Learning Outcomes: Students will be able to:

1. Describe the musculoskeletal anatomy of the leg, ankle joint and joints of the foot and associated connective tissues that support these joints.
2. Identify the functional design of the ankle, subtalar, foot arch, and various foot joints and the osteokinematic and arthrokinematic movements possible at the joints.
3. Describe the origin, insertion, actions, and nerve innervation of the muscles that act on the ankle, subtalar and foot joints.
4. Identify how to strengthen and stretch each of the muscles or muscle groups that cross and act on the ankle, subtalar and foot joints.
5. Describe anatomical deviations of the subtalar joint and forefoot anatomy.
6. Describe mechanisms of injury for compartment syndrome, ankle sprains, great toe and calcaneal deviations, and other identified pathologies.

Anterior Compartment (Anterior Tibial Artery/Veins & Deep Peroneal Nerve)

1. Tibialis Anterior
2. Extensor Digitorium Longus
3. Extensor Hallicus Longus
4. Peroneus (Fibularis) Tertius

Lateral Compartment (Anterior Tibial Artery, Fibular Artery & Superficial Peroneal Nerve)

1. Peroneus (Fibularis) Longus
2. Peroneus (Fibularis) Brevis

Posterior Superficial Compartment (Posterior Tibial Artery/Veins & Tibial nerve)

1. Gastrocnemius
2. Soleus
3. Plantaris

Posterior Deep Compartment (Posterior Tibial Artery/Veins & Tibial nerve)

1. Tibialis Posterior
2. Flexor Digitorium Longus
3. Flexor Hallucis Longus

Anterior Compartment Syndrome

The Ankle and Foot

Inferior Tibiofibular Joint

The inferior tibiofibular joint (Amphiarthroidal – syndesmosis) is the union between the distal tibia and fibula. It is connected by the anterior and posterior inferior tibiofibular ligaments and the interosseous membrane that runs between the two bones. During normal weight bearing movement there can be 1 to 2 mm spread at this joint.

  Figure 1            

Ankle Joint

The ankle is a hinge (ginglymus) joint where the sagittal plane

motions of plantarflexion and dorsiflexion take place. Its

closed-pack position is full ankle dorsiflexion. This joint is

formed by the articulation between the tibia, fibula, and talus.

The joint is called the tibiotarsal, tibiotalar or talocrural joint and

is often referred to as a “mortice” type joint, where the medial and

lateral malleoli of the tibia and fibula respectively form a type of

socket that articulates with the peg-shaped talus bone.

Range of Motion

Dorsiflexion: movement of top of foot toward tibia. ROM 20°

Plantarflexion: movement of foot away from the tibia. ROM 50°

Closed Pack Position: Fully dorsiflexed

Open Pack Position: Planterflexed 10º

Open-Chain Arthrokinematics of the Ankle:

• Dorsiflexion: the talus rolls anteriorly on the

inferior tibia and slides/glides posteriorly.

• Plantarflexion: the talus rolls posteriorly and

slides/glides anteriorly.

  Figure 2

Subtalar & Transverse (Midtarsal) Joints

Two major joints are found between the articulations of the

tarsal bones. The subtalar joint, which is the junction

between the inferior surface of the talus and superior surface

of the calcaneous bones, and the midtarsal 

joint, which is between the junction of the calcaneous and

cuboid bones on the lateral side of the foot, and the

junctions between the talus and navicular bones on the

medial side of the foot. It is at these joints that the foot

movements of inversion and eversion take place.

Subtalar (arthrodial) & Midtarsal (arthrodial) joints

Inversion: turning of foot inward,

toward midline. ROM: 35°

Eversion: turning of foot outward,

away from midline. ROM: 15°

Closed Pack Position: Fully inverted while ankle dorsiflexed

Open Pack Position: Midway, and plantarflexed 10º

Figure 3

Range of Motion

Metatarsophalangeal (condyloidal)

      -Big toe: ROM: Flexion: 45°, Extension: 70°

      -Four lesser toes: ROM: Flexion: 40°,

       Extension: 40° (slight abd. & add.)

• Closed Packed Position: Fully extended
• Open Packed Position: Neutral

Interphylangeal (ginglymus)

       -Big toe: ROM: Flexion: 90°

       -Lesser toes: ROM: Flexion: PIP: 35° DIP:  60°

• Closed Packed Position: Fully extended
• Open Packed Position: Neutral

 Referenced point for abd/adduction is midline of 2nd toe.

 Figure 4

Regions of the Foot

Pertaining to functional aspects of the foot:

• Hindfoot is made up of the talus and calcaneous,

the first part of the foot that makes contact with

the ground in the gait cycle.

• Midfoot is made up of the other tarsal bones
•  – the navicular, the cuboid, and the three cuniform bones,

that serve to provide stability and mobility as it

transmits movement from hindfoot to forefoot.

