For an illustration of Achilles tendonitis, press Press here to view a full size picture.
Tendons are connective tissue bands that attach muscles to bones.
Achilles tendonitis is inflammation in the tendon of the calf muscle near where it attaches to the heel bone. The inflammation causes pain at the back of your leg near the heel. An Achilles tendon may tear, or rupture, during sudden activity such as with jumping or at the beginning of a sprint. Violent stretching of the Achilles tendon can cause it to rupture. Achilles tendonitis causes pain and may cause swelling over the Achilles tendon.