Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus

Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus are described. Clinical examination of 194 patients suggests that the anomaly is present in at least one extremity of 31% of individuals and in both extremities in 14%. Dissection of 43 cadavers demonstrated the anomaly in at least one extremity of 25% and in both extremities of 6%. Four cases are described in which the anomaly probably was responsible for chronic tenosynovitis. The anomaly was excised surgically in all cases.