• Forefoot consists of the 5 metatarsals and all the

phalanges. This part of the foot adapts to the level

of the ground and is the last part of the foot to make

contact with the ground during the stance phase.

Figure 5

Selected Ligaments of the Ankle

Mortice Stabilizers

The anterior inferior tibiofibular and the posterior inferior tibiofibular ligaments, along with the interosseous membrane help stabilized the tibia and fibula.

Deltoid Ligament Complex (medial stabilizers)

1. Tibiocalcaneal ligament (attaches from medial malleolus to calcaneous)
2. Tibionavicular ligament (attaches from medial malleolus to navicular)
3. Anterior Tibiotalar ligament (attaches ant. medial malleolus to ant. talus)
4. Posterior Tibiotalar ligament (attaches post. medial malleolus to post. talus)

Lateral Stabilizers

1. Anterior Talofibular ligament (horizontal attachment from lateral malleolus to anterior talus)

2. Calcaneofibular ligament (vertical attachment from lateral malleolus to calcaneous)

3. Posterior Talofibular ligament (horizontal attachment from lateral malleolus to posterior talus)

Figure 6         

Arches of the Foot

Medial Longitudinal Arch: on the medial border of the foot, this arch runs from the calcaneus anteriorly through the talus, navicular, and three cuneiforms to the first three metatarsals. The talus/navicular at the top-center of the arch serves as the keystone receiving the weight of the body. It is supported by the plantar fascia, plantar ligaments and Tibialis Anterior/Posterior muscles.

Lateral Longitudinal Arch: on the lateral border of the foot, this arch runs from the calcaneus through the cuboid to the fourth and fifth metatarsals. It is also supported by the Peroneus Longus muscle.

Transverse Arch: runs side to side through the three cuneiforms to the cuboid. The second cuneiform is the keystone of this arch.

Figure 9

Note: these arches are maintained by 1) shape of the tarsal bones and their relation to each other, 2) the plantar ligaments and fascia, and 3) key extrinsic and intrinsic muscles.

Spring Ligament (Plantar calcaneonavicular): Attaches medially to the calcaneus running forward to attach to the navicular and provides support to the medial side of the longitudinal arch.

Long Plantar Ligament: This is the longest and most superficial ligament. It attaches to the calcaneus and runs forward to attach on the cuboid and bases of the third, fourth, and fifth metatarsals. It primarily supports the lateral longitudinal arch.

Short Plantar Ligament: Attaches the calcaneus to the cuboid and assists the long plantar ligament in providing support to the longitudinal arches.

Plantar Fascia: Attaches from the calcaneus and runs forward to attach to the proximal phalanges of the five toes. It acts as a tie-rod, keeping the hindfoot secured to the midfoot and the forefoot. This fascia increases the stability of the foot and arches during weight bearing and provides for the Windlass Mechanism.

Figure 10

Figure 11 

Windlass Mechanism: the plantar fascia serves as a tie-rod from calcaneus to the 1st phalanx of the toes, crossing the MTP joint. During push-off, while walking, the MTP joint is extended placing stretch/tension on the plantar fascia which pulls the heel and toes closer together. This raises the arch and locks the bones of the feet for a more rigid foot during push-off.

Retinaculum of the Ankle and Foot

1. Transverse Crural (Superior extensor retinaculum): attaches lateral distal fibula and medial distal tibia

2. Cruciate Crural (Inferior extensor retinaculum): 

“Y” shaped band that connects to the lateral

calcaneous and medial malleolus and plantar

aponerosis

3. Peroneal Retinaculum: 

               Superior: attaches post. lateral malleolus to

               calcaneous

               Inferior: attaches lateral superior calcaneous

               to lateral inferior calcaneous

       4.     Flexor Retinaculum: attaches medial    

               malleolus to medial tarsal bones

Figure 12

Figure 13

Functional Muscle Groups of Tibiotarsal and Subtalar Joints

Compartments

 Figure 14    

Anterior Compartment:

• Muscles: Tibialis Anterior, Extensor Hallicus Longus, Extensor Digitorum Longus, Fibularis/Peroneus Tertius
• Nerve: Deep Fibular/Peroneal
• Vascular: Anterior Tibial Artery and Veins

Lateral Compartment:

• Muscles: Fibularis/Peroneus Longus, Fibularis/Peroneus Brevis
• Nerve: Superficial Fibular/Peroneal
• Vascular: Anterior Tibial Artery and Fibular Artery

Posterior Compartment:

• Muscles: Deep: Tibialis Posterior, Flexor Digitorum Longus, Flexor Hallicus Longus

Superficial: Gastrocnemius, Soleus, Plantaris

• Nerve: Tibial
• Vascular: Posterior Tibial Artery and Veins

Ankle & Extrinsic Foot Muscles – Posterior Compartment

Gastrocnemius

Origin:

