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Ankle joint anatomy

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ankle joint anatomy bones ligaments diagram

This medical anatomical diagram illustrates an anatomic surgical reconstruction of the lateral ankle ligament complex from a lateral view. The diagram depicts the skeletal structures of the distal fibula, talus, calcaneus, and tarsal bones. The primary focus is the surgical reconstruction of the three main lateral ligaments: the Anterior Talofibular Ligament (ATFL), the Calcaneofibular Ligament (CFL), and the Posterior Talofibular Ligament (PTFL). The reconstruction utilizes a split tendon autograft (such as a gracilis tendon) that is anchored to the distal fibula. The graft bifurcates and extends into three distinct limbs, which are secured into bone tunnels on the talus and calcaneus using blue-colored interference screws or anchors. This illustration demonstrates the surgical technique used to manage chronic lateral ankle instability by replicating the native anatomy of the lateral ligament complex to restore joint stability and biomechanical function.

This medical anatomical diagram illustrates an anatomic surgical reconstruction of the lateral ankle ligament complex from a lateral view. The diagram depicts the skeletal structures of the distal fibula, talus, calcaneus, and tarsal bones. The primary focus is the surgical reconstruction of the three main lateral ligaments: the Anterior Talofibular Ligament (ATFL), the Calcaneofibular Ligament (CFL), and the Posterior Talofibular Ligament (PTFL). The reconstruction utilizes a split tendon autograft (such as a gracilis tendon) that is anchored to the distal fibula. The graft bifurcates and extends into three distinct limbs, which are secured into bone tunnels on the talus and calcaneus using blue-colored interference screws or anchors. This illustration demonstrates the surgical technique used to manage chronic lateral ankle instability by replicating the native anatomy of the lateral ligament complex to restore joint stability and biomechanical function.

This medical illustration presents two views of the human ankle joint: an anterior-posterior (top) and a lateral (bottom) view, detailing the primary ligamentous structures and bony anatomy. Key anatomical structures include the distal tibia and fibula, talus, and calcaneus. The syndesmotic complex is represented by the interosseous membrane, anterior inferior tibiofibular ligament (AITFL), and posterior inferior tibiofibular ligament (PITFL). The lateral collateral ligament complex is clearly labeled, showcasing the orientation of the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). The lateral view provides a detailed perspective on the diagonal course of the CFL from the fibular tip to the calcaneus, as well as the inferior transverse tibiofibular ligament. Medially, the deltoid ligament is visible in the anterior view. This educational diagram is designed for orthopedic and radiological study, illustrating the stabilization mechanisms of the ankle joint and the specific spatial relationships between ligaments and tarsal bones involved in inversion and eversion injuries.

This medical illustration presents two views of the human ankle joint: an anterior-posterior (top) and a lateral (bottom) view, detailing the primary ligamentous structures and bony anatomy. Key anatomical structures include the distal tibia and fibula, talus, and calcaneus. The syndesmotic complex is represented by the interosseous membrane, anterior inferior tibiofibular ligament (AITFL), and posterior inferior tibiofibular ligament (PITFL). The lateral collateral ligament complex is clearly labeled, showcasing the orientation of the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). The lateral view provides a detailed perspective on the diagonal course of the CFL from the fibular tip to the calcaneus, as well as the inferior transverse tibiofibular ligament. Medially, the deltoid ligament is visible in the anterior view. This educational diagram is designed for orthopedic and radiological study, illustrating the stabilization mechanisms of the ankle joint and the specific spatial relationships between ligaments and tarsal bones involved in inversion and eversion injuries.

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ankle mortise tibiofibular joint talocrural

This clinical photographic series consists of six panels demonstrating manual joint mobilization techniques for the ankle complex, specifically targeting the talocrural, subtalar, and distal tibiofibular joints. The images depict a therapist performing both anterior-to-posterior (A-P) and posterior-to-anterior (P-A) glides on a patient in a supine position. The top row illustrates talocrural joint mobilization, focusing on the interface between the talus and the mortise to improve dorsiflexion and plantarflexion. The middle row displays subtalar joint mobilization, targeting the articulation between the talus and calcaneus. The bottom row demonstrates glides at the distal tibiofibular joint. Each panel features a blue directional arrow indicating the line of force applied by the therapist's hands, which are strategically placed to stabilize the proximal segment while mobilizing the distal bone. These techniques are characteristic of the Maitland manual therapy concept, frequently utilized in physical therapy to address joint hypomobility and improve range of motion in conditions like spastic diplegia or post-injury stiffness.

