flexor and the finger may no longer be actively extended. This may be corrected surgically by using a slip of the extensor tendon to replace the damaged ligamentous band. Function The extensor digitorum muscle extends the phalanges, then the wrist, and finally the elbow. It tends to separate the fingers as it extends them. In the fingers, the extensor digitorum acts principally on the proximal phalanges, acting to extend the metacarpophalangeal joint. Extension of the proximal and distal interphalangeal joints, however, is mediated predominantly by the dorsal and palmar interossei and lumbricals of the hand. Additional images See also Extensor digitorum brevis muscle (leg) Extensor digitorum longus muscle (leg) Extensor digitorum reflex (Braunecker-Effenberg reflex) References Muscles of the upper limb