Calf

Structure

The calf’s main muscles are the two-headed gastrocnemius, the underlying soleus, and the small plantaris. Together they join to form the powerful Achilles tendon that inserts on the heel bone.

Function

The gastrocnemius is most active during fast, forceful movements such as sprinting and jumping, while the slower soleus dominates during quiet standing and steady walking.

Clinical note

Sudden cramps of the calf muscles are common with dehydration and with rapid changes in activity. A torn gastrocnemius produces a sharp pop followed by bruising.