The FCR is the radial wrist flexor, running in its own fibro-osseous tunnel over the scaphoid and trapezium to insert on the second metacarpal base. It is the primary target of the wrist flexor exercise for carpal tunnel syndrome rehabilitation and is the most commonly stretched tendon in de Quervain release confusion. Its tendon is used as a donor for thumb CMC ligament reconstruction.
| Origin | Medial epicondyle via the common flexor origin |
|---|---|
| Insertion | Palmar base of the second metacarpal (primary) and third metacarpal (minor) |
| Nerve Supply | Median nerve (C6, C7) |
| Blood Supply | Radial artery |
| Actions | Wrist flexion (primary); Radial deviation of the wrist; Weak pronation of the forearm |
|---|
FCR is the most efficient wrist flexor because its central position relative to the radial-ulnar axis allows it to flex without significant deviation, while its lateral position relative to the flexion-extension axis provides powerful flexion torque.
FCR tendinopathy at the fibro-osseous tunnel over the scaphoid-trapezium junction produces radial wrist pain reproduced by resisted wrist flexion and radial deviation that mimics but is distinct from de Quervain tenosynovitis (which is reproduced by thumb motion). Ultrasound-guided injection into the FCR sheath confirms and treats the diagnosis.
The FCR tendon is palpable as the central-radial tendon at the wrist crease between the PL centrally and the radial artery laterally during resisted wrist flexion.
Fibro-osseous tunnel stenosis over the scaphoid producing radial wrist pain managed with injection and rarely surgical sheath release.
