por He gastrocnemius It is a superficial muscle that is located on the back of the leg. It consists of two bellies, one lateral and one medial, which form, together with the soleus muscle, the structure called triceps surae.
Both muscle bundles originate in the femur and travel through the knee to terminate in the calcaneus below the ankle. For this reason it is considered a biarticular muscle and has a fundamental role in maintaining balance, bipedalism and walking.
In its final journey it becomes a single tendinous element that firmly joins both bellies to the tendon of the soleus muscle, forming the calcaneus or Achilles tendon, which is the strongest in the body.
The gastrocnemius muscle works its hardest during physical activity, especially one that involves running or changing speed quickly, such as tennis, soccer, and sprinting, among other sports.
Its injury is common in athletes and usually occurs from inflammation to complete tears of one of its muscle heads.
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Anatomy
The calf is the name given to the posterior region of the leg. It is made up of two muscles, the gastrocnemius or twin, and the soleus that runs below it.
The gastrocnemius is made up of two muscle bellies, one lateral and one medial, which have different origins and a common final tendon insertion.
Origin
The heads that form the gastrocnemius muscle have different origins. The medial portion begins at a posterior projection on the medial aspect of the femur, called the condyle. In this area, the presence of a bag of synovial fluid can be evidenced, which allows the sliding of both muscle heads.
This head also has fibers that insert near the medial aspect of the knee joint capsule.
For its part, the lateral belly begins its journey on the lateral face of the femoral condyle. From there it continues on its way to the knee where some of its fibers insert near the knee joint.
The two heads of the calf go downwards, passing on both sides of the posterior part of the knee, where they delimit an area called popliteal fossa.
Insertion
In the lower third of the leg, both muscle bellies become tendons which unite and form a single structure together with the soleus tendon. This tendon is called calcaneus tendon either Achilles tendon.
This tendon runs for about 15 cm, passes behind the ankle, finally reaching the calcaneus bone where it is inserted.
At this point it is separated from the bone by a synovial sac that facilitates its sliding and prevents friction of the tendon with the calcaneus. The Achilles tendon is the thickest, longest and strongest in the body.
Irrigation
The popliteal artery, a direct branch of the femoral artery, is responsible for supplying the arterial vascular supply to the calf region.
Through its sural, anterior, and posterior collateral arteries, as well as its two terminal branches of the tibial anterior and tibial posterior, it penetrates the muscle bellies and forms an important network in this area.
The veins that drain the leg are formed from the tibial veins ascending through the popliteal and saphenous veins, which empties into the femoral vein.
innervation
The tibial nerve, coming from the trunk of the sciatic nerve above the popliteal fossa, runs downward and is located between the two muscle bellies of the gastrocnemius, providing neurological branches along its route.
This nerve is one of the most important in the posterior region of the lower limb, being in charge of innervating various muscles of the leg and foot.
functions
The gastrocnemius is a muscle with important implications for stability and balance maintenance.
Its main function is the plantar flexion of the foot, this occurs when standing on tiptoes, for example.
In addition, its insertion above the knee makes it an auxiliary muscle in its flexion.
During walking it remains contracted, especially in the first phase, preventing rotation of the tibia and it is especially active in running and jumping.
Its fibers are mainly anaerobic, so it is the muscle that is used in sudden efforts, races and speed changes.
injuries
tear
Gastrocnemius tear is a relatively common injury in athletes. Depending on its severity, there are three types.
The type I tear involves approximately 5% of the muscle, and the patient complains of pain with contraction. In type II, there is tearing of up to 25% of the muscle mass. In these cases, the patient may manifest pain and a sensation of continuous cramping.
On the other hand, the type III tear involves more than 30% of the muscle. The patient presents pain and immobility, calf bruise and swelling.
Large or complete tears may be palpable as a hollow area in the calf and seen as a large area of bruising on ultrasound.
The diagnosis of tear is made by questioning and physical examination, however, when the tear is not very evident, in the mildest cases, imaging tests are used to support the diagnostic suspicion.
Ultrasound is the most widely used test since it is inexpensive, can be performed with portable equipment, and its findings are definitive.
Another advantage of ultrasound is that it can be used to drain areas of fluid or bruises in the region.
Type I and II tears are managed on an outpatient basis with an indication of rest and anti-inflammatories, while type III tears are usually surgical, indicating immobilization and subsequent rehabilitation.
Tendinitis
Muscle inflammation and tendonitis is another of the injuries that frequently occurs in this muscle.
This condition occurs by subjecting it to an overload of work, which ends up irritating the tendon, causing significant and often disabling pain.
Achilles tendinitis is treated with the administration of analgesics and anti-inflammatories in addition to rest.
References
Bordoni, B; Waheed, A; Varacallo, M. (2019). Anatomy, Bony Pelvis and Lower Limb, Gastrocnemius Muscle. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
Binstead, J.T; Varacallo, M. (2019). Anatomy, Bony Pelvis and Lower Limb, Calf. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
Hsu, D; Chang, KV (2019). Gastrocnemius Strain. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
Nsitem, V. (2013). Diagnosis and rehabilitation of gastrocnemius muscle tear: a case report. The Journal of the Canadian Chiropractic Association. Taken from: ncbi.nlm.nih.gov
Werner, B.C; Belkin, N.S; Kennelly, S; Weiss, L.; Barnes, R.P; Potter, H.G; Rodeo, SA (2017). Acute Gastrocnemius-Soleus Complex Injuries in National Football League Athletes. Orthopedic journal of sports medicine. Taken from: ncbi.nlm.nih.gov
Bright, J.M; Fields, K.B; Draper, R. (2017). Ultrasound Diagnosis of Calf Injuries. Sports health. Taken from: ncbi.nlm.nih.gov