Ankle Joint

The ankle is a hinged synovial joint formed between the articular surfaces of the distal tibia, distal fibula, and talus. The ankle primarily allows plantar flexion and dorsiflexion of the foot. The subtalar joint and the other tarsal bones create many synergistic articulations, allowing for a wide range of motion (ROM)—plantar flexion, dorsiflexion, eversion, inversion, abduction, and adduction. The movements are generated by large muscle groups that originate in the leg and insert as well as act upon the bones of the foot and tarsus.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Bones of the Ankle

Ankle joint

Radiograph of the ankle showing the normal anatomy of the ankle and the relationship of the bones and joints

Image by Lecturio.
  • Distal tibia
    • Together with the distal fibula, they form a rectangular mortise (socket) in which the trochlea of the talus sits.
    • Medial malleolus
      • Distal extension of the tibia 
      • Provides medial support
      • Tibial plafond: the distal articular surface of the tibia
  • Distal fibula
    • Together with the distal tibia, they form a rectangular mortise (socket) in which the talus sits.
    • Lateral malleolus
      • Distal extension of fibula
      • Provides lateral support
  • Talus
    • The 2nd-largest tarsal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones
    • Has a wedge-like shape
    • The majority of the talar surface is covered with articular cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage.
    • No tendons or muscles insert into or originate from the talus.
    • Articulates with the tibia, fibula, navicular, and calcaneus bones

Joints of the Ankle

The tibia, fibula, and talus form the ankle joint and, along with the subtalar and talar joints, contribute to the coordinated movement of the ankle.

Lateral view of the ankle

Lateral view of the ankle: Note the 4 different articulations that work synergistically to achieve the full range of motion of the ankle.

Image by Lecturio.

Distal tibiofibular

  • Type: fibrous syndesmosis
  • Components:
    • Medial side of the distal end of fibula
    • Lateral side of the distal end of tibia
  • Supporting ligaments:
    • Anterior and posterior inferior tibiofibular ligaments
    • Transverse ligament
    • Interosseous membrane
  • Function: 
    • Stability
    • Weight-bearing
    • Minimal movement

Talocrural (true ankle) joint

  • Type: synovial hinge joint
  • Components:
    • Medial malleolus of the tibia
    • Lateral malleolus of the fibula
    • Proximolateral facet and trochlea of talus 
  • Supporting ligaments:
    • Medial ligament complex or deltoid ligament:
      • Tibionavicular ligament
      • Tibiocalcaneal ligament
      • Tibiotalar ligament
    • Lateral collateral ligament (LCL) complex: 
      • Anterior talofibular
      • Posterior talofibular
      • Calcaneofibular ligament (CFL)
  • Function:
    • 30–50 degrees of plantar flexion (ankle flexion)
    • 20 degrees of plantar dorsiflexion (ankle extension)

Subtalar (talocalcaneal) joint

  • Type: synovial joint
  • Components: 
    • Anterior, posterior, and middle talocalcaneal joints
    • Composed of 3 alternating convex–concave areas on each of the talus and calcaneus bones
  • Supporting ligaments:
    • Interosseous talocalcaneal ligament
    • Anterior, posterior, lateral, and medial talocalcaneal ligaments
  • Function:
    • 10 degrees of dorsiflexion 
    • Inversion and eversion of the ankle and hindfoot

Transverse tarsal (midtarsal) joint

  • Type:
    • The talocalcaneonavicular joint is a modified ball-and-socket joint.
    • The calcaneocuboid joint is a modified saddle-type joint.
  • Components:
    • Talocalcaneonavicular joint: 
      • Head of the talus
      • Concavity formed by the posterior area of the navicular and anterior area of the calcaneus 
    • Calcaneocuboid joint: 
      • Distal surface of the calcaneus 
      • Proximal area of the cuboid
  • Supporting ligaments:
    • Talocalcaneonavicular joint: articular capsule, dorsal talonavicular ligament, and plantar calcaneonavicular ligament
    • Calcaneocuboid joint: bifurcate (Y-shaped) ligament superiorly, long plantar ligament inferiorly, and short plantar ligament
  • Function:
    • The talocalcaneonavicular joint performs inversion and eversion of the foot.
    • The calcaneocuboid joint performs gliding and rotational movements between the calcaneus and cuboid.

