The FCR is the primary radial wrist flexor, inserting on the second metacarpal base. Its tendon passes through a fibro-osseous tunnel in the groove of the trapezium before insertion — an entrapment site producing FCR tunnel syndrome (a distinct cause of radial wrist pain). The FCR forms the radial border of the carpal tunnel contents and is the key landmark for the volar approach to the distal radius.
| Origin | Medial epicondyle (common flexor origin) |
|---|---|
| Insertion | Palmar base of the second metacarpal (and occasional slip to the third metacarpal) |
| Nerve Supply | Median nerve (C6, C7) |
| Blood Supply | Radial artery |
| Actions | Wrist flexion; Radial deviation of the wrist; Weak forearm pronation assistance |
|---|
The FCR tendon is the surgical landmark for the modified Henry approach to the distal radius in fracture fixation — the interval between the FCR (median nerve side) and the radial artery (radial side) safely accesses the distal radius while protecting the median nerve, radial artery, and ECRL/brachioradialis.
The FCR tendon is palpable at the wrist as the central tendon on the volar radial side between the palmaris longus (if present) and the radial pulse, becoming prominent during resisted wrist flexion with radial deviation.
FCR tendon degeneration at the trapezial tunnel producing radial wrist pain managed with activity modification, injection, and tunnel release.
