The calcaneal (or Achilles) tendon is the thickest and strongest in the human body and is about 15 cm in length. This tendon connects the calf muscle to the heel bone. It puts a spring in the step and helps one to stand on tiptoe. Unlike the other tendons in the body, though, it has no protective covering and is therefore very vulnerable to inflammation and injury. Even shoes that don’t fit correctly can inflame or tear the tendon. The Achilles tendon gets its common name from the Greek warrior, Achilles, who was the son of a sea goddess and of a mortal father. When he was a baby, his mother tried to make him immortal by dipping him in the River Styx. She held him by his heel, which consequently never touched the water, making it his only vulnerable spot. Years later, he died in the Trojan War when his enemy shot him in the heel with an arrow.