To better understand calf strain, it helps to understand the anatomy of the leg.

The entire leg contains four bones:

• Femur: thighbone
• Patella: kneecap
• Tibia: thick bone in the front of the lower leg
• Fibula: thin bone on the side of the lower leg

Below the knee, the lower leg contains two long bones, called the tibia and fibula. The muscles of the lower leg control movement of the foot and ankle. The back of the lower leg is called the calf.

The gastrocnemius is the largest muscle in the calf. The gastrocnemius muscle is attached to the femur in the back of the knee, and turns into the Achilles tendon. The Achilles tendon attaches to the heel. The gastrocnemius flexes the leg at the knee, and plantar flexes the foot (points the toes).

Leg anatomy examples:

• Muscles and bones of the leg
• Achilles tendon