The soleus (also soleus muscle, latin: musculus soleus) is a powerful muscle of the posterior group of the lower leg muscles.
The soleus originates from the head of the fibula and the soleal line of the tibia. The soleus inserts at the calcaneal tuberosity.
The soleus joins with the aponeuroses of the gastrocnemius, forming the calcaneal tendon or Achilles tendon that inserts onto the calcaneal tuberosity.
The functions of the soleus are flexion, supination and adduction of the foot. It also plays an important role in maintaining the standing pose.