Hand Exam: Motor 4/13 – Thenar Muscles

Thenar Muscles (radial group): Instruct the patient “Touch the thumb to the small finger”
All supplied by recurrent branch of median nerve 

Abductor Pollicis Brevis (APD)

  • Origin: flexor retinaculum and tubercles of scaphoid and trapezium
  • Insertion: lateral side of base of the proximal phalanx of the thumb
  • Action: palmar abduction, tiny bit MP flexion and IP extension
  • Innervation: recurrent branch of median nerve

Opponens Pollicis (OP)

  • Origin: Flexor retinaculum and tubercle of trapezium
  • Insertion: lateral side of first metacarpal bone
  • Action: rotates thumb pinch with index finger
  • Innervation: recurrent branch of median nerve

Flexor Pollicis Brevis (FPB)

  • Origin: Flexor retinaculum and tubercle of trapezium
  • Insertion: medial side of base of proximal phalanx of the thumb
  • Action: flexes and stabilizes MPJ
  • Innervation: recurrent branch of median nerve

The 13 muscle groups you need to test in the hand exam:

  1. FPL
  2. FDP
  3. FDS
  4. Thenar muscles
  5. Interosseous
  6. Hypothenar muscles
  7. EPB and APL
  8. EPL
  9. EDC
  10. EIP and EDM
  11. ECRL and ECRB
  12. ECU
  13. Adductor Pollicis


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