Presence of third head of gastrocnemius and entrapment of the sural nerve

Introduction Gastrocnemius is the most superficial muscle of the posterior crural region. It arises by two tendinous heads from the femur. The lateral head originates from the lateral surface of the lateral condyle and the medial head originates from a rough area on the popliteal surface above the medial condyle. The lateral head frequently contains a small sesamoid bone, the fabella. The medial head is larger and longer than the lateral head. Fleshy part of the muscle extends to about midcalf, ends on the posterior surface as a thin, common tendon. This tendon fuses with the superficial surface of the tendon of soleus to form tendo calcaneus. Sural nerve is a branch of the tibial nerve in the popliteal fossa. It descends in the posterior compartment of the leg superficial to the gastrocnemius and pierces the deep fascia in the middle of the leg. It is then joined by sural communicating nerve and supplies the skin of the lower half of the central area of the calf and also over the lateral border of the foot up to the tip of the little toe.