tests for palsy
of the ulnar nerve
, specifically, the action of adductor pollicis
To perform the test, a patient is asked to hold an object, usually a piece of paper, between the thumb
and a flat palm
. The object is then pulled away.
- A normal individual will be able to maintain a hold on the object without difficulty.
- However, with ulnar nerve palsy, the patient will experience difficultly maintaining a hold and will compensate by flexing the FPL (flexor pollicis longus) of the thumb. Clinically, this compensation manifests as flexion of the IP joint of the thumb (rather than extension, as would occur with correct use of the adductor pollicus). Note that the FPL is normally innervated by the anterior interosseous branch of the median nerve. Please be aware, anterior interosseous branch comes off more proximally than the wrist in evaluating lacerations near the wrist.
Another way to perform this test is to have the patient hold the piece of paper between the tip of the thumb and the tip of the index finger. Then, pull the paper out from between their fingers asking patient not to let go of it.
- If the patient has to resort to pad-to-pad pinch, the patient is positive for Froment's sign.
It is named for Jules Froment.