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The National Academy of Sports Medicine

Integrated Function of the Foot & Ankle Complex

Course Objectives

• Explain the interdependent relationship of the foot and ankle as it works synergistically to produce force, reduce force and stabilize the entire kinetic chain during function movements

Anterior Tibialis

• Origin– Lateral Surface of tibia

• Insertion – Medial surface of medial

cuneiform– First Metatarsal

• Innervation– Peroneal N. L4-S1

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Anterior Tibialis cont.

• Isolated function– Dorsiflexion and Inversion

• Integrated Function– Eccentrically decelerates plantarflexion at heel

strike– Eccentrically decelerates pronation of the forefoot

Anterior Tibialis cont.

• Chain Reactions– Weak Anterior tibialis

• Creates eccentric overload to posterior tibialis, soleus, flexor hallucis longus

• May cause increased hip flexor activity during the swing phase of gait increases stress to lumbo-pelvic hip complex in individuals with reduced core stability

Posterior Tibialis

• Origin– Interosseus membrane– Posteromedial fibula– Posterolateral tibia

• Insertion– Tuberosity of Navicular– Medial Cuniform– Metatarsals 2-4

• Innervation– Tibial N. L5-S1

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Posterior Tibialis cont.

• Isolated Function– Plantarflexes foot and inverts the foot– Stabilizes the medial longitudinal arch

• Integrated Function– Eccentrically decelerates subtalar joint pronation by

controlling subtalar joint eversion and internal rotation of the tibia

– Eccentrically decelerates mid tarsal joint pronation assisted by the soleus and anterior tibialis

Posterior Tibialis cont.

• Works synergistically with the soleus, flexor digitorum longus, flexor hallucis longus to decelerate the forward momentum of the lower leg

• During midstance, concentrically accelerates the subtalar joint into supination and externally rotates tibia

Posterior Tibialis cont.

• Chain Reactions– Weak gluteus maximus (tight psoas) weak gluteus

medius (sacroiliac joint) can cause tissue overload to the posterior tibialis and lead to posterior tibialis tendonitis (shin splints)

– Weak posterior tibialis increases the frontal and transverse plane stress to the knee (can cause patellar tendinitis)

– Weak posterior tibialis increases the transverse plane stress in the lumbo-pelvic-hip complex, leading to sacroiliac joint problems

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Soleus

• Origin– Posterior surface of the

head and upper shaft of the fibula and soleal line of the tibia

• Insertion– Calcaneus via the achilles

tendon

• Innervation– Tibial N. S1-S2

Soleus cont.

• Isolated Function– Plantar Flexion

• Integrated Function– Eccentrically assists in the deceleration of subtalar joint

pronation (subtalar joint eversion) and internal rotation of the lower leg at the end of contact phase

– Decelerates ankle dorsiflexion, which assists in knee extension and propulsion

– Accelerates subtalar joint supination with propulsion

Soleus cont.

• Chain Reactions– Weak soleus leads to tissue overload of the other

synergists (posterior tibialis, flexor hallucis longus, flexor digitorum longus) possibly leading to patellar tendinitis, and/or posterior tibialis tendinitis

– Tight soleus decreases sagittal plane dorsiflexion, which increases the frontal plane and transverse plane compensations of the entire kinetic chain

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Gastrocnemius

• Origin– Medial and Lateral

femoral condyle

• Insertion– Calcaneus via achilles

tendon

• Innervation– Tibial N. S1-S2

Gastrocnemius

• Isolated Function– Plantarflexion

• Integrated Function– Eccentrically assists in deceleration of femoral

internal rotation– Eccentrically assists in decelerations of subtalar

joint pronation (eversion and internal rotation)– Concentrically accelerates subtalar joint

supination, assisting in plantarflexion and external rotation

Gastrocnemius

• Chain Reactions– The gastrocnemius can become tight and

overworked from weak proximal external rotators (piriformis, biceps femoris, gluteus maximus)

– Tight Gastrocnemius decreases Sagittal plane dorsiflexion and leads to increased total kinetic chain pronation

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Peroneus Longus

• Origin– Upper two-thirds of the

lateral surface of the fibula

• Insertion– Medial cuneiform and

base of first metatarsal

• Innervation– Superficial Peroneal N.

L4-S1

Peroneus Longus

• Isolated Function– Plantarflexes and everts the foot

• Integrated Function– Stabilizes the first ray in the transverse plane

allowing for proper foot function• Chain Reaction

– Weak peroneus longus allows increased supination, leading to a rigid foot and increased compressive forces in the lumbar spine and sacroiliac joint

The National Academy of Sports Medicine

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