Muscle guide · Lower legs

Tibialis posterior

Also called posterior tib, arch muscle

The tibialis posterior is the deepest muscle at the back of the lower leg. Its tendon runs behind the bony bump on the inside of the ankle and fans out under the arch of the foot.

It is the main support of the inner arch: as you walk it lets the midfoot flatten under load, then locks it into a stiff lever for push-off.

4 exercises 2 stretches6 with 3D demos7 sourcesUpdated 17 October 2026

Where the tibialis posterior is and what it does

Shaded: the calves area. It marks the region, not the exact outline of the tibialis posterior.

Starts at (origin): The backs of both shin bones and the membrane between them, deep in the calf.Posterior tibia, posterior fibula and interosseous membrane
Attaches to (insertion): Many bones under the inner arch and midfoot, mainly the navicular.Navicular tuberosity and medial cuneiform, with slips to the other cuneiforms, cuboid, sustentaculum tali and 2nd to 4th metatarsal bases
What it does: Turns the sole inward; one of the two main muscles that do.Foot inversion
Holds up the inner arch and stiffens the midfoot for push-off.Medial longitudinal arch support
Helps point the foot.Assists plantarflexion
Nerve supply: Tibial nerve (from L4 to S3).

Sources 1, 2, 3

Exercises for the tibialis posterior

In an MRI study, resisted foot adduction (sweeping the foot inward against a band) targeted it most selectively; single-leg heel raises worked it too, though they worked the calf more. In early tendon problems, adding resistance exercise to orthoses and stretching helped more than orthoses and stretching alone.

Single-leg calf raise from a step demonstrated on the 3D figure

3D demoSingle-leg calf raise from a stepIntermediate · A step + A wall

Heel raise with a towel under the toes demonstrated on the 3D figure

3D demoHeel raise with a towel under the toesIntermediate · A step + Other / check instructions

Slow calf raise demonstrated on the 3D figure

3D demoSlow calf raiseBeginner · A wall

Single-leg stand demonstrated on the 3D figure

3D demoSingle-leg standBeginner · A wall

Calf exercises50

Stretches for the tibialis posterior

Posterior Tibialis Stretch demonstrated on the 3D figure

3D demoPosterior Tibialis StretchIntermediate · Other / check instructions

Wall calf stretch (gastrocnemius) demonstrated on the 3D figure

3D demoWall calf stretch (gastrocnemius)Beginner · A wall

Calf and ankle stretches54

Problems linked to the tibialis posterior

Adult flatfoot (posterior tibial tendon dysfunction)

Gradual failure of the tendon lets the inner arch sag. It is the most common cause of a flat foot that develops in adulthood; from behind, more toes than usual show on the outside of the foot.

Source 1

Shin splints on the inner shinMixed evidence

Pain along the inner edge of the shin bone, linked to repeated strain where the tibialis posterior, soleus and flexor digitorum longus attach. It affects 13.6% to 20% of runners. Flat feet can add stress to these muscles.

Sources 4, 5

Shin splints guide

Myths worth dropping

Each grade rates the evidence for the correction.

Arch problems need orthoses, not exerciseEmerging evidence

In a randomised trial of early tendon dysfunction, people who added progressive resistance exercise to orthoses and stretching had less pain and better function than those using orthoses and stretching alone.

Source 7

Routines that train it

Balance exercises routine

Balance practice in 10 minutes: tandem stance, single-leg stands, marches, heel walks, tree pose and floor transfers.

10 minBeginner7 movesA wall, A bench or box

Questions people ask

What does the tibialis posterior do?

It turns the sole inward and is the main support of the inner arch, letting the midfoot absorb load and then stiffen for push-off.

How do you strengthen the tibialis posterior?

Resisted inward sweeps of the foot against a band targeted it most in an MRI study; single-leg heel raises also work it.

What happens when the tibialis posterior fails?

The inner arch gradually collapses. Posterior tibial tendon dysfunction is the most common cause of flat foot that develops in adults.

Muscles it works with

Sources

Anatomy and movement education, not a diagnosis or treatment plan. If you have pain that follows an injury, is severe or getting worse, or comes with numbness, weakness or swelling, get it assessed. Health disclaimer.