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Muscles controlling the thumb


The positioning of the subject is the same for the four tests. So is the positioning of the examiner,

Common mistakes.

The thumb is allowed to hyperextend at the metacarpophalangeal joint.

Anatomical structures tested:

Muscle function:

• Importallt thumb flexors:
– Flexor pollicis longus
– Flexor pollicis brevis
• Less important thllmb flexor:
– Adductor poll ids.

Common pathological situations:

• Pain is present in a tenosynovitis of the flexor poll ids longus.
• Weakness is suggestive of a lesion of a branch of the median nerve
– the anterior interosseous nerve – and, more rarely, of the ulnar nerve.

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