Gastrocnemius Muscle

The Gastrocnemius Muscle is the most superficial muscle in the posterior compartment and forms the proximal, most prominent part of the calf.

The superficial group of calf muscles (muscles forming prominence of “calf” of posterior leg) includes the gastrocnemius, soleus, and plantaris.

The gastrocnemius and soleus muscles share a common tendon, the calcaneal tendon, which attaches to the calcaneus.

See Also: Soleus Muscle

Gastrocnemius Muscle Anatomy

Gastrocnemius Muscle is a fusiform, two-headed, two-joint muscle with the medial head slightly larger and extending more distally than its lateral partner. The heads come together at the inferior margin of the popliteal fossa, where they form the inferolateral and inferomedial boundaries of this fossa, they are easily recognizable in the superior part of the calf of the leg.

Origin

Each head has different origin, the medial head origin from posterior non-articular surface of medial femoral condyle, while the lateral head from lateral surface of femoral lateral condyle

Insertion

The two heads unite into a broad aponeurosis which eventually unites with the deep tendon of the soleus muscle to form the Achilles tendon, inserting on the middle 1/3 of the posterior calcaneal surface.

Innervation

It’s innervated by the tibial nerve (S1, S2) (S1, S2).

Blood Supply

Each head of Gastrocnemius is supplied by a sural branch of the popliteal artery.

Action

Because its fibers are largely of the white, fast-twitch (type 2) variety, contractions of the gastrocnemius muscle produce rapid movements during running and jumping. It is recruited into action only intermittently during symmetrical standing.

The gastrocnemius muscle crosses and is capable of acting on both the knee and the ankle joints; however, it cannot exert its full power on both joints at the same time. It functions most effectively when the knee is extended (and is maximally activated when knee extension is combined with dorsiflexion, as in the sprint start). It is incapable of producing plantarflexion when the knee is fully flexed.

Gastrocnemius Tear

Calf tears are quite common amongst athletes and involve the gastrocnemius, soleus, popliteal, and plantaris muscles. A gastrocnemius tear can result in significant pain, limping, and swelling of the posterior calf as well as substantial functional impairment.

A positive Thompson squeeze test (loss of plantar flexion with calf squeeze) can be useful to diagnose a complete tear. Ultrasound or MRI are also options if the diagnose is still uncertain.

See Also: Thompson Test

Initial treatment involves rest until the patient can walk without limping. A walking boot may be needed for ambulation if the pain is severe. Severe injuries associated with an inability to walk are treatable with a progressive physical therapy regimen tailored to the individual’s patient’s level of baseline function and progress.

The patient should apply ice for 20 minutes four times daily to decrease swelling with an NSAID or acetaminophen to help with the pain.

References & More

1. Clinically Oriented Anatomy – 8th Edition
2. Bordoni B, Varacallo M. Anatomy, Bony Pelvis and Lower Limb, Gastrocnemius Muscle. [Updated 2023 Apr 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532946/
3. Coffey R, Khan YS. Gastrocnemius Rupture. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560869/