Flexor pollicis brevis

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

Position

• Medial part is superficial

Origin

• Flexor retinaculum
• Os trapezium
• Os capitatum

Insertion

• 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

• 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