Which action is primarily performed by the posterior tibialis?

Which action is primarily performed by the posterior tibialis?

• A. Plantarflexion
• B. Inversion
• C. Dorsiflexion
• D. Eversion

Answer: (B)

Tibialis posterior is best known for turning the sole inward. Its tendon runs behind the medial ankle and attaches to the navicular and midfoot bones, so when it contracts it pulls the foot toward the midline, producing inversion at the subtalar and midfoot joints. It can help with pointing the toes (plantarflexion), but the primary action this muscle performs is inversion of the foot. Dorsiflexion is mainly done by the muscles on the front of the leg, like the tibialis anterior, while eversion is mainly produced by the fibularis (peroneus) muscles, and plantarflexion is mainly driven by the gastrocnemius–soleus complex.

Tibialis posterior is best known for turning the sole inward. Its tendon runs behind the medial ankle and attaches to the navicular and midfoot bones, so when it contracts it pulls the foot toward the midline, producing inversion at the subtalar and midfoot joints. It can help with pointing the toes (plantarflexion), but the primary action this muscle performs is inversion of the foot. Dorsiflexion is mainly done by the muscles on the front of the leg, like the tibialis anterior, while eversion is mainly produced by the fibularis (peroneus) muscles, and plantarflexion is mainly driven by the gastrocnemius–soleus complex.