Hand Intrinsic Muscles Mnemonic
Remembers which intrinsic hand muscles are innervated by ulnar vs median nerve. Crucial for understanding hand weakness patterns in nerve injuries.
The Mnemonic
"All For One And One For All (AFL-OAF)"
Breakdown
Adductor pollicis
Ulnar nerve - adducts thumb, Froment sign tests this
Flexor pollicis brevis (deep head)
Ulnar nerve - deep head only, superficial head is median
Lumbricals 3-4
Ulnar nerve - medial two lumbricals to digits 4-5
Opponens digiti minimi
Ulnar nerve - opposes little finger
Abductor digiti minimi
Ulnar nerve - abducts little finger
Flexor digiti minimi
Ulnar nerve - flexes little finger MCP joint
Clinical Relevance
Ulnar nerve palsy causes claw hand (hyperextension MCP, flexion IP of digits 4-5), weak grip, and positive Froment sign. Median nerve palsy causes ape hand and weak thumb opposition.
Study Tips
- ✓Ulnar nerve = most hand intrinsics (hypothenar, interossei, medial lumbricals)
- ✓Median nerve = LOAF: Lumbricals 1-2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis
- ✓Ulnar claw: 4th and 5th digits (ulnar lumbricals affected)
- ✓The more distal the ulnar lesion, the worse the claw (ulnar paradox)
FAQs
Common questions about this mnemonic
Froment sign tests adductor pollicis (ulnar nerve). Ask patient to hold paper between thumb and index finger. In ulnar palsy, they compensate by flexing the thumb IP joint using flexor pollicis longus (median nerve) instead of adducting.
This is the "ulnar paradox." High lesions also paralyze FDP to digits 4-5, so the fingers cannot flex at the DIP, partially masking the claw. Low lesions spare FDP, allowing full IP flexion with MCP hyperextension.