A patient stands on tiptoe and the longitudinal arch visibly rises, producing passive dorsiflexion of the toes. This windlass effect demonstrates which biomechanical principle of the foot?

• A Tensioning of the plantar aponeurosis over the metatarsal heads raises the arch and inverts the hindfoot ✓
• B Contraction of the long flexors actively elevates the arch
• C The spring ligament shortens reflexly to support the talonavicular joint
• D The plantar calcaneocuboid ligament locks Chopart joint in supination

Explanation

Dorsiflexion of the toes winds the plantar aponeurosis around the heads of the metatarsia like a cable around a drum, shortening the distance between heel and forefoot, raising the medial longitudinal arch, and converting the foot into a rigid lever. The same tension supinates and externally rotates the hindfoot via the subtalar joint. The arch rise occurs passively without intrinsic muscle contraction, which distinguishes it from active arch support by tibialis posterior or the long plantar muscles.

Reference: Moore's Clinically Oriented Anatomy, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.