The three muscles that insert on the calcaneal tendon are the gastrocnemius, soleus, and plantaris. Collectively, these muscles are referred to as the triceps surae.
The gastrocnemius is the larger muscle, easily visible and responsible for the calf’s shape. It has two heads that originate from the femur and allow for flexion at the knee joint as well as plantarflexion at the ankle. The soleus lies underneath the gastrocnemius and is more involved in standing and walking, particularly in maintaining posture. The plantaris is a smaller muscle that is often considered vestigial, and while it contributes to the tendon, its role is less significant compared to the other two.
Together, these muscles work to enable powerful movements such as jumping and running, highlighting their importance in locomotion and overall lower limb function.