In humans, the gastrocnemius muscle ( /ˌɡæstrɒkˈniːmiəs/ or /ˌɡæstrəˈniːmiəs/; Latin, from Greek γαστήρ “stomach” and knēmē “leg”; meaning “stomach of leg”, referring to the bulging shape of the calf) is a very powerful superficial pennate muscle that is in the back part of the lower leg.

In human anatomy, the peroneus longus (also known as fibularis longus) is a superficial muscle in the lateral compartment of the leg, and acts to evert and plantar flex the ankle.

In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg (the calf).

The tibialis anterior is the most medial muscle of the anterior compartment of the leg and is responsible for dorsiflexing and inverting the foot.

The tibialis posterior muscle originates on the inner posterior borders of the tibia and fibula. It is also attached to the interosseous membrane, which attaches to the tibia and fibula.