REVIEW ARTICLE Compression

of the median and ulnar nerves at the wrist is frequently encountered. Carpal tunnel syn-drome usually occurs without any obvious extrinsic cause; several cases have however been reported caused by anomalous or hypertrophic muscles. A survey of the literature shows that compression neu-ropathy of the median nerve has been reported in relation with anomalies affecting three muscles: the first (or second) lumbrical, the palmaris longus and its anatomic variants and the superficial flexor of the index finger. In the ulnar tunnel the situation is thoroughly different: so-called idiopathic ulnar tun-nel syndrome is rare and an extrinsic compressing structure can usually be disclosed. Anomalous mus-cles belong to the palmaris longus/abductor digiti minimi group; the flexor carpi ulnaris is sometimes involved. One can suspect the presence of such an anomalous muscle when the compression syndrome concerns a patient who is not within the “usual ” age group with symptoms initiated or aggravated by physical exer-cice