Insertion:

Action:

Nerve Innervation:

Soleus

Origin:

Insertion:

Action:

Nerve Innervation:

Plantaris

Origin:

Insertion:

Action:

Nerve Innervation:

Tibialis Posterior

Origin:

Insertion:

Action:

Nerve Innervation:

Flexor Digitorum Longus

Origin:

Insertion:

Action:

Nerve Innervation:

Flexor Hallisis Longus

Origin:

Insertion:

Action:

Nerve Innervation:

Ankle & Extrinsic Foot Muscles – Lateral Compartment

Peroneus (Fibularis) Longus

Origin:

Insertion:

Action:

Nerve Innervation:

Figure 17

Peroneus (Fibularis) Brevis

Origin:

Insertion:

Action:

Nerve Innervation:

Ankle & Extrinsic Foot Muscles – Anterior Compartment

Tibialis Anterior

Origin:

Insertion:

Action:

Nerve Innervation:

Figure 18

Externsor Hallicis Longus

Origin:

Insertion:

Action:

Nerve Innervation:

Extensor Digitorum Longus

Origin:

Insertion:

Action:

Nerve Innervation:

Peroneus (Fibularis) Tertius

Origin:

Insertion:

Action:

Nerve Innervation:

Intrinsic Muscles of the Foot – Superficial Layer

Flexor Digitorum Brevis

Origin:

Insertion:

Action:

Nerve Innervation:

Abductor Digiti Minimi

Origin:

Insertion:

Action:

Nerve Innervation:

Origin:

Insertion:

Action:

Nerve Innervation:

Abductor Hallucis

Origin:

Insertion:

Action:

Nerve Innervation:

Intrinsic Muscles of the Foot – Second Layer

Flexor Digiti Minimi

Origin:

Insertion:

Action:

Nerve Innervation:

Quadratus Plantae

Origin:

Insertion:

Action:

Nerve Innervation:

Lumbricales

Origin:

Insertion:

Action:

Nerve Innervation:

Intrinsic Muscles of the Foot – Third Layer

Adductor Hallucis

Origin:

Insertion:

Action:

Nerve Innervation:

Plantar Interossei

Origin:

Insertion:

Action:

Nerve Innervation:

Intrinsic Muscles of the Foot – Dorsal Layer

Dorsal Interossei

Origin:

Insertion:

Action:

Nerve Innervation:

Extensor Digitorum Brevis

Origin:

Insertion:

Action:

Nerve Innervation:

Functional Performance of the Foot through Pronation and Supination

The functional use of the lower extremities requires the coordinated movement of several joints. Specifically, the ankle and foot require the

coordinated actions of several muscles and joints. Pronation and Supination are terms that represent tri-planar movements of the foot and

ankle. These motions allow the foot and ankle to assist with balance while adapting to changing surface conditions and then to become rigid

levers to assist with push-off for propulsion.

Pronation & Supination at the “Subtalar” Joint

Pronation involves open chain eversion, abduction, and

dorsiflexion.

Supination involves open chain inversion, adduction, and

plantarflexion.

During Open Kinetic Chain Activities:

• The talus is stabilized in the tibiotalar joint between

the tibia and fibula, while the calcaneus moves,

producing supination and pronation at the subtalar

joint.

--- In Supination the calcaneus inverts in the

     Frontal plane, plantar flexes in the sagittal plane, and

     adducts in the horizontal plane.

--- In Pronation the calcaneus everts in the frontal

     plane, dorsiflexes in the sagittal plane, and

     adducts in the horizontal plane.

During Closed Kinetic Chain Activities:

• The calcaneus moves in the frontal plane, but

cannot move freely in the other planes because it is

fixed to the ground by way of body weight.

--- In Supination the calcaneus inverts, while the

     talus dorsiflexes and abducts. This creates a rigid lever

    for propulsion during gait..

--- In Pronation the calcaneus everts, while the

     talus plantar flexes and adducts. This unlocks the foot

    and ankle allowing the entire foot to make contact with

    the ground and to adapt to a variety of surfaces

Pronation & Supination at the “Transverse Tarsal” Joint

The Transverse Tarsal joint is the junction of the calcaneus and cuboid bones (calcaneocuboid) on the lateral side

 of the foot, and the junctions of the talus and navicular bones (talonavicular) on the medial side of the foot.

Motion at the transverse tarsal joint is necessary for the foot to adjust to and maintain contact with the

 ground regardless of the terrain.

• As the rearfoot moves into supination, the

transverse tarsal joint follows and also supinates.

• As the rearfoot moves into pronation, the

transverse joint can move into supination or

pronation.

Neutral position of calcaneus  

Right leg

Pronation with calcaneal eversion

Right leg

Supination with calcaneal inversion

Right leg