Foot Ankle Complex Handout

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

1

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

2

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

3

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

4

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

5

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

Thank You

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