With the patient relaxed, gently place the fingers around the articulation of the distal metacarpals with the proximal phalanges of the fingers. Either guide or demonstrate motions and observe as the patient moves through metacarpophalangeal flexion, extension, abduction and adduction motions.
Note that the reference for abduction and adduction at these joints is metacarpal 3, not digit 3 nor the middle finger. Therefore, abduction of the middle finger occurs when this finger moves away from this reference in either direction. Adduction of the middle finger occurs when this finger returns to the neutral position. Interestingly, abduction and adduction motions are both performed by abductor muscles, the dorsal interossei. There are no palmar interossei acting on the middle finger.