The authors studied 10 healthy volunteers, simulation varying degrees of finger stiffness to determine the effect on finger strength during power grip. Strength measurements in the ulnar 3 digits diminished significantly when each of the other fingers, including the index, was stiffened. However, index finger strength was unaffected by simulated stiffness of the ulnar 3 digits.
The results of this study demonstrate that the index finger, with its apparently separate FDP muscle belly, is not entirely independent from the shared FDP muscle belly of the ulnar 3 digits. An obliquely oriented soft-tissue connection between the index and ulnar 3 finger FDP musculotendinous units could explain this phenomenon.
Profundus, Flexor, Tendon, Strength
J of Hand Surgery