The soleus muscle is a large, thick muscle located in the posterior (back) region of the lower leg. It originates at the head of the fibula and the posterior surface of the tibia (shin bone), and inserts into the calcaneus (heel bone) via the Achilles tendon. The soleus muscle is one of the muscles that make up the calf, and is located deep to the gastrocnemius muscle.

The main function of the soleus muscle is to plantarflex (point the foot downward) the foot at the ankle joint. This movement is essential for activities such as walking and running, and helps to provide stability and support for the lower limb. The soleus muscle also helps to stabilize the ankle joint, and assist in flexion of the leg at the knee joint.

In everyday life, the soleus muscle is used in many activities that involve plantarflexion of the foot, such as walking and standing on tiptoe. It is also used in activities that require stability and support for the ankle joint, such as standing on uneven ground or climbing stairs.