- Forearm Flexors
- FPL Rupture:
- Thumb Tendon Injuries:
- anterior surface of middle 1/2 of radius; adjacent interosseous membrane and a slip from coronoid process of the ulna or medial epicondyle of humerus;
- FPL tendon rests between two sesamoid bones, & tendon is covered by fibrous canal, annular ligament, which is responsible for trigger thumb mechanism;
- insertion: palmer surface of the base of the distal phalanx of the thumb;
- flexes the interphalangeal joint of the thumb; continued action, flexes the MP and CMC articulations;
- thumb functions most independently (of the digits), but in 10 % of population tip of thumb & index finger function simultaneously;
- synergists: FPB, adductor pollicis;
- nerve supply: median (AIN branch), C8, T1 > C6, C7;
- Pathologic Anomolous Anatomy:
- FPL may have accessory proximal head, which and cause contracture of thumb secondary to elbow injuries as accessory head attaches to medial epicondyle of the humeus;
- muscle belly may be involved w/ in isolated anterior interosseous compression syndromes, in localized ischemic contracture, or in lacerations;
Bridge flexor tendon grafts.
Flexor superficialis tendon transfers to the thumb--an alternative to the free tendon graft for treatment of chronic injuries within the digital sheath.
Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus.