With the exception of the popliteus muscle; all the muscles arising from the lower leg are attatched to bones of the foot. The muscles of the lower leg, can be classified according to their location. They are divided into anterior and posterior groups by the tibia, fibula, and interosseous membrane. The two main groups are divided again into subgroups or layers. The anterior group can be subdivided into the extensor (located anteriorly) and peroneus groups (located laterally). The posterior group can be subdivided into  a superficial layer and a deep layer. Whereas the anterior group is primarily extensors, the posterior group is mainly flexors