Ankle Joint Motions: Dorsiflexion & Plantar Flexion

Motions at the Tibiotalar Joint - Dorsiflexion

• Major dorsiflexors: Tibialis anterior, extensor digitorum longus, and extensor hallucis longus
• The tibialis anterior descends from the anterior tibia, inserting on the medial cuneiform and base of the first metatarsal, on the medial foot aspect.
• The extensor digitorum longus, lateral to the tibialis anterior, inserts on the 2nd, 3rd, 4th, and 5th phalanges.
• The extensor hallucis longus runs deep to the other muscles to the dorsal aspect of the first phalanx (big toe).

Motions at the Tibiotalar Joint - Plantar Flexion

• Major plantar flexors: Gastrocnemius and Soleus
• The gastrocnemius, most superficial, has medial and lateral heads originating on the posterior aspect of the distal femur.
• The gastrocnemius joins the soleus tendon to form the Achilles tendon, inserting on the posterior calcaneus.
• The soleus originates from the posterior tibia, running down to the posterior calcaneus. It does not cross the posterior knee joint.
• Plantaris contributes minor plantar flexion. It runs down the back of the soleus, between the gastrocnemius and soleus.
• The peroneus longus (laterally, everts foot) and posterior tibialis (medially, inverts ankle) contribute to plantar flexion.

Subtalar Joint - Inversion and Eversion

• Inverters: Tibialis anterior and tibialis posterior cause inversion at the subtalar joint but have different motions at the talocrural joint.
• Tibialis anterior is a dorsiflexor, while tibialis posterior is a plantar flexor.
• Flexor digitorum longus and flexor hallucis longus also contribute to inversion, descending with the tibialis posterior on the medial ankle aspect.
• Everters: Peroneus longus, peroneus brevis, and peroneus tertius.
• Extensor digitorum longus provides a minor contribution.
• Peroneus brevis is the most powerful evertor.

Tibiotalar Articulation Anatomy

• The tibiotalar articulation consists of the distal fibula and tibia articulating with the talus.
• The joint forms a square notch where the trochlear surface of the talus fits, providing stability in dorsiflexion.
• The posterior aspect of the talus is narrower, offering less coverage and more room. This creates instability in plantar flexion.
• As the anterior talus is in the ankle mortise, it's very stable, and when the posterior aspect is, its less stable.

Foot and Ankle Sections

• Hindfoot: Talus and Calcaneus
• Midfoot: Cuboid, Navicular, Medial/Intermediate/Lateral Cuneiforms
• Forefoot: Metatarsals and Phalanges
• Knowledge of these bone relationships is important for accurate palpation during diagnostic exams.

Sections - Coronal Plane

• The calcaneus has an articular surface to articulate with the cuboid.
• The navicular articulates with the talus and cuneiforms (lateral, intermediate, and medial).
• The articulation between the calcaneus/talus and the cuboid/navicular is the transverse tarsal joint, also known as the Chopart joint.

Medial and Lateral Columns

• Medial Column: First three metatarsals, cuneiforms, and talus.
• Lateral Column: Fourth and fifth metatarsals, cuboid, and calcaneus.
• These relationships help form the arches of the foot.
• Medial Longitudinal Arch: Consists of the calcaneus, talus, navicular, cuneiforms, and first three metatarsals.
• Lateral Longitudinal Arch: Consists of the calcaneus, cuboid, and fourth and fifth metatarsals.
• Transverse Arch: Composed of the cuboid, cuneiforms, metatarsals, and tarsal-metatarsal joints.

Static Stabilizers of the Longitudinal Arch

• Long plantar aponeurosis (most superficial)
• Long plantar ligament (deep to plantar aponeurosis)
• Plantar calcaneocuboid ligament (short plantar ligament, deep to long plantar ligament)
• Plantar calcaneonavicular ligament (spring ligament, between navicular and calcaneus)