The arch supporter
Tibialis posterior · musculus tibialis posterior
A deep calf muscle whose tendon holds up the inner arch of your foot.
What it does
The tibialis posterior lies deep in the calf between the tibia and fibula. Its tendon curls behind the inner ankle and fans out under the foot, mainly onto the navicular bone. It points the foot, turns it inwards and pulls up the inner arch.
Surprising fact
When its tendon weakens or tears, the inner arch slowly collapses, a common cause of flat feet that develop in adulthood.
Why it matters
Pain and swelling behind the inner ankle, especially in middle age, can be an early sign of this tendon struggling, and early treatment can save the arch.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.