Mednotes.

Ankle and Foot Anatomy

Summary

  • The ankle joints
  • Ligaments
  • Muscles
    • Anterior compartment
    • Superficial posterior compartment
    • Deep posterior
  • Injuries of the subtalar joint

The Ankle Joints

There are two main joints to consider at the ankle

  1. The ankle proper / Talocrural joint
    • Between tibia, fibula, and talus
    • Responsible for plantarflexion and dorsiflexion
  2. The Subtalar joint
      • Between talus and calcaneum
      • Inversion and eversion.

  3. NB there is also an Inferior Tibiofibular Joint just above the talocrural joint, sometimes considered part of the ankle

Ligaments of the ankle

  • There are lateral and medial ligaments
  1. Lateral ligaments – easy to remember if you understand the names
    1. Posterior talofibular lig.
    2. Anterior talofibular lig.
    3. Calcaneofibular lig.

  2. Medial ligament
    • AKA Deltoid ligament

 

Muscles of the ankle and lower leg

There are 4 compartments to consider, each responsible for their own movements

  1. Anterior compartment (Dorsiflexion)
  2. Posterior compartments (Plantarflexion)
    1. Deep post. compartment
    2. Superficial post. compartment
  3. Lateral compartment (Eversion)(Acts on talocrural joint only)

Anterior compartment
  • Supplied by
    • Deep fibular nerve
    • Anterior tibial vessels
  1. Tibialis anterior – responsible for inversion
  2. Extensor digitorum longus– extends the toes (except hallux)
  3. Extensor hallucis longus– extends the hallux

 

Superficial posterior compartment

  • Supplied by the
    • Tibial nerve (Medial sural cutaneous nerve branch)
    • Posterior tibial artery
  • Insert via tendocalcaneus
  1. Gastrocnemius
  2. Plantaris
  3. Soleus
Deep posterior compartment
  • These muscles insert into the sole of the foot

  • Neurovascular supply:
    • Tibial nerve (L5-S2)
    • Posterior tibial vessels
  1. Tibialis posterior
  2. Flexor digitorum longus
  3. Flexor hallucis longus

 

Lateral compartment (Evertors)

  •  Supply:
    • Superficial fibular nerve  (L4-S1)
    • Fibular artery
  1. Fibularis longus
  2. Fibularis brevis

Inversion

  • NB this is carried out by the simultaneous action of:
    1. Tibialis anterior (dorsiflexor)
    2. Tibialis posterior(plantarflexor)

Injuries of the subtalar joint

There are 2 main injuries to consider:

  1. Forced eversion
    • Causes fractures of the medial malleolus
      • Prognosis is good – does not damage deltoid ligament

  2. Forced inversion:
    • Fractures lateral malleolus and tears lateral ligament