What is the Plantaris?
The plantaris is a small muscle in the back of your lower leg, tucked behind the knee and running down toward the heel. It has a short muscle belly near the knee and a very long, thin tendon that travels between the larger calf muscles before attaching near the heel, close to the Achilles tendon. In some people it blends into the Achilles area, and in others it attaches separately, so its exact path can vary a bit from person to person. A small percentage of people don’t have a plantaris at all, and they function completely normally.