RACHEL KLAUS, DIRECTOR OF ACADEMIC SERVICES, EXPERIENCE ANATOMY
This article is brought to you in partnership with Experience Anatomy, a premier anatomy education provider specializing in training and education with true human specimens.
Ask yourself what movements happen at the ankle. Did you say dorsiflexion (bringing the toes towards the shins), plantarflexion (pointing the toes), eversion (turning or rotating outward) or inversion (turning or rotating inward)?
The ankle is a complex joint because in most situations, the ankle and foot function as a unit. Let's dive into the anatomy of some of the joints in the ankle and foot to try and understand how they work together.
The ankle is made of three bones two in the leg and one in the foot. The two bones in the leg, the tibia (shin bone) and fibula (within the leg lateral to the tibia), are strongly anchored together.
Although these two bones articulate (touch) to form the inferior tibiofibular joint, no active movement occurs at this joint. The ankle is made up of the union of the tibia and fibula with the talus bone (a metatarsal) to form the talocrural joint.
The talocrural joint is classified as a hinge joint and allows movement in two directions, dorsiflexion (bringing the toes towards the shin) and plantarflexion (pointing the toes). See the movement in action in the video below. Notice the rounded articular surface of the talus just below the tibia. At the very end, we see a bit of inversion (turning or rotating inward).
Surprisingly, only three muscles are primarily responsible for carrying out the action of dorsiflexion and plantar flexion at the ankle (talocrural) joint.
- Tibialis anterior: shin muscle; dorsiflex the ankle (foot extensor muscles)
- Gastrocnemius: calf muscle; plantarflex the ankle
- Soleus: calf muscle; plantarflex the ankle (Achilles tendon)
Ankle stability is attributed to several different ligaments, a connective tissue composed of strong collagen fibers. Throughout the body, some ligaments look like thick string while others look like narrow or wide bands.
The main function of a ligament is to connect bones to other bones and provide support to that connection. In the ankle, we see six main ligaments that connect the ankle bones not only to each other but also to the foot.
- Anterior tibiofibular ligament: anchors tibia to fibula; resists torsion and inversion stresses
- Posterior tibiofibular ligament: anchors tibia to fibula; resists torsion and inversion stresses
- Anterior talofibular ligament: connects talus to fibula; resists plantarflexion
- Posterior talofibular ligament: connects talus to fibula; resists dorsiflexion
- Calcaneofibular ligament: attaches fibula to calcaneus; allows for eversion/inversion; resists inversion in dorsiflexed position
- Deltoid ligament: attaches tibia to talus, calcaneus and navicular bones
The foot is a complex part of the body with many structures that must work together for healthy function. Inside the foot are seven tarsal bones, similar to the carpal bones found in the wrist, as well as five metatarsals and 14 phalange (toe) bones.
There are eight different-named joints within the foot that allow movements like inversion/eversion, flexion/extension and spreading of the toes. The subtalar joint (joint between the talus and calcaneus) is classified as a plane joint (two flat surfaces that glide) and facilitates inversion/eversion of the foot.
Four muscles are responsible for carrying out the action of inversion and eversion.
- Tibialis anterior: shin muscle; dorsiflex ankle; inversion of foot
- Tibialis posterior: plantarflex ankle, inversion of foot
- Fibularis longus: plantarflex ankle, eversion of foot
- Fibularis brevis: plantarflex ankle, eversion of foot
The foot has unique anatomy because the bones are held together by ligaments to form arches within the foot. These arches play an important role as built-in shock absorbers during walking, running, jumping or other activities that cause impact.
- Plantar calcaneonavicular (spring) ligament: supports the talus, maintains longitudinal arch of the foot
- Long plantar ligament: maintains longitudinal arch of foot
- Plantar calcaneocuboid (short plantar) ligament: maintaining longitudinal arch of foot
If you’re experiencing foot or ankle pain or immobility, schedule an appointment online with one of our specialists today. We utilize the best technologies and techniques available to get you back to doing what you love.
Rachel Klaus has been building the academic programming offered by Experience Anatomy since 2019 by integrating her experience and knowledge of various anatomical resources to provide unique educational experiences.
Rachel received her MS in human anatomy from the University of Colorado School of Medicine where she had the opportunity to work on the Susan Potter Visible Human Project to help develop virtual anatomy resources. In her free time, she likes to recreate outdoors and continue to grow her plant collection.