- origin: posterosuperior aspect of the lateral femoral condyle and the oblique popliteal ligament
- insertion: medial aspect of the Achilles tendon
- action: plantar flexes foot and flexes knee
- arterial supply: sural arteries
- innervation: tibial nerve
- antagonist: tibialis anterior
- key relationships : between the medial head of the gastrocnemius and soleus
Origin and insertion
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 inserts into the medial aspect of the Achilles tendon.
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, and can be used as a tendon graft in reconstructive orthopedic surgery.
In up to 10% of the population, the plantaris is absent and in a smaller number it may be duplicated .