Plantaris muscle

Last revised by Dr Henry Knipe on 16 Sep 2022

The plantaris muscle is one of the calf muscles in the superficial posterior compartment of the leg. It is a long, thin and variably developed muscle that runs from the femur to the Achilles tendon.

The plantaris muscle arises from the posterosuperior aspect of the lateral femoral condyle, close to the origin of lateral head of gastrocnemius. There is often an attachment to the oblique popliteal ligament. As the plantaris crosses the posterior knee joint, it runs medially.

In the calf, it lies in between the medial head of the gastrocnemius and soleus.

Distally, the tendon has a variable insertion pattern but most commonly inserts into the calcaneum either medial or anterior to the Achilles tendon 5.

Plantaris can have variable size, but in most cases is difficult to demonstrate on routine MRI studies. 

Plantaris acts weakly to plantar flex the foot and flex the knee. It is considered a vestigial muscle.

In up to 10% of the population, the plantaris is absent; in a smaller number, it may be duplicated 3.

Plantaris tendon can be used as a tendon graft in reconstructive surgery 5.

  • the plantaris tendon is most easily visualized when there is fluid collection in the myofascial junction between gastrocnemius and soleus, commonly secondary to an injury of the medial gastrocnemius head (tennis leg)
  • plantaris friction syndrome

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Cases and figures

  • Figure 1: plantaris muscle
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  • Figure 2: superficial leg muscles
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