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Hand Anatomy
Muscles of the Hand
| Muscle |
Innervation |
Origin |
Insertion |
Action |
Nerve Root |
| Thenar Muscles |
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| Abductor pollicis brevis (APB) |
median |
Scaphoid, trapezoid |
base of proximal phalanx, radial side |
abduct thumb |
C8, T1 |
| Opponens pollicis |
median |
trapezium |
thumb metacarpal |
abduct, flex, med. Rotation |
C8, T1 |
| Flexor pollicis brevis (FPB) |
median(superficial head), ulnar(deep head) |
trapezium, capitate |
base of proximal phalanx, radial side |
flex MCP |
C7, C8 |
| Adductor pollicis |
Ulnar |
capitate, 2nd/3rd metacarpals |
base of proximal phalanx, ulnar side |
Adduct thumb |
C8, T1 |
| Hypothenar Muscles |
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| Palmaris Brevis (PB) |
ulnar |
TCL, palmar aponeurosis |
Ulnar palm |
Retract skin |
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| Abductor dibiti minimi |
ulnar |
pisiform |
base of proximal phalanx, ulnar side |
abduct small finger |
C8, T1 |
| Flexor digiti minimi brevis(FDMB) |
Ulnar |
hamate, TCL |
base of proximal phalanx, ulnar side |
flex MCP |
C8, T1 |
| Opponens digiti minimi(ODM) |
Ulnar |
hamate, TCL |
small finger metacarpal |
abduct, flex, lat rotation |
C8, T1 |
| Intrisinsic Muscles |
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| Lumbricals |
median, ulnar(ulnar two) |
flexor digitorum profundus(FDP) |
lateral bands(radial) |
extend PIP |
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| Dorsal interosseous(DIO)(DAB) |
Ulnar |
adjacent metacarpals |
proximal phalanx base/extensor apparatus |
abduct, flex MCP |
C8, T1 |
| Volar interosseous(VIO) |
Ulnar |
adjacent metacarpals |
proximal phalanx base/extensor apparatus |
Adduct, flex MCP |
C8, T1 |
Pulleys
- each digit has annular and cruciform pulleys to prevent tendon bowstringing.
- Pulley progression = A1, A2, C1, A3, C2, A4, C3
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Median Nerve
- Index finger abduction
- Thumb anteposition (opposition)
- Index finger pulp sensation
Radial Nerve
Ulnar Nerve
- First dorsal interosseous
- Small finger pulp sensation
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