Flexor and extensor insertions at the hand and wrist

Case contributed by Dr Roberto Schubert

Abbreviations: FDP - M. flexor digitorum profundus, FDS - M. flexor digitorum superficialis, FPL - M. flexor pollicis longus, FPB - M. flexor pollicis brevis, LL - Mm. lumbricales, FCR - M. flexor carpi radialis, FCU - M. flexor carpi ulnaris.  IO - Mm. interossei, LL - Mm. lumbricales, EPL - M. extensor pollicis longus, EPB - M. extensor pollicis brevis, ED - M. extensor digitorum communis, ECRLB - Mm. extensores carpi radialis longus et brevis, ECU - M. extensor carpi ulnaris, APL - M. abductor pollicis longus. Yellow: extrinsic muscles. Blue: intrinsic muscles.

Case Discussion

The lumbrical muscles (LL) act as flexors at the MCP and as extensors at the IP joints. The dorsal interossei (IO) assist the lumbricals in this function. Their main function is to abduct (dorsal IO) or adduct (palmar IO) the fingers.

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Case information

rID: 14718
Published: 24th Aug 2011
Last edited: 27th Jan 2016
Inclusion in quiz mode: Excluded

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