A Fundamental Notion about Ankle Anatomy
The ankle is a complex joint comprised of bones, muscles, ligaments, and tendons. It is connected to the two bones of the lower leg, the tibia and the fibula. The tibia is the shinbone, and the fibula is the lower leg bone. The tibia and fibula meet at the ankle joint with a bone known as the talus. Ligaments and tendons connect the talus to the heel and other foot bones. It makes a part of the tarsus, which is the group of bones that make up this part of the foot.
The ankle has three primary movements: flexion, inversion, eversion, and dorsiflexion. Combined, these movements allow the ankle to rotate like a ball and socket joint, just like the humerus. But it is not a ball and socket joint. The type of joint we find in the ankles is known as a hinged synovial joint. This is a joint with a hinge formed by the tibia and the fibula sitting on top of the talus and held in place with a fibrous structure called syndesmosis. The syndesmosis acts like a band that holds the tibia and fibula together.
Muscles and tendons work together to move and support the ankle.
- The anterior tibialis muscle contracts to achieve foot dorsiflexion, which is essential when walking.
- The posterior tibialis muscle is essential to stabilize the foot at all moments, especially during the gait.
- The extensor hallucis longus muscle helps with dorsiflexion but also inverts the foot and extends the hallux, which is very susceptible to damage.
- The peroneus longus muscle is essential for plantar flexion of the ankle.
- The peroneus brevis muscle helps the peroneus longus muscle and is responsible for more than 60% of the action when you’re everting the foot.
- Through the ankle, we also have tendons passing by that go through this structure and end up in the toes, such as the flexor digitorum longus tendon, which moves the toes down.