Tibialis Posterior

Origin, Insertion, Action, Innervation

Origin: Posterior surface of the interosseous membrane, adjacent posterior surfaces of the tibia (lateral to the soleal line) and fibula (medial surface of the proximal two-thirds)
Insertion: Tuberosity of the navicular bone, with expansions to the plantar surfaces of the cuneiforms (medial, intermediate, lateral), cuboid, and bases of metatarsals 2–4
Action:
Primary: Inversion of the foot
Plantarflexion of the ankle (assists)
Dynamic support of the medial longitudinal arch during gait — the muscle actively lifts the arch during midstance
Innervation: Tibial nerve (L4, L5)

Note on insertion: The broad, fan-like insertion across nearly every tarsal and metatarsal base gives tibialis posterior mechanical advantage over the entire midfoot. No other single muscle has this kind of distributed support for the arch.

Palpation Guide

Client position: Prone with the foot off the end of the table, or sidelying with the medial leg accessible.
Landmark sequence:

Locate the medial border of the tibia. Tibialis posterior lies deep to the soleus and gastrocnemius — it cannot be palpated directly through the calf bulk in the proximal leg.
In the distal third of the leg, tibialis posterior becomes accessible behind the medial malleolus. Its tendon passes posterior to the medial malleolus (in the tarsal tunnel, along with the tibial nerve, posterior tibial artery, and flexor digitorum longus and flexor hallucis longus tendons).
Palpate immediately posterior and inferior to the medial malleolus. The tendon is the most anterior of the three tendons passing behind the malleolus (tibialis posterior, FDL, FHL — mnemonic: "Tom, Dick, and Harry").
Follow the tendon to the navicular tuberosity — the bony prominence on the medial midfoot, approximately 2–3 cm distal and inferior to the medial malleolus.

Tissue feel: The tendon behind the medial malleolus is round and cordlike, rolling under the finger. In tendinopathy, it may feel thickened, tender, or crepitant. The navicular insertion is often tender in clients with posterior tibial tendon dysfunction.
Confirmation test: Ask the client to invert and plantarflex the foot (point the foot down and in). The tendon tightens behind the medial malleolus under your palpating finger.
Common errors:
Confusing with FDL — FDL runs posterior to tibialis posterior behind the medial malleolus. Asking the client to curl the toes (without inverting) activates FDL; asking for inversion without toe movement isolates tibialis posterior.
Missing the navicular insertion — the navicular tuberosity is the key insertion landmark. If you cannot find it, have the client invert the foot; the tuberosity becomes more prominent on the medial midfoot.

Trigger Point Referral

Common TrP locations: The primary TrP is in the proximal muscle belly, deep in the posterior compartment between the tibia and fibula. Access is via the medial tibial border, pressing posterolaterally through soleus.
Referral pattern: Pain along the Achilles tendon and into the plantar surface of the foot, concentrating on the sole and extending to the toes.
Clinical significance: Referral to the sole mimics plantar fasciitis — and because tibialis posterior dysfunction directly contributes to arch collapse and true plantar fascia overload, the TrP referral and the biomechanical pathology often coexist. Treat both the muscle and the fascia.

Trigger point referral diagram — coming soon

Image coming soon. For visual reference, see [Tibialis Posterior at TriggerPoints.net](http://www.triggerpoints.net/muscle/tibialis-posterior).

Clinical Notes

Common conditions:

Posterior tibial tendon dysfunction (PTTD) is the hallmark condition — progressive tendon degeneration that leads to adult-acquired flatfoot. Staged from Stage I (tendinopathy, intact arch) through Stage IV (rigid flatfoot with ankle involvement). MTs encounter Stage I and II most frequently.
A primary factor in foot arch disorders — when tibialis posterior is weak or its tendon elongated, the medial arch collapses, producing overpronation and downstream effects including medial knee stress, hip adductor overload, and altered lumbopelvic mechanics.
Contributes to the differential in plantar fasciitis — arch collapse from tibialis posterior weakness increases tensile load on the plantar fascia. Treating the fascia alone without addressing the muscle fails to resolve the biomechanical cause.
The tendon passes through the tarsal tunnel alongside the tibial nerve. Tendon swelling from tibialis posterior tendinopathy can compress the nerve, producing tarsal tunnel symptoms (burning, tingling on the sole).