Ligaments and Retinacula

Several major ligament complexes exist in the ankle to provide stability and support.

Lateral ligament complex

  • Resists over-inversion of the foot
  • Extends from the lateral malleolus of the fibula
  • Consists of:
    • CFL 
      • Passes posteroinferiorly
      • Attaches to tip of lateral malleolus 
    • Anterior talofibular ligament (ATFL)
      • Extends anteromedially 
      • Attaches to lateral malleolus
      • Most commonly injured ligament 
      • Injured in inversion sprains
    • Posterior talofibular ligament (PTFL)
      • Attaches to malleolar fossa of fibula
      • Located medially, runs horizontally
      • Supports ankle in dorsiflexion
Lateral view of the ankle

Lateral view of the ankle featuring the supporting ligaments of the talocrural and subtalar joints

Image by Lecturio.

Medial or deltoid ligament

  • Stronger than the lateral complex 
  • Resists over-eversion of the foot
  • This ligament originates from the medial malleolus and then fans out in 4 distinct strands:
    • Tibiocalcaneal ligament
      • Courses inferiorly, almost vertically
      • Attaches to the posterior sustentaculum tali or talar shelf of the calcaneus, which is the horizontal eminence
    • Tibionavicular ligament
      • Courses anteriorly
      • Attaches to the tuberosity of the navicular bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones
    • Anterior tibiotalar ligament
      • Short, thin ligament that courses anteriorly and inferiorly
      • Attaches to the medial talus and medial tubercle
      • Lies deeply to the tibionavicular and tibiospring ligaments
    • Posterior tibiotalar ligament 
      • Courses posteriorly and inferiorly 
      • Attaches to the posteromedial surface of the talus bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones
Ankle joint medial view

Medial view of the ankle highlighting the various ligaments of the medial ankle joint

Image by Lecturio.

Syndesmosis of the ankle

  • Responsible for the integrity of the ankle mortise
  • Consists of the following elements:
    • Interosseous membrane
    • Transverse ligament
    • Anterior and posterior inferior tibiofibular ligaments

Retinacula

  • A fibrous band that surrounds or covers and stabilizes tendons
  • Acts as a pulley system to allow a smooth gliding surface for the muscle tendons, which prevents tendon bowstringing
  • Anterior or extensor retinacula
    • Muscular tendons from the anterior compartment of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg pass under this retinacula.
    • Superior extensor retinaculum: a transverse anterior band between fibula and tibia
    • Inferior extensor retinaculum: a transverse Y-shaped band that extends from the medial malleolus and plantar aponeurosis laterally to the lateral surface of the calcaneus bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones
  • Medial or flexor retinaculum
    • Formed by an oblique band that extends from the medial malleolus of the tibia to the medial surface of the calcaneus bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones
    • Muscular tendons from the deep layer of the posterior compartment of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg pass under this retinaculum.
    • Additionally, the posterior tibial vessels and tibial nerve pass under it.
    • Forms the roof of the tarsal tunnel, with a narrow space on the medial side of the ankle through which various structures pass from the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg into the foot:
      • Tibialis posterior flexor muscle
      • Digitorum longus muscle
      • Posterior tibial artery and vein
      • Tibial nerve
      • Flexor hallucis longus muscle
  • Lateral retinacula
    • The peroneal (fibular) tendons pass under the lateral retinacula.
    • Superior fibular or peroneal retinaculum: extends from the lateral malleolus to the calcaneus
    • Inferior fibular or peroneal retinaculum: a continuation of the inferior extensor retinaculum

Muscles of the Ankle and Range of Motion

Muscles

The muscles of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg insert into the bones of the ankle to create movement, and the range of motion (ROM) occurs in cardinal planes.

