Which examination tests radial nerve function?

Which examination tests radial nerve function?

• A. Extension of wrist and fingers against resistance; Sensory: dorsum of thumb; index web space
• B. Flexion of fingers; Sensory: volar hand
• C. Abduction of thumb; Sensory: hypothenar
• D. Oppose pinky; Sensory: radial side of palm

Answer: (A)

Radial nerve function is best tested by asking the patient to extend the wrist and fingers against resistance. This muscle group—the extensor muscles of the forearm and hand—is innervated by the radial nerve, so the ability to maintain or produce extension directly assesses motor function of the radial nerve. For sensation, the radial nerve supplies the dorsum of the hand, including the dorsum of the thumb and the first dorsal web space between the thumb and index finger. Testing sensation in these areas checks the radial sensory distribution. Other options mix different nerves or pair motor actions with sensory areas that don’t match radial nerve distribution. Flexion of the fingers relies mainly on flexor muscles innervated by the median and ulnar nerves with volar (palmar) sensation. Abduction of the thumb involves radial nerve motor, but the sensory area described (hypothenar) is innervated by the ulnar nerve. Opposing the little finger tests intrinsic hand muscles primarily via the ulnar nerve, and the described sensory region doesn’t align with radial nerve supply.

Radial nerve function is best tested by asking the patient to extend the wrist and fingers against resistance. This muscle group—the extensor muscles of the forearm and hand—is innervated by the radial nerve, so the ability to maintain or produce extension directly assesses motor function of the radial nerve.

For sensation, the radial nerve supplies the dorsum of the hand, including the dorsum of the thumb and the first dorsal web space between the thumb and index finger. Testing sensation in these areas checks the radial sensory distribution.

Other options mix different nerves or pair motor actions with sensory areas that don’t match radial nerve distribution. Flexion of the fingers relies mainly on flexor muscles innervated by the median and ulnar nerves with volar (palmar) sensation. Abduction of the thumb involves radial nerve motor, but the sensory area described (hypothenar) is innervated by the ulnar nerve. Opposing the little finger tests intrinsic hand muscles primarily via the ulnar nerve, and the described sensory region doesn’t align with radial nerve supply.