Plantar muscle

The thin plantar muscle, also called the musculus plantaris, is located in the posterior region of the leg, in a deeper plane with respect to the calf; has variable size and length and can sometimes be missing.

Insert

It originates from the inferior part of the lateral supracondylar crest and from the popliteal surface of the femur, above the lateral gastrocnemius. Its thin membranous tendon descends between the gastrocnemius and soleus to insert on the medial side of the Achilles tendon or on the posterior aspect of the calcaneus. It sometimes spreads diffusely into the fascia on the medial side of the ankle joint and the knee joint capsule.

Innervation

Innervated by the tibial nerve.

Action

Its motor action is very weak, causing plantarflexion of the foot and flexion of the knee.

Prevents compression of the posterior tibial vessels when flexing the knee.