Gastrocnemius (lateral head)

Anatomy

Origin:
Lateral head: Lateral aspect of the lateral condyle of the femur.
Medial head: Popliteal surface above the medial condyle of the femur.

Insertion:
Middle part of the posterior surface of the calcaneus by the tendo calcaneus (Achilles tendon).

Key Relations:
-One of the three muscles of the superficial posterior compartment of the leg.
-The gastrocnemius with the soleus gives rise to a tendon called the tendo calcaneus (Achilles tendon).
-The medial head of gastrocnemius forms the lower medial boundary and the lateral head the lower lateral boundary of the popliteal fossa.

Functions

-Plantarflexes the ankle joint with soleus through the tendo calcaneus (Achilles tendon) e.g. standing on tip toes.
-Flexes the knee joint.

Supply

Nerve Supply:
Tibial nerve (S1, S2).

Blood Supply:
-Sural arteries from the popliteal artery
–Posterior tibial artery
-Fibular (peroneal) artery.

Clinical

Calf strain or rupture is a common sports injury which can affect either of the two calf muscles- gastrocnemius or soleus. Calf strain or rupture most commonly occurs in racquet sports, basketball, running or skiing. The patient often presents with a sharp sudden calf pain, tightness followed by swelling and ecchymosis. It is graded according to the severity of the symptoms with grade 1 being a minor rupture and grade 3 being a 90% or full rupture.

Treatment includes RICE (rest, ice, compression and elevation), NSAIDs and sports massage or physiotherapy programme.

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