Which statement best describes the tibialis posterior's role in gait?

Which statement best describes the tibialis posterior's role in gait?

• A. It dorsiflexes the ankle and everts the foot
• B. It externally rotates the knee
• C. It inverts the foot and supports the arch during stance
• D. It flexes the toes

Answer: (C)

The key idea is how the tibialis posterior helps control the foot during the stance phase of gait. This muscle runs behind the medial malleolus and pulls the foot into inversion while supporting the medial longitudinal arch. In early stance, it works eccentrically to slow pronation and prevent the arch from collapsing, contributing to a stable midfoot. As you transition toward push-off, it can assist in maintaining the arch and aiding plantarflexion through its inverting action, helping create a solid lever for propulsion. This combination—foot inversion plus arch support during stance—best describes its role. Dorsiflexion and eversion are handled by other muscles, so those actions aren’t the primary role here. External rotation of the knee isn’t a direct function of the tibialis posterior tendon, and toe flexion is performed by the toe flexors, not by tibialis posterior.

The key idea is how the tibialis posterior helps control the foot during the stance phase of gait. This muscle runs behind the medial malleolus and pulls the foot into inversion while supporting the medial longitudinal arch. In early stance, it works eccentrically to slow pronation and prevent the arch from collapsing, contributing to a stable midfoot. As you transition toward push-off, it can assist in maintaining the arch and aiding plantarflexion through its inverting action, helping create a solid lever for propulsion. This combination—foot inversion plus arch support during stance—best describes its role.

Dorsiflexion and eversion are handled by other muscles, so those actions aren’t the primary role here. External rotation of the knee isn’t a direct function of the tibialis posterior tendon, and toe flexion is performed by the toe flexors, not by tibialis posterior.