Tibialis Posterior…Part 9 of the grumbly muscle blog


What’s a tibialis posterior?

It’s a deep calf muscle that sits beneath the superficial gastrocnemius and soleus muscles.


What does it do?

It plantarflexes the foot (points the toes away from the foot) at the ankle joint and inverts the foot (helps you point the soles of your feet inwards).

It also plays a strong role in stabilising the medial longitudinal arch of the foot.



As the name suggests, it starts out life on the proximal posterior (top & back) of the tibia & fibula and the interosseous membrane (the facia between the two bones).

It curves towards the medial malleolus (knobbly bit of bone on the inside ankle) and then inserts onto all five tarsal bones and the bases of 2nd to 4th metatarsals (the three middle toes).


What can happen when it gets grumbly?

  • If this muscle isn’t functioning, then we struggle to maintain our foot arches and they can drop (flat foot), this is also known as posterior tibial tendon dysfunction (PTTD).
  • It is also complicit in shin splints, also known as medial tibial stress syndrome (MTSS), repeated traction of the tibialis posterior and soleus on the periosteum of the bone which can further lead to a stress fracture of the tibia if symptoms are ignored.
  • It can also rupture.


Why does it get grumbly?

You can get acute injuries but predominantly the muscle suffers from overuse injuries especially repetitive high impact activities like running. Poor biomechanics of the hip may also be involved.


Signs that something just isn’t right…

  • Not being able to do a single leg heel lift is a key one. As discussed earlier,
  • A dropped arch compared to the other foot.
  • Pain and or swelling on the medial (inside) of the lower leg or ankle.


What can we do about it?

It’s such a deep muscle that massage and foam rolling are not going to affect it a great deal so strengthening it is the main option on the table to sort this one out. Orthotics may be able to help in the interim though.


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