M76: Enthesopathies of lower limb, excluding foot

M76.6: Achilles tendinitis

The Achilles tendon connects the muscles in the calf with the foot. When you tense the muscles in your calf, you can point your toes downward. When you raise your toes towards your nose, you stretch the Achilles tendon. You can feel your Achilles tendon at the back of your leg, just above your heel.

An inflammation in the Achilles tendon can affect tendons, tendon sheaths, bursas or joint capsules. Tendons are made up of very firm connective tissue. Tendons attach muscles to bones. A tendon sheath is a covering for the tendon. It cushions the tendon and contains a small amount of fluid. This reduces friction between the tendon and its surroundings. A bursa is a cushion of connective tissue filled with fluid. For example, there is a bursa beneath tendons or between bones and skin. The bursa prevents the tissue from rubbing together. A bursa also enables pressure to be distributed better. Joints are encased in a joint capsule.

An inflammation can be caused by overwork, injuries or pathogens, for example. An inflammation may be painful. The pain may make moving your leg more difficult than usual.