Diagram illustrating the sensory distribution and motor function of the main nerves of the upper limb.
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A version of this illustration in Portuguese can be downloaded here: https://commons.wikimedia.org/wiki/File:Exame_neurol%C3%B3gico_do_membro_superior.png
Case Discussion
The sensory distribution is subject to intra- and inter-individual variability. Some areas that more reliably assess each nerve are 4:
median: palmar aspect of the thumb
radial: dorsal aspect of the proximal phalanx of the thumb
ulnar: the 5th finger
The motor function can be memorized using the "rock-paper-scissors-OK" mnemonic 1-3:
median (rock): flexion of the 2nd and 3rd MCPJs
radial (paper): extension of MCPJs and the thumb; a "thumbs up" can be used alternatively
ulnar (scissors): finger abduction and flexion of the 4th and 5th DIPJs
anterior interosseous (OK sign): flexion of the thumb and the 2nd finger (branch of the median n.)
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