Comprehensive Anatomy of the Foot and Ankle

Original Editor - Carin Hunter
Top Contributors - Carin Hunter

Basic Structure of the Foot and Ankle[edit | edit source]

The ankle or tibiotalar joint constitutes the junction of the lower leg and foot. The osseous components of the ankle joint include the distal tibia, distal fibula, and talus.

The  anatomic structures below the ankle joint comprise the foot, which includes:

  1. Hindfoot: The hindfoot is the most posterior aspect of the foot, is composed of the talus and calcaneus, two of the seven tarsal bones. The talus and calcaneus articulation is referred to as the subtalar joint, which has three facets on each of the talus and calcaneus.
  2. Midfoot: The midfoot is made up of five of the seven tarsal bones: navicular, cuboid, and medial, middle, and lateral cuneiforms.  The junction between the hind and midfoot is termed the Chopart's joint, which includes the talonavicular and calcaneocuboid joints.
  3. Forefoot: The forefoot is the most anterior aspect of the foot. It includes metatarsals, phalanges (toes), and sesamoid bones. There are a metatarsal and three phalanges for each digit apart from the great toe, which only has two phalanges. The articulation of the midfoot and forefoot forms the Lisfranc joint.

Bones[edit | edit source]

The bones of the ankle are named as follows:

The bones of the foot are named as follows:

  • Metatarsals
    • Numbered from medial or first (big toe), to lateral or fifth (little toe)
  • Phalanges
    • Toes 2-5 each have 3 phalanges. The first or big toe (hallux) has only two

Joints[edit | edit source]

Joint Type of Joint Plane of Movement Motion
Talocrural joint Hinge Sagittal Dorsiflexion & Plantarflexion   Formed between the distal tibia-fibula and the talus, and is commonly known as the ankle joint. The distal and inferior aspect of the tibia – known as the plafond – is connected to the fibula via tibiofibular ligaments forming a strong mortise which articulates with the talar dome distally.
Subtalar joint (Talocalcaneal joint) Condyloid Mainly transverse

Some sagittal

Inversion & Eversion

Dorsiflexion & Plantarflexion

Formed between the talus and calcaneus.
  • There are three facets on each of the talus and calcaneus.
  • The posterior subtalar joint constitutes the largest component of the subtalar joint.
  • The subtalar joint allows inversion and eversion of ankle and hindfoot.
Midtarsal joint (Transverse tarsal joints or Chopart’s joint) Talonavicular joint - Ball and socket

Calcaneocuboid joint - Modified saddle    

Largely in transverse    

Some sagittal

Inversion & Eversion

Flexion & Extension

It is an S-shaped joint when viewed from above. It consists of two joints – the Talonavicular Joint and Calcaneocuboid Joint.
Talonavicular joint Ball and socket Largely in transverse Inversion & Eversion Formed between the anterior talar head and the concavity on the navicular. It does not have its own capsule, but rather shares one with the two anterior talocalcaneal articulations.
Calcaneocuboid joint Modified saddle Sagittal Flexion & Extension Formed between the anterior facet of the calcaneus and the posterior cuboid. Both articulating surface, present a convex and concave surface with the joint being convex vertically and concave transversely. Very little movement occurs at this joint.
Tarsometatarsal joint (Lisfrank Joint) Planar The distal tarsal rows including the three cuneiform bones and cuboid articulate with the base of each metatarsal to form the TMT complex. It is an S-shaped joint and is divided into 3 distinct columns:
  • Medial – composed of 1st metatarsal and medial cuneiform.
  • Middle – composed of 2nd and 3rd metatarsals, intermediate and lateral cuneiforms respectively.
  • Lateral – composed of 4th and 5th metatarsals and the cuboid.
Metatarsophalangeal joint   Condyloid Sagittal

Some Transverse

Flexion & Extension

Abduction & Adduction

Formed between the metatarsal heads and the corresponding bases of the proximal phalanx.
Interphalangeal joint Hinge Sagittal Flexion & Extension Formed between the phalanges of the toes. Each toe has proximal and distal IP joints except for the great toe which only has one IP joint.

