The posterior compartment of the leg contains seven muscles and can be subdivided into superficial and deep compartments.
The muscles in this compartment act to plantarflex and invert the foot. They are innervated by the tibial nerve (a branch of the sciatic nerve).
In this article, we shall look at the anatomy of the muscles in the posterior compartment of the leg – their attachments, actions and clinical correlations.
Superficial Compartment
There are three muscles within the superficial compartment of the posterior leg. They all insert onto the calcaneus (heel bone) of the foot, via the calcaneal tendon.
To minimise friction during movement, there are two bursae (fluid filled sacs) associated with the calcaneal tendon:
- Subcutaneous calcaneal bursa – lies between the skin and the calcaneal tendon.
- Deep bursa of the calcaneal tendon – lies between the tendon and the calcaneus.
Gastrocnemius
The gastrocnemius is the most superficial of all the muscles in the posterior leg. It has medial and lateral heads and forms the characteristic “calf” shape of the leg.