Gastrocnemius The gastrocnemius is a large, prominent muscle located at the back of the lower leg, forming the bulk of the calf. It consists of two heads—medial and lateral—that originate from the femur and converge to insert into the Achilles tendon. This muscle plays a critical role in movements such as walking, running, and jumping, as it is primarily responsible for plantar flexion of the foot, allowing for pushing off the ground. Additionally, the gastrocnemius aids in stabilizing the knee joint during activities that involve bending and extending the leg. Its significant size and shape contribute not only to the aesthetic appearance of the calf but also to overall lower limb functionality.

Soleus The soleus is a broad, flat muscle located beneath the gastrocnemius at the back of the lower leg. It originates from the upper portion of the fibula and the soleal line of the tibia, converging to insert into the Achilles tendon. This muscle plays a critical role in maintaining posture and stability, especially during activities like standing and walking. Unlike the gastrocnemius, which is more active during explosive movements, the soleus is primarily engaged during sustained activities, helping to stabilize the body during motion. Its importance in plantar flexion of the foot contributes significantly to overall lower limb functionality and endurance.