Lower limb

Plantaris

Musculus plantaris

Origin

Lateral supracondylar line of the femur, just above the lateral head of gastrocnemius

Insertion

Calcaneus, via a long thin tendon that runs medial to the Achilles tendon

Function

Weak plantarflexor of the ankle and flexor of the knee; of minor functional importance in humans

Innervation

Tibial nerve (S1-S2)

Movement & chain

Works synergistically with gastrocnemius in plantarflexion of the ankle, but provides only a minor functional contribution to force.

Palpation

The muscle belly is barely palpable; the thin tendon is sometimes weakly palpable medial to the Achilles tendon.

Clinical

The plantaris tendon is often used as a tendon graft, for example in ACL reconstructions. The muscle is absent in approximately 10% of people without functional consequences.

Segmental innervation

S1-S2.

In clinical practice

In acute calf pain after sudden exertion ('tennis leg'), a plantaris rupture should be considered alongside deep vein thrombosis.

Region in the model

Lower limb