The Ankle Complex

Components

• Tibial bone
• Fibular bone
• Talus bone

Joints

• Proximal Tibiofibular Joint
  • Limited movement
• Distal Tibiofibular Joint
  • Key function: Maintain ankle stability
  • Major ligaments:
    • Anterior Tibiofibular Ligament
    • Posterior Tibiofibular Ligament
    • Calcaneofibular Ligament
• Talocrural Joint
  • Composed of tibia, fibula, and talus
  • Primary movements: Ankle dorsiflexion and plantarflexion
  • Weight-bearing primarily between tibia and talus
  • Stability enhanced by:
    • Anterior Talofibular Ligament
    • Posterior Talofibular Ligament
    • Deltoid Ligament (medial side, 4 parts)
      • Anterior Tibiotalar Ligament
      • Posterior Tibiotalar Ligament
      • Tibiocalcaneal Ligament
      • Tibionavicular Ligament
  • Closed pack position: Full dorsiflexion
  • Open pack position: 10 degrees of plantarflexion

Foot Anatomy

Divisions

• Hindfoot: Talus, calcaneus
• Midfoot: Navicular, cuneiforms (medial, intermediate, lateral), cuboid
• Forefoot: Metatarsals, phalanges

Important Joints

• Subtalar Joint: Between talus and calcaneus
  • Movements: Inversion, eversion
  • Function: Stabilize foot on uneven ground, allow weight shift side-to-side

Foot Arches

• Medial Longitudinal Arch: Calcaneus, talus, navicular, cuneiforms, first three metatarsals
• Lateral Longitudinal Arch: Calcaneus, cuboid, fourth and fifth metatarsals
• Transverse Arch: Cuneiforms (medial, intermediate, lateral), cuboid
  • Functions: Weight-bearing, shock absorption, force transmission

Muscles Acting on Ankle and Foot

Compartments

Superficial Posterior Compartment

• Muscles: Gastrocnemius (medial and lateral heads), Soleus, Plantaris
  • Functions: Ankle plantarflexion, knee flexion (except Soleus)

Deep Posterior Compartment

• Muscles: Tibialis Posterior, Flexor Digitorum Longus, Flexor Hallucis Longus
  • Mnemonic: Tom, Dick, and Harry

Anterior Compartment

• Muscles: Tibialis Anterior, Extensor Digitorum Longus, Extensor Hallucis Longus
  • Functions: Ankle dorsiflexion, toe extension

Lateral Compartment

• Muscles: Fibularis Longus, Fibularis Brevis
  • Function: Ankle plantarflexion, eversion
  • Note: Fibularis Tertius is present in some individuals

Movement Mechanics

Ankle Dorsiflexion (Open Chain)

• Arthrokinematics: Convex moving on concave (rolling and gliding)
• Prime Movers: Anterior compartment muscles

Ankle Plantarflexion (Open Chain)

• Arthrokinematics: Convex moving on concave (rolling posteriorly and gliding anteriorly)
• Prime Movers: Posterior compartment muscles