Ligaments[edit | edit source]

Ankle ligament injury is the most frequent cause of acute ankle pain. Hence, it is important to understand the anatomy of ankle ligaments for correct diagnosis and treatment.

The ligaments around the ankle can be divided, depending on their anatomic position, into three groups: the lateral ligaments, the deltoid ligament on the medial side, and the ligaments of the tibiofibular syndesmosis that join the distal epiphyses of the tibia and fibula.

The lateral collateral ligament complex (LCL) consists of:

  1. Anterior talofibular ligament: it is the most frequently injured ligament of the ankle. This ligament plays an important role in limiting anterior displacement of the talus and plantar flexion of the ankle.
  2. Posterior talofibular ligament: The posterior talofibular ligament originates from the malleolar fossa, located on the medial surface of the lateral malleolus, coursing almost horizontally to insert in the posterolateral talus. It is the strongest ligament of the lateral ankle. plays only a supplementary role in ankle stability when the lateral ligament complex is intact.
  3. Calcaneofibular ligament: The calcaneofibular ligament originates from the anterior part of the lateral malleolus. Its primary role is to restrain inversion in a neutral or dorsiflexed position, restrains subtalar inversion, thereby limiting talar tilt within the ankle mortise.


The medial collateral ligament (MCL), also known as Deltoid ligament, is composed of two layers; superficial and deep. The MCL is a multifascicular ligament, originating from the medial malleolus to insert in the talus, calcaneus, and navicular bone. It primary restrains to valgus tilting of the talus. Both the superficial and deep layers individually resist eversion of the hindfoot. It also stabilizes ankle against plantar flexion, external rotation, and pronation.

The ligaments of the tibiofibular syndesmosis consist of anterior or anteroinferior tibiofibular ligament, the posterior or posteroinferior tibiofibular ligament, and the interosseous tibiofibular ligament. The syndesmotic ligament complex ensures the stability between the distal tibia and the fibula and resists the axial, rotational, and translational forces that attempt to separate the tibia and fibula.

LIGAMENT DESCRIPTION PROXIMAL ATTACHMENT DISTAL ATTACHMENT FUNCTION
Anterior Talofibular Ligament (ATFL) Flat Weak Band that extends Anteriomedially.

Most commonly damaged ligament of the ankle.

Lateral Malleolus Neck of Talus Restrain anterior displacement of the talus in respect to the fibula and tibia.

Resists Inversion in plantarflexion.

Posterior Talofibular Ligament

(PTFL)

Thick, a fairly strong band that runs horizontally medially.

This ligament is under greater strain in full dorsiflexion of the ankle.

Rarely injured because bony stability protects ligaments when ankle in dorsiflexion.

Malleolar Fossa of Fibula Lateral Tubercle of Talus Forms the back wall of the recipient socket for the talus' trochlea.

Resists posterior displacement of the talus.

Calcaneofibular Ligament (CFL) Round cord that passes posteroinferior Tip of Lateral Malleolus Lateral Surface of Calcaneus Aids Talofibular stability during Dorsiflexion.

Restrain inversion of the calcaneus with respect to the fibula.

Prevent Talar tilt into Inversion.

LIGAMENTS DESCRIPTION PROXIMAL ATTACHMENT DISTAL ATTACHMENT FUNCTION
Anterior Tibiotalar

Ligament

Medial Malleolus Head of Talus Reinforces Ankle Joint.

