Name

# Flexor Digitorum Profundus

Pronunciation

(FLEK-sur dij-i-TOR-um pro-FUN-dus)

Origin/Proximal Attachment

Anterior & medial surface of proximal 3/4 ulna; adjacent interosseous membrane

Insertion/Distal Attachment

Distal phalanx of the 4 fingers (through Flexor digitorum superficialis tunnel)

Action/Relevance

Flexes the distal IP joints, & thus the proximal & middle IP jointsFlexes the wrist if fingers are extended

Innervation

Medial portion: ulnar nerve (C8, T1) Lateral portion: interosseous branch of median nerve (C8, T1)

Notes

The flexor digitorum profundis is a muscle in the forearm that flexes the fingers. It is called an extrinsic muscle, because it action is at a different location to the main body of the muscle.

Flexor digitorum profundis, along with flexor digitorum superficialis have long tendons that run down the arm and through the carpal tunnel that attach to the palmar side of the phalanges of the fingers. This muscle originates from the anterior side of the ulna.

Flexor digitorum profundis lies deep to superficialis, but it attaches more distally. To get around this problem profundus's tendons go through the tendons of superficialis, and end up attaching to the distal phalanx.

It is one of the two flexor muscles of the forearm that are not supplied by the median nerve. (The other is flexor carpi ulnaris.) The medial two digits of profundus are supplied by the ulnar nerve.