Sesamoids in the foot function as pulleys for which muscle?

Sesamoids in the foot function as pulleys for which muscle?

• A. Flexor Digitorum Longus
• B. Abductor Hallucis
• C. Flexor Digitorum Brevis
• D. Flexor Hallucis Brevis

Answer: (C)

Sesamoid bones under the first metatarsophalangeal joint act as pulleys to redirect the pull of the muscle that flexes the big toe. The tendon of flexor hallucis brevis runs around these two sesamoids as it crosses the MTP joint, so the sesamoids change the line of pull and increase the tendon’s moment arm. This setup improves mechanical advantage for flexing the big toe and reduces friction during toe-off in gait. The other muscles listed don’t use these sesamoids in the same pulley-like way. Flexor digitorum brevis and flexor digitorum longus act on the other toes, and abductor hallucis is involved in abduction of the big toe rather than flexion at the MTP joint via the sesamoids.

Sesamoid bones under the first metatarsophalangeal joint act as pulleys to redirect the pull of the muscle that flexes the big toe. The tendon of flexor hallucis brevis runs around these two sesamoids as it crosses the MTP joint, so the sesamoids change the line of pull and increase the tendon’s moment arm. This setup improves mechanical advantage for flexing the big toe and reduces friction during toe-off in gait.

The other muscles listed don’t use these sesamoids in the same pulley-like way. Flexor digitorum brevis and flexor digitorum longus act on the other toes, and abductor hallucis is involved in abduction of the big toe rather than flexion at the MTP joint via the sesamoids.