Flexor digitorum profundus
Arms
Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.
- Origin
- Front and medial surfaces of the ulna and the interosseous membrane
- Insertion
- Distal phalanges of the four fingers
- Action
- Flexes the fingers, including the fingertip joints, and assists wrist flexion
- Nerve supply
- Ulnar nerve and the anterior interosseous branch of the median nerve (C8–T1)
The deep finger flexor, under the superficialis. It is the only muscle that bends the fingertip joints, so it matters most for closing a full grip.