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. 2023 Sep 25;84(5):1031–1046. doi: 10.3348/jksr.2022.0123

Fig. 3. Normal anatomy of the pulley system of the thumb.

Fig. 3

A. The illustration of the thumb pulley anatomy shows two annular pulleys at the level of the metacarpophalangeal joint (A1) and interphalangeal joint (A2).

B. The DI, ADD, FPL and tendon (arrow), FBP, and ABD and OPP are shown well on the T2-weighted axial image. The OPP can be seen inserting into the central palmar fascia (arrowhead).

C. The A2 pulley (arrows) at the proximal phalanx level on the T2-weighted axial image.

ABD = abductor pollicis longus, ADD = adductor pollicis, DI = dorsal interosseous, FBP = flexor pollicis brevis, FPL = flexor pollicis longus, MCP = metacarpophalangeal, OPP = opponens pollicis