Learning Modules - Medical Gross Anatomy
Movements of the Upper Limb - Page 17 of 18

    

Finger flexion and extension

 

The four fingers have 3 different joints at which they can flex or extend - the metacarpophalangeal (MP) joint, the proximal interphalangeal (PIP) joint, and the distal interphalangeal (DIP) joint. Some muscles may flex one of these while extending the other two, or flex two and have no effect on the third.

Muscles: interossei and lumbricals flex the MP while extending the PIP and DIP joints; flexor digitorum superficialis flexes the MP and PIP joints only, while flexor digitorum profundus flexes all three, and is the only muscle capable of flexing the DIP joint.

 

Muscles: interossei and lumbricals extend the PIP and DIP joints while flexing the MP joint; extensor digitorum (communis) extends all 3 joints for all 4 digits, although due to tendinous connections between adjacent extensor tendons there may not be independent movement of all fingers; extensor indicis also extends the index finger (independently) and extensor digiti minimi extends the little finger (independently)


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