Where it is
The back of the lower leg, from the femur to the point of the hock.
- Layer
- Muscles
- System
- Muscles
- Region
- Hind limb
What it is and what it does
It has two heads, which arise from the lateral and medial supracondylar tuberosities of the femur, and it inserts on the calcaneus through the common calcaneal tendon. It mainly extends the hock and slightly flexes the stifle; its lever arm at the hock stays large over the whole range of motion.
The two heads are almost symmetrical, the medial one usually a little larger; the lateral head arises by a broad tendon. In carnivores, a sesamoid bone forms in each tendon of origin and articulates with the femoral condyle. The tibial nerve passes between the two heads; beneath them lies the superficial digital flexor, which adheres to the lateral head.
The common calcaneal tendon is not the gastrocnemius alone, which gives its main part: the tendon of the superficial digital flexor joins it, laterally the tendon of the biceps femoris, medially the combined tendon of the semitendinosus and gracilis. That is why a dog could still stand even if the gastrocnemius and the superficial digital flexor were paralysed. In the racing greyhound the heads weigh 41 and 45 g, with short fascicles of 1.7–2.1 cm: a muscle with a high force-generating potential.
Worth remembering
It extends the hock and slightly bends the stifle.
Names
- Latin term: musculus gastrocnemius.
- In Romanian: Gastrocnemianul (Romanian page).