Overview
It has a lateral and a medial head, between which the superficial digital flexor arises. Its bellies contain much tendinous tissue and continue, at mid-crus, into a strong tendon. The horse also has a small soleus (m. soleus) that joins the gastrocnemius tendon. The common calcanean tendon ("Achilles tendon") is made up of the gastrocnemius tendon, the superficial digital flexor tendon and the tarsal tendons of the biceps femoris and semitendinosus.
Origin
Lateral and medial supracondylar tuberosities of the femur.
Insertion
Calcaneal tuber (tuber calcanei).
Action
Extends the hock and flexes the stifle. It is the main driver of the hock during propulsion.
Innervation
Tibial nerve (n. tibialis).
Clinical relevance
- Rupture of the gastrocnemius or its tendon is uncommon but is described after falls, violent effort or a rough recovery from anaesthesia: the hock drops and flexes when the limb bears weight.
- The tibial nerve runs between the two heads of the gastrocnemius and on the caudal crus; it is blocked proximal to the hock in diagnostic anaesthesia of the pelvic limb.