MedCourseFinder

Structure

Ankle (talocrural) joint

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The ankle is a synovial hinge joint between the tibia, fibula and talus, formed by the mortise of the malleoli gripping the trochlea of the talus. It permits dorsiflexion and plantarflexion, while inversion and eversion occur mainly at the subtalar joint.

Terminologia Anatomica (Latin): Articulatio talocruralis · Open in the 3D atlas

Location

It lies at the distal end of the leg. The tibialis posterior, flexor digitorum longus, posterior tibial vessels, tibial nerve and flexor hallucis longus pass behind the medial malleolus; the fibularis tendons pass behind the lateral malleolus.

Structure

Medial stability is provided by the strong deltoid ligament (tibionavicular, tibiocalcaneal, anterior and posterior tibiotalar parts). The lateral ligament complex is weaker: anterior talofibular (ATFL, most often torn), calcaneofibular and posterior talofibular ligaments. The distal tibiofibular syndesmosis holds the mortise together. The talus is wider anteriorly, so the joint is most stable in dorsiflexion.

Blood supply

Malleolar branches of the anterior tibial, posterior tibial and fibular (peroneal) arteries form periarticular anastomoses. The talus has a vulnerable blood supply (largely entering through the neck), so talar neck fractures risk avascular necrosis.

Innervation

Deep fibular, tibial and sural nerves (L4-S2) supply the capsule, following Hilton's law. Pain and sensation over the dorsum and sole depend on the superficial/deep fibular, sural, saphenous and tibial branches.

Function

Dorsiflexion by tibialis anterior and long extensors (deep fibular nerve); plantarflexion by gastrocnemius, soleus and deep posterior muscles (tibial nerve), the Achilles tendon being the common tendon of the calf. Inversion and eversion take place at the subtalar and transverse tarsal joints.

Clinical correlations

Inversion sprains injure the ATFL first, then the calcaneofibular ligament; the deltoid is rarely torn without a fracture. Malleolar fractures are classified by fibular level relative to the syndesmosis (for example Weber). Achilles tendon rupture presents with a palpable gap and failed Thompson (calf squeeze) test. Tarsal tunnel compression of the tibial nerve causes sole pain and paraesthesia.

Common exam points

  • Lateral ligament complex (ATFL, CFL, PTFL) is weaker than the medial deltoid ligament; ATFL is the most commonly torn ligament.
  • Ankle is most stable in dorsiflexion because the talus is wider anteriorly.
  • Medial malleolus: tibialis posterior, flexor digitorum longus, tibial nerve, flexor hallucis longus (Tom, Dick And Very Nervous Harry).
  • Achilles tendon: Thompson test; rupture often in middle-aged athletes.
  • Talar neck fractures risk avascular necrosis of the talar body.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

References are listed only where the article cites them. See the sources page for the full policy. How sources are chosen and credited

Back to the index