A rare anomaly of abductor digiti minimi.

Two cases with anomalous fascicles in abductor digiti minimi, noted in the course of dissecting 62 adult postmortem forearms, are described. Both fascicles arose from the flexor retinaculum and the antebrachial fascia; one was inserted into abductor digiti minimi and the other on the proximal phalanx of the 5th finger. The anomalous muscles crossed the ulnar nerve and in 1 case also the median nerve. In the 2nd case the palmar nerve to the 5th finger was seen to penetrate the anomalous muscle. The ontogeny, morphology and clinical significance of this anomaly are discussed in relation to previously described anomalies of the hypothenar muscles.