The middle finger FDS slip shares the radial head origin with the index slip, receiving AIN innervation to this component. It is the slip most commonly used as a tendon donor for ring finger extension reconstruction in irreparable EDC injuries.
| Origin | Anterior oblique line of the radius (radial head) and medial epicondyle (humeral head) |
|---|---|
| Insertion | Base of the middle phalanx of the middle finger |
| Nerve Supply | Median nerve (C7, C8, T1) |
| Blood Supply | Ulnar artery |
| Actions | Flexes the PIP joint of the middle finger; Assists middle MCP flexion and wrist flexion |
|---|
The middle FDS slip is a reliable donor for tendon transfer — its harvest produces minimal functional deficit as the middle finger retains FDP function and has adjacent juncturae tendinum from the index and ring EDC slips providing some extension. It is also used in opponensplasty for thumb opposition reconstruction.
Tested by isolated middle PIP flexion with other fingers held extended.
Middle finger FDS tendon slip harvested as a donor for opponensplasty (thumb opposition restoration) in high median nerve palsy, routed through the flexor retinaculum to the APB insertion.