  • Sagittal plane (plantar/dorsiflexion)
  • Frontal plane (inversion/eversion)
  • Transverse plane (internal/external rotation) 
  • Pronation and supination 
    • A combination of all of these motions
    • Involves movement in the talocrural, subtalar, and midfoot joints
    • Pronation (ankle dorsiflexion, subtalar eversion, and forefoot abduction)
    • Supination (ankle plantarflexion, subtalar inversion, and forefoot adduction)
Table: Anterior compartment
Muscle Origin Insertion Action Innervation
Tibialis anterior
  • Lateral condyle
  • Upper tibial shaft
  • Interosseous membrane
Interior surface of medial cuneiform Dorsiflexion Deep fibular (peroneal) nerve
Extensor hallucis longus
  • Anteromedial fibula shaft
  • Interosseous membrane
Distal phalanx big toe Dorsiflexion Deep fibular (peroneal) nerve
Extensor digitorum longus
  • Lateral condyle of tibia
  • Proximal portion of fibula
  • Interosseous membrane
Middle and distal phalanges 2–5 Dorsiflexion Deep fibular (peroneal) nerve
Table: Lateral compartment
Muscle Origin Insertion Action Innervation
Fibularis longus Upper portion of lateral fibula 1st metatarsal,
medial cuneiform
Plantar flexion,
eversion
Superficial fibular
Fibularis brevis Distal fibula shaft Proximal end of 5th metatarsal Plantar flexion,
eversion
Superficial fibular
Posterior compartment: Superficial muscles
Muscle Origin Insertion Action Innervation
Gastrocnemius Medial and lateral condyles Posterior calcaneus Plantar flexion Tibial nerve
Soleus Superior tibia, fibula, interosseous membrane Posterior calcaneus Plantar flexion Tibial nerve
Plantaris Posterior femur above lateral condyle Calcaneus or calcaneus tendon Plantar flexion Tibial from anterior rami S1–S2
Tibialis posterior Superior tibia and fibula, interosseous membrane Several tarsals and metatarsals 2–4 Inversion and plantar flexion Tibial nerve
Posterior compartment: Deep muscles
Muscle Origin Insertion Action Innervation
Flexor digitorum longus Posterior tibia Distal phalanges 2-5 Plantar flexion, inversion Tibial nerve
Flexor hallucis longus Midshaft of fibula, interosseous membrane Distal phalanx of big toe Plantar flexion, inversion Tibial nerve

Neurovasculature

Blood supply

  • Fibular or peroneal artery
    • A branch of the posterior tibial artery
    • Supplies the posterior and lateral components of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg and ankle joints
    • Surrounds the lateral malleolus of the fibula as the posterior lateral malleolar branch
    • Provides peroneal branches at the ankle
  • Posterior tibial artery
    • A branch of the popliteal artery 
    • Supplies the posterior compartment of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg, ankle joint, and sole of the foot
    • Enters the foot by passing behind the medial malleolus of the tibia, where it provides branches to the ankle joint
    • Its terminal branches are the lateral and medial plantar arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries
  • Anterior tibial artery 
    • The terminal branch of the popliteal artery
    • Courses through the anterior (extensor) compartment of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg
    • Gives off malleolar arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries that anastomose around the ankle:
      • The anterior medial malleolar artery connects with the posterior tibial and medial plantar arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries.
      • The anterior lateral malleolar artery connects with the perforating branch of the fibular artery and the branches of the lateral tarsal artery.
Arterial supply of the ankle

The arterial supply to the ankle: Note that the anterior tibial artery is shown as its continuation, the dorsalis pedis artery.

Image by Lecturio.

