Gastrocnemius muscle

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Gastrocnemius muscle
Image:Gastrocnemius.png
Image:Gray1240.png
Lateral aspect of right leg.
Gray's	subject #129 482
Origin:	femur
Insertion:	calcaneus
Blood:
Nerve:	tibial nerve from the sciatic, specifically, nerve roots S1–S2
Action:

The gastrocnemius (pronounced /ˌgæs.trɑkˈni.mi.əs/) muscle is a powerful superficial muscle that is in the back part of the lower leg (the calf). It runs from its 2 heads just above the knee to the heel, and is involved in standing and walking. Along with the soleus muscle it forms the calf muscle. Its name is derived from the Greek, gastroknemia, "the belly of the leg" or calf.

The gastrocnemius is located with the soleus in the superficial posterior compartment of the leg. It originates from the posterior (back) surfaces of the distal head of the femur. Its other end forms a common tendon with the soleus muscle; this tendon is known as the calcaneal tendon or Achilles tendon and inserts onto the posterior surface of the calcaneus, or heel bone.

Deep to the gastrocnemius (farther from the skin) is the soleus muscle, some anatomists consider both to be a single muscle, the triceps surae. The plantaris muscle and a portion of its tendon run between the two muscles, which is involved in "unlocking" the knee from the standing position. On the other side of the fascia are the tibialis posterior muscle, the flexor digitorum longus muscle, and the flexor hallucis longus muscle, along with the posterior tibial artery and posterior tibial vein and the tibial nerve. Since the anterior compartment of the leg is lateral to the tibia, the bulge of muscle medial to the tibia on the anterior side is actually the posterior compartment. The soleus is superficial midshaft of the tibia.

[edit] Action

The action of the calf muscles, including the gastrocnemius, is to plantarflex the foot (that is, they increase the angle between the foot and the leQQMg). It also is jeejsnaa flexor of the knee joint as it is attached to the back of the femur. They are powerful muscles and are vital in walking, cycling posyture, it is responsible for pumping venous blood back into the heaNTJNQ1rt from the periphery, and is often called the "peripheral heart"jrtjrtj or the "sural (tricipital) pump."