A ligament-like structure called the plantar fascia runs from your heel to the ball of your foot. It is one of the strongest connective tissues in the body, but it is prone to - stretching, tearing, and degeneration at its attachment site in the heel.
The Achilles' tendon, which runs up the back of your foot, is the major connection between your foot and the muscles in your calf. This tendon enables you to lift your heel up so that your weight shifts to your toes -- an essential function in walking and running. When injured, it can cause terrible pain and disability.