Lateral head of gastrocnemius

The lateral head of the gastrocnemius muscle originates from the lateral aspect of the lateral condyle of the femur, just above the articular surface, and from the adjacent posterior femoral surface. Its fibers descend obliquely and medially, forming a fusiform muscle belly that is generally shorter and less bulky than the medial head.The lateral head is enveloped by a distinct aponeurosis, which merges distally with the medial head and soleus aponeuroses to form the Achilles tendon. The lateral head terminates more proximally than the medial head, with a mean difference in distal extension of approximately 1.7 cm, although anatomical variation exists.

Origin: Lateral aspect of lateral condyle of femur and capsule of knee joint

Insertion: Posterior surface of calcaneus via calcaneal (Achilles) tendon

Innervation: Tibial nerve (S1–S2)

Blood supply: Sural arteries (branches of popliteal artery), posterior tibial and peroneal arteries

Function: Plantar flexes the foot at the ankle and flexes the leg at the knee