The most crucial elements of the flexor retinacular or pulley system needed for full digital flexion include which annular pulleys?

B. A 2.

D. A 4.

DISCUSSION: The flexor retinacular system from the metacarpophalangeal joint to the distal interphalangeal joint maintains the flexor tendons against the digit during flexion, preventing bow stringing and allowing the digital tip to flex to the distal palmar crease. Division of the A 1, A 3, or A 5 pulleys minimally compromises this function; however, division of the A 2 or A 4 pulleys can significantly limit digital excursion.