(eks-ten'sŏr dij'ĭ-tī min'i-mī mŭs'ĕl) Origin, lateral epicondyle of humerus; insertion, dorsum of proximal, middle, and distal phalanges of little finger; action, extends fingers; nerve supply, radial (posterior interosseous). Synonym(s): musculus extensor digiti minimi [TA] , extensor muscle of little finger.