Flexor digitorum brevis muscle

Last revised by Craig Hacking on 3 Aug 2021

The flexor digitorum brevis (FDB) muscle lies immediately superior to the plantar aponeurosis and inferior to the tendons of the flexor digitorum longus in the sole of the foot.


  • origin: medial process of calcaneal tuberosity and plantar aponeurosis
  • insertion: sides of plantar surface of middle phalanges of 2nd-5th digits
  • action: flexes lateral four toes at proximal interphalangeal joint
  • arterial supply: medial and lateral plantar arteries and plantar arch, plantar metatarsal and plantar digital artery
  • innervationmedial plantar nerve from tibial nerve

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Cases and figures

  • Figure 1: first layer (Gray's illustrations)
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  • Case 1: normal foot MRI
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