Anatomy and Function of the Foot and Ankle

If you coach movement, you don't need to memorise a textbook — but you do need a working model of how the foot and ankle are built and how they move. Here's the version that actually matters on the gym floor.

The bones

From the lower leg down into the toes:

• Tibia — the larger lower-leg bone, on the medial (inner) side.
• Fibula — the smaller lower-leg bone, on the lateral (outer) side.
• Talus — sits above the heel bone and forms the lower part of the ankle joint.
• Calcaneus — the heel bone, and the largest bone in the foot.
• Navicular — a boat-shaped bone in the midfoot.
• Cuboid — a cube-shaped bone on the lateral side of the foot.
• Cuneiforms — three wedge-shaped midfoot bones: medial, intermediate and lateral.
• Metatarsals — the five long bones numbered I to V, starting from the inner side.
• Phalanges — the toe bones. Each toe has three (proximal, middle, distal) except the big toe (hallux), which has two.

The joints

• Ankle joint (talocrural) — tibia, fibula and talus. Allows dorsiflexion and plantarflexion.
• Subtalar joint (talocalcaneal) — between talus and calcaneus. Allows inversion and eversion.
• Transverse tarsal joint (Chopart) — two joints together: talonavicular and calcaneocuboid.
• Tarsometatarsal joints (Lisfranc) — between the tarsal bones and the bases of the metatarsals.
• Intermetatarsal joints — between the bases of the metatarsals.
• Metatarsophalangeal joints — between the metatarsals and the proximal phalanges.
• Interphalangeal joints — between the phalanges. Each toe has two, except the big toe, which has one.

The movements

At the ankle (talocrural) joint:

• Dorsiflexion — lifting the foot up towards the shin.
• Plantarflexion — pointing the foot down away from the shin.

At the subtalar joint:

• Inversion — turning the sole inward.
• Eversion — turning the sole outward.
• Abduction — moving the foot away from the body's midline.
• Adduction — moving the foot towards the midline.

Why movements couple together

This is the part most trainers miss. The foot doesn't move in tidy, isolated planes — the joints are oriented so that certain movements happen together.

• Dorsiflexion, eversion and abduction go together. As the foot dorsiflexes at the ankle, it also everts and abducts at the subtalar joint. This gives you a mobile foot that accommodates uneven ground during initial contact and mid-stance.
• Plantarflexion, inversion and adduction go together. As the foot plantarflexes, it inverts and adducts. This gives you a rigid, stable lever for push-off in walking and running.

Why some movements can't combine

Evolution has limited certain combinations to protect the joint:

• Dorsiflexion and inversion can't occur together — dorsiflexion positions the talus so the ankle locks, blocking inversion.
• Plantarflexion and eversion can't occur together — plantarflexion locks the foot in a way that blocks eversion.

The reasons are structural. Joint orientation dictates which movements pair up, and the ligaments and tendons around the foot are arranged to support those specific combinations — giving stability through the gait cycle and preventing the excessive, injurious ranges the joint isn't built for.

Understand this coupling and foot assessment stops being a list of isolated tests. You start reading the foot as one system that softens to absorb and stiffens to propel.