Gastrocnemius
Definition
Gastrocnemius is the calf muscle
It is visible from the outside of the body.
Situation
The gastrocnemius is located with the soleus in the posterior (compartment of the leg
Attachments
Originates behind the knee on the femur
The origin is by two heads : the medial and the lateral heads
The lateral head originates from the lateral condyle of the femur
The medial head originates from the medial condyle of the femur.
Its other end forms a common tendon with the soleus muscle : Achilles Tendon
Inserts onto the posterior surface of the calcaneus
It crosses two joints : the knee and the ankle
Action
Plantar flexes foot. Flexes knee
Nerve
Tibial nerve (S1, 2)
.
Deep to the gastrocnemius (farther from the skin) is the soleus muscle. Some anatomists consider both to be a single muscle, the triceps surae or "three-headed [muscle] of the calf", since they share a common insertion via the Achilles tendon. The plantaris muscle and a portion of its tendon run between the two muscles, which is involved in "locking" the knee from the standing position. 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 to the mid-shaft of the tibia.
