Which of the following factors would explain why there is a weaker grip on the ulnar side of the hand?

a. Active finger flexion range of motion (ROM) increases from the radial to the ulnar side of the hand, lending to increased occurrence of active insufficiency of the ulnar digits.
b. Active finger flexion ROM increases from the ulnar to the radial side of the hand, lending to increased occurrence of active insufficiency of the radial digits.
c. Active finger flexion is the same in all fingers.
d. Weaker grip is not possible with the ulnar side of the hand.

ANS: A
Due to the greater available ROM at the metacarpophalangeal (MCP) and interphalangeal (IP) joints in the fourth and fifth digits compared with the second and third digits, the muscles of these ulnar digits must shorten over a greater distance and therefore are more vulnerable to active insufficiency.