Muscle
Flexor digitorum profundus
Flexor that reaches the fingertips
High-yield
It is the finger flexor that crosses the DIP joints. The index and middle portions usually receive anterior interosseous supply; the ring and little portions receive ulnar supply.
Overview
This deep forearm muscle sends tendons to the distal phalanges of the four fingers. Each tendon passes through a split in the corresponding superficialis tendon to reach its more distant attachment.
Reference facts
- Origin
- Anterior and medial surfaces of the proximal three-quarters of the ulna, plus interosseous membrane
- Insertion
- Palmar bases of the distal phalanges of digits 2-5
- Action
- Flexes the finger DIP joints and assists flexion at the more proximal finger joints and wrist
- Innervation
- Index/middle portions: anterior interosseous branch of median; ring/little portions: ulnar nerve; chiefly C8-T1, with variation
- Blood supply
- Ulnar and anterior interosseous arterial branches
Clinical correlation
A jersey-finger injury tears this tendon away from its distal attachment, often in the ring finger. Active DIP flexion is lost or reduced; a nerve lesion can also weaken this movement and must be distinguished from tendon injury.
Frequently asked questions
What does the flexor digitorum profundus do?
The flexor digitorum profundus flexes the finger DIP joints and assists flexion at the more proximal finger joints and wrist.
What nerve innervates the flexor digitorum profundus?
Index/middle portions: anterior interosseous branch of median; ring/little portions: ulnar nerve; chiefly C8-T1, with variation.
Where does the flexor digitorum profundus attach?
Origin: Anterior and medial surfaces of the proximal three-quarters of the ulna, plus interosseous membrane. Insertion: Palmar bases of the distal phalanges of digits 2-5.
What is the blood supply of the flexor digitorum profundus?
The flexor digitorum profundus is supplied by the ulnar and anterior interosseous arterial branches.