[Anomalies of muscles and tendons in hand and wrist (author's transl)]

Anomalies of muscles and tendons in hand and wrist are not uncommon. Their signification in practicing handsurgery must be known. They can rarely be foreseen. When found at random during operation, they may be often neglected. But they are sometimes the cause of different syndromes such as disability of some artist's hands, painful wrist by sports of efforts, nerve compression simulating a carpal tunnel syndrome, camptodactylia, etc. They may also necessitate a modification of planning tendon transfers or grafting. On the dorsal aspect one must point out the extensor digitorum brevis; the absence or hypotrophy of extensor communis digiti quinti, anomalies of the connexus inter-tendinei which can hinder the independency of finger extension; numerous variations of the abductor pollicis longus and extensor pollicis brevis, the latter moving often in a proper tendon sheath. On the palmar aspect, beside the classic absence of palmaris longus, one must also know the anomalies of insertion and the possibility of hypertrophy of this muscle, which can compress the median nerve simulating a carpal tunnel syndrome. The digital flexors can present fusions between each other, especially 4th and 5th, or between flexor pollicis longus and flexor profundus indicis. The intrinsics also have variations concerning their numbers and their proximal and distal insertions. Different clinical cases are described and clearly illustrated in colour.