Which muscles support the medial longitudinal arch besides tibialis posterior?

• A. Intrinsic foot muscles
• B. Tibialis posterior and intrinsic foot muscles
• C. Intrinsic foot muscles and plantar fascia
• D. Tibialis posterior

Answer: (C)

The medial longitudinal arch is held up by both active muscle action and passive structural tissues. Besides the tibialis posterior, the intrinsic muscles of the foot—such as those in the plantar group like abductor hallucis, flexor digitorum brevis, and flexor hallucis brevis—help stabilize the arch from within the sole, maintaining its height and resisting flattening during stance and gait. Along with these, the plantar fascia acts as a strong passive support; when the toes rise or the foot bears weight, the plantar fascia tightens (the windlass action), lifting and stabilizing the arch. Put together, intrinsic foot muscles and the plantar fascia provide the additional support the arch needs beyond tibialis posterior.