Accessory flexor digitorum longus muscle

Last revised by Dr Maulik S Patel on 27 Feb 2022

The accessory flexor digitorum longus muscle is an accessory muscle in the deep posterior compartment of the leg with a reported prevalence of 6-8%. Unilateral muscles are more common although bilateral cases have been reported.

  • origin: variable; either the medial margin of the tibia and deep posterior compartment fascia; or the fibula 1,3
  • insertion: variable; either the quadratus plantae muscle, tendon of flexor digitorum longus muscle or both 1,3

The accessory flexor digitorum longus muscle arises from the medial margin of the tibia and the deep posterior compartment fascia or from the fibula. Its insertion may occur into the quadratus plantae muscle, tendon of flexor digitorum longus muscle or both.

  • accessory flexor digitorum longus muscle may compress the neurovascular bundle within the tarsal tunnel and cause tarsal tunnel syndrome 1,3
  • accessory flexor digitorum longus muscle has also been reported to contribute to the development of flexor hallucis longus muscle tenosynovitis 4

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.