The ankle is a complex joint connecting the leg and the foot, playing a significant role in weight-bearing and movement. While many people refer to the lower back portion of this area simply as the “ankle” or “heel,” it is anatomically defined by specific structures and regions. This junction allows for the mobility necessary to walk, run, and balance. Understanding the formal names for this area provides clarity beyond common terminology.
Specific Names for the Ankle Region
The area at the back of the ankle and heel is formally known as the calcaneal region or the posterior talocrural region. The calcaneal region refers specifically to the area surrounding the calcaneus, which is the heel bone. The posterior talocrural region is a more precise anatomical name, indicating the area directly behind the talocrural joint. This joint is the main ankle joint, formed by the leg bones and the talus bone of the foot.
In a broader sense, this entire section of the foot is categorized as the hindfoot, or tarsus. The hindfoot includes the heel and the ankle joint itself. It functions as the initial point of contact with the ground and absorbs much of the impact during walking and running. Medical professionals use the term hindfoot when discussing injuries or conditions affecting the large bones and joint structures located here.
The Defining Structure: Achilles Tendon
The most recognizable feature at the back of the ankle is the Achilles tendon, formally known as the calcaneal tendon. This is the thickest and strongest tendon in the human body, capable of withstanding immense forces during physical activity. The tendon acts as the merged attachment point for the powerful calf muscles. These include the gastrocnemius and the soleus muscles, which together form the triceps surae group.
The Achilles tendon originates in the lower calf and inserts into the posterior surface of the heel bone, the calcaneus. Its primary function is to facilitate plantar flexion, which is the action of pointing the foot downward or pushing off the ground. When the calf muscles contract, they pull on this tendon, creating the leverage necessary for propulsion. Its size and distinct location make the calcaneal tendon the defining soft tissue structure of the posterior ankle region.
The Foundation: Key Bones of the Hindfoot
The solid foundation of the back of the ankle is formed by two large hindfoot bones: the calcaneus and the talus. The calcaneus, or heel bone, is the largest of the tarsal bones and forms the bony prominence that contacts the ground. This irregularly shaped bone is designed to bear the entire body’s weight, transferring the load from the leg to the ground.
Sitting directly above the calcaneus is the talus, sometimes called the ankle bone. The talus connects the foot to the lower leg bones, the tibia and fibula. It is unique because no muscles attach directly to it; instead, it transmits forces between the leg and the foot. The articulation between the calcaneus and the talus forms the subtalar joint, which permits the side-to-side movements of the foot necessary for walking on uneven ground.