If the patient can’t actively flex the thumb IP joint against resistance, this suggests impairment of median nerve motor supply to that muscle.

For sensory function, assessing sensation at the tip of the index finger targets the median nerve’s cutaneous distribution in the palmar hand. Normal feeling there supports intact median nerve sensation in that area.

The other tests point to different nerves or distributions: extending the wrist and fingers tests the radial nerve; abducting the fingers against resistance and sensing the little finger assess ulnar nerve distribution; testing ring finger movement and thenar area sensation mixes non-median functions.