The soleus is a large flat muscle under the gastrocnemius muscle (Fig. 6.87). It is attached to the proximal ends of the fibula and tibia, and to a tendinous ligament, which spans the distance between the two heads of attachment to the fibula and tibia:
On the proximal end of the fibula, the soleus originates from the posterior aspect of the head and adjacent surface of the neck and upper shaft of the fibula.