The Achilles heel (Tuber calcanei) forms the rear part of the heel bone (Calcaneus). The name Achilles heel originates from Greek mythology. The heel bone is the largest tarsal bone and together with the talus forms the rear foot. The Achilles heel serves as a bony protrusion, the base of the Achilles tendon.
As a bony structure, the Achilles heel is a preferred point of attachment for various muscles. The strong Achilles tendon, for example, attaches to the rear part of the bone. There is also a bursa tendinis calcanei (also called bursa subachillea), which protects the tendon and bone from friction and damage.
This bursa can sometimes become inflamed. On the inner side of the Achilles’ heel is the Processus medialis tuberis calcanei, a bony process which also serves as the muscle origin for the muscle flexor digitorum brevis and the muscle abductor hallucis. On the outer side there is also a bony process, the Processus lateralis tuberis calcanei. On the lower side of the Achilles heel, various ligaments are also attached, such as the plantar aponeurosis and various joint stabilization ligaments. Together with the ankle bone and the os naviculare, the heel bone forms the lower ankle joint.
The Achilles heel gives the rear foot its characteristic shape. Its main function is to be the base and origin of various muscles and ligaments. The Achilles tendon is located at the Achilles heel and is visible and palpable in slim people.
The Achilles tendon connects the muscle triceps surae (calf muscle) with the rear foot. When the calf muscle contracts, the tip of the toe tilts forward and the heel moves upwards (so-called plantar flexion). This enables walking on the tips of the toes, for example.
However, the contraction of the calf muscles is generally one of the most important components of the walking process. In addition to plantar flexion, the M. triceps surae also supports supination, the tilting of the foot to the inside. On the inner side of the Achilles’ heel is the origin of the M. flexor digitorum longum (long toe flexor) and M. abductor hallucis (big toe guide).
The M. flexor digitorum longus serves to bend the toes and the M. abductor hallucis guides the big toe away from the other toes and additionally supports the function of the M. flexor digitorum longus. Various ligaments attach to the Achilles heel, such as the sole tendon plate, which connects the heel and the metatarsophalangeal joints of the toes. This connection stabilizes the longitudinal arch of the foot and thus enables stable walking and standing.
Diseases: painful Achilles heel
Pain in the Achilles heel can have various causes. A broken Achilles heel or a torn bone can cause severe pain which is intensified by heel impact. Strained or overstretched muscles are also painful, but usually disappear again after a short time.
Pain in the Achilles heel can also be caused by a torn ligament or tendon and is also increased during movement. The collateral ligaments of the ankle joint and the Achilles tendon are particularly at risk. In addition to tears, tendon inflammation is also very painful and often requires treatment.
Inflammations can affect muscles as well as tendons, bones and bursae. The heel spur (also called calcaneal spur) is a special clinical picture. This is a new bone formation that can exert painful pressure on tendons and other structures like a spur. Circulatory disturbances in the context of arteriosclerosis, for example peripheral arterial occlusive diseases, can lead to pain under stress due to a reduction in blood circulation. This is also known as window dressing disease, since those affected often have to take breaks when walking due to pain.