Question #419

Abductor pollicis longus arises from both the radius and ulna. It is the most lateral tendon to pass under the extensor retinaculum but is closely associated and shares a common synovial sheath with extensor pollicis brevis. It inserts into the lateral aspect of the first metacarpal but also has some fibres extending to trapezium.

It abducts the thumb and the wrist.

It is supplied by the posterior interosseous branch of the radial nerve.

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