Nerve supply

The nerve supply of the ankle is provided by the roots from spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord level L4 to S2. The following nerves also supply branches to the ankle joint:

  • Deep fibular or peroneal nerve
    • 1 of the terminal branches of the common fibular or peroneal nerve
    • Enters the dorsum of the foot under the extensor retinaculum
    • Gives off articular branches to the ankle joint
    • An injury would result in weakness of ankle dorsiflexion and extension of all toes.
  • Tibial nerve
    • 1 of the terminal branches of the sciatic nerve
    • Enters the sole of the foot by passing behind the medial malleolus through the tarsal tunnel 
    • Provides articular branches to the inferior tibiofibular joint and true ankle joint 
  • Sural nerve
    • Formed by the merge of the medial sural cutaneous nerve (from the tibial nerve) and the lateral sural cutaneous nerve (from the common fibular or peroneal nerve)
    • Sensation to the posterolateral aspect of the distal ⅓ of the leg Leg The lower leg, or just "leg" in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg, ankle joint, foot, and heel

Clinical Relevance

  • Ankle sprain: a partial or complete tear in the ligaments of the ankle joint. An ankle sprain usually occurs via an inversion-type injury to a plantar-flexed and weight-bearing foot. The lateral ligaments are more likely to be damaged because of their structure and biomechanics of the ankle. The ATFL is the component of the lateral ligament complex that is most commonly injured. An ankle sprain presents with pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, swelling, and a limited ROM after physical trauma, and it is usually related to a fall or a sports-related injury.
  • High ankle sprain: occurs when there is injury to the syndesmosis between the tibia and fibula because of an injury of the ankle joints or the interosseous membrane. The most common mechanism of injury is extreme external rotation and dorsiflexion of the ankle.
  • Ankle fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures: the most common fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures of the lower extremity. An ankle fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures is generally caused by twisting the ankle with excessive inversion stress, a mechanism that is most common because the medial malleolus is shorter than the lateral malleolus and the medial deltoid ligaments are stronger than the lateral. An ankle fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures presents as pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain in the affected area, difficulty with weight-bearing, and limited ROM. The diagnosis is confirmed via X-ray. 
  • Tarsal tunnel syndrome: a compressive neuropathy caused by compression of the tibial nerve, which is located under the flexor retinaculum at the posterior–medial aspect of the ankle. The syndrome can be secondary to trauma, rheumatoid arthritis Rheumatoid arthritis Rheumatoid arthritis (RA) is a symmetric, inflammatory polyarthritis and chronic, progressive, autoimmune disorder. Presentation occurs most commonly in middle-aged women with joint swelling, pain, and morning stiffness (often in the hands). Rheumatoid Arthritis (RA), postsurgical changes, ganglion cysts, or shoe trauma and generally presents as pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and paresthesia in the medial–plantar surface of the foot, particularly while walking and standing.
  • Achilles (calcaneal) tendon rupture: a complete or partial tear of the mid-portion of the Achilles tendon when the tendon is stretched beyond capacity. Sudden or unexpected dorsiflexion, pushing off a weight-bearing foot, or extreme dorsiflexion during a fall from a height may result in an Achilles tendon rupture. The injury presents as sharp pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, a loud “pop” or similar sound, and swelling at the back of the heel. The Achilles tendon is the most commonly ruptured tendon in the body. Partial ruptures may be treated conservatively, while complete ruptures require surgical repair.

References

  1. Drake, RL, Vogl, AW, & Mitchell, AWM. (2014). Gray’s Anatomy for Students (3rd ed.). Philadelphia, PA: Churchill Livingstone.
  2. Netter, FH. (2006). Atlas of Human Anatomy. Philadelphia, PA: Saunders/Elsevier.
  3. Standring, S, & Gray, H. (2016). Gray’s Anatomy: The Anatomical Basis of Clinical Practice.
  4. Biga, L, Dawson, S, Harwell, A, Hopkins, R, Kaufmann, J, LeMaster, M, Matern, P, Morrison-Graham, K, Quick, D, & Runyeon, J. (n.d.). Anatomy and Physiology: Chapter 11. Oregon State University.

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