This clinical photographic series consists of six panels demonstrating manual joint mobilization techniques for the ankle complex, specifically targeting the talocrural, subtalar, and distal tibiofibular joints. The images depict a therapist performing both anterior-to-posterior (A-P) and posterior-to-anterior (P-A) glides on a patient in a supine position. The top row illustrates talocrural joint mobilization, focusing on the interface between the talus and the mortise to improve dorsiflexion and plantarflexion. The middle row displays subtalar joint mobilization, targeting the articulation between the talus and calcaneus. The bottom row demonstrates glides at the distal tibiofibular joint. Each panel features a blue directional arrow indicating the line of force applied by the therapist's hands, which are strategically placed to stabilize the proximal segment while mobilizing the distal bone. These techniques are characteristic of the Maitland manual therapy concept, frequently utilized in physical therapy to address joint hypomobility and improve range of motion in conditions like spastic diplegia or post-injury stiffness.

**Imaging Modality:** Computed Tomography (CT), bone window settings.

**Imaging Modality:** Computed Tomography (CT), bone window settings.

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Ankle Joint Anatomy

The ankle joint (also called the talocrural joint or tibiotalar joint) is a synovial hinge joint formed by three bones and stabilized by multiple ligament complexes and crossing tendons.

Joint Type and Overview

The ankle is a hinge (ginglymoid) synovial joint. Its primary motions are:
  • Dorsiflexion (~20°) - bringing the foot up
  • Plantar flexion (~45°) - pointing the foot down
It is classically compared to a mortise-and-tenon model: the distal tibia and fibula together form the "mortise," while the articular dorsal surface of the talus (the talar trochlea, or "tenon") fits within it. The talus is wider anteriorly than posteriorly, so the tibia-fibula pincer must dynamically adapt during motion - it widens slightly during dorsiflexion. - Imaging Anatomy Text and Atlas, Vol. 3

Bones and Articular Surfaces

Tibia

  • The inferior articular surface articulates with the dorsal talus (talar trochlea)
  • Concave in the sagittal plane, slightly convex in the coronal plane
  • A smooth ridge divides it into a wider lateral and narrower medial segment
  • The medial segment is continuous with the articular surface of the medial malleolus
  • The medial malleolus has an anterior colliculus, posterior colliculus, and an intercollicular groove
  • The posterior tibial border projects lower than the anterior border

Fibula

  • The lateral malleolus extends further distally than the medial malleolus, reaching lower on the talus
  • Its medial articular surface contacts the lateral facet of the talus (triangular shape)
  • The malleolar fossa on the posterior fibula serves as the insertion point for the posterior talofibular ligament
  • The fibula also forms part of the distal tibiofibular joint

Talus

  • The talar trochlea (superior articular surface) is wider anteriorly - this is why the ankle is most stable in dorsiflexion (wider part locked in the mortise)
  • The medial articular surface is comma-shaped; the lateral surface is triangular
  • The malleoli of both tibia and fibula "envelop" the talus, providing medial and lateral stability - Firestein & Kelley's Textbook of Rheumatology

Ankle Ligament Anatomy

Ankle joint ligaments - anterior and lateral views showing ATFL, CFL, deltoid, tibiofibular ligaments

Medial (Deltoid) Ligament Complex

The deltoid ligament is the only ligament on the medial side. It is a broad, triangular, fan-shaped fibrous band. It:
  • Originates from the medial malleolus
  • Resists eversion of the foot
  • Is torn in eversion sprains
  • Has both superficial and deep components attaching to the talus, navicular, and calcaneus

Lateral Ligament Complex

Three distinct bands form the lateral collateral ligament complex:
LigamentOriginInsertionFunction
ATFL (Anterior Talofibular Ligament)Anterior fibula (lateral malleolus)Lateral talar neckResists internal rotation & inversion in plantar flexion - most commonly injured
CFL (Calcaneofibular Ligament)Fibular tipLateral calcaneus (diagonal course)Resists inversion; bridges both talocrural and subtalar joints
PTFL (Posterior Talofibular Ligament)Malleolar fossa of fibulaPosterior talus (lateral tubercle)Resists posterior displacement; strongest of the three
All three may be injured in inversion sprains of the ankle.

