The ankle region is a complex joint system that connects the leg and the foot, enabling movement. This joint, known anatomically as the talocrural joint, supports the entire body’s weight and withstands significant forces during motion. This article clarifies the primary anatomical components that collectively form what is commonly called “the back of the ankle.”
The Calcaneal Tendon
The most readily identifiable structure at the back of the ankle is the thick cord often called the Achilles tendon. Medically, this structure is known as the calcaneal tendon, named for its attachment point. It is the largest and strongest tendon in the human body.
This strong, fibrous band is composed primarily of collagen, which gives the tendon its strength and elasticity. The calcaneal tendon connects the calf muscles—the gastrocnemius and soleus—to the heel bone. This connection is responsible for plantar flexion, the action of pointing the toes downward.
The transmission of force through this tendon allows for fundamental actions like walking, running, and jumping. Because of the mechanical load placed upon it, the tendon is structured to spiral slightly as it descends, increasing its efficiency and strength. This anatomical arrangement ensures that the force generated by the leg muscles is effectively transferred to the foot to propel the body forward.
Bony Structures Defining the Rear Ankle
Several bones provide the foundational structure of the rear ankle area where the large tendon attaches. The calcaneus, or heel bone, is the largest bone in the foot and forms the base to which the calcaneal tendon inserts. Located directly above the calcaneus is the talus, a bone that articulates with the lower leg bones to form the main ankle joint.
The upper boundaries of the ankle space are defined by the distal ends of the two lower leg bones, the tibia and the fibula. These bones feature bony protrusions known as the malleoli. The fibula forms the lateral malleolus on the outer side, while the tibia forms the medial malleolus on the inner side, collectively creating a socket for the talus.
Common Issues Affecting This Area
Due to the intense forces it manages, the calcaneal tendon is susceptible to strain and injury. One frequent ailment is tendinitis, which involves irritation and inflammation of the tendon tissue. This condition presents as pain or stiffness that feels worse in the morning or after periods of rest.
If irritation is chronic and leads to structural changes, it may be classified as tendinopathy or tendinosis, involving degeneration rather than inflammation. A tendon rupture is a complete or partial tear of the fibers. This acute injury typically results from a sudden, forceful movement and requires professional attention. Persistent pain or stiffness in this region should always be evaluated by a healthcare provider.