Ulnar nerve motor function most directly affects which actions?

Ulnar nerve motor function most directly affects which actions?

• A. Power grip and key pinch
• B. Finger abduction
• C. Wrist extension
• D. Elbow flexion

Answer: (A)

Ulnar nerve motor function is best measured by tasks that rely on the intrinsic hand muscles, especially the interossei and the adductor pollicis. The interossei control finger adduction and abduction and help stabilize the metacarpophalangeal joints during gripping, while the adductor pollicis brings the thumb toward the index finger. This combination is what powers a strong grip and a precise key pinch: the thumb must be able to adduct against the index finger, and the fingers must be held securely in place against resistance. In a power grip, the intrinsic muscles coordinate to flex the finger joints in a way that wraps objects securely, with the interossei helping align the digits and the adductor pollicis contributing to thumb positioning for a solid grip. For a key pinch, the thumb’s adduction provided by the adductor pollicis is essential to press the thumb against the index finger, producing the strong, precise pinch that characterizes this action. Wrist extension is mainly a radial nerve function, and elbow flexion is primarily handled by the musculocutaneous (and some radial) nerves. While finger abduction involves the interossei as well, the most direct and diagnostic actions of ulnar motor function are those that require the coordinated intrinsic muscle activity underlying grip and pinch.

Ulnar nerve motor function is best measured by tasks that rely on the intrinsic hand muscles, especially the interossei and the adductor pollicis. The interossei control finger adduction and abduction and help stabilize the metacarpophalangeal joints during gripping, while the adductor pollicis brings the thumb toward the index finger. This combination is what powers a strong grip and a precise key pinch: the thumb must be able to adduct against the index finger, and the fingers must be held securely in place against resistance.

In a power grip, the intrinsic muscles coordinate to flex the finger joints in a way that wraps objects securely, with the interossei helping align the digits and the adductor pollicis contributing to thumb positioning for a solid grip. For a key pinch, the thumb’s adduction provided by the adductor pollicis is essential to press the thumb against the index finger, producing the strong, precise pinch that characterizes this action.

Wrist extension is mainly a radial nerve function, and elbow flexion is primarily handled by the musculocutaneous (and some radial) nerves. While finger abduction involves the interossei as well, the most direct and diagnostic actions of ulnar motor function are those that require the coordinated intrinsic muscle activity underlying grip and pinch.