- See:
- Forearm Flexors
- FPL Rupture:
- Thumb Tendon Injuries:
- Anatomy:
- origin:
- 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;
- action:
- 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.
Congenital anomaly of the thumb: absent intrinsics and flexor pollicis longus.
Direct end-to-end repair of flexor pollicis longus tendon lacerations.
The vascularity of the flexor pollicis longus tendon.
Restoration of flexor pollicis longus function by flexor digitorum superficialis transfer.
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.