Syndesmotic (Distal Tibiofibular) Ligament Complex

Binds the distal tibia and fibula together to form the mortise:
  • Anterior inferior tibiofibular ligament (AITFL)
  • Posterior inferior tibiofibular ligament (PITFL)
  • Inferior transverse tibiofibular ligament (part of PITFL complex)
  • Interosseous membrane (most proximal, continues the length of the leg)
These ligaments are injured in high ankle sprains and Maisonneuve fractures.

Joint Capsule and Synovium

  • The articular capsule is lax anteriorly and posteriorly, permitting dorsiflexion and plantar flexion
  • It is tightly bound medially and laterally by the ligament complexes
  • The synovial membrane lines the interior and does not communicate with adjacent joints, bursae, or tendon sheaths under normal conditions
  • Synovial swelling tends to bulge anteriorly or anterolaterally (where the capsule is most lax) - Firestein & Kelley's Textbook of Rheumatology

Tendons Crossing the Ankle

All tendons crossing the ankle lie superficial to the articular capsule, each enclosed in a synovial sheath:

Anterior Compartment

TendonAction
Tibialis anteriorDorsiflexion + inversion
Extensor hallucis longusExtends great toe + dorsiflexes
Extensor digitorum longusExtends toes + dorsiflexes
Peroneus tertiusDorsiflexion + eversion

Medial (Posterior to Medial Malleolus) - "Tom, Dick, And Nervous Harry"

TendonAction
Tibialis posteriorPlantar flexion + inversion (supination)
Flexor Digitorum longusFlexes toes + plantar flexes
(Posterior tibial Artery + Nerve)Neurovascular
Flexor Hallucis longusFlexes great toe (lies most posteriorly, under Achilles)
All three medial tendons plantar flex and supinate the foot.

Lateral (Posterior to Lateral Malleolus)

TendonAction
Peroneus longusPlantar flexion + eversion
Peroneus brevisEversion (inserts on 5th metatarsal base)
These extend (plantar flex) and evert (pronate) the foot.

Posterior

  • Achilles tendon - the common tendon of gastrocnemius and soleus, inserting on the calcaneal tuberosity; the strongest tendon in the body, withstanding loads >12× body weight during running; its vascular watershed zone lies 2-6 cm above the calcaneal insertion

Neurovascular Supply

  • Anterior tibial artery / dorsalis pedis supplies the anterior joint
  • Posterior tibial artery passes behind the medial malleolus
  • Peroneal artery contributes laterally
  • Deep peroneal nerve (anterior) and tibial nerve (posterior medial malleolus) cross the joint
  • Sural nerve runs laterally near the Achilles

Range of Motion Summary

MotionPrimary JointNormal Range
DorsiflexionTalocrural~20°
Plantar flexionTalocrural~45°
InversionSubtalar + intertarsal~30°
EversionSubtalar + intertarsal~20°
Inversion and eversion primarily occur at the subtalar (talocalcaneal) joint, not the ankle itself.

Clinical Correlations

  • Lateral ankle sprains (inversion injuries) - ATFL is torn first (most vulnerable), then CFL, then PTFL
  • Deltoid ligament tear - eversion mechanism; often associated with fibular fractures
  • High ankle sprain - syndesmotic injury (AITFL/PITFL); longer recovery than lateral sprains
  • Maisonneuve fracture - fibular fracture at the proximal shaft from syndesmotic disruption
  • Achilles tendon rupture - most common at the watershed zone 2-6 cm proximal to insertion
  • Ankle stability is greatest in dorsiflexion (wider talus locked in mortise) and least in plantar flexion (narrow posterior talus in mortise) - this is why sprains commonly occur with a plantar-flexed foot
Sources: Imaging Anatomy Text and Atlas Volume 3 - Bones, Joints, Vessels and Nerves; Firestein & Kelley's Textbook of Rheumatology; ROSEN's Emergency Medicine; Firestein & Kelley's Textbook of Rheumatology
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