What you'll typically find:

In clients with overpronation, the tendon behind the medial malleolus is often tender, sometimes thickened or boggy compared to the contralateral side. The navicular tuberosity insertion may be exquisitely tender.
The "too many toes" sign is visible from behind — when the client stands, more toes are visible laterally on the affected side because the foot is abducted from arch collapse.
In early PTTD, the client can still perform a single-leg heel raise but with difficulty or pain. Inability to perform a single-leg heel raise indicates Stage II or worse.

Treatment effects:

The muscle belly is deep and difficult to access directly. Work through the medial tibial border — press posterolaterally through soleus toward the interosseous membrane. Slow, sustained pressure is more effective than rapid techniques at this depth.
The tendon behind the medial malleolus responds to gentle cross-fiber friction for tendinopathy. Avoid aggressive friction if the tendon is acutely inflamed.
Strengthening is essential — eccentric heel raises with inversion bias (rise on the ball of the foot, emphasizing the medial side) rebuild tendon capacity. Without strengthening, manual therapy gains will not hold.

Cautions:

The posterior tibial artery and tibial nerve run alongside the tendon behind the medial malleolus (tarsal tunnel). Sustained heavy pressure over the tarsal tunnel can compress both structures. Use precise, moderate pressure directed at the tendon rather than broad compression.
In Stage III or IV PTTD (rigid flatfoot, subtalar involvement), the condition is beyond conservative MT scope. Refer for orthopedic assessment — surgical reconstruction may be indicated.

Postural significance:

Tibialis posterior is the linchpin of the medial longitudinal arch. When it fails, the entire lower kinetic chain compensates: the foot overpronates, the tibia internally rotates, the knee develops valgus stress, the hip adductors overwork, and the lumbopelvic region shifts to accommodate. Restoring tibialis posterior function addresses the root of this chain.

Clinical pearl:

The single-leg heel raise test is the simplest and most reliable functional test for tibialis posterior integrity. If the client cannot perform 5 single-leg heel raises on the affected side without pain or wobbling, tibialis posterior is functionally compromised — regardless of what the tendon feels like on palpation.

Assessment

Single-leg heel raise test:

Client standing on one leg. Ask them to rise onto the ball of the foot 5–10 times. Observe from behind — the heel should invert (turn inward) as they rise. Failure to invert, inability to complete the raises, or pain behind the medial malleolus indicates tibialis posterior dysfunction. Compare bilaterally.

Resisted inversion:

Client supine with the foot in neutral. Resist inversion at the medial forefoot while the client attempts to turn the sole inward. Pain behind the medial malleolus or weakness compared bilaterally implicates tibialis posterior.

"Too many toes" sign:

Observe the client standing from behind. If more toes are visible lateral to the Achilles tendon on one side, the foot is abducted and the arch is collapsed — suggestive of PTTD.

Muscle Groups

Deep posterior compartment (anatomical):

Tibialis posterior (this article)
Flexor digitorum longus
Flexor hallucis longus

Foot invertors (functional):

Ankle plantarflexors (functional):

Tibial nerve group (innervation):

Related Muscles

Synergists for inversion:

Tibialis anterior — dorsiflexes and inverts (anterior compartment counterpart)
Flexor hallucis longus — assists inversion, deep posterior compartment neighbor
Flexor digitorum longus — assists inversion, deep posterior compartment neighbor

Antagonists (eversion):

Peroneus longus — primary evertor
Peroneus brevis — assists eversion

Key Takeaways

Primary dynamic stabilizer of the medial longitudinal arch — dysfunction leads to adult-acquired flatfoot (PTTD).
The single-leg heel raise test is the simplest reliable functional test for tibialis posterior integrity.
Palpate the tendon behind the medial malleolus (most anterior of "Tom, Dick, and Harry") and at the navicular tuberosity.
Treating plantar fasciitis without addressing tibialis posterior weakness misses the biomechanical cause of arch collapse.