Flexor digitorum profundus muscle

Last revised by Andrew Murphy on 17 Nov 2022

The flexor digitorum profundus (FDP) muscle makes up the third layer of the anterior compartment of the forearm along with the flexor pollicis longus muscle. It passes through the carpal tunnel and is one of the extrinsic muscles of the hand. The flexor digitorum profundus muscle is considered a hybrid or composite muscle as it is innervated by two different nerves, the ulnar and anterior interosseous nerve.


  • origin: 

    • medial olecranon, upper three-quarters of the anterior and medial surface of ulna, adjacent interosseous membrane

    • shares aponeurotic attachment to the posterior border of the ulna with flexor & extensor carpi ulnaris

  • insertion: volar surface of distal phalanges of the second to fifth fingers

  • innervation

  • action: flexion at the distal interphalangeal, proximal interphalangeal and wrist joints

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