Muscle Anatomy of the Lower Leg – Gastrocnemius and Soleus

Strained calf muscle concept in x-ray

The Valuable Function of Your Calf Muscles

The bulk of muscle found on the backside of your lower leg is formed by the group of muscles called the triceps surae, commonly known as your calf muscles. The gastrocnemius (pronounced gas-trok-nee-mee-us) is the most superficial muscle that’s most readily seen making the meaty bulge of the upper portion of your lower leg. Underneath the gastrocnemius lies the soleus which is a flatter, but more powerful muscle.

Together, when these two muscles contract, the main function they help you perform is pressing the balls of your feet into the ground (plantar flexion at the ankle) to propel you forward or up into the air. This comes into play when you are walking, running, sprinting, or jumping or any movement that requires you to push away from the ground or point with your toes. If you’re standing and your knees are straight and you plantar flex at the ankle, the gastrocnemius and the soleus work together (synergistically) to create that movement. When your knees are bent, such as in a deep squatting position, the soleus will be the main muscle contracting to stabilize and plantar flex at the ankle to aid in getting you back up to a standing position.

What’s interesting to also know is that your calf muscles greatly contribute to the proper blood and lymphatic fluid circulation of your entire body. When calf muscles contract while you walk, they help to pump fluids back up towards your heart. That’s why these muscles are also known as your “second heart”. If you know someone that stands a lot without moving too much, such as a grocery clerk, you might notice that they may often complain about their feet or ankles being achy and swollen. The reason is that when standing still, fluids will “drain” into the feet and ankles and if you’re not walking (or plantar flexing) with enough frequency, the fluids will pool and the hydrostatic pressure from the swelling (and the static stress from standing) will cause the feet, ankles, and lower legs to ache and feel tired.

The Anatomy of Your Calf Muscles


Lower Leg Calf Muscle Anatomy

The gastrocnemius attaches on the back portion of the two bottom “knobs” of the thigh bone (medial and lateral epicondyles of the femur). This forms the two “heads” of the triceps (three-headed) surae. Because these two heads of the gastrocnemius cross the knee joint, it also works in conjunction with the hamstrings to bend the knee. You experience the workings of this when you walk. As you push the ball of your rear foot to move you forward, you’ll notice that your knee bends. You can thank your gastrocnemius for allowing this smooth transition of muscle contraction from your foot to the ankle through your knee and into the hip.

The soleus muscle attaches onto the upper back portion of your shin bone (tibia) and along the top part of the fibula which is the thinner bone bracing the outside of your lower leg. This forms the third “head” of the triceps surae. The connective tissue coverings of the gastrocnemius and soleus join to form the Achilles tendon that connects into the heel bone (calcaneus).

Watch the video below to see more pictures and explanations of the muscle anatomy of your calf muscles.

Also, be sure to watch the other videos posted below about your calf muscles, Achilles tendon, and feet!

Enjoy! And share this with your friends and family!

Watch other helpful videos to keep your calf muscles happy!

Ankle Circles for Better Ankle & Calf Flexibility

Achilles Tendon Stretch & Mobilization

Stretching Calf Muscles & Plantar Fascia of Feet

How To Stop Leg Muscle Cramps

Mini-Mountain Climbers