What Is the Gastrocnemius Muscle?

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  • Originally Written By: Alex Paul
  • Revised By: C. Mitchell
  • Edited By: Jacob Harkins
  • Last Modified Date: 19 September 2019
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In humans and certain animals, the gastrocnemius muscle is the long, thick muscle that runs down the back of the leg and forms a characteristic bulge at the calf. It is made up of two thick fibrous bands that originate behind the knee with what’s known as two “heads”; it ends at the ankle, right where the foot begins. Its main function is to push the leg down and keep it taut when required during activities such as walking, jogging, or even just standing. The muscle is notoriously strong, but injuries can and do happen. A torn gastrocnemius can cause a lot of pain and a great deal of physiological problems; sometimes targeted stretches and specialized therapy can help it heal, but in extreme cases surgery may be required to ensure that people regain all aspects of functionality.



The gastrocnemius originates toward the bottom of the femur and inserts at the Achilles tendon. The soleus is the other major muscle of the calf and together with the gastrocnemius is important for both flexing the ankle and knee. Sometimes the muscles are grouped together and considered the same,which is logical to a point since they have the same insertion point and work closely together. Both allow plantar flexion of the foot, for instance, which is important in a number of different activities, and their locations overlap in several key places. When it comes to their core composition, though, there is thought to be quite a difference, and they are distinct in terms of muscular fidelity.


The gastrocnemius is made almost entirely of white muscle fibers, which are often classified medically as “fast twitch.” This is usually in reference to how quickly they conduct nerve signals and turn them into physical exertion and movement. The soleus, by contrast, is composed primarily of red fibers, and is an example of a “slow twitch” processor.


One of the most distinctive things about the gastrocnemius muscle is its two heads. This means it attaches on both sides of the knee to provide stability. Medically, this is described as the muscle having both a medial and a lateral attachment to the knee. The gastrocnemius actually takes on a diamond-like shape when viewed from behind as long as the muscle has fully developed.

Primary Function

As a whole, the calf muscles are involved in any action that includes plantar flexion of the foot or flexion of the knee. This includes standing on tiptoes, walking and running. The only difference between the soleus and gastrocnemius muscle when it comes to movement is that the soleus is more active when the knee is bent. In contrast, the gastrocnemius muscle is under most tension when the knee is straight.

Potential for Injury

There are a number of different injuries that could affect this muscle. One of the most severe is a muscle tear that can render the person unable to stand correctly until healed. This can happen for a number of reasons, but major trauma, sports injuries, and overuse tend to be the most common. The muscle is generally designed to withstand a great deal of tension and pressure, but like most anything else, it has its limits. Other injuries include inflammation due to repetitive strains and chronic tightness. Treatment for these injuries depends on the severity of the condition and the exact location of the injury.

Symptoms of a gastrocnemius tear vary depending on severity. Grade 1 tears are usually characterized by a small amount of pain and tightness in the muscle. This usually becomes more apparent a few days after the initial injury. A Grade 1 tear often won’t prevent an athlete from competing although rest may be required for a full recovery. Grade 2 and 3 tears are more severe and may require more extensive treatment, including prolonged therapies and sometimes even surgery.


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Post 2

An injury in this area, especially a large rupture, can mean a lot of physical therapy. People with injuries like this not only need to get their strength back but need to gain back their confidence.

Physical therapists know what you have to do to bring yourself along at the right pace for you. They seem to know how to push just the right buttons to get that extra step from you when you don't think you want to go on.

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