GASTROCNEMIUS

The gastrocnemius muscle is the most superficial of the muscles in the posterior compartment and is one of the largest muscles in the leg. It originates from two heads, one lateral and one medial:

• ▪The medial head is attached to an elongate roughening on the posterior aspect of the distal femur just behind the adductor tubercle and above the articular surface of the medial condyle.
• ▪The lateral head originates from a distinct facet on the upper lateral surface of the lateral femoral condyle where it joins the lateral supracondylar line.

At the knee, the facing margins of the two heads of the gastrocnemius form the lateral and medial borders of the lower end of the popliteal fossa.

In the upper leg, the heads of the gastrocnemius combine to form a single elongate muscle belly, which forms much of the soft tissue bulge identified as the calf .