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Flexor pollicis brevis




Flexor pollicis brevis - anterior view
Flexor pollicis brevis - lateral view

General information

  • This section is strictly limited to anatomy, you might be looking for clinical relevant information which is found under the clinical chapters -- muscles section, click here to go to that page
  • A part of the thenar eminence


  • Medial part is superficial


  • Flexor retinaculum
  • Os trapezium
  • Os capitatum


  • Proximal phalanx of thumb, radial side

Main function

  • CMC thumb
    • Flexion
  • MCP thumb
    • Flexion

Secondary function

  • CMC thumb
    • Abduction

Nerve innervation

  • Segmental
    • C8-Th1
  • Peripheral
    • Median nerve
    • Ulnar nerve

Arterial supply

  • Radial artery


  • Patient position
    • Sitting or supine
  • Place your hand on the medial aspect of the thenar muscles
  • Ask the patient to flex the thumb at the CMC joint while you feel for the contraction in the muscle
  • Seperate the flexor pollicis brevis and abductor pollicis brevis

Strength test

  • Patient position
    • Sitting or supine
  • Ask the patient to hold the thumb flexed at the MCP-joint without the IP-joint flexing
  • Give resistance towards the palmar surface of the proximal phalanx in the direction of extension, so that the patient is giving force towards flexion