
Tibialis Posterior
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The deep calf muscle that inverts the foot and is the primary dynamic support of the medial arch — the antagonist to the fibularis (peroneal) muscles.
Detail
The tibialis posterior lies deep to the soleus in the posterior compartment of the lower leg; its tendon passes behind the medial malleolus to insert broadly across the tarsal bones and metatarsals. Its primary action is inversion — rolling the sole of the foot inward, toward the midline — and it assists plantarflexion. It is the principal dynamic stabilizer of the medial longitudinal arch; dysfunction of this muscle/tendon is the leading cause of acquired flatfoot in adults.
Key facts
- Action: inversion of the foot; assists plantarflexion.
- Primary dynamic support of the medial longitudinal arch.
- Antagonist to the fibularis longus/brevis (which evert the foot).
- Tendon dysfunction is a leading cause of adult acquired flatfoot.
Connections
- Inversion (Foot Movement) — the movement it produces.
- Fibularis Longus (Peroneus Longus) — antagonist (eversion).
- Foot / Ankle Range of Motion — range-of-motion values for the ankle/foot.
- Soleus — synergist in plantarflexion, superficial to it.
Sources
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.