Control Plantarflexion & Eversion

Posterior Tibiotalar

Ligament

Talus Posteriorly Control Dorsiflexion
Tibionavicular

Ligament

Forms most anterior part of the Deltoid Ligament Dorsomedial Aspect of Navicular Reinforces Ankle Joint
Tibiocalcaneal

Ligament

Very thin ligament Sustentaculum Tali Reinforces Ankle Joint

Muscles of the Foot[edit | edit source]

Extrinsic Foot Muscles

These muscles have contractile portions that lie outside the ankle, in the leg, and the tendons of those muscles insert onto the bones of the foot in such a way that ankle motion occurs when the muscles contract

There are four 4 compartments, separated by fascia

  1. Superficial Posterior compartment (Plantar Flexors)
    1. Gastrocnemuis (TA)
    2. Soleus (TA)
    3. Plantaris
  2. Deep posterior compartment (Plantar Flexors)
    1. FHL (inversion) (plantar surface of 1 toe)
    2. FDL (inversion) (plantar surface 2-5 toes)
    3. Tibialis Posterior (inversion) (navicular, medial cuneiform, 2-4 toes, other cuneiforms, cuboid)
  3. Lateral compartment (Plantar Flexors)
    1. PL (eversion, PF first metatarsal) (medial cuneiform and 1 toe)
    2. PB (eversion)  (5 toe)
  4. Anterior compartment (Dorsiflexors)
    1. Tibialis anterior (inversion) (1 toe, medial cuneiform
    2. EHL (inversion)
    3. EDL
    4. PT (eversion)

The dorsum of the foot has only one muscle (maybe 2 depending on classification). This is the extensor digitorum brevis (some authors name the most medial part of this muscle extensor hallucis brevis). Tendons are the main collagenous structures in the dorsum. The tendons connect anterior/dorsiflexor compartment muscles of the leg to the foot bones.

MUSCLE ACTION PROXIMAL ATTACHMENT DISTAL ATTACHMENT INNERVATION BLOOD SUPPLY
POSTERIOR COMPARTMENT
SUPERFICIAL POSTERIOR COMPARTMENT
Gastrocnemius Plantarflexion when Knee Extended

Flexion Knee

Raises Heel during Walking

Lateral Head: Lateral Aspect of Lateral Femoral Condyle

Medial Head: Popliteal Surface of Femur Superior to Medial Femoral Condyle

Posterior Surface Calcaneus via Calcaneal Tendon (Achilles Tendon) Tibial Nerve

S1-S2

Soleus Plantarflexion

Steadies Leg on Foot

Posterior Aspect of Head Fibula

Superior ¼ Posterior Surface Tibia

Soleal Line & Medial Border Tibia

Plantaris Weakly Assists Gastrocnemius in Plantarflexion Inferior end Lateral Supracondylar Line of Femur

Oblique Popliteal Ligament

DEEP POSTERIOR COMPARTMENT
Tibialis Posterior Plantarflexion

Inversion

Supports Medial Longitudinal Arch

Interosseous Membrane

Posterior Surface Tibia inferior to Soleal Line

Posterior Surface Fibula

Navicular Tuberosity

Cuneiform

Cuboid

Bases of Metatarsals 2-4

Tibial Nerve

L4-L5

Flexor Digitorum Longus Plantarflexion

Flexion Lateral Four Digits

Supports Longitudinal Arch

Medial Part Posterior Surface

Tibia inferior to Soleal Line

Broad Tendon to Fibula

Base Distal Phalanges Digits 2-4 Tibial Nerve

S2-S3

Flexor Hallucis Longus Weak Plantarflexion

Flexion Big Toe at all Joints

Supports Medial Longitudinal Arch

Inferior 2/3 Posterior Surface Fibula

Inferior Part Interosseous Membrane

Base Distal Phalanx of Big Toe
LATERAL COMPARTMENT
Peroneus Brevis Weak Plantarflexion

Eversion

Inferior 2/3 of Lateral Surface Fibula Dorsal Surface Tuberosity of Base

5th Metatarsal

Superficial Peroneal Nerve

(Superficial Fibular Nerve)

