MR imaging of flexor digitorum accessorius longus

Objective The flexor digitorum accessorius longus muscle (FDAL), an anomalo us muscle about the ankle, has recently been implicated in tarsal tunnel sy ndrome. The purpose of this study is to document the prevalence of the FDAL , its MR appearance and its relation to the neurovascular bundle in the tar sal tunnel. Design and patients The prevalence of the FDAL was determined from 100 ankl e MR examinations in asymptomatic individuals. The appearance of the FDAL w as summarized from 20 examples of FDAL: six gathered from the asymptomatic group and 14 acquired from a group ro of randomly collected cases of patien ts with ankle complaints. Results The prevalence of the FDAL was 6% calculated from the group of 100 asymptomatic individuals. Possessing a dominant fleshy component in the tar sal tunnel, the FDAL. accompanies the posterior neurovascular bundle as it descends the ankle. Conclusion The FDAL is encountered in 6% of asymptomatic individuals, its p rominent fleshy component in the tarsal tunnel and its close proximity to t he posterior tibial neurovascular bundle readily differentiate the FDAL fro m other medial anomalous muscles on MR imaging.