Thenar atrophy in carpal tunnel syndrome indicates involvement of which muscle group?

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Multiple Choice

Thenar atrophy in carpal tunnel syndrome indicates involvement of which muscle group?

Thenar atrophy in carpal tunnel syndrome points to loss of motor function in the thumb muscles supplied by the median nerve’s recurrent branch. In the carpal tunnel, the median nerve’s motor fibers specifically innervate the thenar muscles—abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. When these muscles lose innervation, they waste away, causing atrophy of the thenar eminence and weakness of thumb opposition and abduction. The hypothenar muscles and interosseous muscles are mainly innervated by the ulnar nerve, so their atrophy isn’t a typical feature of carpal tunnel. Forearm flexors are more proximal to the carpal tunnel and aren’t the defining motor deficit seen with CTS.

Thenar atrophy in carpal tunnel syndrome points to loss of motor function in the thumb muscles supplied by the median nerve’s recurrent branch. In the carpal tunnel, the median nerve’s motor fibers specifically innervate the thenar muscles—abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. When these muscles lose innervation, they waste away, causing atrophy of the thenar eminence and weakness of thumb opposition and abduction. The hypothenar muscles and interosseous muscles are mainly innervated by the ulnar nerve, so their atrophy isn’t a typical feature of carpal tunnel. Forearm flexors are more proximal to the carpal tunnel and aren’t the defining motor deficit seen with CTS.

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