L5 - S2

Peroneus Longus Weak Plantarflexion

Eversion

Supports Transverse Arch

Head & Superior 2/3 of  Lateral Surface Fibula Base 1st Metatarsal

Medial Cuniform

ANTERIOR COMPARTMENT
Tibialis Anterior Dorsiflexion

Inversion

Supports Medial Longitudinal Arch

Lateral Condyle Tibia

Superior ½ Lateral Surface Tibia

Interosseous Membrane

Medial & Inferior Surfaces

Medial Cuniform

Base of 1st Metatarsal

Deep Peroneal Nerve

(Deep Fibular Nerve)

L4-L5

Extensor Digitorum

Longus

Dorsiflexion

Extends Lateral Four Digits

Lateral Condyle Tibia

Superior ¾ Anterior Surface

Interosseous Membrane

Middle & Distal Phalanges of Lateral Four Digits Deep Peroneal Nerve

(Deep Fibular Nerve)

L5-S1

Extensor Hallucis

Longus

Dorsiflexion

Extends Big Toe

Middle Part Anterior Surface Fibula

Interosseous Membrane

Dorsal Aspect of Base Distal

Phalanx of Big Toe

Peroneus Tertius Dorsiflexion

Aids Eversion

Inferior 1/3 Anterior Surface Fibula

Interosseous Membrane

Dorsum Base 5th Metatarsal

Intrinsic Foot Muscles

The plantar aspect of the foot contains the tough fibrous plantar aponeurosis covering muscles and tendons arranged in 4 layers, numbered from 1 superficial to 4 deep:

  1. Layer 1
    1. abductor didgiti minimi,
    2. Flexor digitorum brevis
    3. Abductor hallucis
  2. Layer 2
    1. quadratus plantae
    2. Lumbricals
    3. Long tendons of flexor digitorum longus and flexor hallucis longus
  3. Layer 3
    1. Flexor hallucis brevis,
    2. Adductor hallucis and
    3. Flexor digiti minimi brevis
  4. Layer 4
    1. Interosseous muscles
    2. Long tendons of peroneus/fibularis longus and tibialis posterior

Arches[edit | edit source]

The arches of the foot provide functions of force absorption, base of support and acts as a rigid lever during gait propulsion.

The medial longitudinal arch, lateral longitudinal arch and transverse arch are the 3 arches that compromise arches of foot.

  1. Medial Longitudinal Arch (MLA)
    • It is the longest and highest of all the arches. Bony components of MLA include the calcaneus, talus, navicular, the three cuneiform bones and the first 3 metatarsals. The arch consists of two pillars: the anterior and posterior pillars. The anterior pillar consists of the head of first 3 metatarsal heads and the posterior pillar consists of the tuberosity of the calcaneus. The plantar aponeurosis forms the supporting beam connecting the two pillars. The apex of the MLA is the superior articular surface of talus. In addition to the plantar aponeurosis the MLA is also supported by the spring ligament and the deltoid ligament. The Tibialis anterior and posterior muscles play an important role in raising the medial border of the arch, whereas Flexor hallucis longus acts as bowstring.  
  2. Lateral Longitudinal Arch (LLA)
    • It is the lowest arch and comprises of the calcaneus, cuboid, fourth & fifth metatarsal as its bony component. Like the Medial Longitudinal Arch (MLA) the posterior pillar consists of the tuberosity of the calcaneus. The anterior pillar is formed by the metatarsal heads of 4th and 5th metatarsals. The plantar aponeurosis, long & short plantar ligaments provides support to the LLA. The Peroneus longus tendon plays an important role in maintaining the lateral border of the arch.
  3. Transverse Arch
    • It is concave in non-weight bearing and runs medial to lateral in the midtarsal and tarsometatarsal area. The bony component of the arch consists of the metatarsal heads, cuboids and 3 cuneiform bones. The medial and lateral pillars of the arch is formed by the medial and lateral longitudinal arch respectively. The arch is maintained by the Posterior tibialis tendon and the Peroneus longus tendon which cross the plantar surface from medial to lateral and lateral to medial respectively.