What muscles make up the calf?

• A. Gastrocnemius and Soleus
• B. Tibialis anterior and peroneus longus
• C. Gastrocnemius only
• D. Soleus only

Answer: (A)

The main idea is identifying the two muscles that form the bulk of the back of the leg—the calf. The calf muscles are the gastrocnemius and the soleus. They share a common function of plantarflexing the foot (pushing the foot down, as in standing on tiptoes) and they converge into the Achilles tendon to attach to the heel bone. The gastrocnemius has two heads and crosses the knee as well as the ankle, while the soleus lies underneath and does not cross the knee, making it a powerful plantarflexor especially for standing and endurance activities. The other muscles mentioned are located in different parts of the leg (tibialis anterior is at the front and dorsiflexes the foot; peroneus longus runs along the outer side and everts the foot), so they aren’t calf muscles. Saying both gastrocnemius and soleus properly identifies the calf.