Structure & Function

of the Ankle and Foot

A complicated model of simplicity that you really think little about

until you have a problem with one.

The Foot and Ankle

Terminology

Plantar flexion

Dorsi flexion

Inversion

Eversion

Toe flexion/extension

Toe Flexion Toe extension

The Foot and Ankle:

Arthrology & Osteology

tibia

talus

navicular

calcaneus

fibula

lateral malleolus

Extrinsic Muscles of the Ankle/Foot

• Extrinsic muscles originate on the leg and

cross the ankle joint

• Four anatomical areas

(groups/compartments)

–Superficial Posterior

–Deep Posterior

–Anterior

–Lateral

Superficial Posterior

• Gastrocnemius

• Soleus

• Plantaris

• Location: Posterior

• Possible Actions: Plantarflexion

• Innervation: Tibial nerve

Myology of the Foot & Ankle

Gastrocnemius

Origin Medial head: posterior aspect of the

medial femoral condyle

Lateral head: posterior aspect of the

lateral femoral condyle

Insertion Calcaneal tuberosity via the Achilles

tendon

Innervation Tibial n.

Action Plantar flexion, flexion of the knee

Myology of the Foot & Ankle

Plantaris

Origin Lateral supracondylar line of the femur

Insertion Medial aspect of the Achilles tendon to

insert on the calcaneal tuberosity

Innervation Tibial n.

Action Plantar flexion, knee flexion

Myology of the Foot & AnkleSoleus

Origin Proximal 1/3 of the posterior fibula and

fibular head and posterior aspect of the

tibia

Insertion Calcaneal tuberosity via the Achilles

tendon

Innervation Tibial n.

Action Plantar flexion

Deep Posterior Group

• Posterior Tibialis

• Flexor Digitorum Longus

• Flexor Hallucis Longus

• Location: Posterior and Medial

• Possible Actions: plantarflexion, inversion,

some toe flexion

• Innervation: Tibial nerve

Myology of the Foot & Ankle

Tibialis Posterior

Origin Proximal 2/3 of the posterior aspect of the

tibia, fibula, and interosseous membrane

Insertion Most tarsals and metatarsals as well as

the navicular tuberosity

Innervatio

n

Tibial n.

Action Plantar flexion, inversion

Myology of the Foot & Ankle

Flexor Digitorum Longus

Origin Posterior surface of the middle

1/3 of the tibia

Insertion By 4 separate tendons to the

base of the distal phalanx of the

4 lesser toes

Innervation Tibial n.

Action Flexion of toes 2-5, plantar

flexion, inversion

“tidbit” What’s in a name?

Flexor

Digitorum

Longus

Myology of the Foot & Ankle

Flexor Hallucis Longus

Origin Distal 2/3 of the posterior fibula

Insertion Plantar surface of the base of the distal

phalanx of the great toe

Innervatio

n

Tibial n.

Action Flexion of the great toe, plantar flexion,

inversion

Posterior Deep Group

Anterior Group

• Anterior Tibialis

• Extensor Hallucis Longus

• Extensor Digitorum Longus

• Location: All 3 are Anterior ; 2 are anterior

and medial

• Possible actions: dorsiflexion, inversion,

toe extension

• Innervation: deep branch of the peroneal

nerve

Myology of the Foot & Ankle

Tibialis Anterior

Origin Proximal 2/3 of the lateral surface

of the tibia and interosseous

membrane

Insertion Medial and plantar aspects of the

medial cuneiform and the base of

the first metatarsal

Innervation Deep branch of the peroneal n.

Action Dorsiflexion, inversion

Myology of the Foot & Ankle

Extensor Hallucis Longus

Origin Middle section of the fibula and

adjacent interosseous membrane

Insertion Dorsal base of the distal phalanx of

the great toe

Innervation Deep branch of the peroneal n.

Action Extension of the great toe,

dorsiflexion

“tidbit” What’s in a name?

Myology of the Foot & AnkleExtensor Digitorm Longus

Origin Lateral condyle of the tibia, proximal 2/3

of the medial surface of the fibula and

adjacent interosseous membrane

Insertion Splits into 4 tendons that attach to the

proximal base of the dorsal surface of the

middle and distal phalanges

Innervation Deep branch of the peroneal n.

Action Extension of all joints of toes 2-5 (MTP,

PIP and DIP joints)

“tidbit” What’s in a name?

Lateral Group

• Peroneus Longus

• Peroneus Brevis

• Peroneus Tertius

• Location: 2 are Posterior and Lateral;

tertius is anterior

• Possible actions:

–Post and Lat will evert and PF

–Anterior will evert and DF

Myology of the Foot & Ankle

Peroneus Tertius

Origin Distal 1/3 of the medial

surface of the fibula and

adjacent interosseous

membrane

Insertion Dorsal surface of the base of

the 5th metatarsal

Innervation Deep branch of the peroneal

n.

Action Dorsiflexion, eversion

Myology of the Foot & Ankle

Peroneus Longus

Origin Lateral condyle of the tibia, head and

proximal 2/3 of the lateral surface of

the fibula

Insertion Lateral surface of the medial cuneiform

and plantar base of the 1st metatarsal

Innervation Superficial branch of the peroneal n.

Action Eversion, plantar flexion

Myology of the Foot & Ankle

Peroneus Brevis

Origin Distal 2/3 of the lateral surface of

the fibula

Insertion Styloid process of the 5th metatarsal

Innervation Superficial branch of the peroneal

n.

Action Plantar flexion, eversion

Intrinsic muscles of the foot

Flexor digitorum brevis

ABDuctor Hallucis

ABDuctor digiti minimi

Dorsal interossei (ABDuctors)

Plantar interossei (ADDuctors)

Lumbricals

Flexor Hallucis Brevis

ADDuctor Hallucis

Extensor Digiti Minimi

Myology of the Foot & Ankle

Myology of the Foot & Ankle

If you take a look at just part of what happens during gait,

the foot and ankle go through many changes… and this

is a flat surface!

heel strike foot flat mid stance